93 Roadtrek House Battery Wiring

[yyzclassb]

Have a 93 Roadtrek and having an issue with the house battery wiring.

Checking the house battery storage area and noticed that the fuse holder had fallen out of the plastic mount and was sparking against the metal below. Obviously want to replace the fuse holder, any recommendations on the fuse rating? Is there a schematic for the wiring? Thank you.

[hbn7hj]

Probably 30 amp automatic reset circuit breaker. There should be another one in the engine compartment. The wire should come from the alternator to an isolator or constant on solenoid through a 30 amp circuit breaker to another 30 amp breaker near the battery to the battery.

[yyzclassb]

Originally Posted by hbn7hj

Probably 30 amp automatic reset circuit breaker. There should be another one in the engine compartment. The wire should come from the alternator to an isolator or constant on solenoid through a 30 amp circuit breaker to another 30 amp breaker near the battery to the battery.

Thank you, that makes sense, I will be upgrading the alternator to a high output alternator, 250a max, 125a idle output. Should I get a 250a circuit breaker or would something closer to the ilde output be better? Would a 140a battery isolator be OK ?

[booster]

Originally Posted by yyzclassb

Thank you, that makes sense, I will be upgrading the alternator to a high output alternator, 250a max, 125a idle output. Should I get a 250a circuit breaker or would something closer to the ilde output be better? Would a 140a battery isolator be OK ?

Be aware that going to a much larger alternator in older vehicles can require other modifications to support it. Wiring, breakers and fuses, maybe current limiting and/or shutoff switches, etc. Lots of this has been done and documented here on the forum so available to look at.



Most alternators that claim high amperage at idle are rating them at a standard that uses a quite high alternator rpm point that is usually higher than most of our vans idle at. That means you would likely not see amps that high at idle, probably 100 or less, and if this is your only alternator the engine will also be taking 15-40 amps. The output will also go down as the unit heats up. Realistically, a 250 amp alternator will probably put out about 150 amps continuous if you want to keep it under 225*F case temp, which is a reasonable cutoff but they will run hotter than this and survive with shortened life by some amount.

[mcdave]

In a diagram for a '97-2000 versatile there are two 50A breakers in series between the isolator and the house battery. I believe these are auto-reset breakers.
The house battery will only draw what it needs when charging. Installing a higher amperage alternator will not change that. And the breakers are not for the alternator, they're for the house battery.