My carpenter friend Max has given me a few hand tools with dead batteries. He thought I might get something out of them.
For years I have upgraded tools with worn out batteries with 18650 cells from old laptops, each one with a balancer cable, and a XT-60 plug sticking out. Hey, it was a quick fix, and it worked. But a crappy solution...
This time I would like to standardize it.
Case: Dead NiMh batteries on several fine DeWALT machines. Let's go LiPo, with a standard!
Lipo cell (I chose 5S, 2,2Ah, 40C that fit right into the container) Hobbyking,com item HK-Z22005S-40
Balancer extension cable
DIN 5 pin male
DIN 5 pin female
2 banana plugs
Total cost pr. battery is approx 30 USD.
Step 1: Disassembly
This is quick.
Unscrew the top, and push the power connector in the top down, and release all the old batteries.
Step 2: Mounting the DIN 5 Female Connector
Drill a 16 mm hole in the wide end of the casing. Make you own system, or follow mine on the note. Outer casing (ground) will be ground, and each of the 5 pins will be the anode (+) of each battery.
Take the balancer extension cable, and cut it quite close to the male end. This is for the connection to the battery inside, and the balancer cable on the battery already have plenty of length, so lets keep the long wires on the outside for the charger cable.
Solder the male end to the DIN plug, and put it through the hole.
Step 3: Connecting the Connectors
Here I made a stupid mistake. I wanted to be able to replace the battery in 5 minutes in the future. Hence the balancer plug. But instead of soldering a XT60 connector on the terminals, I soldered the battery directly onto them.
Nevermind, this will last for years, but keep it in mind.
The plug with the battery terminals that we pushed out, was held in place by a NiMh battery, no longer present. So we have to glue it in place to make it stick.
Now we can close the battery container...
Step 4: And the Charging Cable...
Now that the battery is done, we need to make the charger cable. My charger for RC flight requires both a balancer plug, and a banana set for the real juice. Solder the other half of the balancer extension cable onto the male DIN 5, and if you need external + and - like me, fix that too...
- The weight of the battery is now half of the original (485 vs. 950 grams)
- The voltage is 21V charged vs. 19,1V (18.5 vs. 18V)
- The capacity is lower at only 2.2Ah vs. original 2.6Ah
- The current available is 88A vs (a guess) 15-20A.
- Total cost is 30 USD, and 1 hour.
This machine will burn before giving up.