They go bad but put new battery or buy a jumper box small and
https://cimg5.ibsrv.net/gimg/www.off...cab629d486.jpg
they work well

Most folks forget about the extra 0.2V on a lead acid cell.

But I can't see that both batts have a dead cell.

Tartilla,

Yes. Lead acid. One is a Walmart EverStart Maxx, 29 series, the other is a store brand from Sun Auto in Sumerset, KY, 27 series. It’s my intention to replace the 27 with another 29 when it goes bad. After getting a better look at things, it’s the newer one (the 29) that is exhibiting the odd behavior. I had them backwards in my OP.

I don’t keep the habit of removing the batteries from the boat for winter. I usually just put the tender on them and leave them for the winter. As I said, the boat is kept climate controlled.

We don’t have a set winterizing date, since I keep it indoors, and we’ve been know to take advantage of those random Indian summer days. I also sometimes fail to put the tender on them during the summer, because we take it out on a fairly regular basis (might have to change this habit). It may have taken me awhile to get the charger on them after putting it away for what turned out to be the last time. Memory is fuzzy sometimes. I have a suspicion they are both fine. I just have to wake them up.

We’ll see how it goes Monday morning.

Thanks. Brad.

I gave up on those tenders.

If your interested; https://www.offshoreonly.com/forums/...l-battery.html

UnderPsi,

I’m not really sure what I’ve got is a “tender” as such, but more of what you suggested there, just a much cheaper (price and quality) version.

I may have to take you up on that. Let me chew on it a bit.

Thanks. Brad.

2 out of 5 star rating for that battery tickler :)

Sounds like just the port batt. When you remove a fully charged batt from a tender/trickler type charger for a bit then re-attach, its normal for the yellow light to come on for a while before switching to green. I have 5 trickle chargers from 4 different manufs and they all act like that. I suspect the starboard batt will go green if left on trickle charger for a while.

If no joy by Monday, I'd take it back to the store. They will do a quick charge then a load test.

I used to pull batts for winter, but haven't done it for the last few years. Doesn't seem to make any difference. They stay on the maintainer all winter.

If batt isn't sealed, should verify water level is good. A specific gravity test would also be a good idea if you happen to have a tester handy.

Scott,

Yup. The war dept just read me the riot act about not checking reviews on it.

Hey…. It was a semi-impulse buy from Walmart that has lasted me two seasons. I’ll take that these days. But I am getting smarter.

Thanks. Brad.

ZZ,

Yup. It was just the port battery. At least until I swapped the leads. Then both stayed on “faulty yellow”, even after swapping them back. I’m hoping/thinking it’s just the charger that has gone south, if it’s not just that they were allowed to discharge too far before hooking them up. We’ll see.

Thanks. Brad.

Just noticed you're using a 2 bank charger. I have no experience with those. Could be one side died and the other may be affected too??

I bought these single batt maintainers abt 8 years ago from Walmart. They have worked flawlessly on my Interstate marine Batts. On season 6 this year.
https://cimg1.ibsrv.net/gimg/www.off...394d0ddbce.jpg