Charging two batteries thru a Perko switch? Is it possible?

[BigStickFishing]

I have 5 batteries in my boat and only a 4 bank charger. I am wondering if I can use the one bank to charge both cranking batteries by putting the perko switch on both. I was told if I connect the positive lead of the charger to the common of the perko and the negative lead of the charger to the negative terminal of the main cranking battery then it will charge both. Any help will be great.

[Dirt Ball]

Are your cranking batteries connected in parallel?

If so, you can charge them with one bank.

[BigStickFishing]

Yes they are hooked in parallel but run thru a two battery perko switch. I am just curious as two where I would hook up the one bank to charge both batteries?

[PSM207]

Does the perko allow you to select either battery 1, battery 2 and both 1 & 2 combined in parallel?

[BigStickFishing]

Yes I can select Battery 1, Battery 2 or Both on the perko switch.

[Mcjenson]

If you select both it will charge both of them. The only issue is if the batteries charge unevenly. Since they aren’t on a separate channel on your charger, it won’t charge an exact voltage for each batteries charge level, just the average of the two when paralleled. Likely not a huge deal if both batteries are a similar age and in similar condition.

[Brewerbass]

Yes they are hooked in parallel but run thru a two battery perko switch. I am just curious as two where I would hook up the one bank to charge both batteries?

Just hook the charger to 1 of the batteries. Both will charge and also even out and be same voltage

[Skeeter08i]

I did the same thing with adding a 5th battery to my ZX 250. I have the 4 bank to charge the 3 trolling motor batteries and one of the cranking batteries. The other battery I mounted a Noco single bank 10 amp charger next to the 5th battery. Now when my switch is in the off position both batteries are still receiving the 10 amp charging rate.

I then hooked the plugs for both chargers to the adapter below and then mounted that in the factory location were the plug usually comes out.

https://www.amazon.com/NOCO-GCP2-18-...a-820529726782

[Coastal Mountaineer]

https://www.bluesea.com/products/765...ery_Kit_-_120A

Isolates starting battery when not charging, when it senses any charging current to starting battery, it combines them and sends charging current to both.

[limit5bass]

Following

[PMantle]

https://www.bluesea.com/products/765...ery_Kit_-_120A

Isolates starting battery when not charging, when it senses any charging current to starting battery, it combines them and sends charging current to both.

Can lithium be combined with AGM with this? Like, for charging only? Was thinking of putting all electronics on a lithium whilst keeping my AGM for cranking.

[Lightning 6]

Each battery should be isolated from each other & from the 120v circuit. Otherwise your batteries will suffer a premature death. Why-it is unbalanced charging. Smart chargers sense/ identify each battery’s state of charge & adjust the charging amperage & voltage as the battery recovers IAW the charger’s charging profile.

Can you charge batteries wired in parallel with one charging bank-sure….but it is not the correct way to do it.

[Slicefixer]

https://www.bluesea.com/products/765...ery_Kit_-_120A

Isolates starting battery when not charging, when it senses any charging current to starting battery, it combines them and sends charging current to both.

I was tipped off about the ACR Relay by a member here and can testify it works. I spoke to a buddy who owns a highly respected marine dealership (in business for almost 50 years) about it and he said, "it works.... and that's we install one on virtually every boat we sell."

[tajchauvin]

Can you charge batteries wired in parallel with one charging bank-sure….but it is not the correct way to do it.

Do you have a source of why this is not the right way to charge batteries in parallel? You can absolutely charge two batteries in parallel with one charger and it will not hurt either battery. One lead is connected to the positive of battery A and the other lead is connected to the negative of battery B. This will take twice the time to charge but will not at all hurt your batteries. The lower charging amps will actually be better for each batteries health.

Note that batteries should be of same age and size.

B74C6003-DAF7-4B93-9FA7-25CA6DA28181.jpeg

[wmitch2]

^^^^^This^^^^^ It's how I was taught in Electronics A School USN !! Also, it's how I run my Motor Home batteries too !!

[BigStickFishing]

Thank you so much this is exactly what i was looking for.