Geo-TH,In
Well-known Member
I have 4 18v Ni-MH batteries for my dewalt tools. To my knowledge, dewalt makes a charger for such a battery, but I can only buy aftermarket batteries. In 2009 I purchased 2 dewalt Li-ion batteries. One is still good, the other shorted out internally shortly after warranty period.
Well I decided to make a simple load tester using 2 Free (gift) HF EVOM's. The one on the left measured battery voltage, the one on the right amps, used the 10 amp range. On the far right, I used an old junk xrp battery, cut out the old cells and soldered wires to the top where it makes connections to tools. I used flash light as a .6 amp load and then the drill, 4.6 amp load.
To my surprise the very first Ni-MH battery I purchased in 2008 turned out to be the best producing the least voltage loss under load. The Li-ion battery was a close second. All but one Ni-MH purchased in 2013 checked in very close to the Li-ion. So it confirms what I suppected, I had one bad battery.
I know some are in love with Ni-cds. I've never discharged any of my batteries. I just put them in the charger when ever I feel like it. 3 out of 4 isn't a bad record for the Chinese made Ni-Mh battery. 1 out of 2 Li-ion batteries isn't that impressive, not to mention I can get 3000 ma-hr Ni-Mh for less money than Li-ions and Ni-cds. Never had a Ni-cd last more than a few years.
Footnote, As I suspected the 10 amp range on the Free HF voltmeters is protected with a fuse. So, If you want to jump wires out and are not certain if you are going to damage something, use the 10a range as jumpers. I do it all the time. I also blew a fuse today, slowing the drill down by holding on to the chuck. So if you need to jump something out, use the probes on the 10a range.
Well I decided to make a simple load tester using 2 Free (gift) HF EVOM's. The one on the left measured battery voltage, the one on the right amps, used the 10 amp range. On the far right, I used an old junk xrp battery, cut out the old cells and soldered wires to the top where it makes connections to tools. I used flash light as a .6 amp load and then the drill, 4.6 amp load.
To my surprise the very first Ni-MH battery I purchased in 2008 turned out to be the best producing the least voltage loss under load. The Li-ion battery was a close second. All but one Ni-MH purchased in 2013 checked in very close to the Li-ion. So it confirms what I suppected, I had one bad battery.
I know some are in love with Ni-cds. I've never discharged any of my batteries. I just put them in the charger when ever I feel like it. 3 out of 4 isn't a bad record for the Chinese made Ni-Mh battery. 1 out of 2 Li-ion batteries isn't that impressive, not to mention I can get 3000 ma-hr Ni-Mh for less money than Li-ions and Ni-cds. Never had a Ni-cd last more than a few years.
Footnote, As I suspected the 10 amp range on the Free HF voltmeters is protected with a fuse. So, If you want to jump wires out and are not certain if you are going to damage something, use the 10a range as jumpers. I do it all the time. I also blew a fuse today, slowing the drill down by holding on to the chuck. So if you need to jump something out, use the probes on the 10a range.