Battery drain over winter

[Gjac]

I fully charged my 2 6V Sam's Club GC batteries as well as my 12v starting battery in Oct when I winterized the MH. I checked the SOC yesterday and the house batteries were still at 80%. Each year I expect to buy new batteries in spring because these are 16 years old. I have been leaving them off the charger all winter since new in 2007. On my starting battery I disconnected the neg post over winter and that battery only saw a 5% drop in voltage. I post this because a lot of people ask this question about whether to remove their batteries for winter storage and bring them into the house or keep a trickle charger on all winter and all year for that matter. Keeping them on a smart charger or trickle charger seems safer and I realize more batteries die from sulfation, but there is still a chemical reaction taking place while charging and some plate shedding going on. Even during camping season, the MH stays unplugged until they self-discharge 20% then they get fully charged. I'm just curious what others on here do to extend the life of their batteries?

[Gjac]

Another thing I observed, is that my smart charger does not fully charge the batteries. I am guessing it charges to 95-97% SOC, because when I float charge with my old Magnatec 950 constant converter/charger at 13.6v for a few days after the smart charger says full, I can dry camp for a few more days without generator recharge. I have no way of quantifying this, but I think that this automatic charging to 97% or so when you keep your MH plugged in, builds up sulfate over time because the batteries never see 100% SOC. I don't know if anyone else on here has observed this or read anything about it.

[pianotuna]

Gjac,

Keep on doing what you have been.

[KD4UPL]

I leave my batteries in my boat all winter with no charging from about October to April. I just replaced one of them because it was starting to crank the engine kind of slow. It was 9 years old.
I certainly wouldn't want to wrestle those 2 heavy batteries out of the boat and back in every year. I don't know why people think they need a trickle charger all winter.

[Boon_Docker]

I fully charge the golf cart batteries in the fall then disconnect them. They sit outside until spring and lose less than 10% charge over the winter. They are 11 years old and still going strong.

[Trackrig]

I keep my hunting rigs up near Fairbanks, Alaska. The rigs are used for most of the month of Sept to go moose hunting. They're then parked where there is no electricity. Most of the time they won't be started again until July or Aug of the next year when I pull maintenance on the rigs. While I don't disconnect the batteries (each rig has multiple batteries due to the electric winches) I do have nice Blue Seas battery disconnects on them within 2 ft of the batteries.

On the average, my batteries last 7 years. Temps will hit -50F during the winter and my winters last longer than most people's winters are. It's still below freezing most nights.

Bill