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#1
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Charging 8.4V Li-Ion packs for front lights
Folks,
Probably most of you know these kinds of lights: http://www.amazon.com/Masione-Waterp...SFBQ2EJ3NXQB12 The Li-Ion battery packs are a bit wimpy and only provide 1-2h of juice but there are bigger ones: http://www.amazon.com/WindFire%C2%AE...C5RNZVQKDKY 7 Here is my question. Li-Ion is very picky about charging. Go above 4.3V and there may be a need for the fire department to come out. These 8.4V packs contain two battery sets in series. Yet AFAICT there are only two wires in the cable. So how does the charging process get balanced? If they only rely on internal protection electronics which isn't 100% kosher then over time one side will get less and less charge because the other turns off earlier and allows no more current through the stack. Does anyone know? Can anyone share experiences about lifetime? Or about better and more sturdy mounting option for hard MTB use? I'd also like to tie in the rear light somehow plus possibly provide a homebrew voltage readout so I know how much juice is left for the remainder of a ride (most lights have no warning, for whatever reason). I guess that's only possible via a hack and splice. Please, no discussions about dynamo lights if you can help it. Those are simply too weak for my riding. -- Regards, Joerg http://www.analogconsultants.com/ |
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#2
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Charging 8.4V Li-Ion packs for front lights
On 11/1/2014 11:39 AM, Joerg wrote:
Folks, Probably most of you know these kinds of lights: http://www.amazon.com/Masione-Waterp...SFBQ2EJ3NXQB12 The Li-Ion battery packs are a bit wimpy and only provide 1-2h of juice but there are bigger ones: http://www.amazon.com/WindFire%C2%AE...C5RNZVQKDKY 7 Here is my question. Li-Ion is very picky about charging. Go above 4.3V and there may be a need for the fire department to come out. These 8.4V packs contain two battery sets in series. Yet AFAICT there are only two wires in the cable. So how does the charging process get balanced? If they only rely on internal protection electronics which isn't 100% kosher then over time one side will get less and less charge because the other turns off earlier and allows no more current through the stack. Does anyone know? Can anyone share experiences about lifetime? Or about better and more sturdy mounting option for hard MTB use? I'd also like to tie in the rear light somehow plus possibly provide a homebrew voltage readout so I know how much juice is left for the remainder of a ride (most lights have no warning, for whatever reason). I guess that's only possible via a hack and splice. Please, no discussions about dynamo lights if you can help it. Those are simply too weak for my riding. It's not perfectly balanced but it doesn't matter. They will use cells from the same lot which are pretty close. For most multi-cell Li-Ion batteries, cells are charged in series. There are some larger packs where there is a series/parallel arrangement i.e. multiple parallel sets of multiple series-connected batteries. |
#3
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Charging 8.4V Li-Ion packs for front lights
sms wrote:
On 11/1/2014 11:39 AM, Joerg wrote: Folks, Probably most of you know these kinds of lights: http://www.amazon.com/Masione-Waterp...SFBQ2EJ3NXQB12 The Li-Ion battery packs are a bit wimpy and only provide 1-2h of juice but there are bigger ones: http://www.amazon.com/WindFire%C2%AE...C5RNZVQKDKY 7 Here is my question. Li-Ion is very picky about charging. Go above 4.3V and there may be a need for the fire department to come out. These 8.4V packs contain two battery sets in series. Yet AFAICT there are only two wires in the cable. So how does the charging process get balanced? If they only rely on internal protection electronics which isn't 100% kosher then over time one side will get less and less charge because the other turns off earlier and allows no more current through the stack. Does anyone know? Can anyone share experiences about lifetime? Or about better and more sturdy mounting option for hard MTB use? I'd also like to tie in the rear light somehow plus possibly provide a homebrew voltage readout so I know how much juice is left for the remainder of a ride (most lights have no warning, for whatever reason). I guess that's only possible via a hack and splice. Please, no discussions about dynamo lights if you can help it. Those are simply too weak for my riding. It's not perfectly balanced but it doesn't matter. They will use cells from the same lot which are pretty close. For most multi-cell Li-Ion batteries, cells are charged in series. There are some larger packs where there is a series/parallel arrangement i.e. multiple parallel sets of multiple series-connected batteries. Then maybe I should just try these out. If it works I'd have to figure out a more sturdy seat post mount, possibly inside a bottle holder that could at the same time carry the rear light. -- Regards, Joerg http://www.analogconsultants.com/ |
#4
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Charging 8.4V Li-Ion packs for front lights
On Sat, 01 Nov 2014 11:39:11 -0700, Joerg
wrote: Folks, Probably most of you know these kinds of lights: http://www.amazon.com/Masione-Waterp...SFBQ2EJ3NXQB12 The Li-Ion battery packs are a bit wimpy and only provide 1-2h of juice but there are bigger ones: http://www.amazon.com/WindFire%C2%AE...C5RNZVQKDKY 7 Here is my question. Li-Ion is very picky about charging. Go above 4.3V and there may be a need for the fire department to come out. These 8.4V packs contain two battery sets in series. Yet AFAICT there are only two wires in the cable. So how does the charging process get balanced? If they only rely on internal protection electronics which isn't 100% kosher then over time one side will get less and less charge because the other turns off earlier and allows no more current through the stack. Does anyone know? Can anyone share experiences about lifetime? Or about better and more sturdy mounting option for hard MTB use? I'd also like to tie in the rear light somehow plus possibly provide a homebrew voltage readout so I know how much juice is left for the remainder of a ride (most lights have no warning, for whatever reason). I guess that's only possible via a hack and splice. Please, no discussions about dynamo lights if you can help it. Those are simply too weak for my riding. I have one that's about 4 years old. Works OK. The charger is 8.4 volts and the pack has some type of circuit that must balance the cells when charging. Otherwise it would have exploded. There is a board in there, just couldn't read the SMD IC's well enough to see what they were. You can get a USB-to-8.4 converter from dx.com and charge it using a normal 5 volt supply. I have one and it cost $3. Slightly off topic: Many of the newer Chinese lights run from 4.2 volts. I have one that uses 4 18650's in parallel. Much cheaper to build and simpler charging. Hub dyno! Hub dyno! Hub dyno! |
#5
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Charging 8.4V Li-Ion packs for front lights
somebody wrote:
On Sat, 01 Nov 2014 11:39:11 -0700, Joerg wrote: Folks, Probably most of you know these kinds of lights: http://www.amazon.com/Masione-Waterp...SFBQ2EJ3NXQB12 The Li-Ion battery packs are a bit wimpy and only provide 1-2h of juice but there are bigger ones: http://www.amazon.com/WindFire%C2%AE...C5RNZVQKDKY 7 Here is my question. Li-Ion is very picky about charging. Go above 4.3V and there may be a need for the fire department to come out. These 8.4V packs contain two battery sets in series. Yet AFAICT there are only two wires in the cable. So how does the charging process get balanced? If they only rely on internal protection electronics which isn't 100% kosher then over time one side will get less and less charge because the other turns off earlier and allows no more current through the stack. Does anyone know? Can anyone share experiences about lifetime? Or about better and more sturdy mounting option for hard MTB use? I'd also like to tie in the rear light somehow plus possibly provide a homebrew voltage readout so I know how much juice is left for the remainder of a ride (most lights have no warning, for whatever reason). I guess that's only possible via a hack and splice. Please, no discussions about dynamo lights if you can help it. Those are simply too weak for my riding. I have one that's about 4 years old. Works OK. The charger is 8.4 volts and the pack has some type of circuit that must balance the cells when charging. Otherwise it would have exploded. There is a board in there, just couldn't read the SMD IC's well enough to see what they were. Thanks, that is encouraging. You can get a USB-to-8.4 converter from dx.com and charge it using a normal 5 volt supply. I have one and it cost $3. I don't need USB because the bikes stay in the garage. Well, at least since I am married they do :-) Slightly off topic: Many of the newer Chinese lights run from 4.2 volts. I have one that uses 4 18650's in parallel. Much cheaper to build and simpler charging. Newer ones? I looked at some 4.2V solutions but it seems they are going out of style. It sure would be simpler and I could easier splice in a Portland 1/2W rear light that normally takes two AAs. The downside is that when the Li-Ion is down to 3.5V or so the converter in the light would need to draw around 3.5 amps to get it to run at full brightness. That's a bit much for the cable and causes voltage drop. Amazon doesn't seem to have many 4.2V lights anymore. Hub dyno! Hub dyno! Hub dyno! :-) It would be nice to have something that can put at least a little charge back into a Li-Ion and a hub dynamo at a good speed could deliver 5W. For example by switching to a very low power mode or strobe when the charge level becomes iffy. But neither my road bike nor my MTB has that. A roller dynamo would be nice because it can (sometimes) be retrofitted without a major wheel rebuild. -- Regards, Joerg http://www.analogconsultants.com/ |
#6
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Charging 8.4V Li-Ion packs for front lights
On Sat, 01 Nov 2014 17:34:05 -0700, Joerg
wrote: Amazon doesn't seem to have many 4.2V lights anymore. Search Amazon, eBay, and DX.com for "18650 bicycle light". You should find plenty. Amazon shows 2,629 hits of which 615 are bicycle headlight specific. You need one of these. 4200 lumens: http://www.amazon.com/SecurityIng%C2%AE-Waterproof-Temperature-Headlight-Rechargeable/dp/B00K7SRZ4Y -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#7
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Charging 8.4V Li-Ion packs for front lights
On Sat, 01 Nov 2014 20:51:34 -0700, Jeff Liebermann
wrote: You need one of these. 4200 lumens: http://www.amazon.com/SecurityIng%C2%AE-Waterproof-Temperature-Headlight-Rechargeable/dp/B00K7SRZ4Y More power: http://www.amazon.com/Angelbubbles-Aluminum-Waterproof-HeadLight-HeadLamp/dp/B00ILOE8IM/ 8000 lumens using six 18650 cells in parallel. Looking at the Cree XML data sheet: http://www.cree.com/~/media/Files/Cree/LED%20Components%20and%20Modules/XLamp/Data%20and%20Binning/XLampXML.pdf each LED at 2A might put out 692 lumens. With 7 LED's: 7 * 692 = 4800 lumens Not exactly 8000 lumens, but probably accurate if I used an abacus. Of course, that means: 2A * 3.7V = 7.4 watts per LED or: 7 * 7.4 watts = 51.8 watts total power consumption. Well, if you used 10 bottle dynamos, it might work. Of course: 7 * 2A = 14A through the thin pack battery cables isn't going to work very well and might get hot or melt. Too bad LiIon cells have short circuit protection PCB's or you could use the battery pack for emergency welding. One problem... Do you really want "AngelBubbles" inscribed on your headlight? -- Jeff Liebermann 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |
#8
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Charging 8.4V Li-Ion packs for front lights
On Sat, 01 Nov 2014 11:39:11 -0700, Joerg
wrote: Folks, Probably most of you know these kinds of lights: http://www.amazon.com/Masione-Waterp...SFBQ2EJ3NXQB12 The Li-Ion battery packs are a bit wimpy and only provide 1-2h of juice but there are bigger ones: http://www.amazon.com/WindFire%C2%AE...C5RNZVQKDKY 7 Here is my question. Li-Ion is very picky about charging. Go above 4.3V and there may be a need for the fire department to come out. These 8.4V packs contain two battery sets in series. Yet AFAICT there are only two wires in the cable. So how does the charging process get balanced? If they only rely on internal protection electronics which isn't 100% kosher then over time one side will get less and less charge because the other turns off earlier and allows no more current through the stack. Any battery with a voltage higher than the value of a single cell battery, of the same type, is, by necessity, a number of one cell batteries in series. Your 4.3V batteries are, internally, three 1.4V cells. If charging one 3 cell battery causes no problems then it is likely that charging them 2 at a time should present very few additional problems. Does anyone know? Can anyone share experiences about lifetime? Or about better and more sturdy mounting option for hard MTB use? I'd also like to tie in the rear light somehow plus possibly provide a homebrew voltage readout so I know how much juice is left for the remainder of a ride (most lights have no warning, for whatever reason). I guess that's only possible via a hack and splice. Please, no discussions about dynamo lights if you can help it. Those are simply too weak for my riding. -- Cheers, John B. |
#9
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Charging 8.4V Li-Ion packs for front lights
On Sat, 01 Nov 2014 17:34:05 -0700, Joerg
wrote: You can get a USB-to-8.4 converter from dx.com and charge it using a normal 5 volt supply. I have one and it cost $3. I don't need USB because the bikes stay in the garage. Well, at least since I am married they do :-) I bring the pack into the cube at work to top off the charge. Just because I can. Slightly off topic: Many of the newer Chinese lights run from 4.2 volts. I have one that uses 4 18650's in parallel. Much cheaper to build and simpler charging. Newer ones? I looked at some 4.2V solutions but it seems they are going out of style. It sure would be simpler and I could easier splice in a Portland 1/2W rear light that normally takes two AAs. The downside is that when the Li-Ion is down to 3.5V or so the converter in the light would need to draw around 3.5 amps to get it to run at full brightness. That's a bit much for the cable and causes voltage drop. Amazon doesn't seem to have many 4.2V lights anymore. Both lights came from dx.com. I avoided the really cheap and really expensive ones. Both worked out OK. The 8.4 volt pack runs a tail light now. It would be nice to have something that can put at least a little charge back into a Li-Ion and a hub dynamo at a good speed could deliver 5W. For example by switching to a very low power mode or strobe when the charge level becomes iffy. But neither my road bike nor my MTB has that. A roller dynamo would be nice because it can (sometimes) be retrofitted without a major wheel rebuild. It would be nice to try a hub dyno just to see it in action. Think of it as a bucket list item. |
#10
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Charging 8.4V Li-Ion packs for front lights
John B. Slocomb wrote:
On Sat, 01 Nov 2014 11:39:11 -0700, Joerg wrote: Folks, Probably most of you know these kinds of lights: http://www.amazon.com/Masione-Waterp...SFBQ2EJ3NXQB12 The Li-Ion battery packs are a bit wimpy and only provide 1-2h of juice but there are bigger ones: http://www.amazon.com/WindFire%C2%AE...C5RNZVQKDKY 7 Here is my question. Li-Ion is very picky about charging. Go above 4.3V and there may be a need for the fire department to come out. These 8.4V packs contain two battery sets in series. Yet AFAICT there are only two wires in the cable. So how does the charging process get balanced? If they only rely on internal protection electronics which isn't 100% kosher then over time one side will get less and less charge because the other turns off earlier and allows no more current through the stack. Any battery with a voltage higher than the value of a single cell battery, of the same type, is, by necessity, a number of one cell batteries in series. Your 4.3V batteries are, internally, three 1.4V cells. If charging one 3 cell battery causes no problems then it is likely that charging them 2 at a time should present very few additional problems. Not quite. A single Li-Ion cell has a full-charge voltage of 4.2V. Those 8.4V batteries are a series combination of either two single Li-Ion cells or of two bundles of two or more each. This ain't you grandpa's NiCd stuff no more :-) [...] -- Regards, Joerg http://www.analogconsultants.com/ |
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