THE PORTAL HUB - Pinzgauers, Haflingers, Volvo 303s and more!

Battery Tender is a good brand. I have one to keep my LFP 12V AUX battery topped off.

Should be fine keeping your pair of batteries in a float state. I'm a bit surprised you even
need a trickle charger -- assuming you open your Ground switch. Then you only have a
rather small internal-discharge, but that can worsen with age, and Temp.

But -- this trickle charger should be just fine.

Yeah just thought it was a good idea to keep them topped off all the time since it sits sometimes for a week+ plus it can get pretty cold here.

I'm starting to suspect Ill need new ones soon though. The NATO Odyssey batteries seem like the best upgrade but holy crap they are expensive, plus I wonder about the lack of a TPPL or AGM charging profile from the alternator. I've never understood how they push the AGM upgrades for many vehicles when they aren't charging at a high enough voltage.

Experience ... lol. I found that standard AGM batteries will work just fine in the Pinzgauer, but you have to handle the imbalance somehow, topping off, balancer, isolator, whatever system you want.

Also, don't expect them to last more than 4 years ... maximum. It happens that sometimes they'll go longer, but that slight difference in how they charge seems to wear them down faster than a simple 12V system. Topping them off helps, but ultimately it seems to wear them down. I attached a tiny voltmeter in the cab that goes to each battery and stuck a toggle switch on each, so I can check the voltage while running, idling, or off. I also let it sit for weeks at a time without starting. Had to swap out batteries after 3.5 years of use last year. I just assume that they will get wiped out by maybe 2028 at the latest.

Just an FYI, been through 2 sets of Optima Yellow's on my 710K Pinz'y.
Fist set had some years on it from the PO. Second set was all
on my time. Both sets lasted a scoot over 10 years. Ironically,
I just replaced my 2'nd set two weeks ago, Datecode was 8/2015.

So....if your only getting 4 years, could be the Manufacturer?

Just say'n

I had really bad luck with two Bosch AGMs which I assumed were some of the best. This was in an old Gwagen I had... one lasted one year or so, and the other was showing issues at 2 years. My alternator was fine. It did sit sometimes but not that long. I swore AGM off after that.

The Odyssey (Thin Plate Pure Lead) is different than just about every battery out there. Lots in use in military and commercial applications but the charging profile is closer to AGM so if I went that direction, I'd probably plug into a trickle charger that has the TPPL or Odys. profile built in. I've seen a charger that actually had an "Odyssey" option on the battery selector switch.
Check out their 80's vibe factory video. Shows what you are paying for...
https://www.youtube.com/watch?v=JkstixBuwjc

I also have a pair of optima yellow tops that are 8-9 years old and ding well.

Competing datapoint against Optima yellow-top:

I installed an Optima 8037-127-FFP D27F in a daily-driver '07 FJ Cruiser in Feb 2015, and it was unserviceable (low charge retention and poor cranking performance) just over five years later (Aug 2020). The original Panasonic wet cell from 2007 still outperformed the Optima yellow-top despite being eight service years older and 13 years old overall.
Testing the Optima on a professional battery analyzer, even at a relaxed discharge current of 2.5A, it demonstrated only 30.0Ah capacity (room temperature).

I replaced the Optima with a Duralast Gold Battery, 27F-DLG and now five years later it's stronger than the Optima was after the same number of years.

My Optima experience wasn't optimal.