Battery size setup

[Manny]

Just purchased new Nitro Z6
I upgraded to the 24v system for trolling motor.
I told them at bass pro that I just purchased a 185 size deep cycle battery for the pontoon I had. So I asked them to just install one, and I would drop the other in it after pickup.
They also knew it was the bigger 185 size. ( both battery's same brand from bass pro)

They installed the 175 in the boat... After installing my battery I noticed a difference in them.
I ran for a couple months like that with the onboard charger going to green.

Now when I leave the boat plugged in a few days it still won't go to full charge. Light stays red as if it's trying to charge.
Removed them both out and tried to charge at home with my garage charger. I found that neither battery will charge past 70 percent.
What do you think?
Was it the mismatched battery size to screw them both up?
Both only about 4 months old.

Thanks for any help..

[CatFan]

Different sizes wouldn't do that. Have you checked the liquid level in the batteries? Are you sure that a charger bank is connected to each battery?

[Manny]

Yes charger bank connected to each battery...
And no I have not checked levels, will do that next.

Wouldn't seem they would be low in the 4 months I had them..
But will definitely check it out. And try to charge again.

[Barnacle Bill]

Yep, it sounds like one of them is bad (or just low water). Since you have them out, charge them up then have them load tested at your local auto part store. They don't charge for that.

[Manny]

Just read up on batteries they are both maintenance free AGM batteries.
Now what???
I can't get them to charge past 70 percent with home charger.

[wicklundrh]

It isn't the charger that caused the issue. With a 24v system and an onboard charger, your charger is connected to each battery seperatly. The problem however is that you had two different battery sizes connected (in series) to operate your 24V system. Most documentation you will read from a trolling motor company (or any recomendation for a 24v or 36v system) is to utilize the exact same size battery. Reason being is that your have load differential that ends up causing issues (like you are seeing).

AGM batteries are decsigned to not allow for discharges like standard wet cell batteries. I'm not sure about Bass Pro, but cabelas batteries are warrentied for 18 months after purchase. I would contact BP and ask them. If they do, they will give specific instructions for returning them and getting replacments. Make sure you get the same size or you will again have issues.

You can google "same size batteries for 24v system" and find a ton of usefull information.

[Alboy79]

Being only 4months old, are they still under warranty?

[Manny]

Thanks for the info
I'm sure they are still under warranty.

[wicklundrh]

Good deal. Hope they take care of you