Power Tool Batteries in a Series

Batteries, Chargers, and Battery Management Systems.
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unclejemima   100 W

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Power Tool Batteries in a Series

Post by unclejemima » Apr 24 2018 11:53am

I've been using my powertool batteries (Rigid 18V) to power an ebike. Been working great. The BMS in the battery acts as the LVC and everything seems to be great. The power tools themselves only use the positive and negative terminal, meaning the balancing must be coming from the battery BMS...not the tool.

I think these tools you could run both lithium OR nimh...so the tool is basically dumb. Its the batteries that have the brains. In my application this is good.

Only thing now is I'm wanting to hook the batteries in a series, to make 36V.

I'm worried the load will increase on the batteries beyond what they can handle at 36v. Or will each batteries, because they are in a series, still draw at the same load as if I ran 1x 18v?

Thanks!
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unclejemima   100 W

100 W
Posts: 218
Joined: Jun 10 2012 3:59pm
Location: Western Canada

Re: Power Tool Batteries in a Series

Post by unclejemima » Apr 24 2018 11:19pm

Anyone? They are both identical AH batteries (4ah 18v)

So it will be 36v 4ah.

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Marin   1 kW

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Re: Power Tool Batteries in a Series

Post by Marin » Apr 24 2018 11:47pm

It is fine to do this, the batteries share the load, makita 36v tools use 2 18v batteries,
Marin ex-rental hybrid with 48v bionx...sold
Specialized hardrock with magic pie 4-5
Lunacycle with l/r mid drive coming soon
Kona Caldera with QS 30H (maybe), and phase runner
Giant Yukon bbs02
Kona Abra Cadabra bbshd
Wildfire fat bike bbshd

themelon   1 W

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Re: Power Tool Batteries in a Series

Post by themelon » Apr 25 2018 12:46pm

Marin wrote:
Apr 24 2018 11:47pm
It is fine to do this, the batteries share the load, makita 36v tools use 2 18v batteries,
DeWalt has a really funky setup in their FlexVolt batteries. Depending on what they are plugged into they are either 5S3P(20v6ah) or 15S1P(60v2ah). I have a miter saw that uses two of them at 60v in series for 120v.

Now that I think about it, that is what I can use the battery modules from the eAssist units I bought. They are 32s1p, 1kWh, which should be handled just fine by the miter saw...

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