4 -18 V 5Ah lithium roibi power tool batteries connected in series & perallel =36 V 20 Ah

nordic

New Member
Hi I am new to E bike's , just wondering if any one has tried this set up . $250 at Home Depot in Canada for the 4 batteries and a 6 port charger. My battery is dead and just looking for an alternative to a $500 battery and $70 charger. thanks great forum . I have a 350 W rear hub motor and the original battery was 36V 15 Ah
 

Attachments

Last edited:

harryS

Well-Known Member
Have you got a way to put wires on the connectors? You got to do 4 of them and they have to be stable and not come off while the bike is bouncing around on the pavement. These batteries are space inefficient with that tower sticking up. I've seen guys make holes in a bopard and stick the towers in the holes.

Finally the AH won't add up like you thought. The total AH rating for a composite 36V battery made out 4 of these batteries will be 10AH if the individual pack is 5AH. In addition, they might not put out the current you need without shutting down.


It's not a good solution.

I've played around with the bigger Ryobi 40V lawn tool batteries. Like this one from my weedwhacker.

Although it says 40v, it's really a 36V battery in the ebike world. Home Depot charges $130 USD for the 5Ah, 180 watt-hr version that I have. Then you have to get the charger, and make a clip to get the wires onto the battery. I did all of that and made a secure setup. First few tests, the wires would pop off.

I found this battery will power my 36V 250- 500W motors well in pedal assist mode, but blipping the throttle would cause the controllers to want 10-20A, which would shut off the battery. Then it would rest in a minute. So that meant it worked best for my littlest 250W motor with a tiny controller. I could get almost 20 miles out of it with pedal assist at 14 mph.

So this is not a good solution either, but I already had the battery/charger. It does say that the smaller drill batteries won't handle your power surges at all. This battery is used for lawn mowers and chain saws.

Oh, I'm taking it as a spare on a 37 mile ride tomorrow. My regular battery should cover 25 miles, and if I am too tired to finish with leg power alone, I can swap this one in.
 

nordic

New Member
Thanks Harry I looked closer at the 4 pack of batteries and they were 1.2Ah :( . If I went with the 5Ah it would be up there in price.
 

George S.

Well-Known Member
Scrounging like this can work out. Here are three suggestions:

1) This might be the wave of the future. It's the Vruzend system to build packs with a mechanical connection. Micah Toll has a decent video on how it works. Toll has an ebike book and an ebike battery book, both good. I have a kit and I've studied the parts. I have some other battery projects and I like to test them, so i can't handle another pack right now. They are selling some nice looking cells for around $4.50.

2) I made a video about using Titan Flight packs for an ebike battery. I made it so I could send the link to Trent, at Titan. They are kind of working on packs for ebikes, but they are swamped with order for the RC stuff.

3) There is a YouTube page with a lot of information about some hoverboard packs, sold on Ebay. There are a lot of questions, but I have some of the packs and made a 36v ebike pack, with BMS, from two of these packs.

There is a lot of information to process. It pays to learn how to charge cells, how the layout should go, stuff like that. It's better to understand packs and know how to monitor them, as opposed to paying a lot for a sealed system with no user serviceable stuff. It's understandable, but be safe.

It's always great to help someone who wants to make something.

Capture.JPG