Dual Battery Set Up Help (1 Viewer)

[LS1FJ40]

As long as you also run a ground from isolator to negative battery terminal, then I agree.

Right. I thought that ground was part of the start isolation system but the ACR needs to be grounded too.

I ran a 12ga ground from the ACR to the negative post.

 

[LS1FJ40]

 

[Dirty Koala]

Looks good, enjoy your trip.

 

[Payara Offroad]

I had that system in my previous 80 and I installed 2 fuses (one for each battery on the positive wire and as short as possible close to each battery terminal).

 

[Irish Reiver]

@LS1FJ40 what battery terminal connectors did you end up using and would you still recommend them?. I am searching amazon at the moment and there dosent appear to be an outstanding best in class product

 

[LS1FJ40]

I had a cheapo "military" connector. It's crap. I wouldn't recommend it. I bought two of these to have the same connector. I have to make a new ground that has a ring terminal on it. Just was looking at these and wondering why I haven't done this yet.

FYI, it's the same terminal as the positive. My guess is that they never intended anyone to put anything on the negative side so they just leaded the ground in.

@LS1FJ40 what battery terminal connectors did you end up using and would you still recommend them?. I am searching amazon at the moment and there dosent appear to be an outstanding best in class product

 

[Irish Reiver]

Thanks dude. I just ordered 2. I'm sure it is easier to work backwards from this terminal and find the correct cable connectors than the other way round....

 

[LS1FJ40]

Just make a new ground from the battery to the engine block while you are doing everything. I didn't have enough cable so I ordered more but then I got sidetracked... Having both the same makes it cleaner with the top bolt. They don't come with the nut though so you'll have to pick one up at Lowe's.

 

[Hornd]

@LS1FJ40
Did you connect the - posts or run one to frame ground for each battery.

I mounted the ACR on 2nd battery box (LH)
Running my wires in Radiator support.
Bought multi-straded 2 AWG 11' ($25) and it looks to barely be enough. I would not use THHN Wire from Lowes. You want something with lots of strands. Be careful some, Battery Cables/Welding Grounds are not oil resistant.
I'm using auto reset fuses I got on Ebay ($16) and 80 Amp.

 

[Hornd]

I had a cheapo "military" connector. It's crap. I wouldn't recommend it. I bought two of these to have the same connector. I have to make a new ground that has a ring terminal on it. Just was looking at these and wondering why I haven't done this yet.

FYI, it's the same terminal as the positive. My guess is that they never intended anyone to put anything on the negative side so they just leaded the ground in.



View attachment 1351174

If you don't have Amazon Prime, they are $21 a set on Ebay shipped.

 

[LS1FJ40]

Connected the posts.

The wire I used was welding wire recommended by others. It's not from Lowe's. It appears to be good quality stuff.

I mounted my Blue Sea on the passenger side fender.

@LS1FJ40
Did you connect the - posts or run one to frame ground for each battery.

I mounted the ACR on 2nd battery box (LH)
Running my wires in Radiator support.
Bought multi-straded 2 AWG 11' ($25) and it looks to barely be enough. I would not use THHN Wire from Lowes. You want something with lots of strands. Be careful some, Battery Cables/Welding Grounds are not oil resistant.
I'm using auto reset fuses I got on Ebay ($16) and 80 Amp.

 

[mct75]

Is it really a good idea to connect a (possibly) discharged deep cycle battery to a fully charged SLI battery? The two batteries normally different charge profiles/voltages and shunting them together is going to blast current from the alternator/SLI battery into the DC battery. The SLI battery should be able to handle this, but the DC battery might not like such a large "bulk" charge. Yes it does work, but I do not think it is proper.

I've been arguing with myself about this for a while, but I think a more proper way to do this would be to either have another alternator/voltage regulator or a DC powered battery charger for the house battery. Tying it into the ignition and alternator "charge lamp circuit" would ensure that the house batteries are only being charged from a healthy alternator.

Or, run two massive DC batteries permanently connected together, and just don't go camping for more than a week at a time.

You can always be like this guy, that's only 1000 pounds of lead there. I bet he does not worry about the ARB fridge.

 

[Hornd]

Is it really a good idea to connect a (possibly) discharged deep cycle battery to a fully charged SLI battery? The two batteries normally different charge profiles/voltages and shunting them together is going to blast current from the alternator/SLI battery into the DC battery. The SLI battery should be able to handle this, but the DC battery might not like such a large "bulk" charge. Yes it does work, but I do not think it is proper.

I've been arguing with myself about this for a while, but I think a more proper way to do this would be to either have another alternator/voltage regulator or a DC powered battery charger for the house battery. Tying it into the ignition and alternator "charge lamp circuit" would ensure that the house batteries are only being charged from a healthy alternator.

Or, run two massive DC batteries permanently connected together, and just don't go camping for more than a week at a time.

You can always be like this guy, that's only 1000 pounds of lead there. I bet he does not worry about the ARB fridge.

It's my understanding that the Blue Sea 1st chks voltage on primary battery and when it's full it switches over to charge the secondary battery.
Can you explain how they are connected?

 

[mct75]

The SI-ACR is just a relay with some intelligence. Once it trips "on", you've shorted the two batteries together. It's not an intelligent charger or current limiting device. Your SLI battery and alternator begin dumping current into the DC, invariably draining the SLI battery some. Unless I am missing something.

 

[LS1FJ40]

It's my understanding that the Blue Sea 1st chks voltage on primary battery and when it's full it switches over to charge the secondary battery.
Can you explain how they are connected?

That is correct. It isolates the two.

Negative terminal to negative terminal.

Positive terminal of main batt to Blue Sea ACR then Blue Sea ACR to house battery.