Replacement for a 8Fun controller ?

[JohnD]

Would this:-

36V 350W brushless controller for E - bike & scooter - eBay (item 300371271592 end time Nov-21-10 05:49:19 PST)

make a good replacement for the 15amp controller that came with my Sunlova kit - I'm hoping to trade range for speed. The illustrated connectors look fairly similar.

 

[NRG]

Hi John,

Couple of things, this controller is rated for 25amp can your battery / BMS cope with that. It uses Hall sensors, does your motor use them?

You've seen my conversion to these controllers I had to change the connectors, make sure they are really the same and do you need to retain control of lights, front and rear plus any handle bar battery state indicators.

Also, just upping the current won't necessarily mean your speed will increase....it may up hill under load but not top speed.

 

[onmebike]

Controller doesn't appear to have connections for pedelec sensor?

 

[mechaniker]

Hello John,

there are different Bafang SWXK Motor in trade.
SWXK Sensorless and SWXK with Sensor is on the market.
Also Version one and two is on the market. The version two is much more easy to fix a diskbrake too as on version one

If you have a Bafang SWXK with Hallsensor, you can use this controller.
If You have a sensorless Bafang SWXK you cant use 25Amp Controller because the Motor will shake if you use more than 17Amp.

But with more amp you dont receive more speed, you only have a little more power on step hills but you pay for this a high price because 25Amps suck´s on your battery a lot. Also you need a battery what is able to deliver 25Amps and the most cheap batterys cant do this.

If you want more speed, then you need higher voltage, not higher Amp´s

regards
frank

 

[JohnD]

Thanks all, particularly Frank - sounds like I need a 48v battery not an uprated controller.

 

[NRG]

John not so fast. You need to check that your controller will take a 48v battery which on full charge could be 54v. The capacitors and FETs need to be checked for the correct rating and the 5v regulator that supplies the control circuit needs to be within it's maximum input voltage. As these controllers are so cheap it may be best to get a 48v rated one along with the battery

 

[jbond]

If You have a sensorless Bafang SWXK you cant use 25Amp Controller because the Motor will shake if you use more than 17Amp

When you say "shake" are you talking about the brief shudder you get when starting a sensorless motor? Or is it a bigger problem than that?

 

[mechaniker]

When you say "shake" are you talking about the brief shudder you get when starting a sensorless motor? Or is it a bigger problem than that?

Near by, but sorry, my english is to poor to explain this problem.

a short try, the programming on sensorless motor/controller is not so easy and the signal is not so clean as on sensor-motor/controller because it works with "against EMK" i dont know whether it is correct written?

And you must see that a lifepo4 battery is full loaded near 60v. My special crazyman controller is able to handle it but many controller cant handle 60V.
further you must match full loaded battery with in around 55v x 25Amps you send 1350Watt (on phase it is more) to this small 250Watt Motor.

My suggest, if you want drive 48v battery, then use not more as 13Amp´s at the controller.

And we are again on the theme, what the people want?
a bicycle with elelctric support , or a Motorbike?

At time i design a motor for chaindrive because i belief a chaindrive system with 250Watt have enough power for speed and Hill. Supporting speed will be around 35km/h and climbing ability is also enough when you match that a human only have 150Watt, then a 250Watt motor-support should be enough, even on hill´s

regards
frank

 

[flecc]

When you say "shake" are you talking about the brief shudder you get when starting a sensorless motor? Or is it a bigger problem than that?

To help out, yes, I'm confident that is all Frank means with regard to the effect perceived, the momentary starting judder, but he enlarged on the cause by his reference to EMK (EMF for the English language).
.

 

[NRG]

I'm currently running the E-Crazyman controller on my Alien GSII, its sensorless and configured for 20amps, seems to work very well