Battery Question

[angler]

Yes I know. Another battery questions.
I have a 2002 tiffin Allegro Bay and had a question about chassis and house battery.
I have not run it for about a month as I have in the past. When I went to start the motorhome the chassis and house batteries were dead. I had the 12 volt disconnect switch switched. I knew that since none of the lights in the rv worked. I was surprised that the starting battery was dead. If I left the radio on (its hot wired to the battery) would that drain the deep cycles as well? looks like they are all hooked in parallel. I know if I had the inside lights on in the rv it wouldn't drain the starting battery, but was wondering on the chassis 12volt side whether it would drain the deep cycles. Like if I left the headlights on?

[ArchHoagland]

How old are the batteries?

I see you are in Wisconsin. How cold was it?

[Beverley_Ken]

It could be that your batteries are getting a little weak and after a month the parasitic draws on both systems are bringing them down. On the chassis side, the engine control 'computer' and maybe the radio memory feed. Most radios have two 12v feeds, one for the power operating system that you can turn off, and a second (orange on ours) that just feeds the memory. On the coach/house side its quite possible that the propane and other detectors are wired to the batteries before the disconnect and consequently on all the time.
The only sure way to prevent parasitic draws is to disconnect both systems right at the battery terminals.

Ken

[Lwiddis]

What a pain to recharge your idle RV batteries by starting the motor. And you more than likely ruined all of them. Two 30 watt or so solar panels and a couple of $22 WindyNation waterproof controllers would have ended this issue.

[angler]

Good idea about the knife switch. I'll try that. Thank you

[Sam_Spade]

angler wrote:
I was surprised that the starting batter was dead. If I left the radio on (its hot wired to the battery) would that drain the deep cycles as well?

I assume that your use of the term "deep cycles" is referring to the house batteries ?

With the engine OFF and the battery connect switch OFF, the chassis and house batteries should NOT be connected......unless a previous owner has screwed up the wiring or a battery relay has stuck closed.

The radio should affect only the battery that it is connected to.

[jplante4]

There are 2 places where the house and chassis batteries are cross connected

1. Through the isolator
2. Though the battery boost switch

Either of those 2 could be bad. On a previous coach, the PO had a habit of jamming the boost switch with a screwdriver when he charged the chassis batteries. After some time it failed.

Other than that, I'd be looking for a current draw on the house side. Install a knife switch on the negative side of the house and use an ammeter to measure across the open switch.