Lithium battery time....
- Ok, this spring one of my battery packs is fine (the 2 year old one),
the other has a dead battery (the 5-6 year old one. Drat!). From what I
can see the dead battery just has a high resistance, maybe it opened up
over the winter.
Regardless, I'm ready to try lithium. I think Danny tried this last
year; Dan what kind of battery did you use? I'll give it a go.
- The 20AH ones I got were a "special deal", from an e-bike mfg who found
the lot unsuitable for high current usage and couldn't tolerate even one
of the pack going out, too difficult to repair.
Volumetrically, these cells are about 40% less for a 20AH, but it's hard
to get cells which fit. There will be a lot of unusable space. There
are plenty of 20AH LiFePO4 cells which you can't fit 8 of in this case
at all because they're too long or too thick or something. But they're
Unfortunately there still aren't good, cheap sources for LiFePO4.
There's a real problem on top of that in that the cheap batts use
TERRIBLE charge controllers which cause the batts to fail. There has to
be a way to shunt the greatest charging current which can be encountered
to prevent overcharge under worst-case scenario, and there needs to be a
way to shut off the entire pack when any one cell goes below its
eBay shows there's sellers with 24v 20AH batts as low as $279, with
charger... but I gotta say the eBay makers are shady as hell. Lots of
reports of failed batts, failed charge controllers, charge controllers
which could NEVER have done the job required even if everything were
working as designed.
Some have even packaged lithium-ion cells (like li-manganese) as
LiFePO4. Those are a totally different batt, and NOT as good of a
choice for bikes or a Robomower.
On 4/6/2012 4:38 PM, Christopher Zach wrote:
> Ok, this spring one of my battery packs is fine (the 2 year old one),
> the other has a dead battery (the 5-6 year old one. Drat!). From what I
> can see the dead battery just has a high resistance, maybe it opened up
> over the winter.
> Regardless, I'm ready to try lithium. I think Danny tried this last
> year; Dan what kind of battery did you use? I'll give it a go.
> Yahoo! Groups Links
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