Starting the Chinook after letting it sit a week

[DandD2015]

My wife and I have had some problems starting the Chinook Concourse we just bought.

First, I turn the key and it goes clickclickclick but does not turn over. I wondered if I left the headlights or something else on.

Second, I use the boost system---press the switch and turn the key to let the coach batteries jump start it. The first two times I did this, it worked.

Third---and this was just on Friday---when the built-in boost system didn't work, I took my JNC and connected to the battery terminals. Attempt A: no joy. Reseating the clips, it turned over. It looks like there's a little (not a lot) bit of corrosion on the terminals. Hmm.

In each case, when I drive it a bit then stop, restart, it's fine. Right after jump starting it with the JNC, the volt meter was a little above center---and it read there for the rest of the trip.

We've never owned a motor home before and we're not sure what's standard and isn't. We're also not sure what the last owner did that might have modified it etc. For instance, the first time we drained the battery I think it was because of the in dash Sirius stereo. I didn't realize: it was wired "hot." You can listen to it with the ignition switched off completely---so if you forget to turn it off, you can come back later and have a dead battery. The one we discovered recently: the power windows are also wired hot. Wow.

We also have a Tripp Lite charger/inverter. As we were leaving the Chinook today my wife said, "Hey, why are those lights on?" It said it was inverting---but we weren't plugged in to shore power and we didn't have the generator running. I switched it to charge only. As she was saying that would seem only to affect the coach batteries and not starting the car, but I'll throw it in.

As mentioned above we didn't jump it with the built-in boost system. We *tried* but it wouldn't work. I tried starting the generator---nothing. Once I got it jumped, ok, managed to get the generator running.

And to reiterate, every time I get it started, the needle goes to middle of the scale, where it should be.

My theory would be that the battery has power but that maybe the terminal connection is loose. Except if that's true, why doesn't it give us problems the entire trip?

Nothing quite makes 100% sense...anybody care to weigh in?

[westend]

Most of these motorhomes have an isolation relay between the chassis battery and the house batteries. There could be an issue with that relay.

What I'd suggest to do is either call a skilled mobile tech or take the Chinook to an RV service shop and have them go through the different wiring issues, test the batteries, test the alternator, and test the isolation relay. Nothing in your coach needs to be wired "hot" except the radio memory. You have at least one misguided user's (previous owner) ideas about how to power devices.

[DandD2015]

DrewE wrote:
Do you know for a fact that the chassis battery is good? That is, have you had it load tested? It may well need replacement, particularly after being discharged rather deeply a few times (and who knows how many more before you acquired the RV).

The voltmeter when the engine is running tells you next to nothing about the battery status since the alternator is supplying power. All you can tell is that the alternator's voltage regulator is more or less working properly.

The other thing to ascertain is what loads are on the chassis battery when the engine is off. It does sound like some things are wired in a non-intuitive way. The radio, in particular, may actually be powered from the house battery rather than the chassis battery, or perhaps has a switch to select between the two batteries; various RV makers do that in different ways. (This is true even when the radio is mounted in the dash.)

In general, when it comes to details of the electrical systems, there are some things that are rather common, and some that are less so, and some that are downright wrong, but few details that are absolutely "standard."

Thanks for the reply, Drew!

No, I don't know that the battery is good, haven't had it tested. I looked to see if there were any date on it but I didn't find one. I am sure that the Sirius wasn't original---the owners left a receipt in with the manuals showing they had it installed a few years ago.

Hmm, what if they did wire the radio or other things to the coach batts instead? Interesting.

[DrewE]

Do you know for a fact that the chassis battery is good? That is, have you had it load tested? It may well need replacement, particularly after being discharged rather deeply a few times (and who knows how many more before you acquired the RV).

The voltmeter when the engine is running tells you next to nothing about the battery status since the alternator is supplying power. All you can tell is that the alternator's voltage regulator is more or less working properly.

The other thing to ascertain is what loads are on the chassis battery when the engine is off. It does sound like some things are wired in a non-intuitive way. The radio, in particular, may actually be powered from the house battery rather than the chassis battery, or perhaps has a switch to select between the two batteries; various RV makers do that in different ways. (This is true even when the radio is mounted in the dash.)

In general, when it comes to details of the electrical systems, there are some things that are rather common, and some that are less so, and some that are downright wrong, but few details that are absolutely "standard."