Subject:
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RE: Don't use Lithium-Ion batteries
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 3 Aug 1999 20:45:56 GMT
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Original-From:
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Issac Merkle <the_gaff@/spamless/hotmail.com>
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Viewed:
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1014 times
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Someone sent me an e-mail reply saying that they had used an external
Lithium
Ion battery pack to power their RCX, and that after a few days of use the
RCX
appeared to stop working, then they discovered that it only worked with
internal batteries. In other words, they had permanently damaged the RCX by
"burning out" the external power circuit.
The problem this person encountered results from the fact that lithium ion
batteries have a very non-standard voltage of 3.0 - 4.3 volts per cell, and
it
simply isn't possible to build a 9V battery pack out of them. This person
probably had 3 lithium ion batteries in series supplying from 12.9 volts
(when
fully charged) to as low as 8.5-9.5 volts (after the first 90 minutes). The
12.9 volts is probably what damaged the RCX.
<SNIP>
I sent the abovementioned e-mail. I just wanted to add that the battery pack
in question was a 9V racing pack purchased at Radio Shack. According to my
meter, the 9V rating is accurate - though I'm really not educated enough to
know if that would vary under load.
The more I think about it, it may be a NiMH pack, rather than Li-Ion. I'll
have to check.
Regards,
Issac.
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Message has 1 Reply:
 | | Re: Don't use Lithium-Ion batteries
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| From: Issac Merkle <the_gaff@hotmail.com> (...) Note that both NiMH and Li-Ion can put out much higher currents then alkaline cells (alkaline cells have a high internal resistance). Could this person have shorted across the output somehow? That (...) (25 years ago, 3-Aug-99, to lugnet.robotics)
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