Dead Battery Question

I just googled "Engel fridge" Looks like a portable one that uses a cigarette lighter for 12v. You didn't plug that in the cab dash did you?

I bet this has nailed it!!

I just googled "Engel fridge" Looks like a portable one that uses a cigarette lighter for 12v. You didn't plug that in the cab dash did you?

the inverter and fridge were working, house lights worked ?

engine battery dead ?

logic, if it is an inverter power drain, why was the house batteries and inverter still going

the isolator is find, the inverter is find

you have a drain on the chassis side, lights left on? drain in the starter circuit ? shorted diode in the alternator ?
bad chassis battery ?

simple test
charge up engine battery, then disconnect it, then test in again in 48 hrs

get out the amp meter and test the chassis battery wiring
find your drain

BFL13 wrote:
It could be just the same as any car, nothing to do with being an RV with inverter, etc. A "dead battery" that won't crank at all (might get a click) is often a bad connection at a battery post. Clean that up and tighten and starts right up. Not saying that is for sure what this is, but could be.

My feeling also. Take a look at the age of the battery, you just might be due for another one. Other simple thing is a radio was left on or some dome light. Assume you have a van and not an RV at this point.

It could be just the same as any car, nothing to do with being an RV with inverter, etc. A "dead battery" that won't crank at all (might get a click) is often a bad connection at a battery post. Clean that up and tighten and starts right up. Not saying that is for sure what this is, but could be.

Thanks so much. I feel a lot better. I’m currently cruising through Tennessee, and I will do the testing suggested tonight when I arrive at a campground. I may also stop at autozone if I see one soon to get the battery checked. Otherwise, I’ll just do that myself.

Thanks again!

The inverter should cut off at about 10 to 11 volts. This would leave barely enough to turn a light on or run a propane fridge a few more hours. I assume the inverter draws power from the house battery.

Yes the isolator will prevent discharging the chassis battery.
I suspect one of three options:
1) something was left on that drained the chassis battery (fairly good chance)
2) isolator miswired or failed. (seems unlikely)
3) chassis battery just failed. (fairly good chance) How old is it?

Land,

You say the interior lights were still good. Did they stay good when you tried to crank? If yes, the problem is not your isolator.

Better information helps a lot. It may be that what you seem to have is either an unidentified parasitic load on the chassis battery or a just plain bad chassis battery. This is not all that rare. Most new vehicles have a parasitic load in the engine and body control computers that have been common since the late 80s.

Are you sure you did not leave the parking lights or the cab light on?

Next -
You could pull the battery out and schlep it to a car parts place that will test it.
Or
Get a meter (the cheap/free at Hazard Fright will do) and do a short test. Let the coach sit for a day and then put the meter on the engine battery. Now, turn on the head lights. If you look at the top of the battery, it will say RC=100 or something. That is how many minutes you can leave the headlights on and still have starting power.
If you wait half that many minutes and the battery voltage is still above 12.0, the battery is good.

If you plan to keep that battery (as in it passed), then attach two wires to a small light bulb. Remove a battery connection and put the light in series with it. It may light just enough that you can see it with your hand wrapped around it. That is the afore mentioned computer quiescent load. If it is brighter than that, start searching. Have a friend watch while you pull fuses from the chassis fuse panel. If one makes it go dim, you have found the problem.

Good Hunting

Matt

I should have tested the batteries, but we were blocking someone's way to get to work and we had to get on the highway, so we jumped it and took off. Our house batteries seemed fine. The fridge was working, all lights still turned on in the coach. However, the chassis battery was completely drained (would not start).

Sorry for my lack of terminology. To clear things up, we have a Freedom 10 inverter that's wired to two house batteries, and from there, it goes up to the chassis battery with an isolator between. Now I'm a bit freaked about leaving my inverter on at all. Some of my research has made me think a Xantrex ECHO battery charger may help?

When you went out in the morning, battery was absolutely completely dead: are you referring to house battery or chassis battery (i.e. engine would not start)??

In post immediately above, it sounds like your house bank is not low (i.e. above 12 VDC).

Please, post actual voltages, much better for diagnostics than saying "battery dead" or "house lights working".