Power tool batteries

[Waynemarlow]

Hi, excuse my lack of knowledge on batteries and I'm sure this has been asked before.

I need a 5 - 10 A battery pack, 36 - 40 volts for a bafung mid engine conversion of a mountain bike. I don't need too much power, 350W would be enough through the 10 speed gearing I plan to use, its more pedal assist than out right electric bike with occasional pedal input, as I want a workout comparable to what I already do, just I think if I go electric then I'll enjoy the downhill sections more, as its taken less time to get back to the top of which we have plenty of tops in the area I cycle.

So I use 20 volt Li ion tools all the time at work and have 5A batteries available, they are cheap, have good fast chargers, seem to last forever and yet no one seems to series them up to make the 36 - 40 volts I'm looking for. 2 batteries in the rucksack if needed and 2 on board is my thinking which should give me the duration I need.

Any body been there, done it and found its not a good idea, any thoughts as to hows and why not's.

Thanks.

 

[motomech]

They were all the rage 4 or 5 years ago before real Ebike batteries (Li-Ion) became common.
So many are needed to get real capacity and with ea. one encased in their own plastic housing w/ it's own BMS, they aren't that practial.
Search back using key words; tool battery, Ryobi, Craftsman, etc.

 

[dogman dan]

He has the batteries now. That makes it practical for him to multi purpose them. If you dig far enough back, you will see threads where people did this with NiCad tool batteries.

On the other hand, I need my tools, and the batteries. Last thing I will do is pound them to shit on my bikes.

The key thing is the holder, which you can plug the battery into, then opening up the possibility of then connecting in parallel or series. Old chargers or dead tools can be one source of the holder. I've seen the holder home made too.

IMO, run at least 4 ah, and better still 6 or 8 ah. In many cases, the tool batteries are called by the fully charged voltage. So a 20v, would be about 5s. Or they might call the same size 18v.

 

[Waynemarlow]

Yup I have 2 x old chargers that are dead so have good mounts, the question more are what are the cells like as far as power and reliability.

To be honest though the proper bike batteries are now cheaper than power tool batteries if you take into account the time factor to modify and fettle, sometimes it's just better to pay out the cash and enjoy the time riding.

 

[bionx 1954]

I am still using Bosch Fat Packs. The new generation "KOOL" packs are lighter than the old Bat 836, I am currently using Bosch Bat620 a 18V 4A battery. They cost $ 100.00 US for 2 Bat 620. 2 of them to make a 36V @4A packs. I have a Grin charger, but can also charge with the Bosch 830 charger.

So I have made up 2 battery packs each is 36V @ 12a
I use them series to make a 72V @ 12 A