How noisy are NiCD batteries?

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#1
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Hi,

So, I've opened my old supplies, took a few batteries out, NiCD in fact, approx. 2years old and put them in the charger. The charger doesn't semm to notice anything bad, eveythings OK.

In an hour or so, I've noticed a sound. Strange... like like raindrops against a window, only very, very silent. I tried to locate it. It was the batteries. I imidietaly took them out of the charger, and they were still making the sound.

Now: Question: Is it normal for NiCD batteries to be noisy during charging? Or are these batteries DEAD and I should leave them that way?

Thanks,

David

There are pointy haired bald people.
Time flies when you have a bad prescaler selected.

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Hydrogen gas can be released during charging, perhaps it was leaking out of the pressure release valve. It should only happen if they are overcharged though.

Leon

Leon Heller G1HSM

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If the batteries have been sitting around for two years unused they may have shorted internally even though the charger says they are fine.

Do they get hot or warm? If they are getting hot I would say pitch them. If your charger is of the fast variety and the batteries are indeed slightly shorted they might be heating internally. You could try using a 'slow' charger, one that outputs a smaller charging current and see if the cells take a charge.

Lastly, you could just say the hell with it all and buy new ones :wink:

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Hydrogen? Overheating? Run!!!! :twisted:

Nearly as effective as the cigarette-lighting potato...

Ross McKenzie ValuSoft Melbourne Australia

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> If the batteries have been sitting around for two years unused they may have
> shorted internally even though the charger says they are fine.

Supposedly, NiCd cells are not harmed by storing them discharged, even for a long
time. The only thing that damages them is reversing the polarity which can
happen when discharging a battery of NiCd cells where individual cells are
completely discharged before others.

Jörg Wunsch

Please don't send me PMs, use email if you want to approach me personally.

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David,

What was the battery capacity and what was the charge rate? For NiCD (while low energy density) you should easily be able to charge at 10C or 20C.

My two best "battery events" ever were:

1) an 8 cell pack of 2400mAh NiCds in the boot of my car where the insulation on the leads failed and I opened the boot to a large plume of smoke and a pack around which all the cells were now separated (they'd desoldered themselves apart) and the entire heat shrink wrapping had gone (melted into a tight ball). Luckily the car itself wasn't damaged much.

2) The other was a small capacity (700mAh) three cell LiPo pack where, again, the contact insulation failed and the battery exposively discharged. Sadly it was sat on the passenger seat of my BMW Z3 at the time and burnt a rectangular cell shaped hole down through the covering, the heating element and all the internal stuffing right to the floor (the insurance claim form must have been entertaining for someone!). This happened while the car was left in our staff car park at work (because I sometimes go to fly planes/helis during the lunch break). The curious thing was the the entire car was actually full of a white powdery smoke that covered everything. I'm guessing this was some form of oxidized lithium compound and thankfully the lack of oxygen had prevented the usual pretty purple flame that LiPo normally burns with (almost impossible to extinguish)

These days I am far, far, far more cautious with NiCd, NiMH and LiPo battery packs!

Cliff