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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
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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
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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. |
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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
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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
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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
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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
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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
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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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