andrewmcleod
Well-known member
I had a great plan to make an extension lead for my 18V Makita drill. I bought a broken drill and a dead battery off eBay; my plan is to cut the handle off the drill and strip out the battery and connect the two with a cable so that you can keep the drill battery in your bag or stuffed down your top to keep it warm (in cold Alpine caves).
Allegedly my 18V drill has a max power of 400W, so should pull around 20A max. You can then through various online voltage drop calculators rapidly reach the conclusion that you need chunky cable if you don't want to drop more than 0.2V or so (over 3m or so). So off I went to buy some 3 core YY cable with 16mm^2 wire... (I only really need 2 fat wires but you need one to carry the battery thermistor signal).
As I'm sure anyone more familiar with cabling will know, 16mm^2 is a BIG cable. In fact the 8m of cable (to do a pair of battery extenders) weighs about 4 kg...
Now I reckon I can drop to 4mm^2 while only losing about half a volt, but according to this page:
https://www.elandcables.com/cables/yy-cable
even though there is only a quarter as much copper in 4mm^2 instead of 16mm^2 the cable still weighs over 200g a metre.
I know other people have done this - what did they use? (have they just failed to consider voltage drop properly? :-\ )
I could always run the thermistor cable in a thinner wire on the outside to get it down to 2 core but that seems messy.
Allegedly my 18V drill has a max power of 400W, so should pull around 20A max. You can then through various online voltage drop calculators rapidly reach the conclusion that you need chunky cable if you don't want to drop more than 0.2V or so (over 3m or so). So off I went to buy some 3 core YY cable with 16mm^2 wire... (I only really need 2 fat wires but you need one to carry the battery thermistor signal).
As I'm sure anyone more familiar with cabling will know, 16mm^2 is a BIG cable. In fact the 8m of cable (to do a pair of battery extenders) weighs about 4 kg...
Now I reckon I can drop to 4mm^2 while only losing about half a volt, but according to this page:
https://www.elandcables.com/cables/yy-cable
even though there is only a quarter as much copper in 4mm^2 instead of 16mm^2 the cable still weighs over 200g a metre.
I know other people have done this - what did they use? (have they just failed to consider voltage drop properly? :-\ )
I could always run the thermistor cable in a thinner wire on the outside to get it down to 2 core but that seems messy.