Jump starting. Which battery?
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More Turbo
Joined: Sep 2007
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From: Centerbrook, Ct.
Jump starting. Which battery?
I have a 2020 F250 KR with the 7.3L and dual batteries. If I needed a jump, or needed to jump start someone else, which battery should I hook up to? Does it even matter which? I've searched my OM, but found nothing on it.
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Tuned
Joined: Aug 2020
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I also would like to know. Not sure if they are just directly connected to each other, or isolated. Like if you disconnect the positive wire to change the battery, is the red lead still live since its connected to the other battery?
Postmaster
Joined: Jan 2005
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From: BC Canada
Passenger side battery, with two batteries is where the alternators go to, where the starter comes off, all the electronics are on the drivers side, so stay away. Also, don't use the negative terminal on the battery, use a ground location and the positive post for jumping on both vehicles. Decreases risk of battery off gassing igniting from a spark.
Laughing Gas
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Hotshot
Joined: Oct 2015
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The batteries are wired in parallel. The starter is going to pull from BOTH batteries. Will it be a 50/50 load on each battery? Likely not, due to cable length.
Put a DC clamp-on ammeter on both batteries and see what you get.
Put a DC clamp-on ammeter on both batteries and see what you get.
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Laughing Gas
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I use my truck as a mobile office and run a bunch of electronics. In my last truck (GM) I isolated my starter battery with a smart isolator and installed a deep cycle AGM for my other battery that all the accessories were hooked up to. This allowed me to run my electronics for 2-3 hrs without the truck running and then still had a fully charged battery to start the truck.
It was pretty easy to rig up on that truck since it only had one battery and I added the second, then I just rerouted the starter to it and instated the smart isolator(ACR).
I'm thinking it will be more involved if I want to do the same to my new truck which has factory installed dual batteries. I'm guessing they both have things hooked up to them. Ford actually does a good job at wrapping all its wires into one nice clean harness but it makes it hard to trace and follow what wires go where.
Hotshot
Joined: Jul 2013
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Passenger side battery, with two batteries is where the alternators go to, where the starter comes off, all the electronics are on the drivers side, so stay away. Also, don't use the negative terminal on the battery, use a ground location and the positive post for jumping on both vehicles. Decreases risk of battery off gassing igniting from a spark.
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