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Rechargable Cells/batteries for Lights



 
 
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  #1  
Old December 22nd 06, 12:59 PM posted to rec.bicycles.tech
Keiron Kinninmont
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Posts: 5
Default Rechargable Cells/batteries for Lights

Hi,

Currently using a rather bog-standard cateye front light for commuting. It
requires two C/R14/Baby size cells. I'm currently usinf NiMh 2300mAh cells.
Despite the claims of global warming, the rather bitter cold here is having
a noticable effect on the performance of the cells (maybe up to 1/3
reduction). i hear that Cadmium cells suffer less from this effect (despite
their other shortfalls), does anybody know how true this is in a/this
practical sense?

Secondly, i suspect that the longer/faster i ride the colder the light
becomes (fact, i've experimented and the effect is noticable) thus effecting
the battery further and i presume this is to do with a) increased time in
the cold (obviously) and b)wind chill effect. Before i go to the bother of
creating some neoprene light sleeve to increase insulation does anyone know
if this is likely to have the slightest effect?

Any other ideas appreciated

Thanks


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  #2  
Old December 22nd 06, 01:08 PM posted to rec.bicycles.tech
Ron Hardin
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Posts: 145
Default Rechargable Cells/batteries for Lights

Supposedly, Lithium cells thrive in cold. I don't know about the rechargeables.

And NiCd's generate their own heat in use, but of course you're dealing with
greatly reduced capacity compared to NiMH. The heat is probably why there
is reduced capacity, in fact.

If the light unclips, carry a second one in your pocket and swap them, to
double the runtime. Maybe the second one will then heat back up, and you
can continue the process.
--
Ron Hardin


On the internet, nobody knows you're a jerk.
  #3  
Old December 22nd 06, 01:45 PM posted to rec.bicycles.tech
Keiron Kinninmont
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Posts: 5
Default Rechargable Cells/batteries for Lights


"Ron Hardin" wrote in message
...
Supposedly, Lithium cells thrive in cold. I don't know about the

rechargeables.

If anyone knows anything further about rechargeable litium cells i'd be
greatly interested. Truth is i dismissed them because i could only find
1000mAh (limited search i grant you) but will these 1000mAh lithium cells
out perform 1000mAh cells of the other varieties in any respect?


And NiCd's generate their own heat in use, but of course you're dealing

with
greatly reduced capacity compared to NiMH. The heat is probably why there
is reduced capacity, in fact.


sorry, some confusion here i think. are you saying the heat is why NiMH
cells are reduced capacity, as this is what i'm using currently and the temp
is generally cold between 4 and -2 (yes, yes i know you canadians, americans
and russians get proper cold but this is cold for this sceptred isle lying
right in the path of gulf stream)

If the light unclips, carry a second one in your pocket and swap them, to
double the runtime. Maybe the second one will then heat back up, and you
can continue the process.


A fair idea but the commute isn't really long enough that the cells would
warm back up, it's only a 25min max commute, long enough for the negative
effect but not long enough to warm anything back up. Even if i start with a
spare in my pocket it's generally quite cold when i comes to changing it.

Ron Hardin



Cheers Ron.

Additions please folks.


  #4  
Old December 22nd 06, 03:45 PM posted to rec.bicycles.tech
Phil, Non-Squid
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Posts: 75
Default Rechargable Cells/batteries for Lights

Keiron Kinninmont wrote:
"Ron Hardin" wrote in message
...
Supposedly, Lithium cells thrive in cold. I don't know about the
rechargeables.


If anyone knows anything further about rechargeable litium cells i'd
be greatly interested. Truth is i dismissed them because i could only
find 1000mAh (limited search i grant you) but will these 1000mAh
lithium cells out perform 1000mAh cells of the other varieties in any
respect?


And NiCd's generate their own heat in use, but of course you're
dealing with greatly reduced capacity compared to NiMH. The heat is
probably why there is reduced capacity, in fact.


sorry, some confusion here i think. are you saying the heat is why
NiMH cells are reduced capacity, as this is what i'm using currently
and the temp is generally cold between 4 and -2 (yes, yes i know you
canadians, americans and russians get proper cold but this is cold
for this sceptred isle lying right in the path of gulf stream)

If the light unclips, carry a second one in your pocket and swap
them, to double the runtime. Maybe the second one will then heat
back up, and you can continue the process.


A fair idea but the commute isn't really long enough that the cells
would warm back up, it's only a 25min max commute, long enough for
the negative effect but not long enough to warm anything back up.
Even if i start with a spare in my pocket it's generally quite cold
when i comes to changing it.

Ron Hardin



Cheers Ron.

Additions please folks.


Charging Li-ions can be a dangerous matter. Read the FAQ below.

http://www.greenbatteries.com/libafa.html

--
Phil


  #5  
Old December 22nd 06, 04:57 PM posted to rec.bicycles.tech
[email protected]
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Posts: 1,299
Default Rechargable Cells/batteries for Lights

Keiron Said:
lights, cold, batteries suck


Ron Said:
Lithium


Phil Said:
Lithium+charging mishaps = BOOM.



Based on my experience from hobbying around with and occasionally
racing RC's, LiPo's (Lithium Polymer) do indeed thrive in the cold.
Their lifetime is also awesome, and the power curve is nice and
consistant until it drops. One day everybody was paying $100+/pack for
real high-end matched NiMH cells, then LiPo hit the scene & a sick
matched set wasn't worth 50. The difference is huge.

Phil's got a point on the charging thing, but as long as you use the
proper charger and do your due diligence you should be fine. I know
plenty of people who use LiPo's all the time, and have yet to see or
hear of a mishap. They happen, but they can be avoided with basic care
& common sense.

The big drawback for me is the $. I couldn't justify spending the $
for the upgrade. Maybe when all my NiMH stuff gives out, and LiPo
comes down a bit more in price.


Dan

  #6  
Old December 22nd 06, 05:05 PM posted to rec.bicycles.tech
[email protected]
external usenet poster
 
Posts: 2,673
Default Rechargable Cells/batteries for Lights


Keiron Kinninmont wrote:
Hi,

Currently using a rather bog-standard cateye front light for commuting. It
requires two C/R14/Baby size cells. I'm currently usinf NiMh 2300mAh cells.
Despite the claims of global warming, the rather bitter cold here is having
a noticable effect on the performance of the cells (maybe up to 1/3
reduction). i hear that Cadmium cells suffer less from this effect (despite
their other shortfalls), does anybody know how true this is in a/this
practical sense?

Secondly, i suspect that the longer/faster i ride the colder the light
becomes (fact, i've experimented and the effect is noticable) thus effecting
the battery further and i presume this is to do with a) increased time in
the cold (obviously) and b)wind chill effect. Before i go to the bother of
creating some neoprene light sleeve to increase insulation does anyone know
if this is likely to have the slightest effect?

Any other ideas appreciated


I don't use battery bike lights very often, preferring generators.
But:

Rather than insulating the entire light, you might make up an external
battery pack and wire it into the light. That pack might be easier to
insulate heavily, since there's no opening needed for the beam, and no
narrow space to the handlebar. If necessary, a long enough wire could
even allow putting that battery pack in a warm inside pocket.

Finally, that latter scheme is popular with those who mount the
headlight on their head. Again, not my favorite, but something you
could try.

- Frank Krygowski

  #7  
Old December 22nd 06, 05:15 PM posted to rec.bicycles.tech
peter
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Posts: 296
Default Rechargable Cells/batteries for Lights

Keiron Kinninmont wrote:
"Ron Hardin" wrote in message
...
Supposedly, Lithium cells thrive in cold. I don't know about the

rechargeables.

If anyone knows anything further about rechargeable litium cells i'd be
greatly interested. Truth is i dismissed them because i could only find
1000mAh (limited search i grant you) but will these 1000mAh lithium cells
out perform 1000mAh cells of the other varieties in any respect?


Which kind of lithium cells are you looking at? Li+ (lithium ion)
cells are rechargeable and produce 3.6 V, compared to about 1.2 V for
NiMH and NiCd cells. Since you're really interested in the energy
output, you'd be looking at the product of the voltage and the mA-hr
capacity. Therefore a Li+ cell with 1000 mA-hr capacity would be
equivalent to a NiMH cell with 3000 mA-hr capacity. Of course you'd
need to adjust the number of cells you use in series to be compatible
with your light.

There are also Eveready lithium/iron-disulfide AA cells which produce
about 1.6V and a capacity of 2900 mA-hr, but these are not
rechargeable. Both these and the Li+ cells do perform very well at low
temperatures - much better than either NiMH or NiCd. I haven't noticed
much difference in low temperature performance between NiMH and NiCd -
the latter have so much less capacity and also have disposal problems
so I no longer use any.

If the light unclips, carry a second one in your pocket and swap them, to
double the runtime. Maybe the second one will then heat back up, and you
can continue the process.


A fair idea but the commute isn't really long enough that the cells would
warm back up, it's only a 25min max commute, long enough for the negative
effect but not long enough to warm anything back up. Even if i start with a
spare in my pocket it's generally quite cold when i comes to changing it.


That would presumably depend on where the pocket is located. An inside
pocket should stay warm from your body temperature, so the spare pack
would be warm when you start using it.

  #8  
Old December 22nd 06, 05:16 PM posted to rec.bicycles.tech
[email protected]
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Posts: 1,299
Default Rechargable Cells/batteries for Lights

Keiron Said:
If anyone knows anything further about rechargeable litium cells i'd be

greatly interested. Truth is i dismissed them because i could only find

1000mAh (limited search i grant you) but will these 1000mAh lithium
cells
out perform 1000mAh cells of the other varieties in any respect?


The only downsides I'm aware of with LiPo are the hazards with
improper charging/handling and the price. Though they're primarily
RC, Austin over at maxamps.com has been extremely helpful,
knowledgeable and fair with me over the past few years. If you shot
him an email or gave him a jingle he'd most likely be able to help
you out. Last I knew they were getting around 35 for a 2100mah Lipo
Pack, and I think they had a budget charger for around 25. Just a
month or so ago they were running a 3 year 300 cycle warranty special
on all their LiPo products, I don't know if he's got anything going
on for xmas right now.


Dan

  #9  
Old December 26th 06, 12:58 AM posted to rec.bicycles.tech
mark
external usenet poster
 
Posts: 223
Default Rechargable Cells/batteries for Lights

Keiron Kinninmont wrote:
Hi,

Currently using a rather bog-standard cateye front light for commuting. It
requires two C/R14/Baby size cells. I'm currently usinf NiMh 2300mAh cells.
Despite the claims of global warming, the rather bitter cold here is having
a noticable effect on the performance of the cells (maybe up to 1/3
reduction). i hear that Cadmium cells suffer less from this effect (despite
their other shortfalls), does anybody know how true this is in a/this
practical sense?

Secondly, i suspect that the longer/faster i ride the colder the light
becomes (fact, i've experimented and the effect is noticable) thus effecting
the battery further and i presume this is to do with a) increased time in
the cold (obviously) and b)wind chill effect. Before i go to the bother of
creating some neoprene light sleeve to increase insulation does anyone know
if this is likely to have the slightest effect?

Any other ideas appreciated

Thanks


My solution was to lose the battery powered headlight in favor of a hub
generator setup. Completely unaffected by the cold, better light output
than the bog standard cateye, and no screwing around with replacing
batteries, charging batteries, etc. I did continue to run a Cateye
TL-1000 battery powered taillight, mostly because it simplified
switching the light system between my winter commuter (ancient
suspensionless MTB w/ studded tires) and my summer commuter (rather nice
tourer). Two lithium AA (FR6? L91?) batteries power the taillight for
quite a few commutes in colder temps than you describe, although a pair
of NiMH rechargeables will get me to and from work (1 hr 15 min round
trip) with no trouble. Post a query about commuting lights on
uk.rec.cycles and you'll find an awful lot of people living on your
sceptered isle who feel the way I do about hub generators.

mark
 




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