Hi,
	Actually trickle charge is bad for NiMh more of because NiMh's
typically do not need as a high a maintenance current as their NiCd
counterparts ( I recall its somewhere around the order of 5% or
something, not sure really). As such, during trickle charging once end
point is reached they tend to get overcharged.

------------------------------------------------------------------------
Daniel Chia

"Genius is one percent inspiration and ninety-nine percent
perspiration."

     - Thomas Edison

E-mail: danielcjh@yahoo.com.sg
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> -----Original Message-----
> From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu] On
Behalf Of
> Philip Pemberton
> Sent: 27 August 2005 21:33
> To: piclist@mit.edu
> Subject: RE: [EE]: NiCd/NiMH Burp/reflex charging (was [EE] Claimed
new method
> to fast charge NiCds)
> 
> In message
> <570CCF7BBB512341BA0EBA19E95084FB61D8@server.MicroBrix.local>
>           "David Van Horn" <dvanhorn@microbrix.com> wrote:
> 
> > Typical fast charge is around 1C, with a range of 0.5C to 2C.
Outside
> > this range, the end of charge signals will become less distinct.
> 
> 1C it is then. Guess I need to find a 2A PSU.
> Am I right in thinking that trickle charging is actually bad for
NiMHs?
> 
> > Check the cell specs carefully.
> > If they are cheap Chinese cells, I'd advise against anything faster
than
> > 0.5C. And I'd suggest a face shield and gloves.
> 
> Japanese actually. Kodak 1600mAh, "Made in Japan for Eastman Kodak
> Company".
> Very nice cells actually - certainly better than the Chinese-made
Uniross
> junk I used to use in the digicam.
> 
> > 1: Final backup, a timer that simply counts to say 120% normal
charge
> > time.
> > 2: A pipo over temperature cutout made into the battery pack.
> > 3: Absolute temperature of > 40C
> > 4: Rate of rise of temperature > 1C/min
> > 5: Absolute voltage > 1.6V/Cell
> > 7: Negative delta V of a few mV/Sec
> 
> Is it worth monitoring the current going into the cell, or is that not
a
> reliable way to detect end of charge?
> 
> > Good resources, though somewhat conflicting:
> >
> > McGraw-Hill's handbook of batteries
> > Sanyo and Panasonic data sheets.
> > Data sheets from your cell manufacturer.
> > Data sheets on charge ICs from Galaxy power.
> > Data sheets from the Cadex web site.
> 
> Ooo! More light reading for bedtime :)
> 
> Thanks.
> --
> Phil.                              | Acorn RiscPC600 SA220 64MB+6GB
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> philpem@philpem.me.uk              | Athlon64 3200+ A8VDeluxe R2
512MB+100GB
> http://www.philpem.me.uk/          | Panasonic CF-25 Mk.2 Toughbook
> ... DisneyLand: A people trap operated by a mouse.
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