rescuing old NiMH

[rmorein]

I have a Maha 9000 (0G0D01) charger, and a bunch of Power2000 cells, rated 2700 mah, purchased 18 month-2 years ago. I have not properly maintained these cells, and the capacity measurements show this, some as low as 1300 mah.

What's the best way to recover the most capacity out of these cells? They aren't used very much, so use is not an option. Should I repeat the Maha "breakin" cycle, or the "refresh" cycle?

 

[SilverFox]

Hello Rmorein,

Welcome to CPF.

Your best bet is to do a discharge first (500 mA discharge rate is good) followed by the Break-In. If the capacity you get during the Break-In cycle is less than 80% of the initial capacity, it is probably time to recycle those cells.

Keep in mind that the initial capacity may have been different from the labeled capacity. If you don't know the initial capacity you may have to make some educated guesses.

Tom

 

[rmorein]

Tom, thanks. Please clarify: I've done the breakin cycle once. The question is: What should this be followed with? I've read that as many as 10 cycles can be beneficial to capacity recover, but should these be "refresh" or "breakin" ?

 

[stockae92]

does the Maha 9000 refresh old NiMH automatically? or we have to monitor the process on our own?

 

[rmorein]

It goes according to program.

Breakin:
16 hour 0.1C, rest 1 hour, 0.2C discharge, rest, 16 hour 0.1C charge.

Refresh:
recharge, rest 1 hour, discharge, rest, recharge. Charging & discharging rates are programmable.

 

[cave dave]

I have a Maha 9000 (0G0D01) charger, and a bunch of Power2000 cells, rated 2700 mah, purchased 18 month-2 years ago...

Did true 2700mAh batteries even exist 18 months ago? Given the offbrand name, this sounds like a total bogus claim from the get go. There were quite a few different fake claim 2500-3000mAh batteries coming out a few years ago when the mAh wars were really heating up. Generally the higher the claim the lower the actual performance was. I mean if your gonna lie you might as well lie bigger than the next guy.

EDIT
3 negative review and manufacturer response at amazon
http://www.amazon.com/dp/B0009J4YAY/?tag=cpf0b6-20

 

[rmorein]

It probably is bogus. Also, I don't remember the actual date of purchase; it could have been 12 months ago. But whatever the original capacity of the batteries was, they've lost some. I'm seeking advice on the optimum way to restore them as much as possible.

 

[VidPro]

EDIT
3 negative review and manufacturer response at amazon
http://www.amazon.com/dp/B0009J4YAY/?tag=cpf0b6-20

man that guy got nuked in the amason reviews, i wish e-bay was more like that, but reciprocal feedback to the user , keeps people from stomping on the sellers.

----------------------------------

Just do what silverfox said, discharge them, run a break-in (slow charge) , then try and do a refresh cycle (multiple charge discharges) if they dont come up to or above 16-1800, you should toss them out. if they dont start shaping up in the first 3 charge discharge cycles, your just going to waste your time.

its stuff like this that can overheat, and cause more problems than the 10$ of cells, if messing with them alters (in any way) a $40 charger its certannly not worth the insurance you will get from tossing them (or sending them back to the seller)

 

[SilverFox]

Hello Rmorein,

I use the Break-In mode instead of cycling. If you have already done a Break-In cycle, you probably have as good as you are going to get.

It won't hurt to try a few cycles, but don't expect much change.

Tom