1984 K-Blazer, 24 Volt electrical questions
Steven Reiter
4wd and a 6.2 Liter diesel engine. It has 2 12 volt batteries under the
hood hooked in series for a 24 volt electrical power supply. It also
has a cinch connector under the dash that has this 24 volt power going
to it. I don't know where else in the vehicle the 24 volts runs.
I suspect the vehicle is actually running the 24 volts for the
communications equipment the military put in it. All non commercial
diesel vehicles I have seen run two batteries in parallel for higher
current, not in series for higher voltage like this one. I am thinking
it makes more sense to return the vehicle to 12 volt operation, but I
have several questions concerning this.
I presume this vehicle was 12 volts to start with. What systems are
actually driven by 24 volts? Can it be converted back to 12 volts? How
hard is this to do? Are there any companies that can help me that
anyone knows of?
All help would be appreciated.
Thanks,
Steve Reiter
Lewisville, TX
cheyenne
heater blower motor, even bulbs. Converting to 12-volt system is a
major undertaking.
Steven Reiter wrote in message <751rvh$e1f$1...@news-2.news.gte.net>...
Rick de Castro
wrote:
Congratulations. I too have a CUCV (Commercial utility cargo vehicle)
Blazer, M1010.
The electrical system is a bit squirrly. One of the two alternators
is NOT grounded to the rest of the vehicle (it has a "floating
ground", and produces the 24 volts needed.
The starter and glowplugs are 24 volts. I would NOT recommend trying
to restore them to 12 volts, the commercial versions chevy makes have
24 volts for these systems, because they need it.
Everything else on the vehicle is 12 volts, including all the lights,
fan, fuel pumps, etc.
You might want to try to get the shop manual for the vehicle (or a
Chevy of appropriate year with the diesel engine). There is also a
web page dedicated to the 6.2 liter diesel chevy's that has lots of
information http://www.62-65-dieselpage.com/
The one thing to watch out for, like on any diesel engine, is keeping
the fuel clean and dry. Learn how to change (and bleed) the fuel
filters, change them and keep spare filters and the wrenches on hand
to change them.
Good luck!
sbest
wrote:
>I have acquired a 1984 ex-US military Chevrolet full size Blazer with
>4wd and a 6.2 Liter diesel engine. It has 2 12 volt batteries under the
>hood hooked in series for a 24 volt electrical power supply. It also
>has a cinch connector under the dash that has this 24 volt power going
>to it. I don't know where else in the vehicle the 24 volts runs.
> I suspect the vehicle is actually running the 24 volts for the
>communications equipment the military put in it. All non commercial
>diesel vehicles I have seen run two batteries in parallel for higher
>current, not in series for higher voltage like this one. I am thinking
>it makes more sense to return the vehicle to 12 volt operation, but I
>have several questions concerning this.
>
>I presume this vehicle was 12 volts to start with. What systems are
>actually driven by 24 volts? Can it be converted back to 12 volts? How
>hard is this to do? Are there any companies that can help me that
>anyone knows of?
>
>All help would be appreciated.
>
>Thanks,
>
>Steve Reiter
>Lewisville, TX
I am used to the Canadian trucks but I suspect they are similar.
They run a 12v altenator to each battery IIRC. The entire vehicle is
24v. Not hard to obtain 24v bulbs but they usually have to be ordered
and of course cost more. Nice to have a headlamp and a few smaller
bulbs on hand incase you need one this week!
The vehicle can be altered to run some circuits on 12v (as you need
to replace compoments like wipermotors heater fans) by taking a fused
center tap from between the two batteries and running it to the fuse
block (fuse removed) with a spade connector to the circuit side. Look
the circuit over to assure there is no other source of 24v able to
access it. 12v accesories can all be run this way as well.
Steve Best, Nova Scotia, sb...@glinx.com
4 wheel drive van page: http://www.glinx.com/users/sbest
Tire chains, camping gear, tools,82 Bronco and some shooting stuff too.
Willem-Jan Markerink
Steven Reiter <spd...@gte.net> wrote:
>I have acquired a 1984 ex-US military Chevrolet full size Blazer with
>4wd and a 6.2 Liter diesel engine. It has 2 12 volt batteries under the
>hood hooked in series for a 24 volt electrical power supply. It also
>has a cinch connector under the dash that has this 24 volt power going
>to it. I don't know where else in the vehicle the 24 volts runs.
> I suspect the vehicle is actually running the 24 volts for the
>communications equipment the military put in it. All non commercial
>diesel vehicles I have seen run two batteries in parallel for higher
>current, not in series for higher voltage like this one.
You obviously have never seen a cold spec Land Cruiser diesel....since
their release in the late 70's, all cold spec models have been 24V,
although current TDi's only start on 24V, and switch back to 12V when
running. But then again, these are claimed to be capable of handling -50C
without plugging in....8-))
>I am thinking
>it makes more sense to return the vehicle to 12 volt operation, but I
>have several questions concerning this.
>
>I presume this vehicle was 12 volts to start with. What systems are
>actually driven by 24 volts? Can it be converted back to 12 volts? How
>hard is this to do? Are there any companies that can help me that
>anyone knows of?
Don't throw this 24V system overboard too soon....check a few 24V articles
on my homepage, especially the winch-related one:
http://www.a1.nl/phomepag/markerink/main_4x4.htm
The Warn 8274 pulls 6 (SIX!) times faster in 24V under full load than its
12V brother....it makes the choice between electric, hydraulic an PTO all
the harder....8-))
If you stay with 24V, you might consider subscribing to the Diesel Toyota
Land Cruiser list, where both generic diesel questions and 24V-specific
ones are also frequently asked & allowed.
(posted & mailed)
--
Bye,
Willem-Jan Markerink
The desire to understand
is sometimes far less intelligent than
the inability to understand
<w.j.ma...@a1.nl>
[note: 'a-one' & 'en-el'!]
Willem-Jan Markerink
>On Sun, 13 Dec 1998 20:06:13 -0600, Steven Reiter <spd...@gte.net>
>wrote:
>
>>I have acquired a 1984 ex-US military Chevrolet full size Blazer with
>>4wd and a 6.2 Liter diesel engine. It has 2 12 volt batteries under the
>>hood hooked in series for a 24 volt electrical power supply. It also
>>has a cinch connector under the dash that has this 24 volt power going
>>to it. I don't know where else in the vehicle the 24 volts runs.
>> I suspect the vehicle is actually running the 24 volts for the
>>communications equipment the military put in it. All non commercial
>>diesel vehicles I have seen run two batteries in parallel for higher
>>it makes more sense to return the vehicle to 12 volt operation, but I
>>have several questions concerning this.
>>
>>I presume this vehicle was 12 volts to start with. What systems are
>>actually driven by 24 volts? Can it be converted back to 12 volts? How
>>hard is this to do? Are there any companies that can help me that
>>anyone knows of?
>>
>>
>>Thanks,
>>
>>Steve Reiter
>>Lewisville, TX
>
>
> I am used to the Canadian trucks but I suspect they are similar.
>They run a 12v altenator to each battery IIRC. The entire vehicle is
>24v. Not hard to obtain 24v bulbs but they usually have to be ordered
>and of course cost more. Nice to have a headlamp and a few smaller
>bulbs on hand incase you need one this week!
>
> The vehicle can be altered to run some circuits on 12v (as you need
>to replace compoments like wipermotors heater fans) by taking a fused
>center tap from between the two batteries and running it to the fuse
>block (fuse removed) with a spade connector to the circuit side. Look
>the circuit over to assure there is no other source of 24v able to
>access it. 12v accesories can all be run this way as well.
Yuck!
By far the best way to kill a battery in a 24V system is hooking up
significant drains to only one battery.
A certain US magazine (I think it was Petersen 4wd/Offroad) once even
recommended hooking up a 12V winch this way....the result is a potentially
*explosive* constellation....one battery will then be severely overcharged,
the other will never get full....even on a small scale this can and *will*
kill a battery over time.
Nissan once had to perform a major recall on 24V Patrols....some dipswitch
decided that a 24V->12V converter wasn't necessary, and hooked the radio
straight to one of the batteries....and in they came, the trashed
batteries, with the dozens....8-))
More about this Capital Sin of electrical sins on my homepage:
http://www.a1.nl/phomepag/markerink/main_4x4.htm
Btw, what the !@#$%^&*( is the purpose of misc.survivalism in this
crosspost?....8-))
Aaron 'dremu' Shephard
: I have acquired a 1984 ex-US military Chevrolet full size Blazer with
: 4wd and a 6.2 Liter diesel engine. It has 2 12 volt batteries under the
: hood hooked in series for a 24 volt electrical power supply. It also
: has a cinch connector under the dash that has this 24 volt power going
: to it. I don't know where else in the vehicle the 24 volts runs.
: I suspect the vehicle is actually running the 24 volts for the
: communications equipment the military put in it. All non commercial
: diesel vehicles I have seen run two batteries in parallel for higher
: current, not in series for higher voltage like this one. I am thinking
: it makes more sense to return the vehicle to 12 volt operation, but I
: have several questions concerning this.
: I presume this vehicle was 12 volts to start with. What systems are
: actually driven by 24 volts? Can it be converted back to 12 volts? How
: hard is this to do? Are there any companies that can help me that
: anyone knows of?
The CUCV's are, as you say, 24V. Standard gas, and I believe diesel, Blazers
are like the other Chevy trucks, 12V.
If you can operate common hand tools and have a familiarity with the systems
under the hood, you could do the conversion yourself. This is not a five
banana job, I don't think.
First, GET THEE A SERVICE MANUAL! The original Chevy one is good, but it's
$60ish. The Chilton's are cheaper for a reason. ;-)
You will need to replace the starter. The ones for gas trucks are cheap; the
diesel one may be different and so cost a bit more.
You *may* also need to change the flywheel, as I don't know if the CUCV's used
a different one that the standard diesel. One would hope not; but if this IS
teh case, this is where a shop would be needed unless you're clueful and have
lots of tools.
If this was a gas engine, you'd need to swap the coil out. Whatever the hell
injection pumps and/or ignition system is there, will need to be swapped for
the 12V flavour rather than yours if they're electric. Mechanical stuff you
should be able to keep.
Anybody familiar with the 6.2/6.5L diesel wanna pop in here maybe...? might be
a good idea to get a donor truck, or find one at a junkyard and rip stuff out
wholesale, rather than part-by-part.
Finally, the lighting is presumably 24V, so you'll need to replace the marker
lights and headlights. I know from experience that the 12V set will cost you
less than $15 (for all of them! I *love* old domestic trucks! <g>)
Anyway, except for the flywheel, and depending on the complexity of the diesel
fuel delivery system, it should be basically a bolt on (off) swap. I don't
think you'd do it in a weekend necessarily, but it sounds like a fun project.
--
d r e m u @ s l o s h . c o m Slosh Textiles & Beef, LLC
-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
daily driver 74 Blazer weekender 93 300ZX hers 92 Saturn SL2
project car 65 Type III Notchback for sale 88 Pulsar NX Sportbak
Dan D.
->4wd and a 6.2 Liter diesel engine. It has 2 12 volt batteries under the
->hood hooked in series for a 24 volt electrical power supply. It also
->has a cinch connector under the dash that has this 24 volt power going
->to it. I don't know where else in the vehicle the 24 volts runs.
You can check if the vehicle uses both 12v and 24v by looking at the two
batteries. The positive terminal of the low side battery (12v above ground)
is jumpered to the negative terminal of the high side battery (24v above
ground). Is there anything else hooked to this jumper? If not,
you have a purely 24v system.
->I presume this vehicle was 12 volts to start with. What systems are
->actually driven by 24 volts? Can it be converted back to 12 volts? How
->hard is this to do? Are there any companies that can help me that
->anyone knows of?
If your electrical system is purely 24 volts, you would have to
replace every electronic or electrical component.
Be aware that the current to run lights will double if you switch
from 24v to 12v. You will have to replace all the wiring and
fuses to accomodate this. This will be a major pain.
Replacing all of your electricals will also be a major pain and
probably expensive. And I mean EVERYTHING: Starter, coil,
wiring, fuses. Are the oil and fuel pump electrical? Gotta
replace those. Then you have the wipers, washer pump, gauges,
heater fan, climate controls...
But there's an easier solution.
Think about what you want to run off of 12 volts. Maybe a stereo?
Perhaps a CB, or GPS, or a cell phone? That's a total of
how many amps? 5 or 10? It's much easier and cheaper to just buy
a 24v to 12v converter for a few things instead of replacing
so many parts. JC Whitney sells converters pretty cheap up to
25 amps or so.
I have a nifty solution I use in my 24 volt truck. (Unimog)
I have an extra 12v battery. I charge it using a 24v to 12v converter
capable of 5 amps. I got the converter for $5. (Let me know if you
want the address) The things I run at 12v are cell phone, CB, ham radio,
12v fan (until I got a 24v one) and rarely exceed 5 amps, but when they
do I'm drawing from the battery. I can run 5 amps constant and "surge"
is whatever the extra battery will handle. 100's of amps? No problem, it's
a 660 CCA battery. I could run a winch off it if I really wanted to.
It would take a while to charge back up at only 5 amps. I could add
another 12v battery in parallel or a converter that will handle more
amps if it ever became a problem. So far, it handles everything
I've ever needed. The battery didn't even cost me anything because it's
an old battery I didn't trade in for the $5 discount. It won't start
a vehicle as easily as it used to, but it will run radios for DAYS.
If I do get a 12v winch, I'll replace it with a new deep-cycle
marine battery.
Keep a few spare 24v bulbs in the truck. You can't always pick
them up at any gas station, but NAPA stocks a complete line
of 24v bulbs and stuff.
Some people will recommend that you center tap the existing
series-connected batteries. This can damage your batteries
because you end up with uneven charge and discharge. I
definitely would not recommend it!
Some people may tell you that you can't jump start a 24v truck
off a 12v truck. You can, with a little work. Hook their 12v
jumper cables to one battery for a couple of minutes, then move
them to the other battery. Wait a couple more minutes, then
remove the jumper cables. The charge should be topped up enough
to start the truck.
Works great.
If you have the extra 12v battery, you can jump YOURSELF by using
the same process. Pretty slick.
-DanD
--
# Dan D (kd4igw) da...@rmii.com da...@frottage.com http://rmii.com/~dand
# The city- if you can call Great Los Angeles a city; it is more of a
# condition... -Heinlein
Dan D.
->Btw, what the !@#$%^&*( is the purpose of misc.survivalism in this
->crosspost?....8-))
A lot of solar homes/battery backup/etc systems use 24v instead of
12v because it's more efficient. It is common to want to use
12v appliances in one of these dwellings instead of 110vac because
it reduces the load on an inverter and still lets you operate in
case the inverter fails.
I would bet the question of getting 12v from a 24v system is
as popular on misc.survivalism (or other battery storage groups
that discuss off-the-grid solar and such) as it is on military vehicle
groups.
FWIW, you can buy a battery equalizer that will connect to both
batteries in a 24v system and draw equally from both batteries
providing an isolated 12v output. They're efficient, but expensive.
Probably worth the money in a solar house where you may not have
the energy to waste to burn off as heat dropping 24v down to 12v
(like a voltage converter does) and/or can't risk damaging batteries.
Probably not worth the expense in a 24v military vehicle where
energy efficiency is probably not a major concern. They get
pretty crappy gas mileage, after all. :)
Just my 2 cents.
-DanD
--
# Dan D (kd4igw) da...@rmii.com da...@frottage.com http://rmii.com/~dand
# I guess we were all guilty, in a way. We all shot him, we all skinned him, and
# we all got a complimentary bumper sticker that said, "I Helped Skin Bob.
sbest
Ahhh, this is the beauty of the GM two altenator setup!
All the charging current does not need to flow through each battery.
Each battery has its own 12v altenator and voltage regulator and can
recharge at its optimum current. Neat huh?
Only one of the altenators is grounded, the other has an isolated 2
wire output. I read the post about all the lights and accessories
being 12v. This may have been true of the Canadian CUCVs as well, I am
not 100% sure. Many of our vehicles are using 24v bulbs and
accessories so what used what I am not sure. A buddy of mine has a
restored Cdn Jeep on my webpage and it is completely 24v, bulbs and
all.
>Btw, what the !@#$%^&*( is the purpose of misc.survivalism in this
>crosspost?....8-))
Ever try to keep an oddball old 4x4 alive?
Misc.survivalism at its finest!
sbest
>Some people will recommend that you center tap the existing
>series-connected batteries. This can damage your batteries
>because you end up with uneven charge and discharge. I
>definitely would not recommend it!
I assure you that the military CUCV is one of the few 24v systems
where you can safely centertap the batteries if it has the dual
altenators. You comments Dan and WJ, are very accurate for any single
altenator 24v system and should have been noted in my original comment
so other 24v operators wouldn't make that mistake.
Rick de Castro mentioned that the US CUCVs are dual alts as well:
>The electrical system is a bit squirrly. One of the two alternators
>is NOT grounded to the rest of the vehicle (it has a "floating
>ground", and produces the 24 volts needed.
Anyone out there willing to back me up on this one? <GRIN>
Incidently, the Cdn CUCV is 1ΕΊ ton cargo rated, heavy frame and
massive axles, I am guessing the US Blazers are the same. Got to see a
lot on US bases but didn't look them over well, was more interested in
the Hummers I guess.
Willem-Jan Markerink
>series-connected batteries. This can damage your batteries
>because you end up with uneven charge and discharge. I
>definitely would not recommend it!
Hear hear!
In case of winches, you even enter explosive territory, since the unbalance
when charging becomes excessive.
>Some people may tell you that you can't jump start a 24v truck
>off a 12v truck. You can, with a little work. Hook their 12v
>jumper cables to one battery for a couple of minutes, then move
>them to the other battery. Wait a couple more minutes, then
>remove the jumper cables. The charge should be topped up enough
>to start the truck.
>
>Works great.
In 9 out of 10 cases, only one of the two batteries is completely flat, and
you only need to jump that one....the other marginal one will pull you
through. Note that one good (100%) and one bad (0%) is NOT enough to
start....the system really needs more than 12V to crank over....
>If you have the extra 12v battery, you can jump YOURSELF by using
>the same process. Pretty slick.
Cute indeed....:-))
Willem-Jan Markerink
Hadn't thought about that, that's pretty foolproof indeed.
BUT: assuming these two alternators are not 'inline', and both requiring a
pulley: I rather would mount an extra AC unit there, as an air
compressor....or an hydraulic pump for the winch....2x alternator seems a
waste of space....;-))
> Only one of the altenators is grounded, the other has an isolated 2
>wire output. I read the post about all the lights and accessories
>being 12v. This may have been true of the Canadian CUCVs as well, I am
>not 100% sure. Many of our vehicles are using 24v bulbs and
>accessories so what used what I am not sure. A buddy of mine has a
>restored Cdn Jeep on my webpage and it is completely 24v, bulbs and
>all.
>
>>Btw, what the !@#$%^&*( is the purpose of misc.survivalism in this
>>crosspost?....8-))
>
>Ever try to keep an oddball old 4x4 alive?
>Misc.survivalism at its finest!
Only with ones own oil well and refinery....otherwise any car-related
question is silly unpractical luxury....;-))
sbest
Markerink) wrote:
>>>Yuck!
>>>By far the best way to kill a battery in a 24V system is hooking up
>>>significant drains to only one battery. <SNIPPED>
>>>More about this Capital Sin of electrical sins on my homepage:
>>>
>>>http://www.a1.nl/phomepag/markerink/main_4x4.htm
>>>
>>
>> Ahhh, this is the beauty of the GM two altenator setup!
>>All the charging current does not need to flow through each battery.
>>Each battery has its own 12v altenator and voltage regulator and can
>>recharge at its optimum current. Neat huh?
>
WJM:
>Hadn't thought about that, that's pretty foolproof indeed.
>BUT: assuming these two alternators are not 'inline', and both requiring a
>pulley: I rather would mount an extra AC unit there, as an air
>compressor....or an hydraulic pump for the winch....2x alternator seems a
>waste of space....;-))
They are not inline, it is a bit of wasted I guess but the very best
way to maintain a charge in dual series batteries. If many of the
accessories are still 12v as Richard DeCastro mentioned it is no
wonder GM picked this method to charge the batteries. Batteries were
never a problem in those trucks that I recall.
I never liked the idea of two batteries to run a vehicle anyway,
whether series or parallel. Even in parallel any diesel owner will
tell you that the batteries have to be replaced in pairs or short life
will result. Better to have one huge battery to run on and use the
other space for an aux deep cycle battery to run gear when the engine
is shut down or winching or whatever IMO.
Rick de Castro
>On Wed, 16 Dec 98 05:35:39 GMT, w.j.ma...@a1.nl (Willem-Jan
>Markerink) wrote:
>
>>>>Yuck!
>>>>By far the best way to kill a battery in a 24V system is hooking up
>>>>significant drains to only one battery. <SNIPPED>
>>>>More about this Capital Sin of electrical sins on my homepage:
>>>>
>>>>http://www.a1.nl/phomepag/markerink/main_4x4.htm
>>>>
>>>
>>> Ahhh, this is the beauty of the GM two altenator setup!
>>>All the charging current does not need to flow through each battery.
>>>Each battery has its own 12v altenator and voltage regulator and can
>>>recharge at its optimum current. Neat huh?
>>
>WJM:
>>Hadn't thought about that, that's pretty foolproof indeed.
>>BUT: assuming these two alternators are not 'inline', and both requiring a
>>pulley: I rather would mount an extra AC unit there, as an air
>>compressor....or an hydraulic pump for the winch....2x alternator seems a
>>waste of space....;-))
>
> They are not inline, it is a bit of wasted I guess but the very best
>way to maintain a charge in dual series batteries. If many of the
>accessories are still 12v as Richard DeCastro mentioned it is no
>wonder GM picked this method to charge the batteries. Batteries were
>never a problem in those trucks that I recall.
>
Actually, the charging system is a royal pain in the ass. I have to
start the thing every couple of days or disconnect the battery cables
to keep it from discharging. The "offical" 6TN military batteries are
pieces of junk, big, heavy, and expensive, so I use civilian batteries
- I think I have Gp 27's in there now, since thats what I have in all
my vehicles.
BTW, for those who think that the military CUCV's are all 24 volt, why
is the trailer wiring connection stenciled 12v? ALL the lights, the
wiper and fan motor, etc are 12 v on these vehicles. The only 24 v
equipment from Chevy was the starter and glow plugs, and in the
ambulance version the AC fan. Everything else is 12vdc, just like it
is on the civilian version diesels, the old cadillac diesel autos,
etc.
I even found all the tech manuals for these vehicles - from the -10
(owners manual) to the -50P (illustrated parts breakdown). They
occasionally come in handy.