My little hand sander may get 18650ed

[rebelrider.mike]

I don't use this tool often because the batteries are a pain to charge.

They're always dead whenever I need the tool, take a couple hours to charge, and only last about 20 minutes. Also, the original charger is long gone, so I use my universal.

The charger has a refresh mode where it does 4 charge/discharge cycles. I'm trying that tonight to see if it will help. If not, I may look into some lithium cells for it. If I could cram a 2s2p pack in there, the voltage range would be perfect, and it would run 3x longer. Depending on the cell capacity. Plus it would be charged when I need it.

Anyway, just imagining at the moment. I'll see how the NiMH batteries turn out after the refresh.

 

[Korishan]

Those are some oddly shaped cells. Are they about the size of an 18650? Or would you need to make some adjustments to the case and/or 3D print a new holder?

 

[rebelrider.mike]

Each cylinder is a pack of three cells in series. Here's an 18650 for comparison:


I gave up trying it refresh them in parallel after About 24 hours. Four cycles should have only taken 12. One was hot and the other was cold. I've decided to try again with just the cold one this time. NiMH is supposed to get hot when charging.

There are lithium packs available in this format already. But I don't know the manufacturers. So I'd rather make my own. A pair of Samsung INR21700-50E cells would fit pretty good I think. As long as I can fit a BMS in there. Four 18650s might fit if I hollow out the handle. Maybe I could find cells shorter and fatter than 18650s. They'd have to be at least 3.5Ah each though.

Or I could convert it to 120V. It only uses 5.5A at 7.2VDC. I bet I could cram a small power supply in there. Discissions...

 

[Korishan]

NiMH is supposed to get hot when charging.

Gotta pack those electrons in there forcibly

 

[floydR]

A pair of Samsung INR21700-50E cells would fit pretty good I think.

my choice would be the 21700's. You might even be able to get 6000 mAh 21700s
later floyd

 

[Korishan]

Yeah, but he'd have to buy those. He's already the 18650's by the 100's laying around the shop

 

[rebelrider.mike]

True, but none are rated for 6 Amps. I'd have to buy new ones anyway. Unless I want to build a battery pack to hang on my belt. Which I could do...

Well, both NiMH batteries went through the refresh. They have about 1.6-1.7 Ah each. If you discharge them at only 600 mA, and if you use them right away. They still discharge overnight. So I'm gonna call them done as far as being useful.