Dual battery question

Wolfs4evr

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So I ordered my 7.3L powered truck with the 397amp/dual battery option. I wanted redundancy since the weather in Vegas is extremely harsh on batteries and didn't want to be out in the middle of nowhere when a battery decides to unexpectedly die. Plus I want a winch eventually and I run off road lighting. I was a little surprised to see that meant 2 alternators. Wasn't expecting that. Anyways not really sure how the power flows with this setup. Not even sure if I will get an alert in the truck if one fails. Is there anyone out there knowledgeable on said subject that can enlighten me?

The main reason for this post is here in the next couple weeks I plan on installing a ARB twin air compressor. I'm wondering if I need to connect to the passenger side main battery or fine running off the secondary battery? The Ford installed positive battery terminal on the second battery does not have a connection point on it like the main battery. Makes me think you're not supposed to run stuff off the secondary battery. I really want to be able to run off the driver side second battery since the compressor install will be on that side of the truck but want to be correct so will do whatever is needed to be correct.

Thanks, Tom
 

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So I ordered my 7.3L powered truck with the 397amp/dual battery option. I wanted redundancy since the weather in Vegas is extremely harsh on batteries and didn't want to be out in the middle of nowhere when a battery decides to unexpectedly die. Plus I want a winch eventually and I run off road lighting. I was a little surprised to see that meant 2 alternators. Wasn't expecting that. Anyways not really sure how the power flows with this setup. Not even sure if I will get an alert in the truck if one fails. Is there anyone out there knowledgeable on said subject that can enlighten me?


The main reason for this post is here in the next couple weeks I plan on installing a ARB twin air compressor. I'm wondering if I need to connect to the passenger side main battery or fine running off the secondary battery? The Ford installed positive battery terminal on the second battery does not have a connection point on it like the main battery. Makes me think you're not supposed to run stuff off the secondary battery. I really want to be able to run off the driver side second battery since the compressor install will be on that side of the truck but want to be correct so will do whatever is needed to be correct.

Thanks, Tom

I don’t have a direct answer, but it is easier running everything to passenger side. Do you have upfitter switches? If so, I would hook your ARB system to it.
 
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Wolfs4evr

Wolfs4evr

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Distance starts being the enemy. I plan on attaching the twin air to my driver side rear Builtright rack (the only open spot I have without changing stuff up plus it puts the compressor at an easy access spot). The max length power extension one can get is 15ft (I already have laying on my bench). The oem power is 6ft. Giving me 21 feet. From the driver side battery I know no issue but from the passengers side I'm thinking really close to not happening. For the switch I'm just wiring the ARB switch up next to the unit pretty much like the suitcase portable ARB twin is setup. I have the upfitters but have no intention/reason to be running more wires all over nor the requirement to be able to turn on from the cab. Plus eventually there will be more lights so want to save the upfitters for them.

If I have to go to the passenger battery then I'll start rethinking the install all over. I just want it to be correct the first time so making sure all my bases are covered.

Tom
 
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That option did not come on my truck. Can someone post a picture of the set up. Thanks.
 
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Wolfs4evr

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I highly doubt any 7.3L truck sitting on a lot would have this. Advantages of ordering.

20200609_074928.jpg




20200609_075012.jpg

Tom
 

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So I ordered my 7.3L powered truck with the 397amp/dual battery option. I wanted redundancy since the weather in Vegas is extremely harsh on batteries and didn't want to be out in the middle of nowhere when a battery decides to unexpectedly die. Plus I want a winch eventually and I run off road lighting. I was a little surprised to see that meant 2 alternators. Wasn't expecting that. Anyways not really sure how the power flows with this setup. Not even sure if I will get an alert in the truck if one fails. Is there anyone out there knowledgeable on said subject that can enlighten me?

The main reason for this post is here in the next couple weeks I plan on installing a ARB twin air compressor. I'm wondering if I need to connect to the passenger side main battery or fine running off the secondary battery? The Ford installed positive battery terminal on the second battery does not have a connection point on it like the main battery. Makes me think you're not supposed to run stuff off the secondary battery. I really want to be able to run off the driver side second battery since the compressor install will be on that side of the truck but want to be correct so will do whatever is needed to be correct.

Thanks, Tom

Curious where you read that the 397 amp option for 7.3 says 2 alternators? The way I read the description for that package, it says “A 397 amp alternator...” which requires dual batteries. I read that as 1 alternator and 2 batteries
 

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Curious where you read that the 397 amp option for 7.3 says 2 alternators? The way I read the description for that package, it says “A 397 amp alternator...” which requires dual batteries. I read that as 1 alternator and 2 batteries

I was under the impression you could have dual batteries with a larger amp or two smaller ones.
 

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Curious where you read that the 397 amp option for 7.3 says 2 alternators? The way I read the description for that package, it says “A 397 amp alternator...” which requires dual batteries. I read that as 1 alternator and 2 batteries


Furthermore, I want the dual batteries as well, and I’d like to isolate them to run a fridge off one when parked. So then the questions is will the truck start on one battery? I’d need to know the CCA amp/hr rating of each individual battery which the build sheet says is 78 AH.
 
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Wolfs4evr

Wolfs4evr

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Curious where you read that the 397 amp option for 7.3 says 2 alternators? The way I read the description for that package, it says “A 397 amp alternator...” which requires dual batteries. I read that as 1 alternator and 2 batteries
I saw/read/thought the same as you. Was totally surprised to open the hood for the first time and see 2 alternators down in there.

Tom
 
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Wolfs4evr

Wolfs4evr

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Furthermore, I want the dual batteries as well, and I’d like to isolate them to run a fridge off one when parked. So then the questions is will the truck start on one battery? I’d need to know the CCA amp/hr rating of each individual battery which the build sheet says is 78 AH.
The batteries are identical.

20200618_114901.jpg


Tom
 
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Wolfs4evr

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After getting the compressor and playing around with mount locations I decided to mount it in the front of the bed. Which still needs an power extension but not 15ft worth. Looked around and found a 90" power extension which is perfect. 6-10 inches to spare. . Also decided to just go to the passenger/main battery. Since I was running wires up to that side I decided to wire it into the upfitters verse just having a switch back next to the unit.

Still waiting for my ARB remote air fitting and 2m of braided steel airline to show up. Will mount that back by the back of the bed.

Works like a charm. 20-60psi in 3 1/2 minutes.

The 2 40 amp fuses I just ziptied in an easy access place. 1 positive for each motor and 1 combined negative for both motors plus a tiny negative make up the ARB harness.

20200618_114929.jpg


20200618_071517.jpg


20200618_071509.jpg


Tom
 

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After getting the compressor and playing around with mount locations I decided to mount it in the front of the bed. Which still needs an power extension but not 15ft worth. Looked around and found a 90" power extension which is perfect. 6-10 inches to spare. . Also decided to just go to the passenger/main battery. Since I was running wires up to that side I decided to wire it into the upfitters verse just having a switch back next to the unit.

Still waiting for my ARB remote air fitting and 2m of braided steel airline to show up. Will mount that back by the back of the bed.

Works like a charm. 20-60psi in 3 1/2 minutes.

The 2 40 amp fuses I just ziptied in an easy access place. 1 positive for each motor and 1 combined negative for both motors plus a tiny negative make up the ARB harness.

View attachment 2430

View attachment 2431

View attachment 2432


Tom

Did you happen to find out if it has a battery isolator built in or not?
 

Wanabxtrm

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For those with a dual battery, if you disconnect it and run on only one will it throw a code?
 

Chris21667

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For those with a dual battery, if you disconnect it and run on only one will it throw a code?
no it won't it is a in line 12 v system .... it not looking for 24 v when would throw a code if missing one ... disconnected mine to run and drill in the winch cables on my secondary battery no code
 

Wanabxtrm

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no it won't it is a in line 12 v system .... it not looking for 24 v when would throw a code if missing one ... disconnected mine to run and drill in the winch cables on my secondary battery no code

If that’s the case, I would tend to think that adding an isolation switch (if desired) shouldn’t throw off the BMS to much.
 
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