controller upgrade questions

DrV

1 mW
Joined
May 11, 2020
Messages
13
So I currently have a Bafang 48v/500w rear hub motor and the controller for it is 20a max. I am considering upgrading to a KT controller (25A) to get a little more power out of the motor. It seems no one really makes a controller over about 20-22 amps that is a direct swap for the type of controller that typically comes with bafang hub drives, at least those for the motors rated at 500w or less (the higher wattage bafang motors have a 3 pin connection for the motor instead of the 9 pin that I have). So I have a few questions about exactly what to order (and yes, I have been doing a good bit of research).

1. I am planning on ordering a controller like this https://www.aliexpress.com/item/32960618313.html?spm=2114.12057483.detail.3.5fa33c25N1pAK5 and am wanting the 25a WP model as it looks like it has the HIGO connectors. Will I be able to use my current 1-5 cable to run the display and throttle. (the connectors look the same) or do I need to order the 1-5 cable specifically for that controller?
2. I currently have an 850c display that came with the motor, and from what I have been reading, it looks like I will have to order a different display for the KT controller. Can someone confirm this?
3. Should my current pedal assist (magnet wheel) work with the new controller if the connectors look the same?
4. It looks like there are KT controllers that have a higher amperage, but the controller motor connection is a 3 pin (which comes on the larger bafang hub motors) rather than the 9 pin (which comes on mine). Would something like this https://electrobikeworld.com/products/3pin-male-to-9pin-female-motor-adapter allow me to connect my motor with the 9 pin connection to a controller expecting a three pin connection (I know that the the three pin connection actually carries up to 8 inputs/connection signals)?

Thanks in advance!!
 
The more current you try to stuff though those 9 pin connectors, the greater the chance you'll burn them up. I would limit to 22A, because that seems to be what commercial manufacturers do.
 
DrV said:
1. I am planning on ordering a controller like this https://www.aliexpress.com/item/32960618313.html?spm=2114.12057483.detail.3.5fa33c25N1pAK5 and am wanting the 25a WP model as it looks like it has the HIGO connectors. Will I be able to use my current 1-5 cable to run the display and throttle. (the connectors look the same) or do I need to order the 1-5 cable specifically for that controller?

No, the connector isn't the issue; you need a KT compatible display, which the 850C is not.
 
Thanks, Chalo. I wasn't sure if the 9 pin was a bottle neck, that's why I figured 25A would be my max. Thanks E-HP for confirming that I need a KT compatible display (I had sort of suspected that from the forums, but wasn't sure if I had missed something). So the 1 to 5 cables from the controller to the display/throttle/brakes are pretty standard for hub motors and swappable?
 
Any controller can do for phases, halls, brakes and throttle. Only the connectors need to be replaced to match with many of them. The display is another story because there is no standard. Each manufacturer has his own display for his controllers, so it is better to buy the matching display if you are going to replace the controller with another brand.

When a controller is replaced with a more powerful one, it is important to make sure it will not pull more current than the battery and/or BMS is capable to supply. That is why upgrading the power of a bike often require a new controller AND battery.
 
Thanks, MadRhino. My battery bms is rated for 40 amps continuous so it should be good to go.
 

Just some food for thought. I pushed 45A to a 500W geared hub motor with no issues. Not saying it’s good for it as I’m sure it would wear it down faster but at the end of the day hub motors are pretty cheap. If your battery can output 40A you could go bigger. I would find a controller around 30a and just modulate it with the throttle when you don’t need all of that current.

So 20amps controller to 25amp controller…
If you’re only upgrading 5amps you’re not going to get much more acceleration or torque. It might be noticeable but nothing significant that’s why I’m suggesting to go at least 30a.
 
Eastwood said:
So 20amps controller to 25amp controller…
If you’re only upgrading 5amps you’re not going to get much more acceleration or torque. It might be noticeable but nothing significant that’s why I’m suggesting to go at least 30a.

It's all relative, but if you move the slider over on both cases to around 10mph, before the torque curve takes a dive, the acceleration at full throttle is close to a 30% increase going from 20A to 25A.

https://ebikes.ca/tools/simulator.html?motor=MG60_500&batt=B4816_GA&cont=cust_20_40_0.03_V&hp=0&axis=mph&frame=mountain&autothrot=false&throt=100&grade=0&motor_b=MG60_500&batt_b=B4816_GA&hp_b=0&bopen=true&cont_b=cust_25_50_0.03_V
 
E-HP said:
Eastwood said:
So 20amps controller to 25amp controller…
If you’re only upgrading 5amps you’re not going to get much more acceleration or torque. It might be noticeable but nothing significant that’s why I’m suggesting to go at least 30a.

It's all relative, but if you move the slider over on both cases to around 10mph, before the torque curve takes a dive, the acceleration at full throttle is close to a 30% increase going from 20A to 25A.

https://ebikes.ca/tools/simulator.html?motor=MG60_500&batt=B4816_GA&cont=cust_20_40_0.03_V&hp=0&axis=mph&frame=mountain&autothrot=false&throt=100&grade=0&motor_b=MG60_500&batt_b=B4816_GA&hp_b=0&bopen=true&cont_b=cust_25_50_0.03_V

Well 30% increase is good but if he’s going to spend the time and money I say go for more current, Especially since his battery can output 40amps.

If it were me I would just buy a 40 amp controller :lol:
Also the gears in the bafang are easy to change and cheap. That being said I don’t think he would have any issues at 30amps with the bafang
 
Thanks for the suggestions, Eastwood. 25a vs. 20a does have some difference in acceleration at the low end as E-HP pointed out. I would probably consider going to 30 or even 35 amp, as I am not that interested in top speed, but I'm definitely not interested in cutting/splicing wires, etc., and there don't seem to be any controllers over 25A for geared motors that will plug directly into a Bafang with a nine pin motor plug. Most everything I've seen at 30A+ goes to a three pin plug or something else.

I'm not sure that what I asked about in question 4 of my original post is doable as a connection from a 9 pin motor cable to a 3-pin controller connection (Chalo suggested the 9 pin wouldn't handle the current very well at that level), but if someone has done that successfully, I'd like to know.
 
I've done one of these already (500w Bafang, KT-22a/with color display ) and used the 5/1 cable. I had to make a lot of changes due to 3 wire brake switches vs. 2 on the 5/1 cable, the PAS connector didn't match, and there was some issue with the light wire in the 5/1.

I got through it, but it took me a lot longer than I thought it was going to. Turned out really well though. It''ll feed 900w+ to the motor when you pin it, and the power based PAS is a dream compared to the original speed based PAS. Pretty sporty setup.

If you're looking for 40a performance, I'd say you better step up to the plate with a different motor.

I ordered another KT-22a for another bike the other day. This time I went with an LCD3 because the color display has a tendency to wash out in direct sunlight. It looks like (I don't have it yet) that the light wire comes from the controller - and it uses a 4/1 cable. Hoping this setup is a little easier to deal with..... Note also the controller side of the main harness has 8 wires for a 4/1 cable, and 9 wires for the 5/1 so you need to pay attention there. -Al
 
DrV said:
I would probably consider going to 30 or even 35 amp, as I am not that interested in top speed,
Please note that voltage would increase the top speed not amps. Upping the current will just give you more acceleration. If you’re looking to go faster you would need a higher voltage battery, but it sounds like you’re just looking for more acceleration.
DrV said:
but I'm definitely not interested in cutting/splicing wires, etc., and there don't seem to be any controllers over 25A for geared motors that will plug directly into a Bafang with a nine pin motor plug. Most everything I've seen at 30A+ goes to a three pin plug or something else.
I just don’t think you’ll be satisfied with only upping the controller 5amps. Splicing wires is the norm when you’re trying to upgrade your ebike :wink: But I understand if you’re looking for plug and play but as you mentioned the options are limited to only 25amps. chalo is right the nine pin connector wouldn’t handle the current as well even though it would be fine because you’re only using the max current when your accelerating. That being said if it were me I would just cut the nine pin connector off and connect to a controller that meets your needs.
 
No, I really don't want to mess with anything like a shunt mod. After doing a BBSHD conversion on one bike, and a rear hub on another, I want things as simple/plug-and-play as possible.
 
AHicks said:
I've done one of these already (500w Bafang, KT-22a/with color display ) and used the 5/1 cable. I had to make a lot of changes due to 3 wire brake switches vs. 2 on the 5/1 cable, the PAS connector didn't match, and there was some issue with the light wire in the 5/1.

I got through it, but it took me a lot longer than I thought it was going to. Turned out really well though. It''ll feed 900w+ to the motor when you pin it, and the power based PAS is a dream compared to the original speed based PAS. Pretty sporty setup.

If you're looking for 40a performance, I'd say you better step up to the plate with a different motor.

I ordered another KT-22a for another bike the other day. This time I went with an LCD3 because the color display has a tendency to wash out in direct sunlight. It looks like (I don't have it yet) that the light wire comes from the controller - and it uses a 4/1 cable. Hoping this setup is a little easier to deal with..... Note also the controller side of the main harness has 8 wires for a 4/1 cable, and 9 wires for the 5/1 so you need to pay attention there. -Al
Did the new kt-22a with a 4/1 cable make the conversion easier?
 
They do make the controller with 9 pin now
https://www.ebay.com/itm/174797922371?chn=ps&var=473976763416&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=473976763416_174797922371&targetid=1264870805424&device=m&mktype=pla&googleloc=9031525&poi=&campaignid=10454522054&mkgroupid=125880183801&rlsatarget=aud-622027676548:pla-1264870805424&abcId=2146002&merchantid=6296724&gclid=CjwKCAjwzOqKBhAWEiwArQGwaHb6I5-NySafLv26R8I6IOFts3_VFQwus7KmcZRHzoEgdbaOjxMTfRoCpeQQAvD_BwE


Since we all get the same 500w rear bafang hub. Can we compare what speed we getting?.
I just finished my 1st ebike with the stock 18a controller c18 display. Getting 30mph wheel off the ground. And 17 when I am riding :( .
So I am trying to see if this 30a controller will help with the situation. My battery is rated at 30a discharge.
 
Skippo said:
They do make the controller with 9 pin now
https://www.ebay.com/itm/174797922371?chn=ps&var=473976763416&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=473976763416_174797922371&targetid=1264870805424&device=m&mktype=pla&googleloc=9031525&poi=&campaignid=10454522054&mkgroupid=125880183801&rlsatarget=aud-622027676548:pla-1264870805424&abcId=2146002&merchantid=6296724&gclid=CjwKCAjwzOqKBhAWEiwArQGwaHb6I5-NySafLv26R8I6IOFts3_VFQwus7KmcZRHzoEgdbaOjxMTfRoCpeQQAvD_BwE


Since we all get the same 500w rear bafang hub. Can we compare what speed we getting?.
I just finished my 1st ebike with the stock 18a controller c18 display. Getting 30mph wheel off the ground. And 17 when I am riding :( .
So I am trying to see if this 30a controller will help with the situation. My battery is rated at 30a discharge.

What’s your voltage?

The new controller will help with acceleration but it will not help with top speed. A higher voltage battery will give you more mph.

I looked at the link you posted and I would go with the 30 amp controller. It matches your battery and plus you’re not going to be using 30 A often. Just under heavy load.

As I mentioned before if you only up 5 more amps you will be disappointed. In real life application you’re not going to feel too much of a difference with only 5 A.
 
If this controller needs to be wadded into a confined space, suggest you be pretty careful selecting which you buy. It not JUST about max amp capacity if you plan on putting the new controller where the original came from.....and don't forget to allow room for the connectors and the wad of wiring. The different capacity controllers are bigger as the capacity increases.

I'm retired, riding because I enjoy it, so lights are not the big priority here like they may be for some. Not riding at night at all.

That in mind, I did run across this that may simplify them. Haven't tried it yet, but I sure like the idea!
https://www.conhismotor.com/products/unique-design-led-headlight-tail-rear-lights-brake-light-turning-light-for-bafang-mid-drive-motor-kits
 
Eastwood said:
Skippo said:
They do make the controller with 9 pin now
https://www.ebay.com/itm/174797922371?chn=ps&var=473976763416&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=473976763416_174797922371&targetid=1264870805424&device=m&mktype=pla&googleloc=9031525&poi=&campaignid=10454522054&mkgroupid=125880183801&rlsatarget=aud-622027676548:pla-1264870805424&abcId=2146002&merchantid=6296724&gclid=CjwKCAjwzOqKBhAWEiwArQGwaHb6I5-NySafLv26R8I6IOFts3_VFQwus7KmcZRHzoEgdbaOjxMTfRoCpeQQAvD_BwE


Since we all get the same 500w rear bafang hub. Can we compare what speed we getting?.
I just finished my 1st ebike with the stock 18a controller c18 display. Getting 30mph wheel off the ground. And 17 when I am riding :( .
So I am trying to see if this 30a controller will help with the situation. My battery is rated at 30a discharge.

What’s your voltage?

The new controller will help with acceleration but it will not help with top speed. A higher voltage battery will give you more mph.

I looked at the link you posted and I would go with the 30 amp controller. It matches your battery and plus you’re not going to be using 30 A often. Just under heavy load.

As I mentioned before if you only up 5 more amps you will be disappointed. In real life application you’re not going to feel too much of a difference with only 5 A.

I am running at 48v.
Does you guys have similar speed with this g020.500d motor?
 
Skippo said:
I am running at 48v.
Does you guys have similar speed with this g020.500d motor?

The similar G020 Jump bike front motors I've been building lately tend to go 23-24 mph at 48V 22A in a 26"wheel.

What kind of bike are you using? What's the wheel diameter? What's the total weight?

The 30A controller in that listing uses a different motor connector.
 
Skippo said:
Eastwood said:
Skippo said:
They do make the controller with 9 pin now
https://www.ebay.com/itm/174797922371?chn=ps&var=473976763416&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=473976763416_174797922371&targetid=1264870805424&device=m&mktype=pla&googleloc=9031525&poi=&campaignid=10454522054&mkgroupid=125880183801&rlsatarget=aud-622027676548:pla-1264870805424&abcId=2146002&merchantid=6296724&gclid=CjwKCAjwzOqKBhAWEiwArQGwaHb6I5-NySafLv26R8I6IOFts3_VFQwus7KmcZRHzoEgdbaOjxMTfRoCpeQQAvD_BwE


Since we all get the same 500w rear bafang hub. Can we compare what speed we getting?.
I just finished my 1st ebike with the stock 18a controller c18 display. Getting 30mph wheel off the ground. And 17 when I am riding :( .
So I am trying to see if this 30a controller will help with the situation. My battery is rated at 30a discharge.

What’s your voltage?

The new controller will help with acceleration but it will not help with top speed. A higher voltage battery will give you more mph.

I looked at the link you posted and I would go with the 30 amp controller. It matches your battery and plus you’re not going to be using 30 A often. Just under heavy load.

As I mentioned before if you only up 5 more amps you will be disappointed. In real life application you’re not going to feel too much of a difference with only 5 A.

I am running at 48v.
Does you guys have similar speed with this g020.500d motor?

Yeah you should be getting 20+ miles per hour, somethings not right.
 
Chalo said:
Skippo said:
I am running at 48v.
Does you guys have similar speed with this g020.500d motor?

The similar G020 Jump bike front motors I've been building lately tend to go 23-24 mph at 48V 22A in a 26"wheel.


What kind of bike are you using? What's the wheel diameter? What's the total weight?

The 30A controller in that listing uses a different motor connector.

This is my 1st build. I did it on low budget. A $25 huffy all steel full suspension mtb. 26" wheel
The bafang 500w rear Hub kit from Amazon
$65 48v 10.5ah battery with 30a BMS from ellectrico.
Total bike and I weight about 250#
When the wheel is free spin, it did show 30mph.
 

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Skippo said:
A $25 huffy all steel full suspension mtb.

The horrible tires, dragging brakes, and misadjusted bearings of a Huffy MTB could cost you several miles per hour. Also, if the vintage battery can't support the load, voltage will sag and lower the top speed. You could be dealing with both factors.
 
I did put new tires and adjusted the brakes. So no drag for sure. What kind of tires are better choice? I did not check the bearing though. But the front wheel spin fine with no noise.
Chalo bty the eBay 30a controller did have 9 pin plug to the motor. Is that not the same as the bafang?
 
Skippo said:
What kind of tires are better choice?

Not knobbies. Especially not cheap knobbies.

Relatively smooth treaded tires with anti-puncture belts and thin sidewalls would be a good starting point. CST Sensamo Master is one I've tried and liked, that didn't cost much.

Chalo bty the eBay 30a controller did have 9 pin plug to the motor. Is that not the same as the bafang?

Go to the listing and choose the 30A controller from the drop down menu. Then look at the picture. Those are the connections for the 30A controller, which aren't the same as what's on your motor.

You won't be able to plug in the motor you have. If you do it by using an adapter cable, you'll burn the plug.
 
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