Trojan T-125's finally gone

brulaz wrote:

ktmrfs wrote:

...
for the 10 years I had them I was prudent but not anal about maintaining them. I have a trimetric monitor and on most outings they would get down to anywhere from 25% to 40% SOC (60-75% DOD). I was running a dorm fridge, cpap and furnace off them in a homebuilt small toyhauler. Then I'd hit them with the generator and a PD45A charger till they got to about 80%SOC, and repeat. Once home I'd let them get to as close to 100% as I could, but the PD will only get to 14.6V less than what trojan wants.
...

Those are deep discharges!
Roughly how many times a year would you go down to 50% or below?

You've prompted me to take another look at some battery's life cycle charts.

I can't find Trojan's cycle life graph for the T-125, but the T-105RE can do over 1000 cycles when pulled down to 20% SOC.

So you could, theoretically, do 20%SOC 100 times a year over ten years (with no other use). Most people don't even use their batts 100 times a year.

Maybe I'm being too anal about my self-imposed 50% limit. But my cheaper batts (US2200 and Duracell GC2s) aren't near as good as the T-105RE. The US2200 has about the same number of cycles (1150) but that's when pulled down to only 50%. There's only 675 cycles at 20% SOC.

Still, maybe I shouldn't freak out if SOC drops below 50% a few times a year.

Thanks for your report!

they had between 25 and 50 discharges to around 25 percent each year. The trojan website shows life vs. discharge and IIRC it is over 1000 cycles to 25 percent SOC. Remember, thanks to our golfing friends, these batteries are designed for golf carts that often get discharged near this level almost daily and are expected to last years.

RV use is pretty tame compared to golf cart use.

so with a good GC deep discharge, for most rv applications IMHO you can plan on going that deep on a regular basis if you can recharge resonably soon. And that means a GC really has 25% more useable capacity than a comparable 12V jar.

they define end of life at something like 75% of original capacity. likely about where mine are now.

the downside to the GC is the thick few plates means they suck for high current discharge compared to a 12V so for running heavy inverter loads they aren't as good. As I and others have found running a 1000W load on GC really means 4 batteries or an almost fully charged 2 battery set.

But I don't run the microwave that long or that often.

I've talked to several Trojan rep's at RV shows and they all said, taking the GC down to 25 percent is a non issue for RV life, just don't go below that. At the same time they said don't take the Trojan 12V deep discharge down below 50 percent.