Controller Done for?

I'm going to get into my problem at the end, but i'm going to type a bit about what happened before it died in hopes that perhaps if i can get another one or fix this one i can avoid what i did wrong and prevent it from happening again. Because I'm so new to this and because resources seem to be real slim on the subject ANY help would be appreciated.

i got an ebike conversion kit (link)
I got one of those front wheel 1000w motors from I got the kit in the mail and realized i needed a battery, researched batteries, realized it was something i'd have to figure out how to buy one day because $500 wasn't really in my budget.

i got a 48v 17ah battery (link)
couple months later i had an opportunity to get a loan double what the battery costed so i bought the battery with the loan, battery came in, i hooked everything up and connected the loose power wires of the battery to the power cables of the motor, my girlfriend then used the throttle, wheel moved, so the next day i had an electrician solder the connection to a set of male female connectors that were on the battery wire. the next day i was in business, riding around no problem.

bumps would disconnect wires, i kept having to pull over to reconnect
every time i hit a bump i would feel cautious because sometimes a bump would pull on a wire too much and disconnect one of them in the bag. i had the controller and the battery in the bag the motor came with sitting in a basket on the rear mount that the motor came with. So i got used to reconnecting wires anytime i would be driving through traffic and the throttle would suddenly stop doing something. I'd routinely pull over and check all the connections and check the throttle to see if the lights on the battery indicator lit up yet, once they did I lifted the front wheel and made sure the wheel reacted and then i'd be on my way. I knew this was only a temporary fix, maybe i needed to get some better connections from like an electric parts store or reconfigure my setup with longer wires. at first it was the yellow blue and green wires that kept coming undone, i've seen a lot of youtube videos where there's a plastic yellow box to connect them with but my setup came with three lose wires to three lose wires with some sort of rubber neck pieces that pulled over each other to make things snug. I pulled the green rubber back so the connectors were bare and made sure to make those click really secure and once those were secure i had a break for a while.

power cable issues
...but i still had problems, this time it seemed the power cable from the battery would not be disconnected, but nothing would work until I took apart the power connection of the red and black wires from the battery to the black and red wires coming from the motor i would disconnect them and reconnect them they would always spark but then the bike would work again, the other day i was about to do this on the side of the road but no spark, nothing worked, i took it to an electrician he said something about an over current and an electrical arc, i went to an ebike repair shop and he was saying he'd sell me another controller for $100 but the whole kit wasn't much more than that, and i found a bunch of really close controllers online for $20-100 most under $40. I'm not sure if i should open this controller up and find what needs to be fixed or get new connectors because one of the connectors is melted on the white plastic a little bit and the connector inside is kind of sideways counterclockwise. For exchanges, some are sold by other sellers so i contacted the seller and they said they can send me a new controller but it would take 2.5 weeks.


Well-Known Member
I think you might buy a solder gun ($15 at Harbor Freight) and learn how to use it, Replace the battery connectors with XT60 or XT90 connectors. It's common to get a spark when connecting the battery. You can buy an XT90 sparkless connector, or turn your battery off when connecting, if it has a power switch, Maybe you can show some pics of the melted connectors.

While a bag keeps your controller dry in the rain, it doesn't help for heat and maybe those 1000W motors get the controller pretty hot. If the seller is going to send ypou a replacement controller under warranty or for cheap, take the deal. Anything you buy on your own, connectors might not be the same.

No one but electrical geeks will try to repair a controller. They can make these things for under 20 bucks. They might charge us more, but that's business.


Active Member
You should post a picture of the connectors that kept coming loose.
Solder IMHO is a bad connection technique for 20 amp circuits, which is 1000W/50v. Any loosness can cause the solder to melt out. Plus solder takes skill, and a really good iron for 12 ga wires. I solder 12 ga wires to resistors with a 130 W pistol gun.
My "26A" controller that came with my 1000 W wheel, had bullet connectors for DC feed and 3 motor phase wires. I found .157" bullet connectors from Dorman fit them. I've used Dorman on auto ignitiion circuits at 30 amps, Dorman are the real deal (from auto supplies). R**** S**** connectors of similar design used to burn out on that circuit. Other reliable crimp terminal manufacturers in my experience are TE Connectivity, (formerly AMP) Thomas & Betts, Ideal, 3M, Panduit (from electrical suppliers).
When crimping, use a tool from Ideal or Klein. After the tool closes, pull test the connection - if it icomes loose it wasn't tight enough. These long leverage tools make a better crimp than the **** sold at discount stores and a certain tool shop mentioned above selling devices that look just like tools. Crimps do not work on solid core wire.
A new controller for $20-30 is a great debug device, but I would take a meter and measure the voltage on the black & red feed wires going to the controller in case of failure. I found my new $400 battery that dropped power at the 11th mile was bad, and received my money back, by checking with a meter. It to would work a few seconds after the controller was disconnected and reconnected, then the screen would fade out. Probably caused by bad welds in the battery. I took the battery top off and the battery protection board has 0 v on 11 sense wires and a lot less than 48 v on the other three. Probably only 1 of the 14 parallel battery stacks was working when I bought it - it charged from 51 to 58 v in 30 minutes, which is rediculous for a 15 AH battery and a 2 amp charger. Somebody was selling rejects IMHO. He did give me my money back the day I complained, so he can remain unflagged.
A whole new wheel + contoller + sensores & displayes is less than $220 these days, $180 for LED display. I'm happy with my wheel, goofy as it is. New battery got me 6 flat miles today, onward & upward (grades) tomorrw!
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Always check the simple stuff, too (like a blown fuse on the battery). You can cause power surges along the wiring when you hit those bumps. Prefer that you avoid the bumps if possible, or at least don't allow the wheels to slam into a pothole or going over a curb. The wiring should be more durable than what you describe; however, a little preventive riding awareness can go a long way to keeping you on the road. :)

Thomas Jaszewski

Well-Known Member
I'd go to the seller and try to get a controller from them. That way all the wire will match. China is kinda sloppy about having a standard for wire colors.
Next, it helps to have a PROPER solder IRON. A cheap 60W or even 40W will do. The guns are clumsy for smaller work. I've built dozens of bikes and have NEVER had a properly sized wire heat up and melt solder. If that's happening there's an un related problem. Wiring should never reach those temperature, EVER.

Next, take some pictures or wiring and connections. This isn't always the best place for solutions but pictures tell more of a story and get more people interested in helping. There are some good fellows on who can ID the controller and help find. a replacement. POST PICTURES there as well. It draws interest.

ALSO go to youtube and look for soldering lessons. Great stuff and easy to learn. Crimping and using shrink tubing is anther option for doing wires.