Swollen 100AH deep cycle AGM, help.

[RobbieD]

Hello again,

I have an auxiliary 100AH deep cycle AGM under the bonnet of my 4x4. It charges from a 25Amp dcdc charger, off of the start battery which is charged via the cars alternator. I also have a 275w solar panel on roof of car feeding into a 20Amp Epever MPPT solar charger, charging the auxiliary battery. On the load side I have the auxiliary battery supplying a 40litre fridge full time, it never turns off. Work tool battery charger when needed, and various camera and drone chargers and a 1500w inverter that has been used maybe 4 times. This has been running well, batteries are 3 years old, this solar setup has been on for a month or so.

Opened the bonnet today to have a general look and noticed the Auxiliary battery is quite swollen, noticeable on the top and on the short sides. Charge controller appears to be charging ok etc. We have recently done a trip with van and family, fully loaded up steep hills in hot weather. I’m not sure if the hot weather has cooked the battery causing the swelling or if there is a charging / overcharging issue.

how do I go about fault finding the system? And is the battery toast? Noting it is at 13.3 to 13.5 in the morning, bluetooth monitoring on the solar charger is a good thing.

thanks,
Robert

 

[nosys70]

"And is the battery toast? " Yes.

 

[Supervstech]

If it has swollen, it is gone, or nearly so, and not to be relied on...

I would verify the charge parameters on the setup and see if it is wrong...

 

[RobbieD]

No battery I working fine, holding charge..

 

[RobbieD]

"And is the battery toast? " Yes.

Thought that was a question, sorry. Ok.

 

[RobbieD]

If it has swollen, it is gone, or nearly so, and not to be relied on...

I would verify the charge parameters on the setup and see if it is wrong...

Tanks, Will/ can it explode / pop? The charger adjusts charge rate up and down as required, I haven’t changed any parameters.

 

[Supervstech]

Heavy use can kill any LA battery, sudden charging of a heavily discharged battery, or a manufacturers defect and a cell short...

Replace the battery soon, it will NOT be reliable.

 

[RobbieD]

Heavy use can kill any LA battery, sudden charging of a heavily discharged battery, or a manufacturers defect and a cell short...

Replace the battery soon, it will NOT be reliable.

Ok, thank you. Now I’ll want to go Lithium... under bonnet.??‍

 

[SolarRat]

The 25 amp DC-DC charger is about the max you want to charge that battery at. When you added the 275w of solar, that added another 23 amps. So you now have a .5C charge rate while driving, which is way too much for MOST AGMs. Sounds like you were cooking the battery on that long trip. I'd disconnect one charger or the other while on the road before that battery explodes. Also make sure your chargers are set for AGMs, not FLAs. When you switch to lithium, make sure it can handle a 50amp charge (it should), and reset the chargers for lithium..

 

[RobbieD]

The 25 amp DC-DC charger is about the max you want to charge that battery at. When you added the 275w of solar, that added another 23 amps. So you now have a .5C charge rate while driving, which is way too much for MOST AGMs. Sounds like you were cooking the battery on that long trip. I'd disconnect one charger or the other while on the road before that battery explodes. Also make sure your chargers are set for AGMs, not FLAs. When you switch to lithium, make sure it can handle a 50amp charge (it should), and reset the chargers for lithium..

Thank you. I’m new to some of this, so much appreciated. I was wondering that however one of Wills videos discussed how the two types of chargers don’t both charge a once, saying that the MPPT should know if the battery is being charged off the other charger and reduce accordingly? but I could have totally miss understood the gist of the points he was making.
Again, thank you for your time.

 

[SolarRat]

the MPPT should know if the battery is being charged off the other charger and reduce accordingly?

With AGMs, if the battery is at 50% SOC it will probably accept most of that 50a. Once LA batteries near full they will slow their charge accepance. Will they "see" each other? Sort of, by sensing voltage and load, but they will still act like one big 50a charger.

 

[RobbieD]

perfect, I will work on a switch for the dcdc charger so it only uses it when parked in the shed or sun is hiding. A lithium will handle all of the 50Amp, providing chargers are set to lithium?

 

[SCClockDr]

The key parameter with AGM, GEL, & Sealed Lead Acid (LA) batteries is charge voltage. They cannot be pushed like flooded LA batteries as there is no way to replenish the distilled de-ionized water.
A 200 amp charger will not harm them @ 13.2 VDC, where a 3 amp charger @14.6 VDC will kill them over time.
So I'd look @ your DC > DC charge voltage then the SCC's as well.

 

[RobbieD]

Not likely to get 0degrees where I live. The hot one is an issue though