biffa
New member
Just wondering if anyone has any experience with doing this - particularly which voltage to choose. I already run a home made LiPo pack with a 14.4v Makita and think it's great (light weight although bit expensive to build due to protection circuits to handle large currents).
6 cells (nominally 22.2V)
+not going to overload drill circuit (fully charged battery voltage will be 25.2V although this will fall quickly to ~23V)
+My charger will charge up to 6 cells in series
-It's not 24v (running at 85% power of the drill at nominal cell voltage)
7 cells (nominally 25.9V)
+Lots of power, definitely running drill at full whack, 116% of rated power at nominal cell voltage (max battery voltage 29.4v 50% over power!)
-my charger won't charge this - would need a new one
-Is drill going to last all of 5 minutes with extra current going through it?
From what I have read, although I haven't really measured it, lead acids are probably only achieving 23v (nominally 24v) at a 2C (15-20A) load and I'm happy with drill performance there, if only the batteries weren't so heavy. NiMh or NiCad look like the battery voltage is probably ~22v under load (1.1v /cell). LiPo batteries show a far greater output voltage variation over their charge state but cope much better with supplying large currents and maintaining voltage (e.g. for a 10 Ah cell a typical drill current is <2C when most LiPo batteries can provide at least 30C).
Can't really justify or afford buying one of the 36V SDS drills which are designed to work with LiIon/LiPo batteries (there seem to be several Hilti TE10a drills cheap on ebay but I have no idea as to their effectiveness and I think most are 15 + years old).
6 cells (nominally 22.2V)
+not going to overload drill circuit (fully charged battery voltage will be 25.2V although this will fall quickly to ~23V)
+My charger will charge up to 6 cells in series
-It's not 24v (running at 85% power of the drill at nominal cell voltage)
7 cells (nominally 25.9V)
+Lots of power, definitely running drill at full whack, 116% of rated power at nominal cell voltage (max battery voltage 29.4v 50% over power!)
-my charger won't charge this - would need a new one
-Is drill going to last all of 5 minutes with extra current going through it?
From what I have read, although I haven't really measured it, lead acids are probably only achieving 23v (nominally 24v) at a 2C (15-20A) load and I'm happy with drill performance there, if only the batteries weren't so heavy. NiMh or NiCad look like the battery voltage is probably ~22v under load (1.1v /cell). LiPo batteries show a far greater output voltage variation over their charge state but cope much better with supplying large currents and maintaining voltage (e.g. for a 10 Ah cell a typical drill current is <2C when most LiPo batteries can provide at least 30C).
Can't really justify or afford buying one of the 36V SDS drills which are designed to work with LiIon/LiPo batteries (there seem to be several Hilti TE10a drills cheap on ebay but I have no idea as to their effectiveness and I think most are 15 + years old).
