Milwaukee M18 conversions

Nils

10 mW
Joined
May 11, 2020
Messages
21
I got into ebikes about a year ago and have exclusively been using Milwaukee's M18 batteries. I thought this might be a good place to share what I've done.

I chose the M18 batteries because that's the tool platform I use both at home and at work. Since I already had a bunch of batteries and chargers, it seemed wasteful to buy ebike specific batteries. Also, the 12ah versions came available at about the same time I was getting into ebikes, which was awfully convenient. Right now I have them running 2 bafang g310's at 10s and a GMAC at 15s. Creating a robust electrical and mechanical connection proved to be a real pain and time sink, though other than that it's been pretty smooth sailing.

I usually charge the batteries at the same time on two milwaukee chargers and so far have not noticed the battery voltages more than a few hundredths apart when fully charged and discharged. Looking at the CA data, we've run about 30kWh though the combined 4 batteries (plus whatever tool use?) and they seem to be holding up fine.

Here's the progression of adapters -
The first one I built was from chopped up broken tool bases and a bunch of profile cut delrin. It worked fine though it's a pain to assemble and having the batteries back to back requires a lot of space inside the frame.
M18_Conversions_01.jpg
M18_Conversions_02.jpg

The next one was for my wife's bike. It's a combination of machined and laser-cut delrin, and aluminium. I switched to orienting the batteries vertically and even managed to fit a Baserunner controller inside. This might be the fanciest one I built though it ate up enough time that I don't think I'll recreate it.
M18_Conversions_03.jpg
M18_Conversions_04.jpg

This 3 battery version was for a GMAC. Almost entirely machined from a block of delrin. It sort of resembles a vhs tape but does the trick.
M18_Conversions_05.jpg

And, the latest 2-battery version. I'm pretty happy with this one. It takes up a lot less front triangle room that the back to back version, mounts on the bike easily, and has a surface mount xt60 connector, which cleans up the wiring.
M18_Conversions_06.jpg
M18_Conversions_07.jpg
M18_Conversions_08.jpg

I have a powerful mid-drive motor on order that I want to run at 20s. So the next project will probably be putting together a 4 battery adapter.
 
really impressive, sneaking the baserunner in that one bike :thumb:
I almost switched to dewalt so I could run the 60v tools off my bike battery but I like Milwaukee, have you seen the 36v bosch 6ah packs made of 30q?
 
The dewalt flexvolt stuff looks pretty interesting. I know someone with a bunch of the 9ah batteries and at some point I'd like to play around with running them in parallel. I hadn't seen the bosch 36v batteries before, though they seem like a nice shape to work with.

Also just realizing that I probably should have posted this in the build or general threads.
 
The baserunner was a real squeeze. A little more space would have gone a long way.
M18_Conversions_09.jpg
 
Have you continued to use old/broken tools for the metal tabs that slot into the battery? Very clean applications by the way, look very professional. I am always jealous of people's CNC routers and their creations
 
Yeah, I just use the terminal blocks from old tools. I haven’t found a way to buy them, seems like they’re all sold pre-wired to the motor/controller for whatever tool they’re for. They’ve proven to be pretty robust and I haven’t had any issues with them.
 
Nils said:
The dewalt flexvolt stuff looks pretty interesting. I know someone with a bunch of the 9ah batteries and at some point I'd like to play around with running them in parallel. I hadn't seen the bosch 36v batteries before, though they seem like a nice shape to work with.

Also just realizing that I probably should have posted this in the build or general threads.

I've seen adaptor for dewalt XR being sold in ebay.

dewalt batt adapt.jpg
 
Yeah, It seems like these 3d printed adapters have become a lot more common. There are a couple of reasons I went for machining my own as opposed to using the 3d-printed versions -

Strength - Machined delrin (acetal) is a lot stronger than PLA printed parts, this might only matter depending on how it's attached to the bike. Most of the adapters I looked at were PLA, though that might be different now.

Terminals - The adapters I saw used spade terminals to plug into the batteries. Again, likely doesn't matter though I wanted something a little more solid.

More attachement freedom/cleaner wiring - Though it was a bit of a pain, I liked being able to clean up the wiring (at least from the outside) and having something I could drill and tap made it easier to configure how I wanted it.

In the end I think either way could work just fine!
 
Great build and exactly what I've been looking for. Thanks! I have the same batteries planned for an upcoming project. Please could you tell me what gauge and type of wire you used to connect the batteries in series? Also, the wiring to the XT connector, I presume 2 of the 4 pins are the T1 & T2 for temperature? Does one go to positive, the other to negative? Any advice would be greatly appreciated. Ta.
 
Also, Did you do any additional wiring such as diodes around each pack? Do you have any issues with the packs being drained too low or does the BMS for each pack take care of this? Thanks again.
 
I used very fine stranded 12 gauge silicon coated wire. It's nice to have the flexibility and the silicon jacket holds up to the soldering heat just fine. I just did a 72V backpack battery with 10 gauge, but it's a pain because of the increased diameter.

I have no diodes between batteries. The two outer terminals are Batt + and Batt - . I'm not using the inner two, one is for temperature, and I'm guessing the other is for communication between the battery and tool. From what I can tell any sort of low voltage protection is dependent on communication between the tool and battery, so in my case there is none. Any sort of BMS is I think bypassed when discharging through just the battery + and - terminals. You'll notice that the batteries charge through a different + terminal, one that is in the middle and likely goes to a BMS that deals with balancing.

I rely on the low voltage cutoff in the controller to keep the batteries from being drained too low. This assumes that the batteries are draining at the same rate. So far it has been fine. Though the batteries are of similar age and are put on their separate charges at the same time so they are rarely at different voltages. Managing the charging is maybe the biggest pain, but easier if you already have a bunch of chargers lying around. It's really nice to charge them at the same time.
 
Here's the 4 battery 72 volt version.
 

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This is brilliant thanks for your reply. Sorry, I’ve only just seen it. My motor has just arrived so let the building commence!
 
Awesome! This is what I would like to achieve using greenworks 40v batteries, but I do more lawn work than drilling and sawing... My ryobi 18v system is cheap and good for what I use them for, but want to move on to better tool systems.
 
Nils any chance I could buy a 2 battery plug in set up from you?

Or is anyone else building heavy duty adapters for milwaukee to ebike?

Thank you
 
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