| |
In lugnet.robotics.handyboard, Fred G. Martin writes:
> hi dennis,
>
> well, it's just a plain C/10 charge circuit. but i was under the
> impression that nicad's aren't damaged by that. it's possible i'm
> wrong :-).
Hi Fred,
I don't claim to be an expert on these, but what I have read leads me to
believe that this may damage the cells if left on too long.
For common NiCds (800mah AA' for instance) C/10 should really be considered
a fast charge and not a trickle charge. I have truthfully managed to
quickcharge them at 1.5C without appearing to hurt them. The sub-C NiCd's are a
really tough variety that can take a 3C charge as a quick charge. In that
group, we have a rule of thumb of quick charging at 3C or 5Amps max - I'm not
sure where that rule came from, but it appears to work, but only on sub-C cells
(1400-2000mah packs).
If your cells are consistantly warm on the charger then I think you are
pushing them and could be damaging them. The process that causes them to get
warm is interesting, and I'm not sure that I fully understand it, and certainly
don't want to try to explain it in one paragraph or less, but it is discussed in
this next book.
A good book describing charging techniques and what is going on inside a NiCd
is "Maintenance-Free Bateries Lead-Acid, Nickel/Cadmium, Nickel/Metal Hydride A
Handbook of Battery Technology" Second Edition by D. Berndt (1997)
Research Studies Press LTD
Taunton, Somerset, England
John Wiley and Sons INC, New York, NY...
ISBN 0 471 97018 2 (USA)
Another interesting publication is NASA Reference publication 1326 (1994)
"Handbook for Handling and Storage of Nickel-Cadmium Batteries: Lessons Learned"
Gopalakrishna M. Rao, Thomas Y. Yi
Goddard Space Flight Center
Floyd E. Ford (Swales & Associates Beltsville, Maryland)
> any other battery experts out there?
You can try Red's Battery clinic (pages), lots of stuff there:
http://gnv.fdt.net/~redscho/
have fun,
DLC
> fred
>
>
> In your message you said:
> > In lugnet.robotics.handyboard, Fred G. Martin writes:
> > > no i disagree with this answer. the HB is designed to be left on
> > > normal charge indefinitely. the batts can get a little warm. if they
> > > are hot then something is wrong, but a little warm is nothing to worry
> > > about.
> >
> > I was guessing here - most chargers don't check for peak charge, since I
> > didn't know if the Handiboard charger did or didn't... If the charger has a
> > trickle charge of more than C/50 or C/100 then NiCds will be damaged eventual • ly
> > on a long-term charger, but, like I said, I was guessing about the charger
> > circuit on the H-board, there are some pretty smart NiCd peak-charger chips o • ut
> > there.
> >
> > YMMV,
> > DLC
> >
|
|
Message is in Reply To:
 | | Re: Overcharged battery?
|
| hi dennis, well, it's just a plain C/10 charge circuit. but i was under the impression that nicad's aren't damaged by that. it's possible i'm wrong :-). any other battery experts out there? fred In your message you said: (...) ly (...) ut (...) (25 years ago, 15-Mar-00, to lugnet.robotics.handyboard)
|
10 Messages in This Thread:
  
- Entire Thread on One Page:
- Nested:
All | Brief | Compact | Dots
Linear:
All | Brief | Compact
|
|
|
|
