mighty max deep cycle 12v charger

funny and not fun, looks like this Mighty charger is also failing in charging the 12v deep cycle Seal acid battery, not the popular lithium battery.
What I have: two Mighty deep cycle batteries 12v, 100 ah, from truck (burned and recovered). the voltage measures 11.54v after a year sitting on the truck. it has a converter.

What’s the plan: I plan to use this to back up power supply for my Starlink internet and security camera. the area has frequent power outage and thus the need for backup.
I thought this would work: during power on, battery charger to “top off” the two batteries in parallel, so 12v and 200 ah in total, which I hope enough to power starlink 110v, 75 w(?) for a few hours up to two days before pge power is back. I bought the auto switch to detect 110v and 12v battery.

I failed: this is the third smart charger I bought and it looks a fail again. the plugs are correctly connected positive red, and negative black. the voltage stays same after a night charge. it shows in red, that manual says charging. but it stays at 11.54 v. also removed the inverter, disconnect the two battery, just charging one 12v, 100 ah, mighty max sla battery. Same result, no extra juice. this is from the same company that makes the 12v 100 ah battery. the charger has specs: Mighty Max Battery 12V 4AMP Charger MAINTAINER for 12V 35AH EVH12390 SLA Battery.

nuts how things fail. Hope someone out there help me out w a product that will work for the set up and re purpose the battery and converter.

所有跟帖： 

• You need to check both your charger and your batteries. You -jassco- ♂ (277 bytes) () 09/05/2025 postreply 18:11:23

• interesting observation, never thought the battery is dead as vo -leslieking- ♂ (0 bytes) () 09/05/2025 postreply 18:54:00