Subject:
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Re: Batteries?
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 2 Dec 1998 01:48:54 GMT
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Original-From:
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alex wetmore <alex@NOMORESPAMphred.org>
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Viewed:
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2767 times
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On Tue, 1 Dec 1998, Gary Hughes wrote:
> That is the problem with NiCd rechargeables. By the time the battery
> low detector kicks in, it is often too late. And they have a 'memory' so
> you do want to run them down periodically. They are not recommended
> for the PalmPilot for the same reason.
Most everything that I've read on this subject argues that NiCad memory
is mainly a myth. NiCads do get damaged by overcharging or deep
discharging, but except in very controlled situations they don't have
a "memory". I recommend reading
http://www.sheldonbrown.com/marty_sla-nicad.html as an intro to this
subject.
> Now, I THOUGHT NiMH was not supposed to suffer from these
> problems but I haven't verified this. Some folks claim to have had
> good results with NiMH batteries in the PalmPilot.
NiMH cells are harder to charge properly, so they are actually more
prone to damage via overcharging. However they are lighter and have
higher capacity, so they are gaining popularity. For AA NiMH cells I've
had good luck with the Olympus batteries and charger (sold for use in
their digital cameras. http://www.necx.com sells them). The charger
uses delta-V and temp sensors for detecting when charging is complete
and can charge the cells quickly (about 2 hours for 4 batteries).
Most chargers for NiCad and NiMH cells on the market just push current
into the batteries for a given amount of time, and thus can overcharge
the batteries if they are partially discharged. Even cheaper chargers
don't even have the timer.
That said, I don't think that rechargable cells are really necessary
for Mindstorms. I'm still using my original batteries and have had
my Mindstorms kits for a couple of months. I don't get to use them as
much as others on this list, but I do use them a fair amount. The
$50 that one would spend on NiMH/NiCad cells and a quality charger
can buy a lot of Alkaline cells.
> There are also rechargeable alkalines which give you a small number
> of recharges on an otherwise normal alkaline cell.
I've never read a good review of these products. I've read a lot of
bad ones though. Even Consumer Reports has said that they aren't a
good buy.
alex
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Message is in Reply To:
 | | Re: Batteries?
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| re: rechargeables (...) That is the problem with NiCd rechargeables. By the time the battery low detector kicks in, it is often too late. And they have a 'memory' so you do want to run them down periodically. They are not recommended for the (...) (26 years ago, 1-Dec-98, to lugnet.robotics)
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