Do you have to match all four batteries?

Don’t buy what your dealership is trying to sell you!

Hi Mike:

Many thanks for all of your advice in your blog! Most of us are completely in the dark!! I want to purchase four (4) Trojan T105 AGM (217 ah) batteries for my Class A diesel. 

The local RV dealership here in Maine has told me that they can provide me with the following:

1. Two (2) Motive 6 Volt AGM batteries (171 amp hours @ 5 hours); and 

2. Two  (2) Trojan Solar 6 Volt (SAGM 06 220) batteries: (220 amp hours @ 20 hours). 

Can these four (4) batteries be used “properly” together or do I need four of the exact same batteries? 

Will these four (4) batteries charge properly (fully) or will two of the higher amp batteries not charge fully because the lower amp batteries will be fully charged before the higher amp batteries are fully charged?

Will I have less amp hours overall because of the difference in battery amp hours of each battery? I look forward to your thoughts (when you have the time). Many thanks!!!!! M.R.

Dear M.R.

These four batteries need to be matched; exact same brand, model and capacity. If not, you’ll get less performance than you’re paying for, and probably a shorter battery life. Don’t buy what that dealership is trying to sell you.

FYI: Here’s how four 6-volt batteries are hooked up in series/parallel.

Let’s play safe out there - Mike