Battery Isolator Replacement

[JJ1965]

I wanted to ask the experts on here some advice. I replaced the alternator on my 1986 Airstream345 with a higher output cs style GM alternator. Approx 127 amps at cruise and a max of 160 amps. The issue I’ve encountered is the battery isolator. The Sure Power unit is rated at 120 amps. I’m a little confused if the 345 has an isolator or a separator? As far as I can tell the wiring is original with the exception of the alternator. Does anybody have any recommendations of what they have used? I would like to stay with the Sure Power units being as it has lasted all these years. I seem to be able to find units designed for three batteries with the proper amps but not for cs style alternators? I included a pic of the original unit.

[bobmiller1]

Your picture shows an isolator.....the first thing I would do is clean up the wiring mess. Looks to me that you have some add on circuits that should not be wired to the isolator. There appears to be an unused post on the right side. (picture). In any event the rating of your isolator should be printed on a label on the side of the isolator. The rating should march the maximum output of the alternator. Regards, Bob

[JJ1965]

Thanks for the reply Bob. I agree the wiring needs cleaned up! The relays adjacent are really corroded and need replaced as well. I found a Sure Power unit that is compatible with my alternator and has a large enough amp rating. When it arrives I’ll update this thread maybe save someone some searching in the future.

[Boom Sounds]

https://rvlifestyle.com/how-to-test-a-battery-isolator/

You probably have an additional separator/solenoid on the back of the battery tray or in the coach.

[dadstoy]

The wiring on these rigs certainly is typically a nightmare. I replaced my isolator with a high amp Sure Power some years back and its been working great. I also replaced the cable from the alternator to the isolator with a heavy duty cable and fuse. Just make sure the “excitor” wire (terminal E) goes to an ignition on connector. See pic for the model number I installed. The new isolator is a lot larger than the old one. I had to move the windshield washer tank to the passenger side.

[waninae39]

best to keep it close to the battery

[JJ1965]

Thanks for the pics. The wiring is scary to be honest. I guess it’s been fine for all these years but I still update it as I go. That is big! I like the idea of updating the alternator wire. The original is probably sized a little small and I’m sure some added resistance from thirty years of use. Mine shipped yesterday with luck I’ll get it installed next week.

[JJ1965]

I received a new unit from Sure Power on Wednesday. I was able to use the factory location for mounting just had to drill a couple of extra holes. I still need to do some cleaning up of the wiring in this location but the new unit wired the same way as the old one. Works great I put all the load I could on and maintained over twelve volts at idle. All batteries remained charged as well. You can see from the pics that all the connections and relays were heavily corroded. I replace them as well. Sorry for the picture quality.

[mayco]

What a friggin nightmare of wires......and we all face the same mess! (and for your own mental health, don't look under the dash until you really HAVE TO!)

[PeterH-350LE]

then the question remains, which is the safest circuit Breaker replacement:
Type I Circuit Breakers – Automatic Reset, which means the circuit breaker keeps cycling on and off until the overload is removed.
Type II Circuit Breakers – Modified Reset or Non Cycling, where the circuit breaker doesn’t reset until the overload is removed or the power is turned off.
Type III Circuit Breakers - Manual Reset, will not reset until overload is removed

Pictures shows a Type III
To the best of my knowledge, Airstream only used the Type I fire hazard breakers on MH and Trailers

[bkahler]

Originally Posted by PeterH-Airstreamer

then the question remains, which is the safest circuit Breaker replacement:
Type I Circuit Breakers – Automatic Reset, which means the circuit breaker keeps cycling on and off until the overload is removed.
Type II Circuit Breakers – Modified Reset or Non Cycling, where the circuit breaker doesn’t reset until the overload is removed or the power is turned off.
Type III Circuit Breakers - Manual Reset, will not reset until overload is removed

Pictures shows a Type III
To the best of my knowledge, Airstream only used the Type I fire hazard breakers on MH and Trailers

Interesting. I've only seen the Type I breakers available. I would definitely prefer Type III breakers. I guess it's time to look into replacement breakers.

Thanks Peter!

[PeterH-350LE]

Originally Posted by bkahler

Interesting. I've only seen the Type I breakers available. I would definitely prefer Type III breakers. I guess it's time to look into replacement breakers.

Thanks Peter!

Another way for the real nuts among us, would be to run a wiring harness to all the now color coded breakers and an LED panel to the dash. This warning system would work on all three types.

[bkahler]

Originally Posted by PeterH-Airstreamer

Another way for the real nuts among us, would be to run a wiring harness to all the now color coded breakers and an LED panel to the dash. This warning system would work on all three types.

I think you have to much time on your hands.....what you need is another project.....

[JJ1965]

My boat has type III from the factory. They have worked well and still function at twenty years old.