Car battery - Electric blanket
Count Blatchala
I plan on driving to my hometown which will require an overnight stop
and would prefer to sleep in my car to save money for hotel/motel. I
have a 200W inverter for my car and plan would like to plug in an
electric blanket, fold down the seats, and sleep like that.
The electric blanket is rated at 4-5 amps. Will I be able to keep the
blanket turned on all night without draining the battery? I'm sure
there's some sort of equation to answer this but can't seem to be able
to recall this.
Has anyone else tried this? Or can anyone advise the drain on my
battery or if this is practical?
Thanks in advance,
Jim
David Hopper
Power = volts x amps, so your blanket would require 480 to 600 watts
from the inverter, which is too much for your inverter.
Unless you had an extremely strong battery, I would not risk it even
with the proper inverter.
I personally use a sleeping bag in the car and just bundle up well.
Sleeps good.
YMMV
--
David
Tom Biasi
"Count Blatchala" <cblat...@gmail.com> wrote in message
news:da45e6eb-f521-417d...@b7g2000yqd.googlegroups.com...
Your battery will be dead when you wake up.
The blanket will not draw the rated current all the time; it will cycle on
and off.
How much it cycles will depend on the temperature and/or the design of the
blanket.
Worst case is what David has laid out.
In that case and even with more conservative numbers I predict my first
sentence.
GregS
For 500 watts thats 45 amps. 50/50 4 hours max till dead, and it will certainly not start the car.
A 200 watt inverter is less than 2 amps output.
greg
Stormin Mormon
drain on the battery. Can you find a friend along
the way, to visit and camp on their floor? I
agree, a motel is an extra expesnse.
--
Christopher A. Young
Learn more about Jesus
www.lds.org
.
"Count Blatchala" <cblat...@gmail.com> wrote in
message
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Robert Bonomi
Count Blatchala <cblat...@gmail.com> wrote:
>Hello group,
>
>I plan on driving to my hometown which will require an overnight stop
>and would prefer to sleep in my car to save money for hotel/motel. I
>have a 200W inverter for my car and plan would like to plug in an
>electric blanket, fold down the seats, and sleep like that.
>
>The electric blanket is rated at 4-5 amps. Will I be able to keep the
>blanket turned on all night without draining the battery? I'm sure
>there's some sort of equation to answer this but can't seem to be able
>to recall this.
5 amps is *SIX* hundred watts. That's 3 times what your inverter can
provide. (note: the standard cigarette lighter is rated for a max of
100 watts.)
You've got all sorts of problems right there.
>Has anyone else tried this? Or can anyone advise the drain on my
>battery or if this is practical?
the magic incantation is 'watt hours'. or volts times 'amp-hours'.
The electric blanket, drawing 4 amps at 120 volts, is roughly 500 watts.
If it is 'on' 50% of the time (hopelessly optimistic in the environment
you're proposing), thats 250 watt-hours per hour.
Your car battery is rated at somewhere in the range of 50-100 amp-hours
at _twelve_ volts. That's 600-1200 watt-hours. So, _if_ the battery
is fully charged, and you run it stone dead (ignoring how you'll start
the car to drive it), *and* the blanket runs _only_ 50% (figure 70-80%
or more, to be realistic) of the time =AND= your inverter is 100% efficient
(realistically more like 80%, so decrease the time by 20%), you'll kill
the battery in less than 5 hours, _best_ case. More likely around 2.
>
>Thanks in advance,
>
>Jim
y_p_w
> Your car battery is rated at somewhere in the range of 50-100 amp-hours
> at _twelve_ volts. That's 600-1200 watt-hours. So, _if_ the battery
> is fully charged, and you run it stone dead (ignoring how you'll start
> the car to drive it), *and* the blanket runs _only_ 50% (figure 70-80%
> or more, to be realistic) of the time =AND= your inverter is 100% efficient
> (realistically more like 80%, so decrease the time by 20%), you'll kill
> the battery in less than 5 hours, _best_ case. More likely around 2.
Not to mention normal loss of capacity as a battery ages with use.
Seriously - a practical alternative would simply be to bundle up with
a heavy sleeping bag, or maybe two. There are also some 12 volt
specific electric blankets out there. It might be a bit more
efficient than one that operates on AC. I've heard of some who can
get maybe 12 hours out of one on a reasonable size portable battery
jump starter used as a 12V power source. I'd definitely say don't use
your car battery directly. Something like this might work:
http://www.sportsmansguide.com/net/cb/12-volt-heated-travel-blanket-with-safety-timer.aspx?a=492806
Tom Biasi
"y_p_w" <y_...@hotmail.com> wrote in message
news:cfaa4647-2f35-4af0...@y7g2000prc.googlegroups.com...
http://www.sportsmansguide.com/net/cb/12-volt-heated-travel-blanket-with-safety-timer.aspx?a=492806
Make the same calculations that everyone is suggesting using the 4 Amps
specified.
y_p_w
> "y_p_w" <y_...@hotmail.com> wrote in message
>
> a heavy sleeping bag, or maybe two. There are also some 12 volt
> specific electric blankets out there. It might be a bit more
> efficient than one that operates on AC. I've heard of some who can
> get maybe 12 hours out of one on a reasonable size portable battery
> jump starter used as a 12V power source. I'd definitely say don't use
> your car battery directly. Something like this might work:
>
>
> Make the same calculations that everyone is suggesting using the 4 Amps
> specified.
Sure. However - I'd think it doesn't necessarily have to run at full
power with the proper temp/timer control.
And my main point was to not run them off a car's main battery.
Anyone doing this should use something that won't leave one stranded
like a jump starter or a secondary car battery. I've heard of some
secondary battery rigs designed to charge off the alternator but only
draw down when manually selected.