Thanks,
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Hell is truth seen too late. -Hobbs
I don't know how much help this will be, but I picked up a
Datashield AT-1500 for $4.95 when a local electronics
supply outfit was cleaning out one of their warehouses.
It is an UPS that runs from an external 48v battery bank.
The one I've got was never used (or sold, I expect) but it
is as solid as a rock and I can't see much that would make
a used one go bad. You might get lucky, with an old 48v
UPS at a low price. Just another option you might not have
considered.
Luck;
Ken
For a variety of reasons, UPSs generally (there may be important exceptions)
don't make good substitutes for inverters.
Vaughn
I'll take your word for it, that there could be issues for such
broad classifications as "UPSs" (which would cover a range
of devices) and what being "good substitutes for inverters"
might involve. (The one I mentioned weighs over 35#, so
it might not be the best choice to power a laptop in your truck.)
[ but with 1500watts to work with ...]
In general, I don't see a lot of difference between an inverter
and an UPS that is unplugged/disconnected from mains power.
The one I mentioned and a number of the older office appliance
commercial grade UPS were designed to use external battery
banks. Admittedly the charging circuits would go un-used, but I
don't see how that would prevent them from functioning as
inverters.
Then there is what "Neon John" actually asked for in his post:
"Neither output waveform quality nor a built-in charger is
important in this application. Just a simple 48 volt in, 120 volt
out inverter will do." The old UPSs can certainly meet that
list of requirements.
Now the UPS will have "a built-in charger", but you don't
have to plug it in. (You might have to disable the alarm circuit,
though. [ I'd wire in a disable/shutoff switch for the alarm, in
case I wanted it when/if I occasionally charged the battery bank
from the mains or a generator.]
Now, I am very curious as to what those "variety of reasons"
might be. If nothing else, they can be things to look out for when
I finally put the one I have to use.
Luck;
Ken
The (smaller) UPSs that I've played with don't turn on the output unless A/C
power is on. Then, when it goes off, they continue to output.
Interesting, I take it you are referring to those with built-in batteries?
It sounds like a simple relay circuit to work around, though.
Luck;
Ken
>
>The (smaller) UPSs that I've played with don't turn on the output unless A/C
>power is on. Then, when it goes off, they continue to output.
>
You're right Bob, which is why I asked very specifically for a particular
thing. Which, of course, didn't keep the bozos who just wanted to talk from
yammering off-thread.
Let me try this again. I'm looking for an inexpensive 24 or 48 volt INVERTER.
NOT a UPS, NOT combo charger/inverter, not anything else but a simple aluminum
box with terminals for 24 or 48 volts on one end and 120vac out the other. One
just like the many 12 volt in, 120vac out commodity boxes except that 24 or 48
volt electronics are substituted.
If you don't know about SIMPLE, CHEAP INVERTERS then please don't post to this
thread. If you want to talk about 24 or 48 volt UPSs then start your own
thread.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
It isn't Global Warming.... It's Jerry Falwell arriving in hell.
Well, you are really something else. The fact that the UPS
I described meets the requirements you stated:
" Neither output waveform quality nor a built-in charger is
important in this application. Just a simple 48 volt in, 120
volt out inverter will do."
means nothing to you? You take it as "yammering off-
thread"? You are offended because the UPS includes an
inverter as a part of its construction?
Is it that the UPS includes a built-in charger? Does that
mean it really was important?, just important that it not be
there? Why?
So you don't want anyone offering any suggestion but
one that matches each exact word of your post, no
alternatives, should be offered or considered. Your
attitude when offered a simple suggestion, is not only way
too arrogant, but insulting (Bozo, indeed). I had thought
better of you, I guess I was mistaken.
Now, I am waiting for the long list of the Make and
Models of all the "SIMPLE, CHEAP INVERTERS" ,
with 24 or 48 volt input, that all your non-Bozo friends
have and continue to supply, to this thread.
For, if you can't be bothered to entertain any alternative
approach, that is all you have to hope for.
Luck;
Ken
>Does anyone know of a source of inexpensive 24 or 48 volt input modified sine
>wave inverters? I'm not interested in the high dollar Outbacks and Xantrexes
>and stuff. I'm looking for a higher input voltage version of the $149 2500
>watt inverter that Harbor Freight sells. Neither output waveform quality nor
>a built-in charger is important in this application. Just a simple 48 volt
>in, 120 volt out inverter will do. Mild googling hasn't found me anything.
Dunno what you mean by "inexpensive" in this context, nor what power
capacity you are looking for.
http://shop.altenergystore.com/
has the Xantrex DR2424 for $907.50 and several "Samlex" 24V inverters, in
the 1000-1999 watt class, for under $500. (I don't know anything at all
about this Samlex brand). I see there is also a Samlex 1500W / 48V
inverter for $590.40
--ron
I guess I could give them a hand:
http://www.voltageconverters.com/inverters_110v.html
http://www.provantage.com/tripp-pv2400fc~7TRPI00X.htm
http://www.power-one.com/telecom-power/telecom-inverters.html
I have used that Samlex brand for microwave power supplies. They are a good
brand. That said, I think they are above the price point that John is looking
for.
John raised an interesting question, and it shows how important the mass
marget is to production costs. All else being equal, It should be cheaper to
make a 48 volt inverter than a 12 volt one, but there is a huge market for 12
volt inverters, and a much smaller one for 48 volt units. As a result, it is
difficult/impossible to find what John is looking for.
Vaughn
In the past, this group has made 24 volt inverters: http://www.youlung.com/pi.htm
They are on Ebay as Power Jack Shopping Center. They have been pretty
good about pricing stuff (for me) that is not currently on auction.
>On Sat, 02 Aug 2008 02:28:37 -0400, Neon John <n...@never.com> wrote:
>
>>Does anyone know of a source of inexpensive 24 or 48 volt input modified sine
>>wave inverters? I'm not interested in the high dollar Outbacks and Xantrexes
>>and stuff. I'm looking for a higher input voltage version of the $149 2500
>>watt inverter that Harbor Freight sells. Neither output waveform quality nor
>>a built-in charger is important in this application. Just a simple 48 volt
>>in, 120 volt out inverter will do. Mild googling hasn't found me anything.
>
>Dunno what you mean by "inexpensive" in this context, nor what power
>capacity you are looking for.
Cheap: sub-$200.
Power: 2kW, plus or minus.
>
>http://shop.altenergystore.com/
>
>has the Xantrex DR2424 for $907.50 and several "Samlex" 24V inverters, in
>the 1000-1999 watt class, for under $500. (I don't know anything at all
>about this Samlex brand). I see there is also a Samlex 1500W / 48V
>inverter for $590.40
That looks interesting, though people have sent me links via email for far
cheaper ones. I'll post my findings in a few days.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Serenity: That feeling of knowing that your secretary will never tell either of your wives.
| The (smaller) UPSs that I've played with don't turn on the output unless A/C
| power is on. Then, when it goes off, they continue to output.
I have heard that many UPSs do have a circuit that checks for correct power
source wiring (e.g. that hot/neutral are not reversed). This could be an
issue for a UPS that can do pass-through (most do). Cheaper test circuits
might only test the wire expected to be hot, and block powering on if that
one wire is not hot (under the theory that something is wrong in the wiring
feeding it power). Alternative, a test might be sending a small current to
the neutral and expecting it to come back over ground (e.g. that neutral is
indeed correctly bonded). An unplugged unit would fail that test.
There could be a complication if a UPS can turn on with no incoming AC power,
and then when the power does come on, or the unit is plugged in, with the AC
power miswired, and that unit can switch in a pass-through mode.
The (larger) UPS (dual conversion continuous online type) that I have can turn
on from a state where it is off and unplugged. I have not yet had the chance
to test it from an off state plugged into a dead power source, either one that
is correctly wired, or one that is reversed.
This is the model I have right now:
http://www.tripplite.com/EN/products/model.cfm?txtModelID=3300
$472.84 @ http://www.provantage.com/tripp-su1500xl~7TRPL1LK.htm
$499.99 @ http://www.newegg.com/Product/Product.aspx?Item=N82E16842111148
--
|WARNING: Due to extreme spam, googlegroups.com is blocked. Due to ignorance |
| by the abuse department, bellsouth.net is blocked. If you post to |
| Usenet from these places, find another Usenet provider ASAP. |
| Phil Howard KA9WGN (email for humans: first name in lower case at ipal.net) |
| Well, you are really something else. The fact that the UPS
| I described meets the requirements you stated:
|
| " Neither output waveform quality nor a built-in charger is
| important in this application. Just a simple 48 volt in, 120
| volt out inverter will do."
|
| means nothing to you? You take it as "yammering off-
| thread"? You are offended because the UPS includes an
| inverter as a part of its construction?
|
| Is it that the UPS includes a built-in charger? Does that
| mean it really was important?, just important that it not be
| there? Why?
Not all UPSes can successfully operate the inverter part independently.
They may require, at minimum, the UPS controller logic. And that logic
may include battery testing that might be at best confused by an external
DC power source. A true inverter expects (is designed for) an external
battery source.
| So you don't want anyone offering any suggestion but
| one that matches each exact word of your post, no
| alternatives, should be offered or considered. Your
| attitude when offered a simple suggestion, is not only way
| too arrogant, but insulting (Bozo, indeed). I had thought
| better of you, I guess I was mistaken.
|
| Now, I am waiting for the long list of the Make and
| Models of all the "SIMPLE, CHEAP INVERTERS" ,
| with 24 or 48 volt input, that all your non-Bozo friends
| have and continue to supply, to this thread.
An inverter is cheaper than the same inverter packaged with a charger,
battery, and controller that have no use for the application in mind.
An inverter designed specifically as an inverter may well operated in a
different way more suited for the variety of external DC sources that
could power it.
The OP was also not concerned with waveform quality. Presumably, something
that outputs a rough square wave (simple full wave chopper circuit, perhaps)
would suit his needs, provided he could operate it from his 48 volt source,
and that it is cheap (no frills, just work converting 48VDC to some kind of
120VAC).
| For, if you can't be bothered to entertain any alternative
| approach, that is all you have to hope for.
I think the OP is smart enough to have already considered a UPS alternative.
While he and I do rustle feathers a lot, I have seen his posts for years and
I know his technical knowledge is extensive.
I'm not knocking your technical knowledge ... I just happen to not know much
about it. But you can be more of a contribution, allowing others to make use
of your technical knowledge (if you so choose), but understanding better what
people ask for, and try better to stay on track. Or find another thread.
I can understand the temptation to divert the topic to an alternative under
various assumptions of his application. For example, one might assume he is
intending to power some 120 volt incandescent lights. And the alternative
suggestion would be to find 48 volt lights (I've seen them). But such an
alternative suggestion is a waste of time if his application really is to
run a 120 volt space heater, or to power a string of Christmas lights that
I've never seen available for 48 volts (even if the bulbs could be found,
the wiring is likely not rated for the higher amperage involved).
I don't know what his application is because he didn't say. But I'm not
going to make assumptions. If he wanted alternative ways to deal with just
that application, he could state what the application is. That's up to him.
Apparently the 12V-input inverters will be cheaper due to economy of scale
for the "cheap" class. People wanting inverters for permanent home power
systems are more likely to go more rugged units that do at least some kind
of sine wave so more things can operate from it.
I've been (not agrresively) hunting for an inverter that can provide a few
times its normal maximum average operating current briefly for motor start
purposes (like A/C, garbage disposal), like 120 amps for 1 second when it
is normally a 20 amp unit. But it seems to get that 120 amps quick surge
you have to go with something that is designed to deliver 100 amps continuous
which makes the cost go way up (presumably 5x as much or more due to lack of
economy of scale). But if most people don't care to run motors on their
inverted power system, or at least only small motors, I guess then I am
stuck with either buying something way over rated for my real needs, or
designing and building it myself.
It's all part of the economy of scale that favors the cheaper devices that
form a part of the spiral to the bottom of quality.
My post wasn't about ALL UPSs, the type I described
were explicitly designed for an external battery source.
(Again, read my posts, not the clipped versions in a reply.)
>
> | So you don't want anyone offering any suggestion but
> | one that matches each exact word of your post, no
> | alternatives, should be offered or considered. Your
> | attitude when offered a simple suggestion, is not only way
> | too arrogant, but insulting (Bozo, indeed). I had thought
> | better of you, I guess I was mistaken.
> |
> | Now, I am waiting for the long list of the Make and
> | Models of all the "SIMPLE, CHEAP INVERTERS" ,
> | with 24 or 48 volt input, that all your non-Bozo friends
> | have and continue to supply, to this thread.
>
> An inverter is cheaper than the same inverter packaged with a charger,
> battery, and controller that have no use for the application in mind.
>
? Cheaper than $4.95? Did you actually read my post? And
what I described have no internal batteries. The only
requirement Neon John mentioned was a 120v output. He
also implied that it should be able to provide 2500watts.
> An inverter designed specifically as an inverter may well operated in a
> different way more suited for the variety of external DC sources that
> could power it.
>
Now that could require some more explanation, or is it
pure speculation? Particularly about these different versions
of 48v DC.
> The OP was also not concerned with waveform quality. Presumably,
> something
> that outputs a rough square wave (simple full wave chopper circuit,
> perhaps)
> would suit his needs, provided he could operate it from his 48 volt
> source,
> and that it is cheap (no frills, just work converting 48VDC to some kind
> of
> 120VAC).
>
Bozo to Non-Bozo:
Did you snip the part of my post that mentions the list you
would be providing of the Make & Models of all these
inverters that answer Neon John's post. (By the way,
you should be aware that you are disobeying your Master's
edict to not post to this thread unless you could provide him
info on such an inverter.)
>
> | For, if you can't be bothered to entertain any alternative
> | approach, that is all you have to hope for.
>
> I think the OP is smart enough to have already considered a UPS
> alternative.
> While he and I do rustle feathers a lot, I have seen his posts for years
> and
> I know his technical knowledge is extensive.
>
His technical knowledge was never in question, in fact I
have often supported the position he has taken in various
debates. That doesn't mean that he can't be a rude jerk
and act foolishly on this occasion.
> I'm not knocking your technical knowledge ... I just happen to not know
> much
> about it. But you can be more of a contribution, allowing others to make
> use
> of your technical knowledge (if you so choose), but understanding better
> what
> people ask for, and try better to stay on track. Or find another thread.
>
My post was certainly on track, and provided a viable option
that would meet the stated requirement. I will post to threads
that could use my input, even if the responders appear to be
a bunch of self absorbed ingrates.
> I can understand the temptation to divert the topic to an alternative
> under
> various assumptions of his application. For example, one might assume he
> is
> intending to power some 120 volt incandescent lights. And the alternative
> suggestion would be to find 48 volt lights (I've seen them). But such an
> alternative suggestion is a waste of time if his application really is to
> run a 120 volt space heater, or to power a string of Christmas lights that
> I've never seen available for 48 volts (even if the bulbs could be found,
> the wiring is likely not rated for the higher amperage involved).
>
> I don't know what his application is because he didn't say. But I'm not
> going to make assumptions. If he wanted alternative ways to deal with
> just
> that application, he could state what the application is. That's up to
> him.
>
MY only assumption was that he wanted a cheap way to
convert a 48v DC source into 120v AC @ 60cps. I wasn't
aware that it had to have inverter in it's name, or the revered
Neon John would be calling me a Bozo and consider my
suggestion "off topic".
Luck;
Ken
Your imaginations might explain why this might happen
using one of the newer UPS, but is most unlikely for the older
48v UPSs I was describing.
> There could be a complication if a UPS can turn on with no incoming AC
> power,
> and then when the power does come on, or the unit is plugged in, with the
> AC
> power miswired, and that unit can switch in a pass-through mode.
>
?? "with the AC power miswired" ?? Talk about a stretch!
> The (larger) UPS (dual conversion continuous online type) that I have can
> turn
> on from a state where it is off and unplugged. I have not yet had the
> chance
> to test it from an off state plugged into a dead power source, either one
> that
> is correctly wired, or one that is reversed.
>
> This is the model I have right now:
>
> http://www.tripplite.com/EN/products/model.cfm?txtModelID=3300
>
> $472.84 @ http://www.provantage.com/tripp-su1500xl~7TRPL1LK.htm
> $499.99 @ http://www.newegg.com/Product/Product.aspx?Item=N82E16842111148
>
> --
These appear to be current models, with many computer
control features. The older ones I described were much
simpler devices made to provide backup emergency power
to whatever equipment may be plugged into them, not just
computers, (in fact, most business computers in those days
were massive things with their own power arrangements).
There were plenty of smaller data handling devices that
benefited from such protection, though.
While it appears that your only links are to UPSs, that
appear to function a little like the old ones; in that at least
one (yours) can run unplugged, I still see no links that match
your master's edict.
Luck;
Ken
Do you know where this samlex stuff is made? They try hard to obscure who
they really are on the website.
I'm not sure about xantrex inverters, but their support is good on lab
power supplies, even the rebadged ones made in the UK and sold in the US.
| Now that could require some more explanation, or is it
| pure speculation? Particularly about these different versions
| of 48v DC.
It's from engineering notes on some UPSes. They do things like adjust
the inverter based on specific batteries included. They are not designed
for other kinds of batteries or like voltage sources. An inverter that
is designed for general use specifies the voltage, not particular types
of batteries.
|> The OP was also not concerned with waveform quality. Presumably,
|> something
|> that outputs a rough square wave (simple full wave chopper circuit,
|> perhaps)
|> would suit his needs, provided he could operate it from his 48 volt
|> source,
|> and that it is cheap (no frills, just work converting 48VDC to some kind
|> of
|> 120VAC).
|>
|
|
| Bozo to Non-Bozo:
|
| Did you snip the part of my post that mentions the list you
| would be providing of the Make & Models of all these
| inverters that answer Neon John's post. (By the way,
| you should be aware that you are disobeying your Master's
| edict to not post to this thread unless you could provide him
| info on such an inverter.)
Each post can extend the range of topic, once posted. If my post
were a direct reply to John, I'd be replying to what he asked.
FYI, I generally do try to snip down posts to show the _part_ I want to refer
to in my response. I try to avoid just including the whole thing. If someone
wants to read his whole post, they can read HIS whole post.
| His technical knowledge was never in question, in fact I
| have often supported the position he has taken in various
| debates. That doesn't mean that he can't be a rude jerk
| and act foolishly on this occasion.
I don't think he did in this case. Maybe he's a bit rough.
Hopefully so. The info I described came from a support engineer at a
major USA UPS manufacturer. Chinese knockoffs might not have any such
test circuits.
|> There could be a complication if a UPS can turn on with no incoming AC
|> power,
|> and then when the power does come on, or the unit is plugged in, with the
|> AC
|> power miswired, and that unit can switch in a pass-through mode.
|>
|
| ?? "with the AC power miswired" ?? Talk about a stretch!
The complication is an issue of engineering design. They have to take
it into consideration to the extent of making sure at worst it will
gracefully shutdown in miswired cases, while making sure their output
is always safe if the unit stays on. I stated this to explain why a
UPS might shutdown, and thus why it might have some strange circuits
in it that could even be an issue when it's not plugged into AC at all.
I am recently retired, so I don't have access to that equipment to look for
an origin tag. Like everything else, it is likely made in Asia somewhere. I
agree about their website, they and their products have always seemed a bit
mysterious. If it means anything, they do show up at trade shows. So I have
actually seen actual human beings from Samlex.
Vaughn
> So I have actually seen actual human beings from Samlex.
>Vaughn
... they fooled you, too, then .. ? :-)
jt
Any time you post anything anywhere on the internet you take the risk that
someone might respond in an unpleasant manner. Sometimes the responses I
read can only be attributed to drug use. Other times they may actually make
a point. I have been called worse than "Bozo" but the bottom line to me is
that I find the information that I need and accomplish whatever it is I'm
trying to do. I just plain don't care if someone calls me names in the
process. I do, however, usually defend myself but generally limit this to
one or two lines. In your case I probably would have suggested something
like he simply use AC batteries and a transformer and then he could just use
a 12 volt inverter.
I'm a retired Platoon Sergeant, so "Bozo" is hardly a shock to
my system. I was somewhat surprised at Neon John's petulant
response to my original reply, though. I took some effort to
provide it as an alternative suggestion, (read my original post
to this thread, my post, not a clipped version). I have yet to see
how it was OT, and given the lack of listings of 48v DV to 120v
AC devices, an alternative Neon John (or others) might find
worth looking into.
I'm not sure I understand what you mean by "AC batteries",
though? There are a couple of approaches to DC-to-DC
conversion if that is what you are getting at, and could be
another viable alternative, but Neon John would have to
look on that as OT. You are risking being placed in the
Bozo camp, with me.
Luck;
Ken
Are you looking for something for the car? I like my 400 watt Husky
inverter found at Home Depot for approx. $45.
In my mind it was on-topic. In his mind it was off-topic. If it had been
suggested to me I would have appreciated it as something I may not have
considered. He had apparently already considered it at least to the point
of not considering it and had already dismissed it before you suggested it.
I think.
>
> I'm not sure I understand what you mean by "AC batteries",
> though? There are a couple of approaches to DC-to-DC
> conversion if that is what you are getting at, and could be
> another viable alternative, but Neon John would have to
> look on that as OT. You are risking being placed in the
> Bozo camp, with me.
>
Well, that would have been meant as a testy response since AC batteries
don't exist. I would not, however, suggest such a thing to someone who
appears to be a novice and therefore might spend days or weeks searching for
such a thing. Kinda like a left-handed monkey wrench. I'm just not that
mean.
> Luck;
> Ken
>
>
That runs from 24 or 48 volts DC input?
>> I'm a retired Platoon Sergeant, so "Bozo" is hardly a shock to
>> my system. I was somewhat surprised at Neon John's petulant
>> response to my original reply, though. I took some effort to
>> provide it as an alternative suggestion, (read my original post
>> to this thread, my post, not a clipped version). I have yet to see
>> how it was OT, and given the lack of listings of 48v DV to 120v
>> AC devices, an alternative Neon John (or others) might find
>> worth looking into.
>
>In my mind it was on-topic. In his mind it was off-topic. If it had been
>suggested to me I would have appreciated it as something I may not have
>considered. He had apparently already considered it at least to the point
>of not considering it and had already dismissed it before you suggested it.
>I think.
I didn't see Maltby's whole comment, as he's filtered. Just the part that got
quoted. I can't remember why he's filtered but probably an off-topic
political comment at some point. Zero tolerance for that. It's a soft filter
that will expire in awhile. Anyway.
The reason that I sniped at a few people is that I get extremely frustrated
trying to keep the focus of my occasional question on the question. Like
herding cats! When I come to the net and ask a question, I've already googled
and looked in my dead tree library and looked in my fairly large archive of
saved documents and websites. I know exactly what I'm looking for or the
problem I'm trying to solve.
In this case, if I were interested in UPSs or rotary converters or
motor-generators or anything else except inverters, I'd have asked a general
question about where I could find devices to turn 24 or 48 volts into 120
volts. I wasn't. I was looking for a specific thing, a conventional cheap
inverter that would accept a higher than normal 12 volt input.
Problem is, the net is filled with people who just want to say something.
"Hey, look at me, I exist." Then there are those who hijack threads, usually
with inane political crap. Both phenomena have occurred in this thread. Makes
me almost want a moderated group. These phenomena are why Usenet is slowly
dying at the hands of ham-fisted, heavily moderated fora. I *hate* the forum
format so I say this with the utmost regret.
Fortunately, between people in this group who replied via email and people who
replied to the same query on an electric vehicle mailing list, I found exactly
what I wanted, and from more than one source. At the price that I wanted too.
In a separate thread (this one has become hopelessly content-free), I'll post
my results.
>
>>
>> I'm not sure I understand what you mean by "AC batteries",
>> though? There are a couple of approaches to DC-to-DC
>> conversion if that is what you are getting at, and could be
>> another viable alternative, but Neon John would have to
>> look on that as OT. You are risking being placed in the
>> Bozo camp, with me.
>>
>
>Well, that would have been meant as a testy response since AC batteries
>don't exist. I would not, however, suggest such a thing to someone who
>appears to be a novice and therefore might spend days or weeks searching for
>such a thing. Kinda like a left-handed monkey wrench. I'm just not that
>mean.
If he's referring to part of my post, I probably used "AC" to mean air
conditioning instead of alternating current. I'm working on a battery powered
AC unit for my motorhome. An inverter driving a conventional single-phase
capacitor start compressor is one of about 9 different approaches that I've
identified and am evaluating. My goal is to be able to get through a night of
air conditioning without having to run the generator. This has already been
done for semis and boats but the systems are expensive. I'm going to do it
for RVs and do it cheaply.
An inverter driving a 60hz compressor motor may turn out to be too inefficient
but at least now I have that option to evaluate. One of the variations that
I'll be evaluating is to use two inverters, phase-locked 90 degrees apart, to
directly drive the two windings of a capacitor-run compressor. According to
my still-fairly-crude SPICE model will be significantly more efficient than
one inverter. So will running a smaller compressor at more than 60 hz.
I could simply design a purpose-built inverter for the project. No big deal. I
started designing solid state motor drives back in 1980. But I'm trying to
build this system from off-the-shelf parts, perhaps slightly modified, so that
others will be able to duplicate the project. I wonder how many people in
this group would LOVE to have an efficient 1 to 1.5 ton AC that operated
directly from 24 or 48 volts DC? Especially if the core of the system is a
cheap ChiCom window unit, disassembled for its useful parts.
John
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
I didn't claw my way to the top of the food chain to eat vegetables!
If you wish to filter my posts, please go ahead. While you
appear to be saying that NG threads are some sort of a
restricted forum that function to answer just the OP's interest/
query; I believe that the subjects raised and issues discussed
are there for the benefit of all who follow their interest in the
subject being discussed. This may shock you, but it is
possible that others might benefit from a reply that you don't
find useful. Another shock; if someone wants to reply in the
exact manner that you seem to be looking for - they can.
Nothing anyone else, (even me) might post or do, can stop
them, from posting a reply that conforms to your edicts, if
they want to.
> The reason that I sniped at a few people is that I get extremely
> frustrated
> trying to keep the focus of my occasional question on the question. Like
> herding cats! When I come to the net and ask a question, I've already
> googled
> and looked in my dead tree library and looked in my fairly large archive
> of
> saved documents and websites. I know exactly what I'm looking for or the
> problem I'm trying to solve.
>
Well you may keep your cats penned at home, on the
usenet all the cats run free. If they have something that
they feel aids the discussion, an idea, a question, or even
a gripe/complaint, they are purrfectly able to jump in.
Well... such preparation is commendable, but somewhat
uncommon. Most posters who adopt this attitude won't do
the simplest search before, arrogantly demanding that only
their approach to a problem be considered. Many of them
seem to approach a NG as if it were the paid support
function of whatever tech. has disturbed their lives.
> In this case, if I were interested in UPSs or rotary converters or
> motor-generators or anything else except inverters, I'd have asked a
> general
> question about where I could find devices to turn 24 or 48 volts into 120
> volts. I wasn't. I was looking for a specific thing, a conventional
> cheap
> inverter that would accept a higher than normal 12 volt input.
>
And you got so many replies that you would say matched
your request! There is obviously no reason to consider
alternatives, right?
> Problem is, the net is filled with people who just want to say something.
> "Hey, look at me, I exist." Then there are those who hijack threads,
> usually
> with inane political crap. Both phenomena have occurred in this thread.
They have??? Where? My ISP must be short changing me.
If any hijacking occurred it was occasioned by your OT name
calling and expounding on your philosophy of how the Net is
operating, and the motivations of the posters.
Again, if there were any who had wished to reply in a
manner you would have found more appropriate, nothing
was stopping them. I doubt their minds were so captivated
by the fact that UPSs include an inverter function, that they
neglected to supply you the answer you wanted.
> Makes
> me almost want a moderated group. These phenomena are why Usenet is
> slowly
> dying at the hands of ham-fisted, heavily moderated fora. I *hate* the
> forum
> format so I say this with the utmost regret.
>
> Fortunately, between people in this group who replied via email and people
> who
> replied to the same query on an electric vehicle mailing list, I found
> exactly
> what I wanted, and from more than one source. At the price that I wanted
> too.
> In a separate thread (this one has become hopelessly content-free), I'll
> post
> my results.
>
This is another example of how your approach differs from
mine. To me, having off thread discussions on the subject,
is a disservice to this NG. At least an "on topic" summary
should have been posted to this thread. The ideas presented
in your off thread discussions, might have been of real value
to others, reading this thread. I also would feel an obligation
to provide any "results", to this very thread, (especially, if I
had started it).
[ By the way, the off thread discussion about, what an ass
I am, could be left out of the summary, but that would be
your call.]
Now that you have described your project in more detail, I can
get even more "OT", from your point of view.
Have you considered this ( I know you hate Wiki, but too bad
it provides a quick and dirty starting point):
http://en.wikipedia.org/wiki/Inverter_(air_conditioning)
If you could find a cheap air conditioner that is using this
approach, you might be able to eliminate the rectifier and
provide a PWM control circuit to feed the air conditioner's
special built-in inverter, from your 48v DC source. It might
require a solid state DC-DC converter as well. Again, this
is another idea that you could consider.
While Neon John might consider it a hijack attempt, I
at least, would like to consider any thoughts others might
have on the idea.
Luck;
Ken
What I don't like about forums is that they are so limited and Usenet is
worldwide.
>
> An inverter driving a 60hz compressor motor may turn out to be too
inefficient
> but at least now I have that option to evaluate. One of the variations
that
> I'll be evaluating is to use two inverters, phase-locked 90 degrees apart,
to
> directly drive the two windings of a capacitor-run compressor. According
to
> my still-fairly-crude SPICE model will be significantly more efficient
than
> one inverter. So will running a smaller compressor at more than 60 hz.
I assume you will be using two inveters that are already designed to be
connected in series?
>
> I could simply design a purpose-built inverter for the project. No big
deal. I
> started designing solid state motor drives back in 1980. But I'm trying to
> build this system from off-the-shelf parts, perhaps slightly modified, so
that
> others will be able to duplicate the project. I wonder how many people in
> this group would LOVE to have an efficient 1 to 1.5 ton AC that operated
> directly from 24 or 48 volts DC? Especially if the core of the system is
a
> cheap ChiCom window unit, disassembled for its useful parts.
Before I die I hope to find a cheap way to run AC so I'll be very interested
in your results. Meanwhile it's a good thing that evaporative cooling works
where I live.
BTW: this really is OT but I recently discovered that a problem with my
eu2000 abdomination of a couple of years ago probably was not a problem with
using the servo-controlled carburator. I was having problems with
inconsistant engine speed at low RPMs. It turns out there is something
wrong with the GC135 engine I was using. It keeps losing and recovering
power which causes it to slow down and speed up. So far I have not figured
out why. I have adjusted the valves, thoroughly checked the fuel system,
checked for spark failure, put in a new spark plug, eliminated the
possibility of the spark system grounding out, and anything else I can think
of. Maybe it has a bad governor gear but the problem still exists if I hold
the throttle in place. I can't just pull the head and check for carbon
deposits because it's one of those slant engines. I have a pile of "other"
ignition modules but none of them will fit on the CG135 even using only one
screw. It'll cost be about $45 to find out if it's the ignition. In any
case it looks more promising now to attach the PMA and Eco Throttle carb to
another engine. The really weird part of the whole thing was that when the
muffler fell off (the screw holes keep stripping and I have to re-tap them
bigger) the thing was putting out more power than ever--for a couple of
minutes. I tried a muffler for an 8 HP engine and it soon went back to
losing power.
Inverter (air conditioning)
From Wikipedia, the free encyclopedia
Jump to: navigation, search
The inverter tag found on some air conditioners signifies the ability of the
unit to continuously regulate its thermal power flow.
Traditional reverse-cycle air-conditioners use a heat pump that is either
working at maximum capability or switched off, as the compressor's speed
cannot be varied. In order to regulate temperature a thermistor is used to
measure the ambient air temperature and switch the compressor on when the
ambient air temperature is too far from the desired temperature
Air-conditioners bearing the inverter tag use a variable-frequency drive to
control the speed of the motor and thus the compressor. The
variable-frequency drive uses a rectifier to convert the incoming AC current
to DC and then uses pulse-width modulation of the DC current within an
inverter to produce AC current of a desired frequency. The AC current is
used to drive a brushless motor or an induction motor. As the speed of a
brushless motor is synchronised to the frequency of the AC current, it is
thus possible to build a compressor that can be run at different speeds.
Similarly, the voltage and frequency can be varied as needed to efficiently
run an induction motor at different speeds. A microcontroller can then
sample the current ambient air temperature and adjust the speed of the
compressor appropriately.
Eliminating stop-start cycles increases efficiency, extends the life of
components, and helps eliminate sharp fluctuations in the load the
air-conditioner places on the power supply.
The inverter principle has been applied to a wide range of household
appliances including microwave ovens, washing machines, and so on.
Retrieved from
"http://en.wikipedia.org/wiki/Inverter_%28air_conditioning%29"
Chances are you already know about it, but this
http://www.perr.com/forum/viewforum.php?f=2 is my favorite small engine forum.
--
Vaughn
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Nothing personal, but if you are posting through Google Groups I may not receive
your message. Google refuses to control the flood of spam messages originating
in their system, so on any given day I may or may not have Google blocked. Try
a real NNTP server & news reader program and you will never go back. All you
need is access to an NNTP server (AKA "news server") and a news reader program.
You probably already have a news reader program in your computer (Hint: Outlook
Express). Assuming that your Usenet needs are modest, use
http://news.aioe.org/ for free and/or http://www.teranews.com/ for a one-time
$3.95 setup fee.
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
Will poofread for food.
This is a technology that sort of snuck up on me over the last two or three
years. All of the really high efficiency central air conditioners lately seem
to use the VFD principle.
Just this week, I was shopping for a new mini-split for my bedroom. The
conventional units were SEER 13, but the similar inverter units were SEER 19.
That is a big difference! I do worry about the extra electronics though. I
live in a high-lightning area.
----------------------------------------------------
Getting back to John's project, vehicle DC-operated AC units are "out there"
in at least two applications that I can think of, but not anywhere where you are
likely to find one cheap. The first place that I ever noticed them is in light
aircraft. Expensive! Now, I understand the Prius has a DC AC unit. I imagine
that your average Prius is still several years from the junkyard, so I will be
interested to see the results of John's tinkering.
Here in FL, PV and a DC-operated AC unit could be a match made in heaven.
The output from the PV would closely track your need for AC on a hot day; so the
more the sun shines, the more power would be available to rev up your AC unit.
While it may be unlikely that you could get lucky at your local
"Pick&Pull", an examination of how the Prius functions, if it is
a DC "AC" as you describe, could be worth looking into, and not
only for Neon John's project.
> Here in FL, PV and a DC-operated AC unit could be a match made in
> heaven. The output from the PV would closely track your need for AC on a
> hot day; so the more the sun shines, the more power would be available to
> rev up your AC unit.
>
> Vaughn
>
I would think many in humid places like Florida could benefit
from having an air conditioner that would run continuously while
the sun shines. It could both cool, and more importantly, dry the
air. If it ran off dedicated PV panels, it could have a significant
impact on the monthly electric bill, even if it only provided a part
of the total cooling load. If it were a modified "inverter" air
conditioner, and would be working harder as more solar power
is available, it might be even more effective.
OT- You know I think I may have figured out what got me on
Neon John's Filtered list. It could have been my; "Why don't
we "Matrix" the cows, for power?" thread from awhile back.
Luck;
Ken
| If you wish to filter my posts, please go ahead. While you
| appear to be saying that NG threads are some sort of a
| restricted forum that function to answer just the OP's interest/
| query; I believe that the subjects raised and issues discussed
| are there for the benefit of all who follow their interest in the
| subject being discussed. This may shock you, but it is
| possible that others might benefit from a reply that you don't
| find useful. Another shock; if someone wants to reply in the
| exact manner that you seem to be looking for - they can.
| Nothing anyone else, (even me) might post or do, can stop
| them, from posting a reply that conforms to your edicts, if
| they want to.
When someone talks about something related to the previous post, it can
extend the subject. That extended subject is now a wider scope of
acceptable responses, and the OP's question might not be the target of
the response.
Still, there are frequently many people that respond with the OP's
question as the intended target, but don't actually answer that question.
They often do the effect of making up the question they wish the OP
had asked, and answer that one.
| Well you may keep your cats penned at home, on the
| usenet all the cats run free. If they have something that
| they feel aids the discussion, an idea, a question, or even
| a gripe/complaint, they are purrfectly able to jump in.
Staying on topic, considering it can expand, is the civil behaviour.
Got a different topic? Start a new thread with a new subject.
People do get filtered or blocked when they don't follow that or
other civil behaviours.
| Well... such preparation is commendable, but somewhat
| uncommon. Most posters who adopt this attitude won't do
| the simplest search before, arrogantly demanding that only
| their approach to a problem be considered. Many of them
| seem to approach a NG as if it were the paid support
| function of whatever tech. has disturbed their lives.
That doesn't mean we have to patronize them. OTOH, some people really
to the initial leg work then someone accuses them of not doing it.
How did they (think that they) knew the OP didn't?
|> In this case, if I were interested in UPSs or rotary converters or
|> motor-generators or anything else except inverters, I'd have asked a
|> general
|> question about where I could find devices to turn 24 or 48 volts into 120
|> volts. I wasn't. I was looking for a specific thing, a conventional
|> cheap
|> inverter that would accept a higher than normal 12 volt input.
|>
|
| And you got so many replies that you would say matched
| your request! There is obviously no reason to consider
| alternatives, right?
Since the OP in this thread asked for an inverter, I never considered a
UPS as a solution. From my experience, components inside a UPS are not
always suitable to operate independently, at least not in a "UL listed"
safe way. While I know that parts from a UPS can be used to this, I do
know the OP knows this, and I am confident enough he knows this to not
be concerned with raising it.
> This is a technology that sort of snuck up on me over the last two or
> three
> years. All of the really high efficiency central air conditioners lately
> seem
> to use the VFD principle.
>
> Just this week, I was shopping for a new mini-split for my bedroom. The
> conventional units were SEER 13, but the similar inverter units were SEER 19.
> That is a big difference! I do worry about the extra electronics though. I
> live in a high-lightning area.
Vaughn, just make sure that you have a GOOD Set of Varisters, or Zots
across the Power Lines to Ground and a good, solid, Low Impedance
Central Ground for your House, and you will be fine. Most VFD's these
days are Industrial quality.
--
Bruce in alaska
add <path> after <fast> to reply
Thanks. I didn't know about it cause I don't like forums very much ;-)
I guess I didn't put that very well about forums not being world-wide. They
are just a lot harder to find than Usenet and then you need a bunch of
passwords and such and only a few people are likely to actually read your
posts etc.
This is grasping at straws, and if you can find any that are cheap, please
share-
for 48 to 120, there are telecom inverters. Lucent and Major Power make
them, and they're very expensive but available in that power range.
It's possible there are used ones out there for pennies on the dollar,
like with ferroresonant power conditioners.
And they expensive because?
1. 48 volts is harder to deal with than 12 volts.
2. There's very little consumer market for 48 volt stuff.
3. Telcom needs special features in their inverters.
4. It's easy to overprice stuff being sold to big corporations.
Vote now.
>| for 48 to 120, there are telecom inverters. Lucent and Major Power make
>| them, and they're very expensive but available in that power range.
>
>And they expensive because?
>
>1. 48 volts is harder to deal with than 12 volts.
Actually 48 volts is EASIER to deal with at a given wattage than 12 volts. For
power FETS, what almost every inverter uses, the conduction losses are
proportional to I^2R. A 48 volt inverter draws but a quarter the current of a
12 volt inverter of the same size. All else being equal, that equals 1/4 the
number of FETs and 1/16th the thermal losses. It's rare to find a power FET
with a voltage rating lower than 60 volts anymore so the same device will
probably be used at both 12, 24 and 48 volts. The lower voltage simply
requires more of 'em.
The economy of scale of 12 volt inverter manufacturer is more than offset by
the reduction in power devices and the reduced heat that has to be disposed
of. That's why, with the help of some folks who actually know what they're
talking about, I've been able to find high voltage inverters in the same price
range as 12 volt one.
JOhn
--
John De Armond
See my website for my current email address
http://www.neon-john.com
http://www.johndearmond.com <-- best little blog on the net!
Tellico Plains, Occupied TN
Remember, amateurs made the Ark, professionals made the Titanic.
Perhaps, you could provide these sources, if not as a consideration
to those who may have been following this thread, then to increase
the sales of these products. Even if you feel none who posted here
are among the "folks who actually know what they're talking about"
there could be a lurker, who has a clue. Besides you stated earlier:
"I could simply design a purpose-built inverter for the project. But I'm
trying to build this system from off-the-shelf parts, perhaps slightly
modified, so that others will be able to duplicate the project."
I actually think there are a few of us here who would be interested in
48v "SIMPLE, CHEAP INVERTERS", it is the subject of the thread,
no one will claim you are going OT. Is there some reason you are
keeping the sources secret? A special deal? (That would be OT
by your definition.)
Luck;
Ken
huh?
> 2. There's very little consumer market for 48 volt stuff.
so?
> 3. Telcom needs special features in their inverters.
actually they don't.
> 4. It's easy to overprice stuff being sold to big corporations.
wrong
You still can't figure it out?
I take that as a vote for #2, #3, or #4.
| The economy of scale of 12 volt inverter manufacturer is more than offset by
| the reduction in power devices and the reduced heat that has to be disposed
| of. That's why, with the help of some folks who actually know what they're
| talking about, I've been able to find high voltage inverters in the same price
| range as 12 volt one.
That's great news. Viva la 48 volts!
Where's your vote? This was a poll/vote. You're supposed to vote. Of course
there are trick answers in there.