When do you throw your NiMHs out?

[oldtimer]

I have dozens and I don't know what to do with them. How do you gauge whether the cell is still good or not? Should I keep the Eneloops and just throw out the rest? If not, how about NiCds?

 

[smokinbasser]

when they no longer accept a charge or don't hold a charge.

 

[SilverFox]

Hello Oldtimer,

In general, rechargeable cells are considered crap and ready for recycling when they no longer provide about 80% of their initial capacity, or when they no longer can hold decent voltage while under load. Also, a cell becomes crap when it develops a high rate of self discharge.

Many check new cells to establish baseline capacities for comparison. If you don't have that, you can always go by the labeled capacity.

I prefer not to keep track of and use crap cells, but there is some life left in them if your application is not too demanding, and if you can tolerate use and charging oddities and problems. Others continue to use them until they can no longer read a voltage from them, often encountering issues while charging and use.

Tom

 

[bcwang]

It's so hard for me to throw away cells if they can hold any charge and run something battery powered. So far, the only nimh cells I had to throw out are ones that leaked stuff out the top and caused corrosion all over.

Oh, and there was one that was like dead shorted. 0v, no charger could charge it at all, or it charged it forever but nothing ever came of it, like it was just a solid block of metal. That battery actually was some old cell that I bought a long time ago but never used. I did a refresh in the C808m, partway through I noticed it had stopped charging first, thought it had terminated early. I wanted to restart it since it hadn't been charging that long but it was burning hot, hotter than any battery I've ever touched. I pulled it out and left it out, a long time later it was still burning hot. Finally it cooled and had 0v when tested. Must have been an internal short, it was so hot it melted a bit of the charger.

I'm still keeping my sanyo 2500s that take 4 hours to charge at 1amp because the self-discharge is so high. The cells cosmetically look almost perfect, and they can still drive certain things just fine, so it's hard for me to justify throwing them out.

 

[VidPro]

When they are a bigger pain in the butt than the value of the item itself.
sometimes you just have to walk away :mad:

 

[zipplet]

I just retired a set of 4 GP 2700's. They'd been overdischarged a couple of times leading to gas forming in a Fenix L2D a couple of years or so ago. They'd also been charged using a 15 minute charger several times.

I retired them because even at only 700mA rate on the Lacrosse, they would overheat after only 1200mAh had been put into them by the charger due to high internal resistance I assume. Funnily, flash amping yielded 9+ amps! They were also very out of balance and a refresh cycle a couple of months ago didn't really help.

More eneloops for me I guess :)

 

[tabetha]

I've thrown out a couple of cells that just didn't want to party, but otherwise I just use them, don't bother with the checking balancing thing, but as I've now got mostly hybrid type cells I might start to.
Most of mine are used till flat then recharged on lowest rate.
tabetha

 

[clintb]

When they are a bigger pain in the butt than the value of the item itself.
sometimes you just have to walk away :mad:

"You got to know when to hold em, know when to fold em,
Know when to walk away and know when to run.
You never count your batteries when youre sittin at the table.
Therell be time enough for countin when the testin's done."

As wise as those words are, it is fun (in a sick sense of the word) to see if you can revive some crap cells. I'll do a break-in on the C9000, a discharge, and if that doesn't do anything, I'll smack 'em with a 1C charge and discharge. I like being evil to crap cells. :)

 

[Jay T]

Once I start swearing at them. "WTF dead again %$#^&& ^%$ @("("

 

[oldtimer]

How do you test if the internal resistance is too high and they get too hot? Just by feel? I've charged all my batteries including the Eneloops with the 15 minute charger and they worked fine although they get hot sometimes.

 

[n3eg]

It's so hard for me to throw away cells...the only nimh cells I had to throw out are ones that leaked stuff out the top and caused corrosion all over.

Oh, and there was one that was like dead shorted.... did a refresh in the C808m...it was burning hot, hotter than any battery I've ever touched...later it was still burning hot....it was so hot it melted a bit of the charger.

"You got to know when to hold em..."

LOL...

Crap cells are not worth burning equipment, chargers, and fingers over.
It's a bad habit to get into, especially if you're going to move up to Li-Ion some day...

 

[jtr1962]

When they start developing internal shorts (i.e. they either stay at 0V or self-discharge really quickly). At that point, they're useless except as ballast. High impedance cells on the other hand are still useful in items where they'll be charged and discharged at low rates. Oddly enough, many cells I have which test at 50% capacity or less at high rates will give me nearly 100% capacity at 10 or 20 mA. Perfect for wall clocks, solar garden lights, pretty much any device where there is a constant but low current drain. Only caveat is once they start self-discharging faster than usual, then they go out of service. That's usually a sign of the beginning of the end. I don't actually throw my old cells away, but just write NG or NFG (when the cell really pisses me off) on them so I know not to use them. Oh, and high-impedance cells should only be trickle-charged. Forget fast charging them. Too many things can go wrong.

 

[LuxLuthor]

When the neighbor's cat is in heat. I ran out of shoes.

 

[clintb]

LOL...

Crap cells are not worth burning equipment, chargers, and fingers over.

Even in my R/C days with NiCd and NiMh saddle packs being charged at 6A, I've never been burned. I've seen 'em get hot enough to split the shrink wrap, leak a bit, but never more than that. I think I've got a bit of experience in the field of rechargeable batteries. ;)

It's a bad habit to get into, especially if you're going to move up to Li-Ion some day...

"if" I'm going to move up? Already there, and graduated from the endless barrage of UltraFire, etc... chargers. Hobby chargers for me!