paddywack Posted May 6, 2011 Report Share Posted May 6, 2011 heres one for all you shooting diy ers, what would i have to do to run my 12v 100amp lamp (home made, car spot) off an18v 1.5ah battery from my battery drill? my little makita drill came with three compact batteries which work on the lamp but produce too much heat. would some sort of resistor help, and if so how long could i expect from each battery? if someone with a bit of electrical knowhow could suss this i,m sure loads of people have access to this type of gear Quote Link to comment Share on other sites More sharing options...
shoughton Posted May 6, 2011 Report Share Posted May 6, 2011 Firstly I think you mean 12v 100W lamp, not 100A lamp. 100W means that the lamp takes just over 8A (100W divided by 12v). You could use a resistor to drop the required 6v - but the resistor would then itself dissipate 48W. It would need to be very large and would get very hot. What a waste of power. A better way would be to use a power controller - similar to the ones used to control the speed of rotaries. BUT it really isn't worth any of this trouble. You said that the capacity of the batteries is only 1.5Ah. As you would be taking 8A from it they would only last a maximum of 11 minutes!!!! (1.5 Hours divided by 8A) Sorry I can't be more positive. It's just the wrong battery for the job. Steve Quote Link to comment Share on other sites More sharing options...
Frenchieboy Posted May 7, 2011 Report Share Posted May 7, 2011 Sorry but is it really worth the trouble doing what you are suggesting mate? If you are planning on using the cordless drill batteries you suggested your lamping time per battery is going to be pretty short and is going to involve a lot of messing about. Why not just get a Sealed Lead/Acid 12 Volt 7 AH battery to use for your lamping. These batteries can usually be bought for around £15 new, will last for a couple of hours with your lamp, is small enough to fit into the pocket of most Camo coats and is clean and will not leak - And of course there is no messing about with resistors or voltage droppers! Just a suggestion to save you time, money and a lot of messing around! Quote Link to comment Share on other sites More sharing options...
webber Posted May 7, 2011 Report Share Posted May 7, 2011 webber sells Yuasa batteries. PM for details. webber Quote Link to comment Share on other sites More sharing options...
Frenchieboy Posted May 7, 2011 Report Share Posted May 7, 2011 webber sells Yuasa batteries. PM for details. webber It's a Yuasa battery that I use and I can highly recommend them! I don't know what price Webber charges but they are very good value for money and last very well! Quote Link to comment Share on other sites More sharing options...
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