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#1
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using rechargable batteries on the bike
I have a number of new 3000 mah 1.2 volt rechargeable batteries
to use for lighting on the bike. What is the recommended bulb voltage & amperage especially to get a good beam on the headlight. I suspect somewhere around 2.0 to 2.2 volt but I cannot find anyone selling bulbs like this in the UK. TIA -- Dave Croft Warrington England |
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#2
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Dave Croft wrote:
I suspect somewhere around 2.0 to 2.2 volt but I cannot find anyone selling bulbs like this in the UK. And you never will. Hook six of these batteries in series to get 7.2V. Over-voltage a 6V MR16 bulb by 20%. See "http://www.e-go.gb.com/parts.asp" to obtain a 6 volt/5 watt MR16 lamp. I haven't seen MR16 6 volt lamps, at more than 5 watts, except integrated into some emergency lights, and these don't have a front glass attached, see "http://www.cooperlighting.com/specfiles/productinfopdf/EADX0497.pdf". Steve http://bicyclelighting.com |
#3
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Quoth Dave Croft:
I have a number of new 3000 mah 1.2 volt rechargeable batteries to use for lighting on the bike. What is the recommended bulb voltage & amperage especially to get a good beam on the headlight. I suspect somewhere around 2.0 to 2.2 volt but I cannot find anyone selling bulbs like this in the UK. Most bicycle lights run on 6 volts. 5 of your 1.2 volt cells in series (head to tail) would give you that. Many 6-volt bike lights are set up to run on 4 1.5 volt cells, typical voltage for disposable cells. If you run 1.2 volt rechargeables, you only get 4.8 volts, but in practice this tends to work OK too. Sheldon "Sparks" Brown Newtonville, Massachusetts +------------------------------------------+ | Genius is one per cent inspiration and | | ninety-nine per cent perspiration. | |. --Thomas Edison | +------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com http://sheldonbrown.com |
#4
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Sheldon Brown wrote:
... Many 6-volt bike lights are set up to run on 4 1.5 volt cells, typical voltage for disposable cells.... The actual voltage will depend on the resistance of the circuit and the internal resistance of the cell. A standard alkaline-manganese battery will have an open circuit voltage (when new) ranging from about 1.58 to 1.61 volts {1]. Voltage will drop to the range of 1.5 to 1.3 volts for devices intended for use with such batteries. While the open circuit voltage of a NiCad or NiMH cell will be lower, these cells have a much lower internal resistance than the alkaline cell, therefore their voltage will not drop as much into a low resistance load, such a halogen bulb. [1] At least this is true for the thousands of commercially produced LR-03 (AAA), LR-6 (AA), LR-15 (C) and LR-20 (D) alkaline-manganese cells I have measured. -- Tom Sherman |
#5
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Most rechargeable batteries have much lower internal resistance than comparable disposable types. Lower internal resistance means less voltage depression under load. A 6V nominal alkaline pack might drop to 5.5 V under a 1 amp load where a NiCd will only drop to 5.4 V. NiCd are rated at 1.2 V nominal per cell but in actuality, this is the median voltage over the entire charge. Full charge is 1.4 V and completely empty is 1.0, both measured under load. Alkaline cells are only 1.5 V per cell at full charge but drop to about 1.35 at near total discharge. -- Weisse Luft |
#6
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Sheldon Brown wrote:
Most bicycle lights run on 6 volts. 5 of your 1.2 volt cells in series (head to tail) would give you that. Many 6-volt bike lights are set up to run on 4 1.5 volt cells, typical voltage for disposable cells. If you run 1.2 volt rechargeables, you only get 4.8 volts, but in practice this tends to work OK too. The reason it works is that 4 alkaline cells, rated at a nominal 1.5V each, deliver less than 6V under the heavy, multi-watt load of a bike light. With this in mind, these lights use lower voltage bulbs to begin with, which are a good match for 1.2V rechargeables. Matt O. |
#7
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Dave Croft wrote:
I have a number of new 3000 mah 1.2 volt rechargeable batteries to use for lighting on the bike. What is the recommended bulb voltage & amperage especially to get a good beam on the headlight. I suspect somewhere around 2.0 to 2.2 volt but I cannot find anyone selling bulbs like this in the UK. A 2.4 volt Krypton bulb* powered by 2 x 1.2 volt NiCad or NiMH 'C' cells will produce enough light to be seen by (brighter & whiter than 2 x 1.5 volt alkalines), but barely enough of a beam to see by. An LED lamp would be more useful if battery power is limited as they are much more effecient. * Available cheaply in the UK from shops like Wilkinsons. MR11 & MR16 bulbs: www.ricam.co.uk www.gbbulbs.co.uk www.lumicycle.co.uk (5 & 12W MR11 spots) ~PB |
#8
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Pete Biggs wrote:
An LED lamp would be more useful if battery power is limited as they are much more effecient. They are much less efficient in terms of the power required to produce an identical beam. |
#9
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I wrote:
Most bicycle lights run on 6 volts. 5 of your 1.2 volt cells in series (head to tail) would give you that. Many 6-volt bike lights are set up to run on 4 1.5 volt cells, typical voltage for disposable cells. If you run 1.2 volt rechargeables, you only get 4.8 volts, but in practice this tends to work OK too. Matt O'Toole wrote: The reason it works is that 4 alkaline cells, rated at a nominal 1.5V each, deliver less than 6V under the heavy, multi-watt load of a bike light. With this in mind, these lights use lower voltage bulbs to begin with, which are a good match for 1.2V rechargeables. Yes, I know that, but it wasn't relevant to the OP's question, and I didn't want to confuse him or or her with extraneous details. Sheldon "Simplicity" Brown +-----------------------------------------------------------+ | Sometimes the only thing more dangerous than a question | | is an answer. --Ferengi Rule of Acquisition #208 | +-----------------------------------------------------------+ Harris Cyclery, West Newton, Massachusetts Phone 617-244-9772 FAX 617-244-1041 http://harriscyclery.com Hard-to-find parts shipped Worldwide http://captainbike.com http://sheldonbrown.com |
#10
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Steven M. Scharf wrote:
Pete Biggs wrote: An LED lamp would be more useful if battery power is limited as they are much more effecient. They are much less efficient in terms of the power required to produce an identical beam. See http://nordicgroup.us/s78/wattslumens.html Where data is presented to show that LEDs can be more efficient than incandescent lamps (though perhaps not by as much as some might think). In practice I have changed from a 6W halogen bulb to a 1W Everled replacement bulb. With the same 5xAA NiMH power source I am now getting about 6 hours run time instead of 1.5 hours, the same or better illumination. Bike lights will always be a compromise between power, weight and run-time. LEDs can certainly help increase run-time. As ever, a bright light is one thing, but getting the light in the right place is another. It is a much discussed point that mounting lights in a sensible place and using an appropriate beam can make much better use of the light available. Andrew Webster |
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