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lippij

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About lippij

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  • My Toyota Motorhome
    83 Toyota Huntsman

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  1. Looks exactly like that. The new alternator looks to me like a Nippondenso, but I have no idea about what the old one. I'm pretty sure the old isolator worked at one point, but that was also before the new alternator was installed. My worry is that my new alternator won't work with the 3 terminal isolator. If I go with a 4 terminal it looks like I only need to run one new wire with a 6 amp breaker between the E terminal of the isolator and the ignition wire in the alternator harness.
  2. With it OFF both batteries are ~12.5 V, which is also what's measured at the isolator terminals. Of course this is with the spare battery not the original dead coach battery.
  3. After a couple days waiting for a new fuel pump last night I was able to fire up the engine again… First of all, my isolator has 3 terminals but is solid state (big and blue, mostly a heat sink) and is aged to the point where the labels have worn off and the terminals are pretty corroded. At the moment I have no easy way to charge my dead battery, but I did wire another good spare battery in place of the coach battery and at the isolator I measured: 12.5 V @ coach battery terminal (coach battery voltage) 15 V @ truck battery terminal 15.5 V @ alternator terminal @ the truck battery I measured 14.7 V Then I also continuity checked the isolator and got an open (in both directions) between the alt and coach battery terminals, but got continuity between the alt and truck battery terminal. This sounds to me like a burnt out diode in the isolator. So I think I should pick up a new 4 terminal solid state isolator and run a few new wires. At the moment there definitely isn't a fuse/CB between the isolator and the coach battery, is it a good idea to add one there? I'm still wondering why the 3-terminal isolator worked in the first place? Different type of alternator?
  4. Hi Everyone, I'm a newbie to the RV thing and I recently went in on an 84 Huntsman with a friend which we picked up in NY and drove to CA. I'm quickly falling in love, but on her maiden voyage across the country we ran into a few electrical problems... It started with us having problems keeping the coach battery charged, then over the course of a couple days the electrical system was on the fritz then eventually the alternator went out, engine stalling at low RPM, battery and brake dash lights on. A new alternator seemed to fix the problem and got us to CA where I've since done a quick and dirty investigation. The battery isolator (3 terminal) is charging the chassis battery but not the coach battery: 14.5 V across chassis battery, 11.9 V across the (probably bad) coach battery. My theory for why this happened: - The coach battery was damaged after sitting around for years with infrequent charging (the RV went through ~5 years of very little use before we got our hands on it) - We killed the battery for good after a couple charge cycles - The dead coach battery started putting a big load on the alternator causing it to overheat and burn out - At some point one of the diodes in the isolator also burnt up due to the high load Does that make sense? I have also read a few other threads about battery isolators and it seems like "Toyota RV's need a 4 terminal isolator" is a common theme, but the isolator in there is a 3 terminal. Could that be part of the problem? Do I need to replace my old 3 terminal with a 4 terminal? I still don't fully understand why the 4 terminal isolators are preferable. My other worry is that some other short/electrical issue caused the alternator to go in which case replacing the battery and the isolator won't actually fix the issue. Any and all help is appreciated, John
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