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I have an old 1998 Safari class C. It came with a solenoid style battery isolator which appears to need a replacement. Would I gain anything by changing it to a electronic box isolator? It would be more expensive, but I never had a problem in my PleasureWay and that's the style I had. Has anyone done this? The present one is 4 pole.

curry wrote: ↑Sun Aug 23, 2020 11:23 am I have an old 1998 Safari class C. It came with a solenoid style battery isolator which appears to need a replacement. Would I gain anything by changing it to a electronic box isolator? It would be more expensive, but I never had a problem in my PleasureWay and that's the style I had. Has anyone done this? The present one is 4 pole.

curry
See: https://batteksystem.com/2018/04/relay- ... plications

Interesting. Thanks.

Yes, there ARE options to the diode-based battery isolators.

The diode-based isolators do turn some of the power from the alternator into HEAT-- that is why the fins on them that dissipate the heat. Voltage drop around .7 VDC.

Yes, smart or solenoid-based isolators eliminate that small amount of the alternator output that is turned into heat. Some are bi-directional so converter or inverter/charging of the house bank will also automatically charge the chassis battery.

Another very KISS choice is a simple marine ON-0FF battery switch. Alternator B+ and chassis battery to one lug and house battery to the other lug. Switch OFF and the alternator charges only the chassis battery. Switch ON and both banks are charged. Can be used for charging both banks from the converter or inverter/charger. Also, a good "boost switch".

wolfe10 wrote: ↑Sun Aug 23, 2020 1:30 pm Yes, there ARE options to the diode-based battery isolators.

The diode-based isolators do turn some of the power from the alternator into HEAT-- that is why the fins on them that dissipate the heat. Voltage drop around .7 VDC.

Yes, smart or solenoid-based isolators eliminate that small amount of the alternator output that is turned into heat. Some are bi-directional so converter or inverter/charging of the house bank will also automatically charge the chassis battery.

Another very KISS choice is a simple marine ON-0FF battery switch. Alternator B+ and chassis battery to one lug and house battery to the other lug. Switch OFF and the alternator charges only the chassis battery. Switch ON and both banks are charged. Can be used for charging both banks from the converter or inverter/charger. Also, a good "boost switch".

The '78 Winnebago Class C had a CHARGE/RUN rocker switch operated constant duty solenoid that did just that,

I've had both style systems. My previous coach had the solenoid style and the solenoid went bad in it. I found a replacement for a reasonable price at a local auto parts store. The two important features were, it had to be constant duty rated, and had to have silver contacts. I don't remember the price, but it was under $50. and it took about 15 minutes to change out. As far as I know the original solenoid had lasted over 20 years. I currently have a diode based one and it's 22 years old and working fine but I've read where they can go bad, and back feed into the alternator, draining the batteries. Probably pretty rare though.

astrnmrtom wrote: ↑Thu Aug 27, 2020 10:24 am I've had both style systems. My previous coach had the solenoid style and the solenoid went bad in it. I found a replacement for a reasonable price at a local auto parts store. The two important features were, it had to be constant duty rated, and had to have silver contacts. I don't remember the price, but it was under $50. and it took about 15 minutes to change out. As far as I know the original solenoid had lasted over 20 years. I currently have a diode based one and it's 22 years old and working fine but I've read where they can go bad, and back feed into the alternator, draining the batteries. Probably pretty rare though.

Tom,

A diode based isolator failing in the way you describe, were it back feeds into the alternator is rare and would be the better way to fail. The more common and destructive failure is, when the diode fail inside the isolator, it cuts the power connection between the alternator and the battery. This is the equivalent of disconnecting the positive cable while the engine is running. With old technology alternators, you could get away with it. With today's modern alternators, it will blow the diodes (rectifier bridge) and the voltage regulator inside the alternator, hence it pretty much cooks it. There have been more than a few Safari owners who lost multiple alternators until they finally figured out the cause. One went through four alternators until the alternator rebuilder finally figured it out. If one installs/connects a solenoid based isolator correctly, this destructive situation can not happen, even if the solenoid fails. So a solenoid based isolator is the less risky way to go and it is also more efficient, as you don't have voltage loss and the accompanied, heat that you have with a diode based isolator. Sooner or later all parts fail, the difference between the two styles is, one is a minor inconvenience, and the other is an expensive and destructive failure.