I have an 18v 15S, sub-C Nicad Black and Decker weed whacker. Packs died of course. Replaced with 6S 18650 cells. Runs like hell, but the motor fried in about 3 sessions. After much searching, replaced with a similar motor. It also only lasted 3 sessions so I’ve seriously over volt/amp the thing. 2nd motor replacement didn’t go well.
Got another unit for free with dead batteries. Tried it with 4S this time. Works about ‘normally’. I have a friend with one but he’s got an old pack, probably not long for this world. I’d like to make him a pack with removable cells so they can be pulled out and charged in a stock 18650 charger.
For my own use I use a hobby charger and put a balance tap on it.
The 4S holders I’ve seen are all flat, and use wiring that does not look robust enough for the amperage required.
Ideally I’d like a 2x2 holder that has decent wiring.
Anyone know of such a device?
They are 2x 18650 holders but I think the quality is good. I have (I think) the analagous 2x 26650 holder, and it’s good quality. Tough reinforced nylon. You would have to connect them together somehow to make it 4x 18650.
What about an old powerbank? I got one of these dell ones someone was giving away at a trade show, they run on 4x low amp 18650s so maybe can retro fit it?
The key there is “low amps”. Weed whacker runs about 15A. Tried it the first time with scavenged cells that were OK for LED lights. That was a complete flop.
Need to use top grade, high amp cells for this application (LG HE2, Samsung 30Q), and even those get pushed pretty hard.
Worst case, just make your own. 2 plastic discs of the right diameter, a few Cu strips (no springs) to make contact from one cell to the next, spacer/standoff/long-screw down the middle to keep the discs together.
It won’t be “ready made” and each recharge will require mild “disassembly” (loosen screws vs removing, then snug up after the cells are replaced), but it’ll work.