Sorry, can’t trim the long quote in this software.
A bank of four 12v batteries will indeed provide four times the run time
even at the same amp-hour rating. If the inverter is supplying, say, 1200
watts at 120VAC, it will draw 1200 watts from the 48VDC, plus inversion
losses (which I’ll ignore because it’s not part of my point). 1200 watts at
48 volts is 25 amps, and a bank that can supply 100 amp-hours (using four
100AH 12V batteries in series) will run four hours, nominally. Those same
four batteries, wired in parallel and feeding a 12V inverter, will provide
400ah, but that 1200 watts will require 100 amps, and the bank will still
last four hours.
The difference is the wiring. Wiring for 25 amps will be much smaller than
for 100 amps.
But the problem is figuring out how to charge a 48-volt battery bank.
Rick “power is power” Denney
> Well that is a find
>
> My experience with UPS units is they have little long term operating time.
>
> Now a 48v sine wave inverter is good for certain uses, but I think you
> would have to
> scratch your head to get it working in the GMC.
>
> To extend the run time, or to run all the time would need solar panels and
> a battery bank.
> The GMC probably would complain with the battery weight you would need
> from the battery bank.
>
> I have a 12v ups I was going to use in the GMC until I connected a
> frequency meter to the
> 120v output. All was good at line power, 60 hertz but when the 120v power
> was dropped,
> The frequency meter jumped to 200 hertz. This may or may not have been a
> glich with the
> UPS but I decided to go with a Sine wave 12vdc inverter.
>
> Either way if you are looking for big power out of an inverter, you will
> have a problem having a big enough
> battery bank (WEIGHT) and if plans are to add solar, you can't get enough
> solar panels for heavy power
> supply over a long term.
>
> I'd have to crunch the numbers again but a 12v inverter with a tolerable
> battery bank may supply 1 to 5 amps
> with little problems, 6to 8 would even work but maybe not continually and
> 9 amps and up for short periods.
>
> The 48v unit just doesn't seem doable as a bank of 4 12v batteries
> connected in series for the 48v is going to be from 300 to 400 lbs and will
> only
> supply about 100 amps (the volts add up, not the AH's).
> To get any good run times you'd have to add more batteries, 4 batts at a
> time, which not only questions the weight problem but where would you put
> them.
>
> Charging the batteries would be the next question, and again, you don't
> have enough roof for solar panels for that 48v UPS batteries.
>
> THE BEST SENARIO would be a 12v system, charged by solar (eventually)
> powering 12v applicances. An inverter
> is a power hog, 10A at 120v needs 100A of 12v battery power. If you have
> 2 batteries in parallel, that might get you 18 hours, maybe.
> so 100AH at 48v supplying a 10 amp load would run about 30 amps, (real
> rough figures) but you want to keep your battery load around 5A per bank
> which
> means you need about 5 or 6 battery banks of 4 each... It's starting to
> not sound so feasible.
>
> Just to know
>
> The higher the DC voltage supply, the lower the amp draw...
> I can't see how you could get that unit operational in a GMC from its
> needs.
>
> A 12vdc sine wave is pretty much doable, but you will have power limits
> and length of run but the battery bank is not impossible.
> A 24v sine wave is also doable but now you have banks of 2 12v batteries
> in series, 100AH per bank. But weight will again factor in.
>
> The only thing that might be possible is Lithium batteries, they put out
> big power, have large storage and are very
> light, HOWEVER you need to do your homework with Lithiums.
> They are EXPENSIVE to purchase and they have limitations. They can't be
> charged if in freezing cold temperatures. If you try, the battery is
> destroyed. Lithium batteries like a more "normal" temperature operating
> range. I read that range is 70 to 80 but the electric cars have them.
> HOWEVER, keep in mind, and I will use the Chevy VOLT as an example.
> The VOLT lithium battery has many monitors on it and temperature is one of
> the main monitor points. The car will heat or cool the battery as needed
> to prevent warping and shorting of the battery plates. They use a
> separate radiator cooling/heating system to accomplish this.
> A lot of people are jumping on the lithium battery band wagon, which in a
> way is good, but are not being told about these limitations...
> --
> GatsbysCruise. \
> 74GMC260 Former Glacier Model style. \
> Waukegan, Illinois \ Keep those MiniDiscs Spinning \ MY GREYHOUND IS
> FASTER THAN YOUR HONOR ROLL STUDENT \
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> UBUNTU VOYAGER - Berzin Auto Center
>
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--
Rick Denney
73 x-Glacier 230 "Jaws"
Off-list email to rick at rickdenney dot com
