Milwaukee M18 tool battery communication protocol

47 pointsposted 5 months ago
by jakogut
(github.com)

10 Comments

bombcar

5 months ago

These batteries are fun to use for “other things” - like running a kids 12v battery jeep on 18v - but the TOOL is what has battery protection; the batteries will discharge until they actually kill themselves.

If you really want to use it outside m18 tools you want something that turns off when voltage drops below 17 or 16 or so.

tehwebguy

5 months ago

Is that true? Seems like a waste to have all the extra guts in the battery and not include protection for this.

justsomehnguy

5 months ago

> Seems like a waste

Exactly opposite from the manufacturer POV.

You are making N tools with N protection circuits and N x M batteries.

Instead of N tools, N x M batteries and N x M protection circuits.

dnemmers

5 months ago

I’ve personally killed an m18 battery by having it ‘discharge’ outside of a proper tool. (Rigged up to some temp lighting.)

Once drained, the charger would no longer re-charge, and if I remember correctly, after opening the pack up, cells were at very low voltage.

mindslight

5 months ago

Same here with a Dewalt 20V. I left it in an adapter to a Ryobi tool. I really should have known better, too.

rasz

5 months ago

All the extra guts is there only to log stuff so they can deny warranty claims.

bombcar

5 months ago

It’s true. Maybe some other brand has an off switch in the battery, but if so I don’t know of it.

Remember it would have to switch up to 20+ amps of 18v so it would be a hefty relay.

throwaway81523

5 months ago

Ryobi has undervoltage protection in the battery. They had to do that to preserve battery compatibility across the transition from nicad to lithium. Milwaukee just said screw compatibility, go buy new everything.

bombcar

5 months ago

Both are owned by TTI amusingly.