Adding an External Charging Port for a Cordless Drill.

This is an instructable for a makeshift battery charger. It's totally my creation and may result in battery fires in the future. Follow at your own discretion 🤣

I found a $8 drill at a Good Will Store, order a charger that sadly didn't fit. Perfect time for a hack.

Supplies

Some kind of terminal connector kit with pins & sockets https://www.amazon.com/920PCS-Terminals-Assortment-Terminal-Connectors/dp/B09Q5GG9M7/ref=sr_1_9?keywords=2mm+connector+kit&qid=1661879297&sprefix=2mm+conn%2Caps%2C86&sr=8-9

Any cheap 18v batter recharger. https://www.amazon.com/gp/product/B07PPTNHNM/ref=ppx_yo_dt_b_asin_title_o03_s00?ie=UTF8&psc=1

18-16 gauge stranded hook up wires https://www.amazon.com/NTE-Electronics-WH616-02-25-Stranded-Length/dp/B0087OTFAC/ref=sr_1_4?crid=GCK80OU7YGZG&keywords=16+gauge+stranded+wire&qid=1661879583&sprefix=16+gauge+stranded+wire%2Caps%2C60&sr=8-4

Soldering supplies, ohm meter, utility knife, drill press

Step 1: The Sad Discovery

Folks at Good Will can't find me a recharger for their $8 drill. The one I order form Amazon can't slide in plastic housing; negative terminal is 0.5" inch away to even make contact, AND both have female clips. Minor defeat 😝

Step 2: Surgery Time

I opened the charger port for a closer look. Upon examination, I found there's no electronics on the board, and no room to solder a new male connector. On the drill end, the slide-in battery back has 15 cells connected in series with no monitoring electronics, I do have some wiggle room for an external connector. Going in!

Flux and solder in matching wires, cut off the connector ends of the charger, checking for correct polarity, and plug in for initial charging test.

AVOID TOUCHING ANYTHING ELSE for fear of shorts & shocks.

Step 3: Add a Connector With Correct Polarity

I then envisioned the battery pack having some kind of external jack, plugging in like a USB device. I don't have any polarized connectors, plus there's no room to solder/glue in a flat USB port. My next best thing to ensure correct placement is to make an L-shape connector with pin-outs at the corners. Make one single pin + 1 on double connector, then super glue them together. Make a female end for battery pack, male end on the charger. Use ohm meter along the way to check for continuity.

Step 4: Crimping Doesn't Work for Me!

Side note: the expensive crimp tool just didn't work for me. I ruined many pings on either not crimping exactly on insulation, or simply flatten the stupid thing! I went old school and did manual, 2 stage crimp instead.

Step 5: Make a New Hole

Remove batter cells, measured and drill access holes. Use knife to square out corners, then shape to fit. Test for functionality before reassembly.

Step 6: Enjoy Charging With Caution

This seems to work but battery feels hot to the touch after 3 hrs, and indicator remains red. So far functional enough. Still not confident leave it overnight, yet I'm happy.