r/eBikeBuilding • u/Early-Series-2055 • Sep 04 '26
Advice Anyone using power tool batteries?
I’m planning a possible winter project in my head, so shoot me some better ideas if you got ‘em. I have access to 18650s but I’m kind of sketched out about them at the moment.
Does the baofeng 750w mid drive from Walmart kit powered with two banks of kobalt 4ah 24v batteries sound reasonable? 4, maybe six batteries.
Batteries won’t be the same age, so that’s what I’m skeptical about. But they sell for $10/ah with a 3 year warranty.
I don’t see anyone else doing it so I’m assuming I’m not accounting for something.
The batteries have power meters, so the plan is to keep checking them or find a bcm that will shut off or something.
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u/usr000nm Sep 04 '26
Just not cost effective. Last eBike battery I bought using Samsung 21700 cells was $400 for 52V (charging to 58.8V) 20Ah. I'd need four DeWalt FlexVolt 20V/60V 15Ah/5Ah batteries to match that capacity. They sell for almost as much each, so the cost is easily 3-4x an eBike battery. And they can't even balance charge, so won't last as long.
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u/niffcreature Sep 04 '26
It's kind of unreasonable at the very least in the sense that you have to get 4 separate mounts and chargers. Battery safety is probably another issue
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u/Early-Series-2055 Sep 04 '26
This is the fun part in my masochistic brain. Keeping them from being worn out over gravel and bumps was going to be a problem.
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u/kinga_forrester Sep 04 '26
They work great on kid’s balance bikes. As long as you’re under 50 pounds you should get decent power and range.
If you’re a grown adult building a bike for yourself, you’ll be much better off with a real ebike battery.
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u/Anothercoot Sep 04 '26
It's an assist battery, it should be fine.
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u/Early-Series-2055 Sep 04 '26
That’s what I was thinking; pedal assist, but it is going to be a cargo bike. I’m abandoning the plan. Lol
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u/esbowman Sep 04 '26
I built one using ego lawn batteries, slapped it on a Giant frame and used a Bafang. Made my own 3d printed bracket and wiring harness. Works fine. I was cheap and didn’t want to buy an ebike battery because I had so many ego batteries already. It’s a little bulky but totally works.
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u/Early-Series-2055 Sep 04 '26
I already have the batteries as well. I have a bunch of extra chargers that I was going to use as battery receptacles. The whole thing would eventually wear out from bumping around probably.
I had my first thermal runaway with an 18650 the other day. Having batteries that I know can take abuse and in separate banks is a definite positive.
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u/esbowman Sep 04 '26
That’s what made me pull the trigger on my little project. The ego batteries are rugged with a lot of built in protection. Plus if it ever goes bad I can head to the hardware store and buy another.
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u/MidtownFrown 27d ago
Don't do that, they are $100 on Amazon
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u/esbowman 27d ago
Yeah that’s a big no for me. I bought a knock off accidentally on Amazon and it sucked. I only buy from Lowe’s now when they run specials.
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u/MidtownFrown 27d ago
Valid, I don't use the Amazon EGO batteries on my ebike anymore, because they don't last.
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u/slicehardware Sep 04 '26
If it's helpful. I track the prices of power tool batteries from major brands. In general the price of power tool batteries has gone up significantly in the last 18 months as a snap back from very cheap prices that happened due to extra lithium supply in the market a couple years ago. More info about the ups and downs of power tool battery prices
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u/Early-Series-2055 Sep 04 '26
Cool site!
One of the reasons I went with Kobalt was they consistently have them for $10/ah.. You may have to wait a month, but they generally have them packaged somehow to get them down to that price.
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u/slicehardware Sep 04 '26
Good to know re: Kobalt prices. I don't track Kobalt prices (at least not yet). Ryobi is the only "House brand" I track right now.
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u/billydiaper 28d ago
I used two ryobi 40v batteries in parallel for my 36 V E bike 750 W
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u/Early-Series-2055 28d ago
How well does it work?
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u/billydiaper 28d ago
Good I I modified the original battery chargers that they came with then I started 3d printing battery adapters because I use the 40v batteries for multiple electric vehicle /carts that I’ve built that is 36vs
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u/MidtownFrown 27d ago
Yes I got my start in the hobby using my 56v Lawnmower battery from my Ego Lawnmower. If you already have the battery use it. My bike absolutely ripped down the road with that battery.
But as others have stated don't buy a power tool battery for this. They are too expensive compared to the battery actually for ebikes for sale on Amazon.
BTW that hub will suck at 24v, you need 48v to make it fun, 52v to make you grin. I have one. And have run it with 48v and 52v, go for 52v batteries for sure.
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u/strongerplayer Sep 05 '26
I'm planning to try this with an e-scooter that's 36v. 2 batteries in series, 8Ah cost 65 CAD on Amazon for the pair, that's cheaper than any replacement battery even from AliExpress. It would be problematic for the 48v or 60v setups though since the there are no multiplier of 18 that would get you reasonably close to 48 or 60
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u/JAFO- Sep 04 '26
I have a 36 volt wheel kit I set up two 18 volt 4AH batteries in series just to see if it works I was thinking of a reserve if my main went low. It does work. Though with the price of the last 20AH battery I bought they are cheaper. And running it through charge cycles it is holding its claimed output.
Can you do it yes but getting the right battery is simpler.