Subject:
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Re: Battery Charging Question
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Thu, 30 Mar 2000 01:56:27 GMT
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Viewed:
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6542 times
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Hi,
Yes, I read that too. But the pack was NiCd, mine is NiMH. According
to some people, the charging methods between the two are different. I don't
think I can charge NiMH pack like a NiCd pack (or can I??).
--
Ray
Aaron Dwyer <handyboard@media.mit.edu> wrote in message
news:1072F1A27E99D3119747005004B9A38040993F@MAIL...
> Ray
>
> This is a post that Dennis Clark answered thoroughly for me just last • week.
>
> By the way thanks for that Dennis, I think I forgot to before.
>
>
>
> In lugnet.robotics.handyboard, Aaron Dwyer <AaronD@nulec.com.au> writes:
> > hi all
>
> > the batteries are from mobile radios. motorola. 7.5V. 1200mAh.
> > Nickel-Cadmium.
> > can someone enlighten me on the best method to rejuvenate and charge • these
> > type of batteries are.
> >
> > motorola have a quick desktop charger available for $110, but i want to • try
> > it myself first.
>
> You will need some good equipment, or you will need lots of patience and • a
> good DVM.
>
> Here are the steps to rejuvinating old NiCds IF they can be recovered. If
> they
> have suffered the effects of overcharging (common) then they may not be
> recoverable.
>
> 1. Discharge the pack completely at a C/10 or C/20 rate (60-120ma in this
> case)
> Complete discharge is considered to be .9V per cell. In a 6 cell • (7.2V)
> pack, this is 5.4V. WAIT FOR THE PACK TO COOL TO ROOM TEMP.
>
> 2. Charge them gently with a C/20 charger (C=1200mah in this case,
> so C/20 is 60ma) until they are full. This is roughly 20 hours. The
> pack
> should be just slightly warm. Check on it from time to time, if it • gets
> hot before 20 hours are up (at 60ma) then you have a dead pack, recycle
> it.
>
> 3. Do a high current discharge of 5 to 10Amps. A 1200mah pack is sub-c
> cells
> and they can handle that current easily. Discharge until the pack
> reaches
> .9V per cell, for a 6-cell pack, this is 5.4V. WAIT FOR THE PACK TO • COOL
> TO ROOM TEMP.
>
> 4. Do a high current charge of the pack until peaked. This is where you
> need
> the good equipment. You want to charge the pack at 3C at least
> (3.6Amps).
> This will take about 20+ minutes. You want a delta-peak detecting
> charger
> to do this - RC car chargers are designed to do this. If you decide to
> do it by hand, then you have to put a volt meter on the pack. The
> voltage
> of a NiCd pack will rise as it is charging, so you need to provide a
> constant current source to handle this. The pack is peaked when the
> voltage
> starts to drop. I use a peak charger, but I know that about .1V • dropoff
> is
> not uncommon. An analog charger is best for this, watching the needle
> and
> noting its location is easier than tracking a digital readout. WAIT FOR
> THE
> PACK TO COOL TO ROOM TEMP. It will get a little warm during this
> process,
> if the pack gets hot, then then reduce the charge rate, and repeat • steps
> 1-4, if it still gets hot, recycle the pack.
>
> 5. Repeat Step 3.
>
> If the pack is recoverable, you should now have a decent NiCd battery
> pack.
>
> Yeah, its complicated and a mistake at any point in this process can
> result
> in a fire or explosion - I use a discharger that detects the proper cutoff
> point and a delta-peak detecting charger that I can set the charge rate on
> and
> it tracks peak voltage and capacity. If your 6-cell pack has a peak • voltage
> over about 10.5V its a pretty crappy pack and not very good for high • current
> duties. You will need a power supply that is at least 12V to do this kind
> of charging, and it has to handle about 5Amps to boot. Heat is the enemy,
> NiCd's hate high temperatures.
>
> have fun!
> DLC
>
> > -----Original Message-----
> > From: Ray Tang [mailto:raytang_1@hotmail.com]
> > Sent: Thursday, 30 March 2000 10:38
> > To: lugnet.robotics.handyboard@lugnet.com
> > Subject: Battery Charging Question
> >
> >
> > Hi all,
> > I was wondering if any battery expert can help me on
> > this. A friend of
> > mine gave me a NiMH battery pack for my HB expansion board
> > AUX power supply.
> > It is rated 6V, 3 AH (yeah, he gave me the spec.) but there
> > is no charger.
> > I know charging NiMH is complicated. I was wondering if
> > anyone knows a
> > ready-to-use charger circuit, or just the config of the
> > charger, or some
> > info on how I should charge it. Thanks!
> > By the way, All Electronics (www.allelectronics.com)
> > sells some cheap
> > Nickel-Cadmium packs. Some of them are 6V at 600 mAH for about $5.00.
> >
> > --
> >
> > Ray
>
>
> --
> Aaron Dwyer PH +61 7 3249 5635
> Systems Engineer FAX +61 7 3249 5888
> Nulec Projects http://www.nulec.com.au
>
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Message has 1 Reply:
 | | Re: Battery Charging Question
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| (...) It is basically charged the same way and has all of the faults of he NiCd (voltage depression, etc.) but while it has a higher average capacity, it does not have as much current delivery (higher internal resistance.) The cells peak charge in a (...) (27 years ago, 30-Mar-00, to lugnet.robotics.handyboard)
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Message is in Reply To:
| | RE: Battery Charging Question
|
| Ray This is a post that Dennis Clark answered thoroughly for me just last week. By the way thanks for that Dennis, I think I forgot to before. (...) You will need some good equipment, or you will need lots of patience and a good DVM. Here are the (...) (27 years ago, 30-Mar-00, to lugnet.robotics.handyboard)
|
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