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Are my old AGM batteries worth anything? Where do I dispose of them?

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Sparky7

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I have 4 AGM batteries that wore out after 3.5 years of light use. Before they died I bought 8 more (before I realized AGMs are junk). The newer set is only two yrs. old and is already showing signs of death.

Are they worth anything? If not where should I dispose of them?

Thank you!
 
Sounds like bad luck - I have a set of AGM that are 15 years old and still working - I retired them to lighter duties about 18 months ago (they now run my greenhouse) but until then they were working well.

They do have value, take them to a scrap yard and they should pay you for them based on weight.
 
Cant speak but most states in the US do have manditory recycle laws and recycle centers where batteries are recycled. They are worth 5.00 to 12.00 each here in California
 
sunshine_eggo said:
Quality deep cycle AGMs are not junk. Being "maintenance free," some equate that to being abuse tolerant, and that's just not the case.

They are very particular about how they are treated. If you have them in series, they can be killed quite quickly if not charged properly.
Click to expand...
The first time I had 4 6 volt for a 24v system. The guy that set up my system never put thermometers on them. They where in a shop that didn't get used in the winter much but where still hooked to the panels. I was told that was probably the reason.

The second set sat for a year before I could use them but the voltages where still good. I have 8 6 v for 48 volts.
 
Tecnodave said:
Cant speak but most states in the US do have manditory recycle laws and recycle centers where batteries are recycled. They are worth 5.00 to 12.00 each here in California
Click to expand...
We can take them to the recycling center but I know they won't give you much for them.
 
Sparky7 said:
The first time I had 4 6 volt for a 24v system. The guy that set up my system never put thermometers on them. They where in a shop that didn't get used in the winter much but where still hooked to the panels. I was told that was probably the reason.
Click to expand...

Any lead acid of any type that is operated without temperature compensation during charging will experience accelerated degradation.

For the periods of disuse, the batteries should have been disconnected for up to 3-6 months OR set to charge and float at 6.6-6.9V


Sparky7 said:
The second set sat for a year before I could use them but the voltages where still good. I have 8 6 v for 48 volts.
Click to expand...

Critical that all 8 of them are indicating the same voltage when the string voltage is at absorption. The higher ones are being overcharged and the lower ones are being undercharged. Overcharging AGM at higher voltage rapidly kills them. Undercharging them isn't good either.

Temperature compensation enables on the new bank?
 
Sparky7 said:
I have 4 AGM batteries that wore out after 3.5 years of light use. Before they died I bought 8 more (before I realized AGMs are junk). The newer set is only two yrs. old and is already showing signs of death.
Click to expand...

AGM are not junk.

Bigger question, how are you killing them?
 
sunshine_eggo said:
Any lead acid of any type that is operated without temperature compensation during charging will experience accelerated degradation.

For the periods of disuse, the batteries should have been disconnected for up to 3-6 months OR set to charge and float at 6.6-6.9V




Critical that all 8 of them are indicating the same voltage when the string voltage is at absorption. The higher ones are being overcharged and the lower ones are being undercharged. Overcharging AGM at higher voltage rapidly kills them. Undercharging them isn't good either.

Temperature compensation enables on the new bank?
Click to expand...
Yes, I have two charge controllers and they both have temp sensors.

What should my charge voltages be and how long should I set them for?
 
pollenface said:
AGM are not junk.

Bigger question, how are you killing them?
Click to expand...
I’ve learned some hard lessons. The first time The system was set up by a solar guy. The second time I built the system with the advice of the company I bought everything from. It seems like there is so much guess work in setting up battery parameters. I found them too finicky to be a practical purchase unless you're a battery expert maybe. I'm looking into Lifepo.
 
sunshine_eggo said:
Any lead acid of any type that is operated without temperature compensation during charging will experience accelerated degradation.

For the periods of disuse, the batteries should have been disconnected for up to 3-6 months OR set to charge and float at 6.6-6.9V
Click to expand...
Lots of people here with more experience with modern batteries than me

But want to add if your batteries are out of service for the season keep them someplace cold.
And simple two stage battery charger is fine to give them a bi weekly or monthly top up for a day

Do this like religion top up cold storage and that’s just as good maybe gentler than keeping them warm on a float charge
 
Fullrivers are good batteries. I have a couple of their 215Ah 12V. Beasts, but tough to kill.


Absorption to 7.35V * 8 = 58.8V; however, it's critical that none of the 6V be over the 7.35V, so you may need to lower the absorption to the point that none are over 7.35. Eventually, if regularly charged to full, they should equalize, and you can increase the voltage.

Float at 6.8V * 8 = 54.4V. Important that they are all as close to 6.8V as possible.


Temp comp should be set to -4mV/°C/cell.
 
DPC said:
Lots of people here with more experience with modern batteries than me

But want to add if your batteries are out of service for the season keep them someplace cold.
And simple two stage battery charger is fine to give them a bi weekly or monthly top up for a day

Do this like religion top up cold storage and that’s just as good maybe gentler than keeping them warm on a float charge
Click to expand...

Per that battery manual, storage below 68°F is safe. Most AGM retain charge very well and can go 3-6 months between charges with no degradation. Longer when cold.
 
What do you do for a living ?
You seems to have the knowledge of a lot of things

Cold is your friend with lead acid
As long as they don’t freeze cold slows down everything extending their life when I’m storage
 
Last edited:
sunshine_eggo said:
Fullrivers are good batteries. I have a couple of their 215Ah 12V. Beasts, but tough to kill.


Absorption to 7.35V * 8 = 58.8V; however, it's critical that none of the 6V be over the 7.35V, so you may need to lower the absorption to the point that none are over 7.35. Eventually, if regularly charged to full, they should equalize, and you can increase the voltage.

Float at 6.8V * 8 = 54.4V. Important that they are all as close to 6.8V as possible.


Temp comp should be set to -4mV/°C/cell.
Click to expand...
Thank you
I'm pretty sure that's what they are set for. I will double check tomorrow. Ho should I test them to see if non are over 7.35? Do I have to disconnect all of the cables to test each better alone?
 
Regardless of if they will hold a charge or not, they are never junk. Junk is thrown into the track but the least recycle core charge I have ever gotten for an FLA regardless of condition is $10.
 
hwse said:
Regardless of if they will hold a charge or not, they are never junk. Junk is thrown into the track but the least recycle core charge I have ever gotten for an FLA regardless of condition is $10.
Click to expand...
I paid about $8500 for them so $10 is pretty insignificant.
 
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