How does one charge a dual battery vehicle?

RKW wrote:
The driver side battery was dead. No measurable capacity. The passenger battery had a capacity of 550. I replaced both. I also bought a Battery Tender and will mount it somewhere under the hood.

So you go long periods without running the truck? Hence the battery tender?
Good call if it sits for months at a time.
If it's a regular or semi regularly driven vehicle, a tender is unnecessary.

^ This. Next topic...

RKW wrote:
What is the proper method of charging the batteries in a vehicle with dual batteries? Specifically my 2015 Ford SuperDuty Diesel.

Hook up the charger to which ever battery is easiest to get to. The batteries are connected in parallel.
They will both charge when a charger is connected to one of them

RKW wrote:
The driver side battery was dead. No measurable capacity. The passenger battery had a capacity of 550. I replaced both. I also bought a Battery Tender and will mount it somewhere under the hood.

I had to replace my OEM set on my 2015 this fall as well. I don't know if it's climate related or what, but I can't seem to ever get more than about 4 years out of car/truck batteries before they need to be replaced.

My 2000 F350 diesel gets used so little, I keep it on a 6A three stage smart charger, mounted just in front the secondary battery. I hate replacing 2 batteries....$$$$

The driver side battery was dead. No measurable capacity. The passenger battery had a capacity of 550. I replaced both. I also bought a Battery Tender and will mount it somewhere under the hood.

Thanks for the responses. I ended up charging a single battery while it was in parallel. I'll have the health of the batteries checked and will replace based on the results.

cummins2014 wrote:

RKW wrote:
What is the proper method of charging the batteries in a vehicle with dual batteries? Specifically my 2015 Ford SuperDuty Diesel.

My question ,why are you having to charge them ?? Reason I ask is its a 2015 ,and I suspect you are due for new batteries. Just went thru this. I jumped it twice , drove it ,and it started okay the next day, the day after no go. That was enough of that , new batteries .

The biggest signs on the Ram trucks, and my son experienced it too, was crazy stuff happening electronically , radio not working etc. There is no slow cranking with these Rams, telling you the batteries are getting bad, its just one day it won't start. Just a click.

As far as charging I would disconnect them ,and charge separately.

My 2015 with 60K on the clock got batteries in Sept. If the voltage drops to much the "electronics" terminate the start sequence.

RKW wrote:
What is the proper method of charging the batteries in a vehicle with dual batteries? Specifically my 2015 Ford SuperDuty Diesel.

My question ,why are you having to charge them ?? Reason I ask is its a 2015 ,and I suspect you are due for new batteries. Just went thru this. I jumped it twice , drove it ,and it started okay the next day, the day after no go. That was enough of that , new batteries .

The biggest signs on the Ram trucks, and my son experienced it too, was crazy stuff happening electronically , radio not working etc. There is no slow cranking with these Rams, telling you the batteries are getting bad, its just one day it won't start. Just a click.

As far as charging I would disconnect them ,and charge separately.

harmanrk wrote:
Start the engine and let the alternator(s) do its job. .

I don't remember ever having to charge my truck's batteries. I didn't have any phantom loads that would draw it down.