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Can a dynamo be used to reharge a small lead acid battery?
I have dynamo lights (6v) which I am thinking of boosting with a 10W lamp
powered by a 6v lead acid battery for cummuting. as my journey to work is in daylight... could the dynamo be used in daylight to charge the lead-acid battery? nick |
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#2
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Can a dynamo be used to reharge a small lead acid battery?
"Clarks" wrote in message
... I have dynamo lights (6v) which I am thinking of boosting with a 10W lamp powered by a 6v lead acid battery for cummuting. as my journey to work is in daylight... could the dynamo be used in daylight to charge the lead-acid battery? nick Sheldon Brown has a bit on his web site about charging batteries and rectification. http://www.sheldonbrown.com/dynohubs.html Paul. (PS Remove junk to reply) |
#3
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Can a dynamo be used to reharge a small lead acid battery?
In theory yes with a suitable converter.
Of course what you really need is it linked to the brakes to shift the hundreds of joules of available energy from you at speed into the battery when you squeeze. Jon |
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Can a dynamo be used to reharge a small lead acid battery?
"Clarks" wrote in message
... I have dynamo lights (6v) which I am thinking of boosting with a 10W lamp powered by a 6v lead acid battery for cummuting. as my journey to work is in daylight... could the dynamo be used in daylight to charge the lead-acid battery? What the others said: it *can* be done, but it is difficult and rather unsatisfactory. I use the SON in 12V mode and a headtorch with a four C cells in a belt pack - the batteries last about a year because the headtorch only gets used in the really dark bits. -- Guy === WARNING: may contain traces of irony. Contents may settle after posting. http://chapmancentral.demon.co.uk |
#5
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Can a dynamo be used to reharge a small lead acid battery?
Tony W must be edykated coz e writed:
"Clarks" wrote in message ... I have dynamo lights (6v) which I am thinking of boosting with a 10W lamp powered by a 6v lead acid battery for cummuting. as my journey to work is in daylight... could the dynamo be used in daylight to charge the lead-acid battery? You will gather from others that is possible but tricky. Remember, to charge a battery you will need more volts than the battery has to drive the charging current in. You will lose about 1.4V across any rectifier. So you will need more than, say 7.5V to even start. Two things are going for you. The dynamo produces an ac voltage with an RMS average of 6V -- so during parts of the cycle it will be above the magic 7.5 V And, the dynamo -- unless 'clamped' will produce more volts the faster your little legs pedal. So, without some fancy chopper circuits its unlikely that you would get much power into your battery -- unless you go for a 12 V dynamo. But, frankly, why? As a home electronics project it might be fun but as practical engineering there are better solutions. T Er with a bridge rectifier you can obtain 10v dc from a 6v ac generator. -- Ian http://www.catrike.co.uk |
#6
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Can a dynamo be used to reharge a small lead acid battery?
"Tony W" wrote in message ... Remember, to charge a battery you will need more volts than the battery has to drive the charging current in. You will lose about 1.4V across any rectifier. So you will need more than, say 7.5V to even start. A bridge rectifier will multiply the AC by 1.42 giving 8.52 VDC with a capacitor across the output to smooth it (which the battery effectively is). You then need to limit the voltage to, say, 7 volts. A voltage regulator is one way of achieving this but I don't know if you'll get one for exactly that value, another crude way is by using a zener diode. But your biggest problem will be producing enough power from a dynamo to charge a SLA sufficently for your return journey in the dark. Put simply the dynamo will top up the battery at less than a third of the rate your 10w lamp will consume power, assuming no other losses. Pete |
#7
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Can a dynamo be used to reharge a small lead acid battery?
Clarks wrote:
I have dynamo lights (6v) which I am thinking of boosting with a 10W lamp powered by a 6v lead acid battery for cummuting. as my journey to work is in daylight... could the dynamo be used in daylight to charge the lead-acid battery? nick It can be done, most texts describing this will be German, as a SON hub is probably mandatory. A good start is www.enhydralutis.de, but only if you read german. But a good 12v Setup (Bisy FL/E6 etc) is probably superior to messing about with a poorly designed 10w light, and will run without batteries straight from the dynamo -- Marten Gerritsen cycle-imports & framebuilding |
#8
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Can a dynamo be used to reharge a small lead acid battery?
Quoth Nick Clark:
I have dynamo lights (6v) which I am thinking of boosting with a 10W lamp powered by a 6v lead acid battery for cummuting. as my journey to work is in daylight... could the dynamo be used in daylight to charge the lead-acid battery? Thanks to stupid German regulations, cycle dynamos put out only 3 watts of power. This means that even if the charge/discharge cycle were 100% efficient, you'd need to ride 2 hours by daylight to store enough juice to run your 10 watt lamp for one hour of darkness (with the dynamo helping.) Thus, this is not practical on the scale you describe. Battery/dynamo systems can work if the light is low enough wattage to be powered by the dynamo alone. In such setups, a small battery can serve to keep the light going whilst you're stopped for traffic signals and the like. I used to have a setup like this with an old Sturmey-Archer Dynohub, 30 years ago. I used a full-wave bridge rectifier and nickel-cadmium batteries. It worked pretty well. In addition to keeping the light lit when I was stopped, the low internal resistance of the NiCd batteries kept the voltage from getting too high and burning out the bulbs whilst descending (this was on a tandem, and I commonly would hit speeds that would have toasted standard bulbs if connected normally to the Dynohub.) Sheldon "These Days I Use A Lumotec 'Standlicht' Headlamp With My Shimano Dynamo Hubs" Brown Newtonville, Massachusetts +------------------------------------------------------------------+ | Honestly, I think we should just trust our president in every | | decision that he makes and we should just support that. | | -- Britney Spears, September 4, 2003 | +------------------------------------------------------------------+ 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 |
#9
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Can a dynamo be used to reharge a small lead acid battery?
M-Gineering import & framebouw must be edykated coz e writed:
Sheldon Brown wrote: Quoth Nick Clark: I have dynamo lights (6v) which I am thinking of boosting with a 10W lamp powered by a 6v lead acid battery for cummuting. as my journey to work is in daylight... could the dynamo be used in daylight to charge the lead-acid battery? Thanks to stupid German regulations, cycle dynamos put out only 3 watts of power. Whoa.... Most dynamo's put out 0.5 amps. With the official bulbs this translates to 3 watts. Change the bulbs and you can get quite a bit more power. -- Marten What about the Dymotech S12 from Busch and Muller, it has a 12v, 6w output? -- Ian http://www.catrike.co.uk |
#10
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Can a dynamo be used to reharge a small lead acid battery?
Sheldon Brown wrote:
Quoth Nick Clark: I have dynamo lights (6v) which I am thinking of boosting with a 10W lamp powered by a 6v lead acid battery for cummuting. as my journey to work is in daylight... could the dynamo be used in daylight to charge the lead-acid battery? Thanks to stupid German regulations, cycle dynamos put out only 3 watts of power. Whoa.... Most dynamo's put out 0.5 amps. With the official bulbs this translates to 3 watts. Change the bulbs and you can get quite a bit more power. -- Marten |
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