Suggestions for battery isolation

davron94 wrote:


*A* There is a battery isolator controller, but I'm not sure what that does.

*B* I'm kind of confused about how everything should work together and what this controller does.

*C* I'm assuming that i should install a switch of some kind to disconnect the chassis battery from the house batteries,

*D* but do the house batteries need to be disconnected from each other also?

*A* the "battery isolator controller" is a printed circuit board called a bidirectional isolator relay delay - BIRD. it eats both batteries until they cannot be rescued.

*B* there is also the isolator solenoid that BIRD controls - it either entangles the engine and house batteries so they act in parallel whenever either one is being charged; otherwise, it is supposed to keep them totally isolated. mostly, it just keeps them entangled all the time.

*C* your better option is to pull the fuse on BIRD and disconnect the isolator relay, which it totally fried for you a few years back

*D* not at all - the group of house batts, when connected in parallel, simply act as one 12 volt battery

like many RV gadgets, BIRD is a Rube Goldberg, only it cannot hold up to its overcomplicated manner of doing the simple job of acting as a single engine/house connect switch to charge both, and as a jumper cable (the emergency start toggle on your dashboard should the engine batt be too low).

wolfe10 wrote:
Suspect the OP's "battery isolator controller" is the "salesman switch" I mentioned.

Could also use a mechanical switch instead, as Don posted.

The OEM system is a BIRD I suspect the OP is confusing parasitic drain and / or a bad battery with a lack of anything at all.

Suspect the OP's "battery isolator controller" is the "salesman switch" I mentioned.

Could also use a mechanical switch instead, as Don posted.

davron94 wrote:
There is a battery isolator controller, but I'm not sure what that does. I'm kind of confused about how everything should work together and what this controller does,

I think a few folks missed this comment in the middle of the OP.

Charging from the alternator is usually either through a SOLENOID-BASED ISOLATOR or through a DIODE-BASED ISOLATOR.

Now, you likely also have (completely separate from the above) a "salesman switch" which turns off most/all the house circuits. Often, things like refrigerator, propane sensor, etc are wired directly to the house battery, so the salesman switch does not necessarily turn off all electric loads.

As DrewE said, the chassis battery and the house batteries are not normally connected to each other when the engine is not running. If the solenoid is defective so that the contacts are closed then the two batteries would be connected. You can check this with your multimeter. If you have a battery isolator of a different type it may connect the two batteries together under different conditions.

Many MHs have a battery disconnect switch that disconnects the house battery from the house. When it's in storage and not plugged in, you should disconnect the battery with this switch. If you don't have one, pianotuna's switch would be a good addition.

Hi,

My oem is a switch from Napa auto. $5.95 rated at 1000 amps contacting and 100 amps continuous.

175 amp switch

Typically you do have an isolator setup. One common setup is to have a fairly high current capacity relay (or solenoid--different names for the same thing) that ties the two systems together when the engine is running and leaves them separate otherwise. Often there's also an emergency start button that will also operate this relay in case the chassis battery is dead but the house battery is charged, acting as a sort of built-in jumper cables.

There are various more or less complex circuits that control the relay, ranging from manual switches (on older motorhomes mainly, I think) to tying into the ignition switch circuits to rather complex purpose-built circuits incorporating voltage sensing and time delays.

The house batteries should generally remain interconnected with each other. It's a single 12V battery bank; the fact that it may be composed of various combinations and permutations of physical units is immaterial from the electrical system design.

Note that there are often parasitic loads on both the house and chassis systems that can drain one or the other battery over time: the propane and CO detectors on the house battery, for instance, and the chassis computers, radio, remote locking receivers (if applicable), etc.