Battery not holding charge

[Markuson]

Glad it's working but sounds like you're having to tender with an external charger regularly. A PITA no?

The challenge with boosting output for AGMs is only part of the problem and you're right that voltage itself isn't a big deal. Where it is more stress on the alternator is that AGMs have low internal resistance compared to FLA. That's how they're able to charge quicker than FLAs, advertised up 5x faster. Which means its sucking down much more current from the alternator.

Incrementally more voltage from the diode mod, and potentially 5x the current output adds up to be a big deal in load, heat, and stress on the alternator. Especially if the batts are in a low state of charge. Same reason why lithium's have been known to burn up alternators, but even more aggressively.

I follow the logic, but my truck is 15 years ild on the same (original) alternator.

Here’s how I make trickle-charging not a pain:

-I mounted a MALE AC/110 plugh to my fear bumper.
-This plug connects to 3 things:
1. Battery tender hard-wired to main (kept under the carpet under front passenger seat, and charge cable goes through firewall on passenger)
2. Battery tender 2 (same spot, same routing)
3. National Luna Fridge (Fridge automatically allows AC power to take over from battery power when connected.

When traveling, my aux battery lowers my fridge and MUCH more while its charged properly via my redarc.

Why its EASY and not a oain at all:

When in my driveway, I simply plug the FEMALE end of an extension cord to the MALE…and both chargers activate…& fridge switches itself to house power automatically.

Plugging in a single cord takes about 4 seconds because I’ve done the work.

Bonus: This also means I’ll never be locked out of a dead battery truck (that cannot electronically unlock doors)…because even if the battery dies, I can supply power to the batteries via the external male plug.

PS- Worth noting…that a similar setup worked for me for years even BEFORE I added the redarc to charge the Aux while driving… including Baja Mexico and other trips where I could NEVER plug in.

Originally, my main battery was tasked with charging BOTH batteries directly…snd the HKB helped then, too, snd still led to AGMs that long-outlived their expected life. This despite the fact that I run more electric power devices (even a full-power microwave) via my truck than anyone know.