Proper wiring in of a battery maintainer

[firefighter_2000]

I’ve searched and found several different answers. Looking for answers and “why”, not just an answer of this is how I do it.
I recently purchased a Battery Minder 2012-AGM. There is a Y cable that will allow the charger to connect two (or up to 8) batteries to the unit. Since the batteries are connected together with a large gauge cable is it necessary, or good practice, to use the Y & connect to both batteries, or is connecting to one battery sufficient.
Again, looking for answers, and a brief why that’s the best practice.
Thanks
Craig

 

[DavidC]

I connect to only one battery, the pass. side to be specific. I would think using the Y the maintainer may pick up a low/failing battery and keep cranking the juice to the system. My theory anyway.

 

[lpennock]

When batteries are connected in parallel you only need to connect to one battery to charge all them. Large gauge wire has almost no voltage drop at the current levels the chargers will put out so effectively all the batteries will see the same voltage but get 1/N were N is number of batteries charging current. Simple application of ohms law. Voltage in a parallel circuit is constant, current is devided by the rule of E/R. So if R is the same each battery will get the 1/N the current.

Now if R is different in one of the batteries you could get a case were that battery would take more or less current (failing batteries normally have lower R so take more current). In this just connecting in parallel won't balance the batteries; however, the Y adapter won't help either unless you break the parallel connection between the batteries.

Bottom line, as long as the batteries are connected in parallel the Y adapter does nothing. The Y adapters are necessary when batteries are in series. This allows each battery to only see the 12V from the charger even though the system is running a 24V (or more depending on battery count). This is the way you use a 12V charger to charge batteries in a 24V system. Without the Y adapter you would need a 24V charger and then each battery would see 100% of the current but only E/N of the charger voltage.

 

[firefighter_2000]

That’s EXACTLY the type of response I was hoping for!
Thanks!

 

[BigPapa]

Your alternator is only connected to the passenger side battery.

 

[firefighter_2000]

That’s another great point, I didn’t consider!

 

[AH64ID]

Over the years I’ve noticed that a lot of people use battery tenders on the passenger side. There is no benefit to one side or the other, so it must come down to proximity to power. Just a random observation.

I have a pigtail for my NOCO installed on the drivers battery as that’s the closest to power for me.

 

[DavidC]

Over the years I’ve noticed that a lot of people use battery tenders on the passenger side. There is no benefit to one side or the other, so it must come down to proximity to power. Just a random observation.

I have a pigtail for my NOCO installed on the drivers battery as that’s the closest to power for me.

There are no extra wires on the pass. side for me so installing the ring terminals was the easiest on that side without interrupting anything else.

 

[MrZippy]

I connected mine to the drivers side cause it was easiest. Ran it out the front of the grille.

 

[SBettencourt]

I connected mine to the drivers side cause it was easiest. Ran it out the front of the grille.

This is how I did mine. Connected to DS battery terminals. The pigtail hangs behind the bumper opening until I need it.

 

[DeansRedRam]

Still have the factory batteries in my 18... These trucks come with AGM batteries I believe right?

If so, I would have to go out and get a new battery charger!

 

[AH64ID]

Pretty sure my 18 doesn’t have AGM’s, just maintenance free.

You most likely don’t need a different charger.