Batteries

[sparkydog]

I currently have 4 six volt batteries, rated at 400ah each. So the question is, do I have 800ah of power available, when fully charged. Ours is an all electric coach with residential fridge with 2000W inverter charger. Thanks

[DBeauchamp]

Yes, 800 is the correct answer.

[BryanL]

instead of amp hours for measuring energy capacity, use a proper unit like watt hours. If you must use a unit like amp hours, always qualify it with the voltage at which it is measured.

For watt hours, take the amp hour rating for each battery times its voltage to get the watt hours of energy rating for the battery. Watt hours in the thousands, or kilowatt hours (kWh) is the unit of energy most folks see on their electrical bills.

Add the watt hour ratings for each battery in your bank to get total rated energy capacity.

Note that all lead acid batteries have close to the same energy density by weight (45 wH/kg re batteryuniversity.com). If you use the 50% discharge point for optimum cost efficiency (re smartgauge.co.uk), this comes down to 12 - 15 usable watt hours per pound of battery.

The fridge probably consumes about 1 kWh of energy per day. The alarms and such stuff probably run at about 20 watts or close to 500 watt hours per day. You can get an idea of the energy reserve in your batteries if you know their usable watt hours and then add up all the watts for how many hours that use the battery electrical energy.

[KIX]

Quote:

Originally Posted by sparkydog I currently have 4 six volt batteries, rated at 400ah each. So the question is, do I have 800ah of power available, when fully charged. Ours is an all electric coach with residential fridge with 2000W inverter charger. Thanks

yessir, 800 amp hours however they should not be discharged beyond 50% so, you have 400 amp hours that you can use before recharge.

[sparkydog]

Ok I think I've got it. Now it seems like it's hard to start the generator, when I let the voltage drop to 11.8 volts on the meter. I've read where some routinely take their batts down to 11.0 volts. Will genset still start on that low voltage? My batteries are about 1 yr old, and barely drop below 12.2 volts on an overnight stay, so that's good. Batteries are series/ parallel configuration 12 volt.

[KIX]

12.1 volts is 50% .......according to the battery table I have tried to attach.

[sparkydog]

Thanks Kix, That the chart I was looking for. Looks like I don't want to go below 12.1volts. I think that's doable!

[KIX]

You're welcome! Glad to help.

[wa8yxm]

4 400 amp hour six volt (How big are those suckers) in a series/parallel configuration

Bat1-Bat2
Bat3-bat4

Is indeed 800 amp hours.

[sparkydog]

They are Interstate batteries. I was told at the dealer they are deep cycle batteries that they use in aerial lifts. They are huge. I don't remember the part numbers. They also have pro fill caps for filling. As I learn more, they are probably overkill.

[mr300ce]

Quote:

Originally Posted by sparkydog They are Interstate batteries. I was told at the dealer they are deep cycle batteries that they use in aerial lifts. They are huge. I don't remember the part numbers. They also have pro fill caps for filling. As I learn more, they are probably overkill.

No, No, just go boondocking more often, and for longer stays.