upgrading controller on 48v 1000w system

[Slowplow]

Hi folks,

I need some tech help if possible.

little bit of background info 1st

I have built my own ebike from an old greenedge kit and upgtaded it with a cyclotricity kit (1000w 48v system) for off road use.

I have built my own battery packs (13s 8p) from lithium ion 18650 cells all series connection have 4 amp fuse wire connections (for safety) and BMS installed on each and extra set of 2 *7s jst xh balance leads installed that allow me to manually equalize the cells using a lipopal (great device well recommend) and then i fit 2 low voltage buzzer monitoring when out and about (works great) when keeping everything tickety boo.

Now for my issue.

The original controller from cyclotricity was a 48v 30 amp system which failed after a year and half of heavy use (battery still going good). I decided to experiment a bit and found a website called wing ebikes that seemed to sell kits that had the same connectors as my kit so decided to buy a 48v 40amp controller (as i wanted to see if i could get a bit more power out of my system)

so my original system was 48v *30amp = 1440w
new controller makes it 48v*40amp = 1920w

I have installed the new controller without issue but don't see any gain in speed or torque which has me puzzled?

When i test the motor without friction the top speed mph is the same as the old 30amp controller 39.1 mph?

Should this have increased? i'm 100% sure its not restricted but cant see any way to get extra power out of the controller

any help would be appreaciated.

regards

slowplow

 

[Deleted member 4366]

The speed won't increase at all because you have the same motor and same voltage. In the lower RPM range, you should have higher torque, but when you get to 30 mph, the motor is limiting the current rather than the controller, so no difference in torque after that. The only thing that would be different would be the hill-climbing and initial acceleration.

 

[Slowplow]

Many thanks d8veh

I have just taken it out for first test ride as the weather has been horrid (and came back to your email). You were spot on i should have realized if i need more speed i will need to up the voltage.

I checked it on my turnigy and its pushing out 1700w (so 35amp max)
It is indeed better on hills and the initial response was faster acceleration.

I'm at 54.6v battery at moment max so not sure 14s 58.8v will work on my 48v system i think it will blow it up?

have you ever tried?

 

[Deleted member 4366]

14S won't blow it up, but I've heard of some controllers having a high voltage cut-off - in particular KT controllers like yours. I don't know at what voltage that would happen though. My gut feel is that 14S should be OK.

 

[Slowplow]

I think i will tinker further!

I have been looking at Lunacycles who sell a 52v 300w charger that can adjust the voltage capacity from 100% 90% or 80% which may allow me to get past the over voltage cut out issue if my controller has it built in.

I was going to try and adjust the pot on my 48v aluminium case charger but may play save and just get the new one as it now comes with LCD display.

It states under voltage protection on the controller but i can't see anything about over voltage protection? But i will take your word on that.

Just need to find a 14s bms module now. are you a fan or do you balance manually ?

Ty for you input very helpful

 

[Deleted member 4366]

I always use a BMS now. I got fed up with having chargers and wires all over the place. The new Speedict does up to 15S and has the advantage that you can adjust the max cell voltage to whatever you want, so if your controller reacted to the higher voltage, you could turn it down a bit on the BMS. It's relatively expensive though:

https://www.speedict.com/

 

[Slowplow]

LOL

Just blown the kt1 lcd display after a 15mile ride. I hadn't realised if i upgrade the controller i need to upgrade the lcd display.

Will get the kt3 as think that can cope with 40amps 1700w controller.

Its all fun!

 

[Deleted member 4366]

The LCD works completely independently from the controller, so you can't blow it by using a different controller. it makes no difference if the controller is 10 amps or 100 amps.

The only things that matter are the voltage and the correct connections.

 

[Slowplow]

That's good to know!

The display just gradually dimmed to nothing displaying as if powered off was not instant power failure.

I will take the display apart and see if i can fix it. May be just a blown cap, dry joint hopefully.

 

[Slowplow]

Good news the controller had a faulty battery connection that was stopping any voltage to the lcd1 display. Purchased a new lcd3 before i realized but not fussed as its alot better then an lcd1. I like the watts and temperature indication thats on the lcd3 so all good in the end!