Subject:
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Re: rechargeable 9V battery packs for RCX/JCX and Legos motors
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Newsgroups:
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lugnet.robotics
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Date:
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Sat, 15 Sep 2001 17:17:09 GMT
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Viewed:
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565 times
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Terry King wrote:
>
> > > We're thinking of college labs where they will have 12 or 20 JCX systems
> > > and where feeding them alkalines is just not practical or cost effective.
> > > Charging 120 AA cells gets awkward too, so some sort of self-contained
> > > rechargeable pack seems a good idea.
>
> I would like to follow up on this. The school I volunteer at to teach
> LEGO Robotics now has 4 RIS 1.5 and 4 RIS 2.0 and batteries are a real
> problem. Disassembling kids robots to change batteries is a pain!
>
> I have been using 1800MAh NiMh AA cells in digital cameras, GPS etc
> with great success. BUT they are easy to physically swap the batteries.
>
> Here's what I plan to to experiment with, and I would like any
> suggestions or collaborative efforts from you LugNuts:
>
> 1. Install 6 AA NiMh cells in an RCX with no external power connector.
> 2. Connect a thin two-wire cable internally to the RCX + and - points
> and route it securely to the outside.
> 3. Externally recharge the battery pack with a suitable charger.
>
> Here are my current questions and concerns:
>
> A. What is a 'suitable charger'? (6 cell chargers are unusual...)
> - Easiest is a 1/10 C (Say 150Ma) constant current charger overnight.
> How about cheap 12V wall wart with series resistor ??
> - There are available fast chargers but they are more expensive. (See
> http://www.mahaenergy.com/products/radios/amateur/chargers/mhc777.htm
> for an example. Expensive, but maybe OK for a school/lab )
>
> B. What is a suitable connector?? The problem is that BOTH the battery
> connection and the charger connection are 'live' and can short out
> against a metal object, so the typical "source is Female and load is
> Male" doesn't work. Need some small, simple, cheap hermaphroditic
> connector. I am leaning toward a simple .100 dual socket with one
> inserted pin (result, one male, one female, no shorts).
> **Sorry for all this sex discussion; I know we have kids here :-)
>
> I'll do a little more research; I have the NiMh specs available..
>
> Any suggestions and/or comments welcome!
>
> Terry King ...In The Woods In Vermont
>
> ...associated :) with:
Caution... Most chargers out put much more then the RCX can handle. I
recall there being a thread that cautioned against charging in the RCX.
Dean
--
Dean Husby
LUGNET Member #320
TFM's LEGO Workshop - http://www.akasa.bc.ca/tfm
The Vancouver LEGO Club - http://www.akasa.bc.ca/vlc/
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