On Tue, 04 Jan 2005 at 07:23 GMT, Gags (aka Bruce)
was almost, but not quite, entirely unlike tea:
> "suzyj" <[email protected]> wrote in message
> news:[email protected]...
>> The battery can be either my nightstick battery (3Ah 6V NiMH) or else
>> an 8.4V 8.9Ah pack I made with eight 18650 Li+ cells. The luxdrive
>> thingy is very cool, and takes anything from 5V up to lots (I've tested
>> it to 12V, and it works fine) to power the LED.
> what do you use to charge the Li+ batteries?? I must say that i have never
> looked at using or charging them although I do have an old battery pack from
> my Laptop (I think it was Li-Ion....is that the same??) that wouldn't charge
> anymore. I don't know if you can recondition Li-Ion batteries or
> not.....might have to actually do a bit of a read-up on latest technologies.
They're tricksy. On the cheap, you might be able to get away with a
constant current followed by constant voltage (much like in the lead
acid case), but only if you are accurate to better than 1%, and don't
trickle charge them. And don't expect it not to blow up.
I did the obvious google search (something like "charging li-ion
circuit") a few weeks back, because I have a 2 year old dell laptop
battery that has plenty of charge in the cells (enough to light a
spare 12V halogen, if I use 3 of the cells instead of the 4), and it
registers as almost full, but the circuit refuses to charge or
discharge.
> BTW.....how expensive are the cells to buy and where can you get them??
You can't buy then separately, because they are so damn dangerous to
charge. They only ever come in manufactured packs with the charging
circuits built in.
The cells in mine are made by Panasonic though, if you really know
what you are doing.
Somewhere (I seem not have bookmarked it???) I had a datasheet for a
charging chip. Not sold by Jaycar - perhaps rs-components could do it?
Does things like senses temperature (sudden temp rise means that it is
fully charged in both NiMH and Li-ion cases), under/over voltage,
current, time and a bunch of other things which I have forgotten.
Maybe the LM3647?
Sorry for being so vague. It's been months since I sorted out my
bookmarks, and hence I can't find anything I have added in the last
few months.
From Jaycar, I recently bought their 19 LED red rear stop light
replacement, with the intention of building a PWM dimmer and flashing
circuit, and hooking it all up in a secure housing. From there, I
could use either the 14.8 volt Li-ion battery, or a 12V SLA and
connect up both it and a front halogen bulb. But unfortunately, I
still have rather too much real work to do.
--
TimC --
http://astronomy.swin.edu.au/staff/tconnors/
As a computer, I find your faith in technology amusing.
