Subject:
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Re: R: RCX as programmable battery charger
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Newsgroups:
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lugnet.robotics
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Date:
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Mon, 14 Oct 2002 23:11:06 GMT
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Viewed:
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985 times
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Camp0s wrote:
> Thanks for that info, i also searched with google about maximum output
> power, but the only thingh i got was 10 mA from the the microcontroller chip
> and a lot about firmware, programming and other stuffs.
>
> What i'm whising to do, is not just a "current producer for the cell phone
> battery", it's something you put the battery into it and pressing two button
> you can choose to:
>
> fast charge;
> discharge and then charge;
> do many discharge/charge cycles;
> keep the battery on with some pulse;
> ....and so on.
>
>
> I've just few question before the practise:
>
> the 350 Ma output is from a single output, or from all three outputs?
> and, if i'm using one output i should do not use the others two if not just
> for little power, for example lighthing those little lego lights ?
>
> About the discharge, i just need to set the output to "reverse", setting a
> "slow velocity" (so 1/8 pwm) and then check the voltage to not let it run
> too much down (3 nicd--> about 1.2 v per battery, stop discharge at
> 3.6~3.4V) what could happen if i drain too much batteryes, about 2.7 V ?.
What you're trying todo is known as "reflex" loading.
Search for it on the internet.
The protocol is about this
- load with 5 times the capacity for 1 sec (so it's full in about 10
minutes !!)
- discharge with 50!!! times the capacity for about 100 msec
- wait a few msec and measure voltage
- if not full repeat
In stead of 5*/50* you also could use 1*/10*, still maximum 1 hour
charging time.
>
> Last, monitoring the voltage. How can i do that done by the RCX ? just need
> the 0~5V range, are there some RCX sensor preset?
In the passive sensor mode the sensor inputs just reads the voltage
between 0 and 5 Volts. So just connect the positive output of the motors
through a 1 kOhm resistor to a passive sensor port.
>
>
> About negative-pulse charging:
>
> start cicle
> max (350) milli amp charge for 1 second
> 2 millisecond rest
> max (-350) amp Negative-Pulse for 5 milliseconds
> 10 millisecond rest where battery is evaluated and if everything is OK and
> the battery in not yet fully charged the 1 second pulse cycle is repeated
> end cicle
>
> would this cicle be ok ?
as I said, look for "reflex charging"
I think the link is even in this newgroup a few weeks ago.
Stef Mientki
>
>
> -----Messaggio originale-----
> Da: news-gateway@lugnet.com [mailto:news-gateway@lugnet.com]Per conto di
> Terry King
> Inviato: lunedì 14 ottobre 2002 21.53
> A: lego-robotics@crynwr.com
> Oggetto: Re: RCX as programmable battery charger
>
>
> In article <NGBBLFNPCLBPEJNIJPOEKEIJCCAA.camp0s@libero.it>, lego-
> robotics@crynwr.com says...
>
> > I was looking at my 1 years old cell phone, its battery is deteriorationg
>
> so
> This could be done... I think. Learning how it all works is
> enough of a reason to make a $100 microcontroller charge $10 batteries...
>
> The Rcx outputs current limit at about 350 Ma, as I recall
> (Info is on the WWW - search on "Rcx Internals" ).
> The output voltage is about
> 1.5 volts LESS than the supply. I assume you'd run
> this off a plug-in power supply.
>
> So, let's say you want to charge 3 nicads, putting out
> up to 1.5 volts into them. Decide what MAXIMUM current
> you want to limit to, as use a series resistor to
> limit the current. MAybe that would be something
> like 100 Ma. So, figure it out, like this:
>
> 3 Nicads max voltage= 4.5
> 9Volts (Into Rcx) minus about 1.5 equals 7.5 out of Rcx
> So you want a voltage drop of 7.5 - 4.5 = 3 volts at .1 Amps (100Ma)
> R = Voltage Over Current R = E / I so R = 3 / .1 = 30 ohms.
> A standard resistor value is 27 ohms. Ooops, how much POWER ??
> P = E * I so Power (Watts) = 3 * .1 = .3 watts so you need at least
> a 1/2 watt resistor.
>
> Now, the Rcx has pulse width "speed" control, from full-on down
> to on 1/8th of the time. It's fine to charge batteries with a pulse.
> So you can set the current lower than your maximum by setting the
> "speed". Oh, some Nicad and alkaline charges actually put a short
> NEGATIVE (Opposite polarity) pulse thru the battery when charging.
> Search on "Pulse Battery Charging" on Google.com
>
> So, you can control charging current, possible negative-pulses,
> and time. If you want to make a fast-charger, you may want to
> measure temperature of the battery too.
>
> There's plenty to start experimenting with!
>
>
> --
> Regards, Terry King ...In The Woods In Vermont
> tking@waitsriver.k12.vt.us
>
>
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Message is in Reply To:
 | | R: RCX as programmable battery charger
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| Thanks for that info, i also searched with google about maximum output power, but the only thingh i got was 10 mA from the the microcontroller chip and a lot about firmware, programming and other stuffs. What i'm whising to do, is not just a (...) (22 years ago, 14-Oct-02, to lugnet.robotics)
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