# amp-dropping light bulbs????



## rcnerd (Jan 14, 2003)

Hey everyone....

I heard that BRP makes a device which utilizes ligfht bulbs to reduce charge current to allow smaller cells to be charged from a sub-c, 4amp charger.

Could someone describe the wiring? I'm trying to help a friend get his micro airplane flying, and he's on a tight budget, so I'm thinking of using the lightbulb method to allow use of an old charger I have. 

I _would_ just buy a BRP unit (and support a great sponsor) but I need to get an even greater current drop, since we are charging 270 mah nicads, not 600 mah AA's

Does this lightbulb device work w/ peak chargers?

could you do the same thing using resistors??

Thanks in advance for any info.....


----------



## hankster (Jan 1, 1998)

Putting light bulbs in a charger circuit will not reduce the charge current, only the voltage. Unless the charger has adjustable current settings you can not use it to charge 270 mAh cells.


----------



## BudBartos (Jan 1, 1970)

It will drop from 4 amp to about 2.5 on 6 cell. I would not think it will work on those real low MAH cells.


----------



## rcnerd (Jan 14, 2003)

is it a 1157 automotive bulb(s)?? just one?

is it in series or paralel?

does it 'confuse' peak chargers?

thanks!


----------



## BudBartos (Jan 1, 1970)

We use a 1157 with bothe filiments connected in series. I will work with some peak chargers but some of the new one it will not. It was made for the timmer chargers .


----------



## rcnerd (Jan 14, 2003)

Thank you for the info....I will experiment.....or maybye just make my friend buy a charger!!!


----------



## k1m (Sep 25, 2001)

rcnerd said:


> is it a 1157 automotive bulb(s)?? just one?
> 
> is it in series or paralel?
> 
> ...


The bulbs are acting like resistors. I believe if you put the bulbs in series with the battery you will lower the voltage to the cells. If you put the bulbs in parallel with the battery you will increase the current draw on the charger. If the charger only puts out 4 amps and the bulbs take 2 amps, I would think the battery would be charging at the remaining 2 amps. What effect that has on the peak detection circuit of the charger depends on how it's designed.
 
The best way it would seem to me would be to experiment with a trickle charger and keep track of how long it takes it to get the cells warm. That's how most low mah cells are charged.


----------

