Electrical help....
- Thread starter goucho
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SilverFox
Flashaholic
Hello Mzzj,
Your solution would simplify things...
Tom
Your solution would simplify things...
Tom
If i were to use the three AA NiCd rated at 1200mAh, would i still need to limit my incoming current so as not to "overcharge" the batteries? Also, if my generator produces a voltage range of 4.5v-6v, will that be too much voltage for the 3.6v (3x 1.2v) batteries to handle? or is the incoming current the only thing I should be worried about?
SilverFox
Flashaholic
Hello Goucho,
NiCd chemistry is tough. It will probably handle anything you can throw at it. You can keep an eye on cell temperature, and if the cells start to heat up (above 120-140 F) stop charging them.
Tom
NiCd chemistry is tough. It will probably handle anything you can throw at it. You can keep an eye on cell temperature, and if the cells start to heat up (above 120-140 F) stop charging them.
Tom
SilverFox said:
Thanks for all your help in the matter. I am just wondering how you went about getting these numbers... If you could explain (including any equations you used) that would be extremely helpful. I'm just trying to gain a better understanding! Also, how would I know what charging current i would be getting without physically testing it? Finally, wouldn't I be limited to the 1.36A given from the max output of the generator? Thanks again!
SilverFox
Flashaholic
Hello Goucho,
I was looking at your stall current of 6.9 amps and thinking you may be able to get around 50% of that.
Lets look at some numbers. I am going to round things off so we have even numbers, but you can tweak them however you see fit.
First of all, yes, you will have to do some testing to see how well things work out.
Your LED current is 350 mA. By the time you add a circuit or resistor, you will most likely be drawing around 500 mA from the battery pack. You want a 20 minute run time, so you are looking at around 170 mAh of capacity from the battery.
Let's look at a charge rate of 1000 mA. Charging has losses, so you will probably need to generate around 200 mAh to get 170 mAh out. 200/1000 = 0.2 hours of charge time, or 12 minutes.
If you wanted to charge the 1200 mAh battery up from empty, you would need to generate around 1440 mAh of capacity. If you are capable of 1000 mA, it would take you around 86 minutes to do a full charge.
Tom
I was looking at your stall current of 6.9 amps and thinking you may be able to get around 50% of that.
Lets look at some numbers. I am going to round things off so we have even numbers, but you can tweak them however you see fit.
First of all, yes, you will have to do some testing to see how well things work out.
Your LED current is 350 mA. By the time you add a circuit or resistor, you will most likely be drawing around 500 mA from the battery pack. You want a 20 minute run time, so you are looking at around 170 mAh of capacity from the battery.
Let's look at a charge rate of 1000 mA. Charging has losses, so you will probably need to generate around 200 mAh to get 170 mAh out. 200/1000 = 0.2 hours of charge time, or 12 minutes.
If you wanted to charge the 1200 mAh battery up from empty, you would need to generate around 1440 mAh of capacity. If you are capable of 1000 mA, it would take you around 86 minutes to do a full charge.
Tom
