[PLUG-TALK] NiCad questions

[Larry Brigman]

On Mon, Sep 14, 2009 at 9:47 PM, John Jason Jordan <johnxj at comcast.net> wrote:
> I have various power tools that use 18v NiCad battery packs. I bought
> most of the tools and four battery packs last summer. I remember using
> the drill to put up a fence. I could go about four hours on one battery
> pack. The battery packs recharge completely in one hour.
>
> The tools remained vrtually unused over the winter, but now I am using
> them again. I am lucky to get half an hour out of a battery before it
> needs to be recharged. Sometimes a battery pack acts dead even though
> it has been in the charger for over an hour and the charger says it is
> fully charged.
>
> At the time I bought the tools I could have gone with lithium ion
> battery packs instead. But the price for a dual pack of NiCad was $50,
> and a single lithium ion  battery was $90. The li-ion literature says
> "twice the power." Hmm, twice the power, but 3.6 times the price. I'm
> not a math genius, but I think I can figure this out.
>
> However, if the NiCad batteries go flooey after a few months, perhaps
> the li-ion batteries are a better deal. Before I spend a couple hundred
> dollars on li-ion batteries and a new charger I thought I'd ask for
> comments and suggestions.

NiCad batteries can get a memory of the capacity that is being used and only
charge/maintain at that level.  Also, temperature effects all
batteries.  If the batteries
got to freezing temps then I would not expect them to do well until
they were re-conditioned.

Re-conditioning NiCad's requires a full drain and then a full
re-charge (multiple times).

Try a total drain on one of the batteries and then do a full
re-charge.  After the re-charge
determine if the normal usage life of the battery is longer or not.
It might only be
10-15 minutes more.  If it is more, then repeat until it is back to
close to normal.

Lithium Ion batteries don't have the memory effect but require the charger to be
accurate and monitor pack charge rate vs temperature.