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I have a 2022 F350 diesel with dual batteries. I don't use the truck often in the winter and would like to keep it hooked up to a Battery Tender. I have not had a truck with dual batteries before. Is it okay to hook the charger up to just the battery on the driver's side? I'm not sure how to properly handle this to ensure both batteries are properly charged. TIA
I thought I read they are isolated from each other, at least when the ignition is off. Never got a definitive answer. I was planning on adding 2 plugs, one for each, so I can keep each one on a battery maintainer without opening the hood. Note I have a gas with duel batteries. Not sure if the diesels are wired differently.
Ctek recommended that I attach the positive to one battery and then negative to another. I have been doing that to my dual battery 2023 7.3 gas engine.
I thought I read they are isolated from each other, at least when the ignition is off. Never got a definitive answer. I was planning on adding 2 plugs, one for each, so I can keep each one on a battery maintainer without opening the hood. Note I have a gas with duel batteries. Not sure if the diesels are wired differently.
I use the Battery Minder 128CEC2 (https://www.batteryminders.com/batte...er-maintainer/) on all my batteries and added a Y-splice so I could keep both of my TT batteries on charge in my garage during the winter (which are finally giving up the ghost after 9 years). I also have the dual-battery setup on my 7.3, so if there's concern about isolated batteries, couldn't you just hook both up to the same charger through spliced cables? To this point I've just been hooking the charger to one battery with the expectation that both are charging.
Interesting. I always understood it that they were connected and putting the maintainer on one worked for both. But now that it seems to be in question, I'll put a voltmeter on each battery when the maintainer is on. If there is a difference in voltage between the batteries, I'll assume they are not connected.
On my 23 the batteries are connected in parallel. On the passenger side is the BMS sensor. I have the red wire from my pigtail on the passenger positive terminal and the negative on the truck side of the BMS sensor. This way the BMS can sense that I'm putting charge back in from the battery tender.
The references to "charging" in my 2020 owner's manual are for wireless gadget charging. Did find this, though...
Does this suggest that, when charging a dual battery system, one should not connect a lead to pos of one batt and the neg of the other? I've wired my maintenance charger to the driver's side battery simply because there was room, grounded to the chassis as per above. Wish there was better info from Ford but they don't even include an engine overview diagram for the dual battery set-up in the owner's manual.
Batteries are tied together if the above diagrams are correct..
info from this thread: https://www.ford-trucks.com/forums/1713837-dual-batteries-charging.html
Don't overthink it. Both batteries are in parallel. Put the positive lead from the charger onto one of the positive posts. Put the negative lead from the charger onto one of the negative posts or to a chassis electrical ground if that makes you feel better.
Ford's warning regarding connecting to the battery post is for accessories added to the truck, not for battery charging while the truck is not in use.
Don't overthink it. Both batteries are in parallel. Put the positive lead from the charger onto one of the positive posts. Put the negative lead from the charger onto one of the negative posts or to a chassis electrical ground if that makes you feel better.
Ford's warning regarding connecting to the battery post is for accessories added to the truck, not for battery charging while the truck is not in use.
I think another reason to connect the negative to a grounding bolt is to avoid sparks near the battery vent.(if you go post to post).
For my own piece of mind, I checked both batteries with a multimeter after having the driver's side battery on a maintenance charger for a couple of weeks. They were at identical voltages, fully charged.
The requirement for connecting to a ground stud instead of the negative battery post is due to the BMS. The BMS needs to measure the flow of current into the battery to accurately measure the battery state of charge and "health". If your vehicle does does not have the sensor on the battery cable, you don't have BMS. A couple of downsides to improperly measured battery SOC is auto start/stop won't work properly and automatic power down on accessory may happen prematurely. Many people disable BMS by unplugging the current sensor without problem.
I believe the instructions not to connect to the negative terminal, to avoid issues with the BMS are only important in regard to accessories that would be operated with the engine or ignition on.
I don't see how charging the batteries would cause any issues with the BMS, with the ignition off, and don't think it would be an issue even with it on.
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