Re: [NTLK] a question about batteries

From: Johannes Wolf (mp2100_at_mail-gw.estec.esa.int)
Date: Thu Sep 30 2004 - 08:09:35 PDT


The charging time is a function of the charging current you apply.
The limitation of common cells is the temperature rise and more important
the pressure rise inside the cell.
In the worst case the internal overpressure may result in busting the cell.
Therefore the charging current of all common chargers is limited.

In case of Rayovac they seem to have found a solution to control the
internal pressure of the cells.
Thus they can handle a much higher charging current without damaging the
cell, resulting in a shorter charging time.
I could not find any information about what is the capacity of the new IC-3
batteries.
This information would allow to calculate the value of the charging current
they use.
charging current(mA) = capacity (mAh) / charging time (h)
Assuming a cell capacity of 1000mAh they would apply something like 4 Amps.
This would of course definitely kill any other standard cell.

Cheers
Johannes

> -----Original Message-----
> From: newtontalk-bounce_at_newtontalk.net
> [mailto:newtontalk-bounce_at_newtontalk.net]On Behalf Of Scott Lewis
> Sent: Thursday, September 30, 2004 4:21 PM
> To: newtontalk_at_newtontalk.net
> Subject: Re: [NTLK] a question about batteries

> On Sep 29, 2004, at 2:19 PM, Martin Joseph wrote:

> > 15 minutes ? What kind of batteries are these? Or are you saying you
> > have some special charger for NiMH batteries that can charge them in 15
> > minutes? Either way enquiring minds want to know...

> Again, I wish I knew what type of batteries they are! I can only
> presume they are NOT NiMH, since they Rayovac does not advertise them
> as NiMH. Rayovac's previous charger was a 1 hour charger, and was
> specifically designed to charge NiMH and NiCAD. This charger charges
> their "I-C3" batteries in 15 minutes, and all other NiMH and NiCADs
> overnight.

> In my opinion, these batteries last as good as any 2000-2200 Mah
> batteries you would find in a local retail store (ie Radio Shack
> brand).

> This is the real deal though - 15 minutes. They get a little hot, and
> Rayovac actually built a little fan into the charger to keep the
> temperature down.

> I just went to their web site, and in fact they are a derivative of
> NiMH. Apparently I-C3 stands for "In-Cell Charge Control", you can read
> about it here: http://rayovac.com/products/recharge/15minutes/qa.shtml

> According to the site, they are in fact NiMH, and can be charged in any
> NiMH charger - but not in 15 minutes (obviously).

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