chassis battery recharge

I have several different chargers. First I have a trickle charger which provides the very least current and works well to keep my motorcycle battery up to full. Won't be good for a MH, tho.

Second I have a HF solar panel, good for 15 Watts. Marginal and will recharge my MH starting battery in a a week or two depending on how low it is.

Third I have a small-scale charger I now keep on my starting battery and it will recharge in a few days, again depending on how low it is.

Fourth I have a garage charger which will send 10 Amps to the battery. I use it occasionally at home for any vehicle but I don't schlep it around with me in the MH.

I am thinking about roof-mounted solar for the future.

The answer depends on your make and model..

In the old days the isolator relay was operated by the ignition switch for the most part, It connected the two systems only when the engine was running, This system is lower in cost than what I will describe next so .... Of course back then when the engine was OFF it was OFF, I mean there was no engine control computer that needed full time power, The Radio really turned OFF, about the only thing that might draw power.. Was a clock.

Today There are many "Vehicle" systems that still draw power. I listed 3 of them above but here may even be more.. So a vehicle just sitting eats it's battery.

So they developed the Bi-Directional Isolator.. (We refer ot it as a BIRD here, Bi-directional Isolator Relay Delay) This device measures voltage both sides of the realay and if it sees a high enough voltage (I do not know the trip point but let's say 13 volts) it closes so the house can charge the chassis, or the other way around after a delay of say 30 seconds.

So the two answers, depending on the make and model are:

1: We did not install a BIRD
2: BIRD defective.

NOW TO FIX:

Two ways
1: Upgrade isolator and control to BIRD system (Expensive)
2: Trick-L-Start,, This is a monodirecitonal isolator just like the one you have now.... but in the other direction, Simple 3 wire hookup (Both of the big wires on the isolator relay plus ground) fully automatic operation.

I use a Trik-L-Start for this purpose. Permanently mounted and it works like a charm. Really useful while she is in storage between trips. We went to start her for a trip several years back and chassis battery was dead. Prevents that from happening again.

Dave

Coming from old school I try not to mess with anything connected with the Truck system especially the Alternator and using the Truck batteries for anything that were not designed to be used with.

This to me is my only way to get back home so I sort of keep steered away from it. Once you turn the ignition key 'OFF' your truck battery system is designed on its own to shut down systems etc to keep the truck start battery in good working for long periods of times when the truck motor is not running.

However you can add all sorts of things to trickle charge the truck start battery on your own I reckon. The small solar trickle charge units comes to mind sitting on the truck dash. You have to plug this into a 12VDC receptacle that doesnt auto turn off however. Most of my 12VDC receptacles associated with my truck all turn OFF after a short time out once the iginition key is turned off.

Just my take on the subject...
Roy Ken

Because, IF they were connected to charge and your Converter failed to charge, BOTH battery banks would go dead and you could not start the chassis engine. Most GAS motorhomes do not have a dual charge system from the House Converter charging system, but some do. Most Diesel motorhomes have such a relay system that charges when on Shore, but the systems are kept separate by a relay system. Some (Tiffin and others) have a Battery Maintainer 120 volt charger connected direct to the Chassis batteries. This system does not rely on the House battery charge system. Anytime you are connected to 120 volts, this charger trickle charges the chassis batteries. You need to call your RV maker and ask if yours has such a system, it may be malfunctioning. Doug

Mostly due to cost.

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