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Lithium-Ion parallel charging and some other li-ion stuff

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Date: Wed, 7 Nov 2001 23:36:40 +1100

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Hi everyone,

Last post for tonight, hope I haven't rattled you too much, I hope that =
something useful / interesting comes out of each for at least somebody. =
Some questions on charging (and discharging?!?!) lithium ion batteries. =
I've been reading through the wear hard archives, but i was wondering if =
anybody has been doing this sort of stuff long-term and has noticed any =
effects. the archive posts are from when doug was testing out some =
parallel charging etc...

a) does putting two 3.6v lithium-ion battery packs in series equal a =
7.2v pack of the same amp-hour rating for all charging / discharging / =
usage purposes? i assume they are just made up of cells inside and 7.2v =
packs just have twice the cells, so it should be the same deal?

b) are all lithium-ion cells essentially the same, i.e. i have a generic =
7.2v lithium ion charger for various models of camcorders (+ =
infolithium), can i use this to charge 7.2v mobile phone lithium-ion =
batteries or is there something I should know? (assuming that all =
contacts except for + and - are ignored as with infolithium)

c) excuse my ignorance, but if lithium-ion cells suffer no memory =
effect, why would we ever discharge them?

d) has anybody experimented long term with charging or discharging large =
numbers of lithium-ion batteries in parallel? i would need to charge =
perhaps 8 or 16 pairs of 3.6v cells (as 7.2v cells). i'm guessing this =
drives up the current a bit so depending on the charger i probably =
wouldn't be able to do more than 2 or 3 pairs at once.

e) i've looked on the web, but can't find anything. why do two =
lithium-ions in parallel not invisibly appear to a charger as a single, =
large capacity cell? if you have a website with any info on this i'd =
appreciate it!

f) i know many of you run a pair of infolithiums in series to get 14.4 =
volts, do you all dissasemble that for charging individually, or is it =
possible to charge "14.4 volt" lithium ions?

g) are there any reccomendations for diode / bridge rectifier setups to =
use / charge many many infolithium cells. I keep reading about these to =
stop the batteries from trying to charge each other when in parallel and =
the like. I understand the principle of a diode / bridge rectifier, but =
i don't understand the circuit to arrange this. would this allow many =
cells to be charged more easily without destroying chargers/

Thanks for any help with any of the above!

Nick

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<DIV><FONT face=3DArial size=3D2>Hi everyone,</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Last post for tonight, hope I haven't =
rattled you=20
too much, I hope that something useful / interesting comes out of each =
for at=20
least somebody. Some questions on charging (and discharging?!?!) lithium =
ion=20
batteries. I've been reading through the wear hard archives, but =
i was=20
wondering if anybody has been doing this sort of stuff long-term and has =
noticed=20
any effects. the archive posts are from when doug was testing out some =
parallel=20
charging etc...</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>a) does putting two 3.6v lithium-ion =
battery packs=20
in series equal a 7.2v pack of the same amp-hour rating for all charging =
/=20
discharging / usage purposes? i assume they are just made up of cells =
inside and=20
7.2v packs just have twice the cells, so it should be the same=20
deal?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>b) are all lithium-ion cells =
essentially the same,=20
i.e. i have a generic 7.2v lithium ion charger for various models of =
camcorders=20
(+ infolithium), can i use this to charge 7.2v mobile phone lithium-ion=20
batteries or is there something I should know? (assuming that all =
contacts=20
except for + and - are ignored as with infolithium)</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>c) excuse my ignorance, but if =
lithium-ion cells=20
suffer no memory effect, why would we ever discharge them?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT><FONT face=3DArial =
size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>d) has anybody experimented long term =
with charging=20
or discharging large numbers of lithium-ion batteries in parallel? i =
would need=20
to charge perhaps 8 or 16 pairs of 3.6v cells (as 7.2v cells). i'm =
guessing this=20
drives up the current a bit so depending on the charger i probably =
wouldn't=20
be able to do more than 2 or 3 pairs at once.</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>e) i've looked on the web, but can't =
find anything.=20
why do two lithium-ions in parallel not invisibly appear to a charger as =
a=20
single, large capacity cell? if you have a website with any info on this =
i'd=20
appreciate it!</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>f) i know many of you run a pair of =
infolithiums in=20
series to get 14.4 volts, do you all dissasemble that for charging =
individually,=20
or is it possible to charge "14.4 volt" lithium ions?</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>g) are there any reccomendations for =
diode / bridge=20
rectifier setups to use / charge many many infolithium cells. I keep =
reading=20
about these to stop the batteries from trying to charge each other when =
in=20
parallel and the like. I understand the principle of a diode / bridge =
rectifier,=20
but i don't understand the circuit to arrange this. would this allow =
many cells=20
to be charged more easily without destroying chargers/</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Thanks for any help with any of the=20
above!</FONT></DIV>
<DIV><FONT face=3DArial size=3D2></FONT> </DIV>
<DIV><FONT face=3DArial size=3D2>Nick</FONT></DIV></BODY></HTML>

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