Quote:
Originally Posted by Chance
To keep it simple and straight forward, and avoid confusion, I believe it’s best to keep power numbers (in Watts) separate from battery ratings (in Amp-hours). Unless it’s specifically mentioned otherwise, 400 Ah is just that — regardless of voltage. What that 400 Ah can and can not accomplish obviously depends on voltages, but that’s a more complicated analysis involving other equipment because they are not 100% efficient, hence math is a bit more complicated. In this case it is implied an inverter would convert 12 VDC battery power to 120 VAC power required by an air conditioner, but that’s jumping the gun because more and more motorhomes are making use of both 12 and 48 VDC air conditioners.
Obviously 400 Ah of battery capacity at 48 VDC is a lot more energy than 400 Ah at 12 VDC, but both are still 400 Ah. That part of rating doesn’t change.
I’d stick to basics or confusion will be off the charts.
Without additional explanation, the number he listed are just wrong. And if goal is to power an inverter to then power an air conditioner, more information and calculations are needed.
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Wouldn't it be simpler to just use Watts and Watt-hours for this sort of stuff? That way, any differing voltage can be disregarded. For example, if you have four 1200Wh batteries, you can power an 1100W A/C for about 4 hours, no matter if it runs on 12, 24, 48 or 110V. Of course you have to consider inverter losses and such, but just a rough percentage will give an idea.
With A/C's (and fridges etc) cycling on and off this is a very rough estimate anyway, greatly affected by the ambient temp and how low you set the temp controller...