Can NiMh AA's That Have Been Fast Charged Be Saved By Going To Overnight Charge?

I have a few sets of Duracell NiMh 2650mAh AA's that I've been using on a 15 minute charger and I'm now noticing that they don't have the same capacity and life that they used to have. I also understand more about batteries now so I don't plan on using fast chargers any more and will probably order some new batteries soon.

Rather than trash these batteries I'm wondering if they are just shot or if they can be brought back to life by charging them in a standard charger for the 8 or 10 hours it take for a full charge.

Can batteries that are dying be saved?

Im pretty sure that they will never be back to brand new, but they can certainly be helped. Though Im not sure that simply slow charging them will do it. You need something to re-condition them. Might be time to upgrade to a really nice smart charger like the Maha C-9000. Check it out at thomasdistributing.com​.

ben_r_ wrote in post #6467382
Im pretty sure that they will never be back to brand new, but they can certainly be helped. Though Im not sure that simply slow charging them will do it. You need something to re-condition them. Might be time to upgrade to a really nice smart charger like the Maha C-9000. Check it out at thomasdistributing.com​.

Thanks Ben,

That's pretty much the path I'm going down. I wish they had a smart charger that would condition and analyze 8 AA'a at a time. The C-9000 with do 4. Do you know of a one that can handle 8? I've seen the Maha that will charge 8 at a time but it doesn't do the conditioning and analysis.

TMR Design wrote in post #6467734
Thanks Ben,

That's pretty much the path I'm going down. I wish they had a smart charger that would condition and analyze 8 AA'a at a time. The C-9000 with do 4. Do you know of a one that can handle 8? I've seen the Maha that will charge 8 at a time but it doesn't do the conditioning and analysis.

Nope, the C-9000 is the one I own and I have never seen one that will do all the things it will do but charge 8 batteries at a time. It is unfortunate.

ben_r_ wrote in post #6467810
Nope, the C-9000 is the one I own and I have never seen one that will do all the things it will do but charge 8 batteries at a time. It is unfortunate.

Hmm, ok then can you charge 2 sets of 4 overnight or would that involve having a second C-9000?

TMR Design wrote in post #6467821
Hmm, ok then can you charge 2 sets of 4 overnight or would that involve having a second C-9000?

Actually in the C-900 reconditioning a battery (four can be done at a time) takes almost three days. It goes through several slower than the last recharge and discharge cycles. You cant fix a messed up NiMh battery with just one charge no matter how slow its done.

Do the Maha MH-C800s or Maha MH-C801d do what you are looking for?
I think a few people here use the 8 battery chargers.

http://thomasdistribut​ing.com …6egukakeob90udi​udhij2ukr3

http://thomasdistribut​ing.com …6egukakeob90udi​udhij2ukr3

gool wrote in post #6472134
Do the Maha MH-C800s or Maha MH-C801d do what you are looking for?
I think a few people here use the 8 battery chargers.

http://thomasdistribut​ing.com …6egukakeob90udi​udhij2ukr3

http://thomasdistribut​ing.com …6egukakeob90udi​udhij2ukr3

I've seen those and they look nice. They don't analyze but then again I'm not sure how much I need that. If the charger is good and will condition the batteries correctly then I'm leaning towards grabbing one of the chargers that will charge 8 at a time.

Try it and see. Is it that much of a gamble?

Once a battery loses a significant amount of its capacity its better to just toss it (by toss I mean recycle). They are cheap. Plus old, damaged (15 minute charging is convenient but every cycle of it damages them) batteries are the ones that smart chargers like to catch fire to. The chemistry is altered and they don't behave like a normal battery that the charger is expecting, and can miss the charge peak and overcharge them untill it catches fire or its hard coded time limit is reached. In either case it isn't good for the battery.

My advice is to stop using 15 minute chargers and instead just buy more spare cells. Maybe keep a set or two of non-rechargable lithium batteries around for when you are really in a bind. Their shelf life is just short of forever.

Stregone wrote in post #6474953
Once a battery loses a significant amount of its capacity its better to just toss it (by toss I mean recycle). They are cheap. Plus old, damaged (15 minute charging is convenient but every cycle of it damages them) batteries are the ones that smart chargers like to catch fire to. The chemistry is altered and they don't behave like a normal battery that the charger is expecting, and can miss the charge peak and overcharge them untill it catches fire or its hard coded time limit is reached. In either case it isn't good for the battery.

My advice is to stop using 15 minute chargers and instead just buy more spare cells. Maybe keep a set or two of non-rechargable lithium batteries around for when you are really in a bind. Their shelf life is just short of forever.

Thanks Stregone,

You're right and that is what I've decided to do. I'm going to be ordering some good NiMh AA's and a good charger. I've already trashed the cells I was using and have a bag of standard Alkalines as backups. I'll still use the AA's as I need them but my ultimate solution is going to be the Al Jacobs Black Box. He's a very bright guy that understand batteries and build power supplies for the medical field as well as for photographers. His design is a better one that Quantum or Lumedyne in my opinion.

ben_r_ wrote in post #6471544
Actually in the C-900 reconditioning a battery (four can be done at a time) takes almost three days. It goes through several slower than the last recharge and discharge cycles. You cant fix a messed up NiMh battery with just one charge no matter how slow its done.

Actually, I think you are referring to the "break in" mode. The recondition mode doesn't take that long on mine.

J.

JohnJ80 wrote in post #6476928
Actually, I think you are referring to the "break in" mode. The recondition mode doesn't take that long on mine.

J.

You are correct. My mistake. Its been so long since I have had to "recondition" a battery since I threw out all my old ones when I made the switch to eneloops that I forgot the term Maha used.

Eneloops are great - what I use too but I do make sure to break them in.

J.

JohnJ80 wrote in post #6477248
Eneloops are great - what I use too but I do make sure to break them in.

J.

Same here, every single one gets a break-in run right out of its packaging.