Flat AGM's

[pappawheely]

I have a couple 12 volt, group 31 batteries that were neglected and discharged. I have been trying to restore them using my Ctek MXs 5.0 charger. I did the trick were you hook the bad battery in parallel with a good one to charge. I got one up to 9 volts, and the other to 6, but they won't charge on their own. Anything else I can do? What to do if they are bad, recycle? Sell for the raw materials?

 

[Joe917]

recycle at any battery seller

 

[Redline61]

Unfortunately you best bet is what Joe917 mentioned.

 

[dstefan]

If you really want to revive them (and intend to keep with AGMs in future) maybe try another charger?

Odessey’s chargers have some additional capabilities and are AGM specific. You might call them to see if it’s worth getting one. Their CS has always been real helpful to me.

That Ctek is only ~5 amps. AGMS need a lot more to charge properly. My Odessey charger is the smallest they make (I think) at 25 amps.

Good luck!

 

[dur66@msn.com]

I have a couple of Odyssey batteries in my Avalanche. I can tell you that they will last longer than a conventional battery, but they do require a special charger.

 

[Kevin108]

I've used the trick before where you hook a good battery in parallel to the bad battery to trick the charger into starting. You can remove the good battery after 5 minutes or so.

Some modern batteries have their own protective measures. If the parallel charge start doesn't work, I've heard you can tap a wrench across both terminals to reset them before charging. Haven't tried that one myself, but if I thought I could get a little more life out of a $400 battery, I definitely would. Just be smart about it. Take it out of the vehicle, wear some PPE, etc.

 

[pappawheely]

I've used the trick before where you hook a good battery in parallel to the bad battery to trick the charger into starting. You can remove the good battery after 5 minutes or so.

Some modern batteries have their own protective measures. If the parallel charge start doesn't work, I've heard you can tap a wrench across both terminals to reset them before charging. Haven't tried that one myself, but if I thought I could get a little more life out of a $400 battery, I definitely would. Just be smart about it. Take it out of the vehicle, wear some PPE, etc.

Not sure if this is a real thing, or you're just an instigator Kevin. ?

 

[2.ooohhh]

I've had fair luck recovering aging AGMs using my Ctek Multi 7002. If they don't start charging because they are flat I put the 7002 in power supply mode and force some current into them for a bit (20-30 min) then switch the charger over to the AGM charge mode. Not sure why the magic number seems to be 6A on recovery charging agm's but I know my 7002 have a dramatically better rate of recovery on them than my smaller ctek charger/maintainers.

 

[Kevin108]

Not sure if this is a real thing, or you're just an instigator Kevin. ?

I don't know if it's real or not either, but if anybody has a dead AGM to donate, I'll give it a try.

 

[pappawheely]

I don't know if it's real or not either, but if anybody has a dead AGM to donate, I'll give it a try.

I tried it, didn't even get a spark.

 

[SBSYNCRO]

I had a dead 100 ah Trojan battery that sat for a year without being charged by the previous owner of my trailer. Using my CTEK charger it would only hold about 1/2 its rated charge, even after repeated attempts. I found a local shop with a new Snap-On battery charger and had him do a high voltage profile charge on it to attempt to "de-sulphate" it. Lo and behold after I brought it home and topped it off again with my CTEK, it produced 90% of its rated capacity before getting to 50%. I've been using it that way for about 2 years now. I paid $20 for the battery charge - a lot cheaper than the $500+ it would have cost for a new one!

 

[Photomike]

I have a REALLY old charger of my Dad's that is the dumb charger. You put it on a battery and it will charge it, does not do any checks just sends juice.

This will work to get a battery to start charging if it is REALLY dead. Then you can finish off with a better charger that will top up and recondition.

Check with some old neighbors to see if they have one kicking around.

 

[pappawheely]

I have a REALLY old charger of my Dad's that is the dumb charger. You put it on a battery and it will charge it, does not do any checks just sends juice.

This will work to get a battery to start charging if it is REALLY dead. Then you can finish off with a better charger that will top up and recondition.

Check with some old neighbors to see if they have one kicking around.

Crap! I had one of those but gave it to someone else.