#1
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Cold charging
Upon getting home from work this evening and putting my Lumicycle
battery on to charge, I was struck by how cold the battery felt. Are there any particular problems associated with charging cold batteries? Is it best to charge them while cold, or is it better to let them warm up to room temperature first, or does it make no real difference. -- Danny Colyer URL:http://www.colyer.plus.com/danny/ Subscribe to PlusNet URL:http://www.colyer.plus.com/referral/ "He who dares not offend cannot be honest." - Thomas Paine |
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#2
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Cold charging
Danny Colyer wrote:
Upon getting home from work this evening and putting my Lumicycle battery on to charge, I was struck by how cold the battery felt. Are there any particular problems associated with charging cold batteries? Is it best to charge them while cold, or is it better to let them warm up to room temperature first, or does it make no real difference. From what I've read on various websites, NiMH and Li-Ion batteres take the charge better if you first let them warm up somewhat after using them in wintery conditions. I think 10 degrees C is OK. ~PB |
#3
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Cold charging
On Fri, 24 Feb 2006, Danny Colyer wrote:
Are there any particular problems associated with charging cold batteries? Is it best to charge them while cold, or is it better to let them warm up to room temperature first, or does it make no real difference. The serious no-no for NiMH and NiCd is charging them when they're hot (from energetic discharge). I don't think charging them when they're cold will hurt, but I've never seen anything categorically stating that. I let mine warm up a little before charging, just-in-case. regards, Ian SMith -- |\ /| no .sig |o o| |/ \| |
#4
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Cold charging
Ian Smith wrote: On Fri, 24 Feb 2006, Danny Colyer wrote: Are there any particular problems associated with charging cold batteries? Is it best to charge them while cold, or is it better to let them warm up to room temperature first, or does it make no real difference. The serious no-no for NiMH and NiCd is charging them when they're hot (from energetic discharge). I don't think charging them when they're cold will hurt, but I've never seen anything categorically stating that. A bit OT, but my Nokia mobile was flashing 'battery low' since last night. Still alive and kicking this morning but still showing '1 bar' of battery left. It's been in my pocket all day which is substantially warmer than in this house and it is now saying the battery is over half full! I've noticed similar discharging performance with bike lights which die when out in the cold, but have plenty of juice left when brought inside to recharge! pete |
#5
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Cold charging
Jon is Away! wrote:
Pete Biggs wrote: From what I've read on various websites, NiMH and Li-Ion batteres take the charge better if you first let them warm up somewhat after using them in wintery conditions. I think 10 degrees C is OK. The very act of charging them with a fast charger will warm them. I'm not sure of the exact chemistry, but from what I understand I suspect that allowing them to warm a little first will not hurt, since most have optimal ranges for charge + discharge. I wonder two things about the Lumicycle Li-Ion charger: 1. It first tests the battery to decide whether it needs a blast of fast charging (red mode) before the main, more gentle charge which takes some hours (amber mode), before trickle charging (green mode). Would it get a valid reading at the start when the battery is freezing cold? 2. If it starts on amber mode (maybe red as well), the battery doesn't become warm for some time if it's very cold to begin with, so I think the charging may be more efficient or "fuller" (?) if the battery was allowed to warm up naturally before charging. IIRC they don't discharge as efficiently in the cold, so if they are getting cool on your ride, you might consider knitting a woolly cover for them. Jpegs please if you do. I might take that suggestion quite seriously! My spare DIY NiMH battery has no insulation at all so maybe I should wrap it in something warm. I aint doing no knitting though! ~PB |
#6
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Cold charging
Pete Biggs wrote:
I wonder two things about the Lumicycle Li-Ion charger: 1. It first tests the battery to decide whether it needs a blast of fast charging (red mode) before the main, more gentle charge which takes some hours (amber mode), before trickle charging (green mode). Would it get a valid reading at the start when the battery is freezing cold? My gut feeling is that it should do, but I wouldn't like to be sure. I have a feeling that the P.D. will remain the same, but the efficiency of conversion from chemical energy to electrical energy will be weakened. I have however drunk a couple of bottles of strong Belgian beer so this is liable to nothing more than cobblers. 2. If it starts on amber mode (maybe red as well), the battery doesn't become warm for some time if it's very cold to begin with, so I think the charging may be more efficient or "fuller" (?) if the battery was allowed to warm up naturally before charging. As I mentioned earlier (and others have said the same) charging only becomes an issue at high temperatures, although it might potentially take more energy (i.e. longer) when cold. At high temperatures, the rate of conversion to chemical energy is lower than the energy input and more heat is produced. In NiMH or NiCad batteries this causes them to expel hydrogen which reduces the battery's capacity and adds the exciting risk of a small bang. With Li-ion batteriers this is more of an issue that can result in a very large bang (see for example: some Nokia phones). Thankfully your Li-ion batteries will contain circuitry to prevent this from occuring. I might take that suggestion quite seriously! My spare DIY NiMH battery has no insulation at all so maybe I should wrap it in something warm. I aint doing no knitting though! Despite the humour it is genuine. Discharge rates are far more obviously affected by low temperatures, so keeping your batteries warm on cold nights will allow you to take the long route home. My home made battery packs (Which closely resemble sticks of dynamite) are made from plastic plumbing tube, PVC tape and heatshrink which means that the contents do probably hold temperature for a while. Jon |
#7
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Cold charging
Jon is Away! wrote:
IIRC they don't discharge as efficiently in the cold, so if they are getting cool on your ride, you might consider knitting a woolly cover for them. Jpegs please if you do. G Problem is, I'm so confident about the security of my bike when I'm at work (covered up, covered by CCTV that I can monitor from my desk, directly outside the main door and directly beneath my office window) that I don't bother removing the lights and battery, so by the time I ride home it's been in out in the cold for 9 hours. I've never had a problem, though. My commute doesn't take anywhere near long enough to discharge the battery fully, and it can easily handle 2 days of commuting between charges. I might get into the habit of letting it warm up indoors for an hour or so before charging, though. -- Danny Colyer URL:http://www.colyer.plus.com/danny/ Subscribe to PlusNet URL:http://www.colyer.plus.com/referral/ "He who dares not offend cannot be honest." - Thomas Paine |
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