Battery Mixing for Boondocking

[Homerjoeyt]

I currently have the 165W solar panel setup in my new travel trailer. The battery it came with is an Interstate Deep Cycle SRM-24 550 CCA. I am thinking of adding another Interstate battery EFB24M with 700 MCA. Is there a problem with running these two in parallel? Also, i am assuming they will both charge off of my solar panel system, correct?

[howson]

I currently have the 165W solar panel setup in my new travel trailer. The battery it came with is an Interstate Deep Cycle SRM-24 550 CCA. I am thinking of adding another Interstate battery EFB24M with 700 MCA. Is there a problem with running these two in parallel? Also, i am assuming they will both charge off of my solar panel system, correct?

Hmmm...I know it's possible to parallel batteries of the same capacity and type. Not sure about mixing same type but different capacities. TucsonJim ?

Before you invest more $$ in a lead-acid, consider going with one lithium. If you're into details as to "why", this video by Morton on the Move goes into excruciating detail.

[JCR GD]

I think charging properly will be the problem. The different capacities will probably cause the solar controller and converter/charger fits. May overcharge/boil smaller batt and/or never completely charge larger.

[TucsonJim]

The following information is from Optima battereries.

"We would strongly discourage anyone from connecting (dissimilar) batteries in series or parallel applications, if the batteries are not identical in age, size and type. It sounds like your batteries are different in each of those ways. Different brands of batteries can have different charging and discharging characteristics, with some accepting a charge or delivering current faster than others. That can be true even if the batteries are the same size. Different types of batteries (flooded or AGM) also can have different charge/discharge characteristics. When you connect two or more batteries that don't charge and discharge at the same rate, one battery will probably end up overcharged and/or one battery will end up undercharged. Neither is a scenario you want to have happen to your batteries, as it will probably shorten the lifespan of both and could create a potentially create a dangerous situation, if one battery gets severely overcharged.

The same is also true of batteries that are identical in every way, except that one battery is older than the other. As batteries age (or get used), their charge/discharge profile changes. As such, they essentially charge and discharge at a different rate a year later, than they did when they were brand-new. That means you shouldn't connect batteries together that aren't the same age or haven't been used in the same application since they were new, even if they are the exact same make and model.

Unfortunately, that means when one battery in a bank of two or more batteries needs to be replaced, they should all be replaced at the same time. That doesn't mean the other functioning batteries should be discarded entirely, but they should not be used in an application that has batteries that differ in age, size or type. For some marine and RV applications that use a lot of batteries, it may make sense to isolate a larger bank of nine batteries into three smaller banks of three batteries, instead of connecting them all together. That way, if one battery goes bad, far fewer batteries need to be replaced."

Source:
https://www.optimabatteries.com/expe...es-in-parallel

Jim

[Homerjoeyt]

Thanks guys, unfortunately this was not the answers i was looking for but now that i need to buy two new batteries or maybe just one lithium battery i gave to think about this a little.

[Jlawles2]

Homerjoeyt If you can find one and it fits in the box, the Interstate battery https://www.interstatebatteries.com/...ategoryid=true carries almost the same total capacity as the 2 batteries you were considering for the about the same price as the one.