Battery problem

Coach-man wrote:

tenbear wrote:
My OEM disconnect switch disconnects practically everything. I have had my MH stored for 3 weeks, not connected to power, and the battery voltage hardly changed at all. The engine started right up.

You say "engine started right up"? The house battery has nothing to do with starting, and neither does your disconect switch. The disconnect switch is wired to your house battery, but leaves thins like your steps, LP detector, and sometimes the radio, stereo, which draw power and in some cases run down the battery.

I know the engine and coach batteries are two separate systems that in my case are only connected when the ignition switch is on. I only mentioned the coach battery to indicate that neither battery was discharged during the 3 weeks that I was not connected to power.

burlmart wrote:
edited for clarity

ECones wrote:

FWIW, we left this morning with the battery fully charged, and the battery was at 13 volts. We drove with the switch in "Use" for about four hours, and when we stopped it was at 12.45. I don't know if that's significant or not.

this is very significant.

i still am assuming your rig has BIRD, and it should have kept the house batt charged. 12.45V is a BIG drop

it looks like your engine's 14V(presumed) is not charging the house batt as it should if your BIRD is working. both batts should charge when either is getting over 13.2

i am suspecting a prob in BIRD hookup, or else it's solenoid (Relay)

locate this solenoid and there should be 12V on the two small terminals (if plugged to shore and in USE, or if engine is on and in USE). the 2 large terminals go off to the pos pole of the house and the engine batts . touch either and chassis frame and get that batt's voltage (solenoid is likely close to frame. guess you could trace red cables from either batt)

I felt it was significant as well. Thanks.

I'm much more comfortable working on things with two wheels, but I'll try what you suggest sometime next week. I don' know if it has a BIRD or not. I'll try to figure that out. And ... I'll try to find it ;)

I just want to identify the problem while the rig's under warranty, so maybe I can get it fixed.

adding to my previous post on engine not charging house...

12.45V is about 3/4 capacity. assuming your house batt has a capacity of maybe 110 amp-hours, in 4 hours your batt went from 110 to 0.75x110, or 7 amps per hour.

Coach-man wrote:
You say "engine started right up"? The house battery has nothing to do with starting, and neither does your disconect switch. The disconnect switch is wired to your house battery, but leaves thins like your steps, LP detector, and sometimes the radio, stereo, which draw power and in some cases run down the battery.

To the OP your measure of 12.45 volts on the battery is almost dead. The engine alternator should have been charging as you drove. You either have a big drain on the battery or the battery is bad!

You are correct in 99% of your response. If the engine is running, the alternator would show a higher voltage at the house battery. However, after a short time of the engine no longer running, the voltage will drop to the steady state. According to this
Battery voltage (Temperature compensated) the battery would be 75% if the temperature is 80 degrees.

tenbear wrote:

Coach-man wrote:
I hope you are aware that the so called disconect switch disconects pratically nothing! Purchase a marine type disconect switch and install it next to the battery, one that disconects everything for storage, that should help.

My OEM disconnect switch disconnects practically everything. I have had my MH stored for 3 weeks, not connected to power, and the battery voltage hardly changed at all. The engine started right up.

Your disconnect switch is obviously not wired the same as mine.

You say "engine started right up"? The house battery has nothing to do with starting, and neither does your disconect switch. The disconnect switch is wired to your house battery, but leaves thins like your steps, LP detector, and sometimes the radio, stereo, which draw power and in some cases run down the battery.

To the OP your measure of 12.45 volts on the battery is almost dead. The engine alternator should have been charging as you drove. You either have a big drain on the battery or the battery is bad!

edited for clarity

ECones wrote:

FWIW, we left this morning with the battery fully charged, and the battery was at 13 volts. We drove with the switch in "Use" for about four hours, and when we stopped it was at 12.45. I don't know if that's significant or not.

this is very significant.

i still am assuming your rig has BIRD, and it should have kept the house batt charged. 12.45V is a BIG drop

it looks like your engine's 14V(presumed) is not charging the house batt as it should if your BIRD is working. both batts should charge when either is getting over 13.2

i am suspecting a prob in BIRD hookup, or else it's solenoid (Relay)

locate this solenoid and there should be 12V on the two small terminals (if plugged to shore and in USE, or if engine is on and in USE). the 2 large terminals go off to the pos pole of the house and the engine batts . touch either and chassis frame and get that batt's voltage (solenoid is likely close to frame. guess you could trace red cables from either batt)

A local RV dealer recommended we use "Store" when the RV is plugged into shore power. But my book says that it goes to a maintenance mode and won't overcharge, so it seems it should be on virtually all the time as well.

Ours is plugged to short power virtually all time time anyway.

FWIW, we left this morning with the battery fully charged, and the battery was at 13 volts. We drove with the switch in "Use" for about four hours, and when we stopped it was at 12.45. I don't know if that's significant or not.

After reading through this, I think we should leave the switch in "Use" unless we really are storing it off power. We do plug in when it's parked at our home.

I think some may be in the weeds here. The STORE switch is to be used while the unit is in long term storage or non use for a time. Leave it in the USE position at all other times. In the STORE position battery is not getting charged from the engine or when plugged into ac. You may be replacing a good battery for nothing.

Coach-man wrote:
I hope you are aware that the so called disconect switch disconects pratically nothing! Purchase a marine type disconect switch and install it next to the battery, one that disconects everything for storage, that should help.

My OEM disconnect switch disconnects practically everything. I have had my MH stored for 3 weeks, not connected to power, and the battery voltage hardly changed at all. The engine started right up.

Your disconnect switch is obviously not wired the same as mine.

Some of those phantom loads can be hard to detect unless you use an amp meter. The cumulative draw can be quite high. I have installed positive cut off switches in several RV's and has definitely helped my situation.