XPost: rec.crafts.metalworking   
   From: muratlanne@gmail.com   
      
   "David Billington"  wrote in message news:sagndj$cm2$1@dont-email.me...   
      
   On 17/06/2021 12:52, Jim Wilkins wrote:   
   > ...   
   > So does anyone have hands-on experience with replacement drill battery   
   > packs that use NiMH cells instead of the original NiCads?   
   >   
   I can't help with your query but last year I converted my 14.4V Bosch   
   NiCd battery pack to Lithium. I found 4 18650 Li cells was close at   
   14.8V and fitted beautifully in the Bosch pack, 3 fore aft, and 1   
   across, these were tabbed cells so I made a simple PCB to couple them   
   and hold them together, on top of the PCB I mounted a supervisory board   
   for over charge, over discharge sensing and wired to the standard   
   battery pack contacts. For the charger I used a 4 cell Lithium charger   
   wall wart and gutted the original NiCd charger to just leave the bare   
   PCB and charging contacts with leads to those and a socket to connect to   
   the Li charger plug with its lead going into the original charger in   
   place of the mains lead. I've had no problems and it has revived a   
   useful tool and the new pack is 3.6Ah as opposed to the original 1.2Ah.   
      
   Thanks. Were you able to determine the battery discharge rating and the   
   tool's current draw?   
      
   The tabbed 18650s I've collected are in outdated cell phone chargers, so   
   they may not have a high enough discharge current capacity, maybe only 2C. I   
   bought them to refurbish old laptop batteries and since a few had dropped   
   slightly below 3V and self-disabled, I recharged them directly with a lab   
   power supply, as I learned to do at Segway. Unlike a smart charger, a   
   current-limited power supply will try to recover a fully discharged battery.   
      
   I suppose I could measure the drill's stall current with a 20A power supply   
   or 12V battery and the 18650's max output (outdoors) with my 1 Ohm 1000W   
   rheostat.   
      
   I stopped testing the NiMH in the DeWalt charger when the voltage rose above   
   19V. They came at 16.5V and charged reasonably quickly at 17~18V 0.5A from a   
   power supply, to the endpoint of 0A drawn at 17V. Anderson PP45s fit   
   directly onto the battery contacts and I wired the charger contacts to   
   external PP45s.   
   https://www.powerstream.com/NiMH.htm   
      
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