Battery Isolator in a Subaru Conversion

[hansie]

I know this subject has been gone over time and time again , but in a subie conversion can I just use a Sure Power battery isolator ? Just coming off the post on the alternator and splitting to each battery ?
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Karl Bower

[dobryan]

There should be no difference in how you set up an aux battery charging system just because it is a subaru vs wbx engine.

All the normal methods will work fine. (At least they always have on mine. Caveat, I have never used the 'blue' wire to trigger a relay for charging, that may be different, I do not know.)
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

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[crazyvwvanman]

If you mean one of their old school diode based isolators then NO, that isn't the way to go.

You can use one of their relay based ACR products or an ACR type from many other brands. I'm partial to the 1314A but other models do mostly the same thing.

Since your van had the factory aux battery relay the wiring needed for an ACR is already there under the driver seat. Depending on the size of the battery and how deep you will draw it down this may need some improvements.

EDIT:::
Here is a basic ACR for such a job.
Compact and suitable for wiring of a reasonable size, like the factory aux battery setups have.

https://www.ebay.com/itm/Victron-Combiner-12-24V-1...741930177?

https://www.amazon.com/Victron-Cyrix-ct-24V-Batter...ix+battery


Mark

[crazyvwvanman]

By the way, Subaru conversions do have issues with various existing aux battery setups.
I have helped many people with this after their Subaru conversions.
This is due to differences from the Bosch alternators that VW originally fitted to Vanagons.
Use of an ACR relay type product avoids the issues that otherwise can arise.

Mark

[skills@eurocarsplus]

^^^^

yes the subaru alternator will trip the relay and charge ok, but the battery light may be lit if wired like it would be for a bosch alt.

i have a photo of a "cheat sheet" someone sent me, it may have been from smallcar's install (not sure) but it outlines what to do.

message me and i can email it to you if you want it
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[hansie]

Thanks for the help and replies. I just made my order Mark and thanks Donny for the help.
Karl
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Karl Bower

[crazyvwvanman]

Many people who already had an aux battery setup and then convert to Subaru need to change something to get the aux battery to charge with the Subaru.

The ACR (automatic charging relay) is a common answer for Subaru conversions that want an aux battery.

An ACR needs 3 wires to charge the aux battery from the alternator.

1. it must have a ground connection (usually a small short wire to a nearby screw)
2. it must have a connection to the aux battery positive (heavy enough gauge to safely carry the expected amps)
3. it must have a connection to alternator power, usually at the starting battery positive (heavy enough gauge to safely carry the expected amps)

Since the alternator uses the van chassis ground as part of it's charging path any battery to be charged by it needs to have a negative chassis connection (heavy enough gauge to safely carry the expected amps)

Mark

[skills@eurocarsplus]

i've emailed a few folks the wiring instructions to do this.

if anyone else needs it, PM me with your EMAIL ADDRESS

i have messaged back with a few people that didn't supply any email info, so there are like 2 or 3 that asked and i never heard back.

the subaru alternator will close the relay for the batteries but the charging light stays lit. it will charge, but the light stays on. this wiring (which i forget from the top of my head) will solve that. i always have to go back an look. i simply don't do enough aux battery stuff to even try and remember it
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[crazyvwvanman]

It isn't true that the Subaru alternator will always close the relay that the Bosch alternator could. Some relays need more.

The "solution" given in those instructions is a weak one for aux battery relay control purposes, IMHO.
Moving the relay blue control wire to the "X" circuit is preferred, NOT to the 15 circuit.

Mark