Di-Directional Isolator

camperdave wrote:
Whoa! Red flag here, what's killing your battery?

Normal usage, our inverter runs a couple 110 VAC appliances while traveling.

For a schematic of the Winnie set up which includes a battery disconnect switch look up for example the schematic for my rig under "RESOURCES" tab on the Winnie home page.

I have battery disconnect and battery mode relays(solenoids) and no problems.

My Bounder had an Inteletec BIRD at for 26 years worked fine. Never a failure, I agree that you have a problem in the charging circuits that is blowing the BIRD and that should be your focus.

Tom/Barb wrote:

MrWizard wrote:

best guess without more info
is you run the house batteries really low, take off down the highway and the alternator amps into the house batteries is too much for the contacts

We charge all night off the 50 amp External power, house batteries show 13.4 volts
as we drive the house battery voltage drops to 9.0 volts, because they are not being connected to the chassis battery pack.

There must be a better way.

Whoa! Red flag here, what's killing your battery?

You have some problems that you need to locate and solve. The fact that you are burning out isolators is just a side effect of the problem. When you start the engine, your coach battery should be getting power from the alternator and charge to full power. Maybe the isolator isn't built for the amperage that your alternator is pushing. I switched to an old style solenoid style isolator instead of the solid state isolator and haven't had a problem.

Check all of your connections and make sure that they are clean and tight.

MrWizard wrote:
bi-directional is a relay, whichever charge side gets to above 13.2v
Pulls in the relay to charge the other side

Uh. no. Bi-Directional is a control board. When one of the batteries gets up to (I will accept your 13.2 volts) it tells the relay to pull in.

But the Control board is what makes it bi-directional

Mono-directional do not have a control board. they just read the ignition lead.

And, yes, there is a KISS mechanical solution. But, it does require an owner to know just a little about their electrical system.

Use a simple marine ON-OFF switch such as this: https://www.perko.com/catalog/battery_switches/150/medium_duty_battery_disconnect_switch/

It is rated at 250 amps continuous duty. Yes, there are ones rated even higher for a little more money.

Wire alternator output (B+) and chassis battery to one lug. House battery to the other.

Switch OFF means alternator charges only chassis battery. Switch on, alternator charges both banks. Also a good battery combine option.

Particularly if going from CG to CG where you will have shore power, kind of crazy to pay fuel to run the alternator harder to OVER-charge the house bank all day while driving.

Disconnect the ignition line and solenoid line and hook them together.
I suspect you have more problems though.

MrWizard wrote:

best guess without more info
is you run the house batteries really low, take off down the highway and the alternator amps into the house batteries is too much for the contacts

We charge all night off the 50 amp External power, house batteries show 13.4 volts
as we drive the house battery voltage drops to 9.0 volts, because they are not being connected to the chassis battery pack.

There must be a better way.

MrWizard wrote:
yes a 'continuous duty 200amp contact relay/solenoid'

turned on/off by a 10amp toggle switch on the dash

best guess without more info
is you run the house batteries really low, take off down the highway and the alternator amps into the house batteries is too much for the contacts

these bi-directional are most often used in situations where the RV will be parked in place with shore power, and the bi-direct keeps the chassis battery charged by siphoning power from the house charging converter over to the chassis battery, so it doesn't go dead because of no alternator charging

in reality the Bi-Directional Isolator controls the Relay that connects and disconnects the two battery packs when either has a charging source and there is a 1.3 volt difference.
This one will not connect the house battery to the Chassis battery when the engine alternator is running at 14.3 Volts, and the coach battery is down to 11.0. But the system works normal in all other respects.

Isolator

yes a 'continuous duty 200amp contact relay/solenoid'

turned on/off by a 10amp toggle switch on the dash

best guess without more info
is you run the house batteries really low, take off down the highway and the alternator amps into the house batteries is too much for the contacts

these bi-directional are most often used in situations where the RV will be parked in place with shore power, and the bi-direct keeps the chassis battery charged by siphoning power from the house charging converter over to the chassis battery, so it doesn't go dead because of no alternator charging