[Coco] OT: Battery chargers

[gene heskett]

On Saturday, October 15, 2011 06:01:52 PM Tony Schountz did opine:

> Thanks much for the replies Gene and JP. Here's the charger:
> 
> http://www.newegg.com/Product/Product.aspx?Item=N82E16817355042
> 
No where near smart enough to charge an NiMh battery correctly.  No thermal 
controls, possible a flat top detector though, meaning that it expects the 
voltage to rise slowly, and shuts off when the voltage no longer rises 
between sample periods.

> I have 9V connector with wires from the charger to the battery pack.
> Here are the cells that are in the pack:
> 
> http://www.batteriesinaflash.com/assembly-cells/nimh/2-3a/2-3a-rechargea
> ble-battery-1400mah-nimh-1-2v-ft-w-tabs

Doesn't look too bad, but never heard of that brand name.  Tadiran or 
Panasonic likely a better battery.
 
> There are 8 in the pack, which looks like this:
> 
> http://www.bhphotovideo.com/c/product/44660-REG/Rollei_66251_Nicad_Batte
> ry.html
> 
$169 ea?  That is about a 1000% markup.
> Thanks,
> 
> Tony
> 
There are some controller chips about that are smart enough to autodetect 
the battery chemistry and act accordingly, but I doubt a $27 charger would 
sport one of those.

I would be tempted to repack the box with nicads, and find someone to 
repair your OEM charger, that could give you better results in the long 
run.

> On Oct 15, 2011, at 12:36 PM, gene heskett wrote:
> > More than likely is is Tony, NiMH batteries have a higher self
> > discharge rate than NiCads.  Couple that with the miss-match between
> > the charger and the cells, it could be that they are not being fully
> > charged.  Most Nicad chargers use a temp switch in the batteries (the
> > third connection to the charger) which turns the charger off when the
> > batteries start to heat from overcharge.  No clue how your PowerEx
> > works.  Web page links?
> > 
> > I personally would have put some lithium cells in it, but the charger
> > MUST be one designed for that chemistry else they will be ruined or
> > possibly even explode.
> > 
> > NiCads are a PIMA, but their relatively low self-discharge compared to
> > some of the other, higher energy density batteries can be a useful
> > feature.
> 
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Cheers, Gene
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