Engine battery good condition but drained

Not all charging systems are the same in RVs. My 2011 Chateau never charged the chassis battery from the converter. I had the schematics from Thor that showed that. I know my current rig does charge the house battery when the engine is running. I know that from measuring the battery (soon to be two 6V golf cart batteries).

mightykandy wrote:
Got it to a battery store and it was diagnosed as dead battery. Changed it. Thank you all for the feedback.

OK now you should verify the charging systems are working.

Alternator should put 13.4 to 14.4+ volts on the battery terminals when running.

When stopped but plugged in you want the house charging system to maintain the battery. Plug in and check voltage is 13.2+ volts to indicate charging.

If you are not getting the voltage you expect please post the reading and we can help set it right.

A battery can appear to be fine when it's fully charged and then slowly die; or be unable to sustain cranking voltage. One classic field test for a battery's condition is to turn on the headlights, then attempt to start the vehicle. If the headlights dim/go out, your battery is low.

Several folks have mentioned corrosion on the terminals, and that's certainly a possibility; a loose connection at the battery terminal or cable will have the same effect.

If your battery cable connections are corroded on the other end, where they fasten to the vehicle, you can get a similar situation in which a battery will fail to start the vehicle unless it's at peak power; many vehicles also have a ground strap that ties the motor to the frame, and corroded connections on that will have the same impact.

Or, you may have a component that's drawing current even when the motor is off (call it phantom draw), which will cause even a brand new battery to appear to be faulty. All modern vehicles have low amperage draws built in, but it's usually such a small draw that a battery will be capable of starting the vehicle for at least two weeks, and often even more (in contrast, my 1972 Chevy truck can sit for two months and still start right up, because, when the motor's off, there's no current flowing unless I leave the headlights on).

Get the battery tested first; just about any place that sells batteries (auto parts store, battery retailer, Costco, etc.) can test your fully charged battery. They usually do it for no charge, since it's a way to sell batteries. If it's in good shape, then check your cable/ground cable connections and try out the battery.

If those are OK, you may have a phantom draw. If you're competent with automotive electrical stuff, you can attach an ammeter in the battery circuit and check for current (there are, more expensively, inductive meters that can measure amperage when their jaws are looped around a wire); if there's current flowing, pull the fuses one by one until it stops. If it continues even when you've tested all the fuses, then you've probably got a stretch of wire on which the insulation has failed (cracked and oily or worn through). Tracking a failed wire can be (a) really entertaining, (b) really maddening, or (c) usually both. If you're not (yet) competent with electrical stuff, this is what the mechanic will do, while charging you his/her hourly rate.

Why did it get severely discharged? If you don’t find out, the problem will happen again.

One possibility not mentioned is too many starts and not enough running time. Check the voltage before starting - should be close to 12.6.

Check the voltage with engine running to see the charging effectiveness - should be over 14, especially right after a start. I carry a voltmeter on a cigarette lighter plug to monitor these voltages.

Got it to a battery store and it was diagnosed as dead battery. Changed it. Thank you all for the feedback.

How old is the battery?

check the battery voltage with the engine running, headlights on, and should be 13.5 to 14.8 normally if the alternator is ok. Normal meter voltage of battery should be 12.6 min, but only way to really check a battery is to have it fully charged, then do a load test. As others have said check the battery terminals make sure they are clean and in good shape.

First thing is to remove the battery wires and clean the terminals on the battery and inside the wires. Start the engine with the emergency battery switch and then check the voltage while the engine is running. If voltage is lower than 13 volts then alternator maybe the problem or the ground wire to the battery may have come loose.

Mandalay Parr wrote:

mightykandy wrote:
I connected the multimeter to the battery and I get 12.47 volts

Please measure again under load like while starting.
Jerry Parr

Check it with the engine running too.

mightykandy wrote:
I connected the multimeter to the battery and I get 12.47 volts

Please measure again under load like while starting.
Jerry Parr