So I am going to assume my isolator is broken (judging by how old it is) and NOT that it was wired wrong. Although it does seem to be wired differently than the instructions I see for new ones. For example... the alternator goes to the isolator, but the isolator does NOT go to the engine battery. It is as if the alternator itself splits the charge to the engine battery and THEN also to the isolator. Picture of My isolatorLike A,E,F are all linked together. E comes FROM my alternator and then A just loops up to the isolator (to give it power). C must be wired to my ignition to turn it on and off and I assume the BLACK wire D goes to charge my house battery (It vanishes into the firewall). Although there would then me NO "Negative" running from the isolator to the house battery. NO LINE goes from the isolator to my engine battery, that battery is connected directly to the alternator.line F is a mystery... (It is red) and it travels to some kind of thing pictured HERE that seems to be attached to my air conditioning (That is not working AND not even connected anymore)... Not sure if that is relevant. So TWO questions... 1. How many AMPS do I need the new isolater to be? I saw one on Amazon that was 80 amp and I imagine the one I have is that small at least.2. Any advice on how to connect the new one? I will just kind of copy the way it is hooked up now (even though it is slightly different than the directions say)

I would go to a relay rather than a diode. I replaced mine with units rated at 200 amps.

Is it possible for the OP to drop down several topics and review my response including photos and link to a smart solenoid? i just lost my appetite looking at that image of the OP's. There is no reason to endure such a improvised disaster in waiting.

pianotuna wrote:I would go to a relay rather than a diode. I replaced mine with units rated at 200 amps.X2. I would never go back to diodes.Much more reliable and no voltage drop.

What the OP has is a relay- A is a common hot lug, that's hooked to the relay through a circuit breaker, which is mounted to the control post of the relay- used to be common, kind of wonky to me. C is the control lead from a switched ignition lead. The engine battery must be hooked to the alternator elsewhere.

Only armageddon prevention protection should be placed in between an alternator and the chassis battery. The safest protection as far as reliability is concerned is a fusible link. Fuses can corrode, breakers can break, and switches are controlled by mistake makers.In my designs I am so touchy about this that I insist on a straight run from alternator output stud direct to battery positive. A 2nd cable from battery positive gets distributed after a very short run. The manifold at that point gets branch over current protection devices.Why people gnaw fingernails to the quick over the supposedly "exposed therefore vulnerable" alternator to chassis battery wire is beyond me. The circuit is protected by a fusible link. Want tough high temperature wire? Use XL cross linked polyolefin insulated wire. Insulation is extra hard and extreme temperature resistant. Black nylon spiral wrap can be applied over the cross link wire. Then, it would take pressing directly against an exhaust manifold or hammer and chisel to compromise its integrity.Ill furnish a link below in another response to a relay that shames the reliability of a metal an relay if an individual insists on using a control wire or switch.

Help replacing an OLD isolator | Good Sam Community

25 Replies

MEXICOWANDERER
Explorer
Jul 26, 2017
Only armageddon prevention protection should be placed in between an alternator and the chassis battery. The safest protection as far as reliability is concerned is a fusible link. Fuses can corrode, breakers can break, and switches are controlled by mistake makers.

In my designs I am so touchy about this that I insist on a straight run from alternator output stud direct to battery positive. A 2nd cable from battery positive gets distributed after a very short run. The manifold at that point gets branch over current protection devices.

Why people gnaw fingernails to the quick over the supposedly "exposed therefore vulnerable" alternator to chassis battery wire is beyond me. The circuit is protected by a fusible link. Want tough high temperature wire? Use XL cross linked polyolefin insulated wire. Insulation is extra hard and extreme temperature resistant. Black nylon spiral wrap can be applied over the cross link wire. Then, it would take pressing directly against an exhaust manifold or hammer and chisel to compromise its integrity.

Ill furnish a link below in another response to a relay that shames the reliability of a metal an relay if an individual insists on using a control wire or switch.
Chris_Bryant
Explorer II
Jul 25, 2017
What the OP has is a relay- A is a common hot lug, that's hooked to the relay through a circuit breaker, which is mounted to the control post of the relay- used to be common, kind of wonky to me. C is the control lead from a switched ignition lead. The engine battery must be hooked to the alternator elsewhere.
ScottG
Nomad
Jul 25, 2017
pianotuna wrote:
I would go to a relay rather than a diode. I replaced mine with units rated at 200 amps.

X2. I would never go back to diodes.
Much more reliable and no voltage drop.
MEXICOWANDERER
Explorer
Jul 25, 2017
Is it possible for the OP to drop down several topics and review my response including photos and link to a smart solenoid? i just lost my appetite looking at that image of the OP's. There is no reason to endure such a improvised disaster in waiting.
pianotuna
Nomad III
Jul 25, 2017
I would go to a relay rather than a diode. I replaced mine with units rated at 200 amps.

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Help replacing an OLD isolator

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