Subject:
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Re: Automatic RCX Battery Recharging
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Mon, 23 Sep 2002 18:32:59 GMT
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Viewed:
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2642 times
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Brian Bagnall wrote:
> Some of us on the leJOS mailing list were discussing auto-battery recharging
> with the RCX. Here's some technical thoughts from Philipe Hurbain that might
> be useful to others.
>
> p.s. If anyone has anything to add to this please do. • Yes Brian, and read my P.S. ;-)
>
> -*-*-*-*-*-
>
> I think that the solution may be rather simple if you can accept a few
> drawbacks.
>
> As all batteries are serially connected, fast charging methods must be
> avoided, so you have to use slow charge.`
This is not necessairly true.
If you use the right charge method, load time less then 15 minutes,
without degrading the batteries (even with positiv effect on the
lifetime/capacity) is very well possible (I already do this for more
then 10 years).
The method is called REFLEX charging.
The principle is as follows: charge with very high current (4C to 10C)
for about 1 second, discharge with 10% of the charge current (0.4C ..
1C) for a short time, then measure the voltage. Stop the whole process
when the voltage starts to rise fast.
With this charge principle it's even possible to recover completely
defective batteries.
At the moment we're even trying to load normal (non-rechargeable)
batteries with this charger. We are able to load normal batteries but
the total capacity isn't high enough.
> Now the drawbacks: • This only yields for normal charging !!
> - Charge is slow, 12 hours for full charge
> - Battery life might be shortened, C/10 during 12 hours is fine with fully
> discharged batteries, but you may be overcharging if they were not
> exhausted.
> - Charging serially connected batteries is not very good (some get less
> charge than others, and in the long run, they will get reversed biased
> during use and rapidly destroyed). I suggest removing batteries from time to
> time, discharge then recharge them on a standard battery charger)
With reflex charging all these drawbacks will turn 180 degress into
advantages!!!
P.S. Brian, I didn't know where to find you, I used your beautiful RCX
picture for my simulator, Andy said it was ok. So if you've objections,
please let me know. A preview can be seen here:
http://oase.uci.kun.nl/~mientki/PIC/JALss/JALss_RCX_devices.htm
Stef Mientki
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Message has 2 Replies:
 | | Re: Automatic RCX Battery Recharging
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| Hello, (...) The only problem with that is that you will have to guarantee a max. voltage of 9 or 10 V at the RCX. I don't think usual charging circuits have a voltage limit that makes sense ... Greetings Horst (22 years ago, 23-Sep-02, to lugnet.robotics.rcx)
| | | Re: Automatic RCX Battery Recharging
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| I agree that there are much faster charging methods, but the slow one has the advantage of simplicity (this was implied in the original question)... I wonder too how to design a connector with contacts that reliably carry 4 to 10 A currents and (...) (22 years ago, 23-Sep-02, to lugnet.robotics.rcx)
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Message is in Reply To:
| | Automatic RCX Battery Recharging
|
| Some of us on the leJOS mailing list were discussing auto-battery recharging with the RCX. Here's some technical thoughts from Philipe Hurbain that might be useful to others. p.s. If anyone has anything to add to this please do. -*-*-*-*-*- I think (...) (22 years ago, 23-Sep-02, to lugnet.robotics.rcx)
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