house battery


S

SURVEYOR1

New Member
I use a single 80 amp hour battery. 5 years old and doesn't seem to hold a charge.
I removed it and put an ohm meter across the leads and read about 2 ohms which indicates to me a pretty good load on the bat. even though nothing is "on".
What is the normal amount of resistance across the cables with the battery removed ?
 
TexasClodhopper

TexasClodhopper

Senior Member
Re: house battery

Look at it kind of in reverse.

If your "normal" load was 10 amps, then assuming a 12 volt battery the resistance of the "load" would be 1.2 ohms.

For twice that amount of "load" (20 amps), the resistance would be one-half of the previous calculation or 0.6 ohms.

I doubt you have a meter that is accurate at that resistance range. It doesn't matter what it says, it isn't accurate.

You will be much better off measuring the current with the voltage applied than measuring the resistance.

Different RVs will place different "loads" on different battery configurations.

Yours is probably just the battery gone bad, but you can verify it once you get a new battery.
 
S

SURVEYOR1

New Member
Re: house battery

Thanks for the reply.
Following that logic and assuming (for a minute) that my meter is correct, then my unit is placing a constant 6 amp load on the battery when it is "at rest". Would that be normal or excessive ?
 
S

SURVEYOR1

New Member
Re: house battery

more info:

I pulled the battery, charged it and am running an AC house fan on a 350 watt inverter to see how long it takes to discharge. Just for grins & giggles I put the ohm meter between the leads of the inverter and it read 1.2 ohms in the off position. So that little inverter (in the off position with nothing plugged into it) is "drawing" more power than my van. I guess I can live with that.
 
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