Aux Battery ACR - Wiring and Fuses

[Franklll]

I have spent many hours researching all of the threads about these setups. I think I have decided what to do with my 78 Westy(with a little help from Scott@German Supply) There have been a few specifics I am having trouble locating....What size wire and fuses do i need? Does the ACR need to be fused? also, do i need to hook up the SI on the ACR?

Cheers,
Frank

[WhirledTraveller]

No fuse on the ACR.

Fuses in your fuse box should be sized appropriately to the expected load. 15 amp fuses will cover a lighter/stereo/etc pretty well.

I wouldn't bother with the Starter Isolation circuit. Unnecessary in this application. It will isolate automatically anyway because the voltage will be below 13 volts during starting.
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1977 Westy, Automatic. Big Valve heads, CS Cam.

[Franklll]

Thanks for the help
If i use 4-15 amp fuses in the aux fuse box does my main fuse @ the battery have to be 60A? that seems really big. does the volmeter need to be fused?

[germansupplyscott]

the ACR we sell has a fused ground.
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SL

[aeromech]

Frank,
It looks to me like you're making this a lot harder than it really is. I've installed 3 or 4 aux batt systems in bay window buses and I used components purchased from West Marine. They have several articles on their web site with descriptions, drawings, and advice. Here's some links:

http://www.westmarine.com/webapp/wcs/stores/servle...nd-Battery

http://www.westmarine.com/webapp/wcs/stores/servle...ers-Relays

http://www.westmarine.com/webapp/wcs/stores/servle...ge-Battery
_________________
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[germansupplyscott]

[aeromech]

[Franklll]

Aeromech,
Maybe you are right, as this is my first shot at it i will simplify. I am going to drop the whole voltmeter idea and just get the aux battery running. I'll run extra wires to the front in case i want to add it later.

So the only question i have left is the fuse/wire size @ the battery for the aux fuse box? I understand it depends on my load but, unfortunately my brain only works in the ac world.
Looking at some pictures it looks like guys are using around a #8AWG. What have you guys used in the past?

Thanks for all of the help
Cheers

[telford dorr]

[aeromech]

I used a 6 gauge wire from the aux battery to a 30 or so amp fuse in the engine compartment and from there up to the front of the bus where I located the aux fuse block under the dash. I think bigger is better. I installed inline fuses between the batteries and the ACR. These were big fuses but I don't the size but at least 75 amp. The wires I used for that were around 1/0 awg welding cable. Like I said bigger is better. Here's some pics.

And here's a different bus

And here's a third one

and a fourth

_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[Franklll]

. I borrowed this pic but it's exactly like mine. Bluesea Automatic Charging Relay

I have had my second battery working for a few years and now I'm putting the batteries back in after winter and the second battery isn't charging. The Acr green light is flashing("combining" I believe it says) it's only showing about 5 volts when the van is running.

Does anyone have any ideas what might be wrong?

[aeromech]

I have had my second battery working for a few years and now I'm putting the batteries back in after winter and the second battery isn't charging. The Acr green light is flashing("combining" I believe it says) it's only showing about 5 volts when the van is running.

Does anyone have any ideas what might be wrong?

You'll need to read the literature on the ACR but as I recall the green combine light stays illuminated when closed (combined). It flashes when there's a problem. Your problem is probably that one of your batteries has too low of voltage. You'll need to put a charger on it and bring it up to around 10 volts before the ACR will close.

The reason for this is safety. Let's say you're out at sea in your boat with several scantily clad babes in small bathing suits listening to music and having a fantastic time. Now one of your batteries gets an internal short. If the ACR was allowed to close then your remaining good battery would be connected to a dead short (the other bad battery) and you wouldn't be able to start the engine.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[Mal evolent]

you got a part number and a source for scantily clad babes in small bathing suits?
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Baja Bugs for Volkswagen Virgins: Index

[Koeppler]

I’ve seen a lot of these Blue Sea ACR and battery switch installations on The Samba where both pieces are stuck to the battery somehow. So what’s the secret? I see screws and stuff but I know no one is actually screwing into their battery.

Can anybody help a guy out and explain how these bits get adhered to the battery?

[aeromech]

The top pic is mine. Here’s what I do.

Buy a battery hold down from Blue Sea. Take a piece of lexan plastic. Drill, countersink, and mount the appliances. Then sandwich the lexan between the top and bottom of the battery holder. Be sure to secure the battery tray to the vehicle so the battery can’t move.
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[Koeppler]

[mikedjames]

Your fuses go at the battery or power supply end to protect the wire from overheating when you short it, so the max fuse rating is defined by the wire gauge.

But if you know a wire is never going to need to provide a large current, then fitting smaller fuses than the wire gauge maximum is a good idea, it keeps voltage drops down, and protects against damaging other smaller gauge wires that might come into contact with the heavy wire.
It potentially stops loads/ equipment at the far end from completely self-destructing when it develops a fault too, although well designed kit should have its own correctly rated input fuses too.
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[aeromech]

Link


Here’s my latest aux battery installation into a 1972 camper. Just completed 2/10/24
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound

[sodbuster]

[aeromech]

That’s awesome
_________________
Lead Mechanic: San Diego Air and Space Museum
Licensed Airframe and Powerplant Mechanic
Licensed Pilot (Single engine Land)
Boeing 727,737-200-300-400,757,767
Airbus A319,320,321
DC9/MD80
BAe146
Fokker F28/F100
VW type 1 1962,63,65,69,72
VW Type 2 1971 (3 ea.) 1978, 1969
VW Jetta
VW Passat
Capable of leaping tall buildings in a single bound