Controller issue

bschemers

New Member
Region
USA
City
Highland
Hi everyone,
After going around and around with the company in China I bought my bikes from, I am hoping to get some help on this forum. Bought a couple bikes from China, some are 500 watt and some are 750 watt. Both bikes have Bafang hub motors. They both also have the same controller. All was good until I had a couple 750 watt bikes burn up controllers. Being I have no data on what the controllers are other then what is on the tag, I went back to the company I bought the bikes from to get spares. They said they no longer have that style controller. They switched to a water proof design that has the one cable to 4 design. I had to switch everything over to the new wiring, The only thing that remains original is the 48 volt battery and the 750 watt Bafang motor. I am installing all the new parts on a working bike so that I know there were no other issues. The battery is a 13ah with Samsung cells.
The first picture is the old controller and the second is the one they sent me with all the new parts.
The problem I am having is when using the throttle only function. Applying the throttle with the tire off the ground everything works. As soon as I sit on the bike to add load, the bike will jolt forward two inches and shut down. If i get the bike rolling, I can then roll into the throttle and it wont shut down. I can also give it a very very small amount of throttle to get it rolling and then slowly roll into it.
The only thing I can think of is the new controller is overloading the BMS. The old controller is only a 18 amp and the new one is a 25 amp. If that is the case, what should my next option be. How do I find a controller that will work with the new color screen? or the old screen for that matter? If I could find a controller that works with the old system, I would just return everything I don't need and get my money back.

Any help would be greatly appreciated.
 

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AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Because I have experience with them, and they are priced reasonably, I would suggest you look into KT controllers. New controller AND display (a good one - LCD3) are less than a hundred bucks. There's enough of them in use where there is some support for them as well. They come in waterproof and non waterproof versions.

The power shutting down like that could be voltage sag - or maybe a 48v controller being asked to run on a 36v battery.
 

bschemers

New Member
Region
USA
City
Highland
I thought about the battery being an issue. I have a couple spare batteries and tried three of them after a full charge netting about 52.4 volts on average each. I will look into the KT Controllers.