Newby, looking for technical help on Carrera Crosscity E. No power assistance when pedaling.

Popps

Finding my (electric) wheels
Jul 31, 2019
6
0
Bought the bike a while back second hand and now cannot get it to power on. The battery seems OK, shows full display on the led screen, but will not dive the motor when I pedal. Is there technical information available that may help me diagnose the problem? Any pointers would be appreciated
 

Fat Rat

Esteemed Pedelecer
Jun 7, 2018
1,897
719
UK
Hi welcome
Hope you get your issue sorted soon
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
16,975
6,636
59
West Sx RH
Firstly you need to confirm the battery voltage once it has been charged, you will need a volt meter to get a reading from the discharge pins. Also confirm the charger output voltage when plugged in to the wall socket, charger should give 42v reading and battery should be approx. 41.5 - 42v when fully charged.
No use trying to find anything wrong until the two above voltages are confirmed and we know the battery voltage is correct and in the right ball park.
 

Popps

Finding my (electric) wheels
Jul 31, 2019
6
0
Thanks Nealh
Just checked both battery and charger, all good. Battery out of frame and no load at 41.6 v , and connected to charger and charging battery output is 42 v, charger also showing 42v when no load. I presume this tells me the battery is good and holding charge. I had charged the battery a week ago and only checked the voltage this morning.
I will now check continuity throughout the cables.
 

Popps

Finding my (electric) wheels
Jul 31, 2019
6
0
Another thing, what should the led display be showing when I swith it on. On mine, as I swith on, the bank of 4 led's light up red plus the first Mode (low) also red.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
16,975
6,636
59
West Sx RH
LCD displays all differ though most work in a similar way, 4 Red LED's sounds good each LED equates approx. to 25% of the battery charge. The mode LED is just an indicator to show the mode you are in, I assume you have three modes L, M & H.

Thanks for confirming the voltages they all look good numbers wise Popps.

Next I would have a look at a few items.
1. Brake levers, if they have a brake cut off to cut the motor/controller power then make sure the levers seat fully when released.

2. A more likely scenario is the cadence/PAS sensor on the bottom bracket, there should be a magnet disc with 5 - 10 magnets insitu on the inside of the chain rings and a sensor in a fixed position by the bottom bracket.
The sensor should be as mentioned fixed and not allowed to rotate at all, the magnet disc should firmly be fixed to the chain ring or crank shaft so it only rotates with pedalling. Some sensors have a small Red LED that pulses as a magnet passes the sensor, ensure the magnets align with the sensor head as they pass.
The gap between said disc and sensor should be 1 or 2 mm.
The sensor is a hall sensor (three wires), if possible poke your probes in to the rear of the connector or use some needles first and check you are seeing 4 - 5v between Gnd & V+. Next probe the Gnd & Signal wire as you rotate the cranks you should see the voltage pulse on and off as the magnets pass the sensor.

3. From the hub motor follow the motor cable, you should come across a Julet multi pin connector along the chain stay. Check that it is fully pushed together, most have a pair of raised arrows to align and a raised stop line where the two parts push to.

4. Continue following the motor cable to the controller and make sure the three phases connections are contacting properly and not shorting or have damaged wiring, sometimes a fault can be seen as the connector( if they have plastic shrouds ) melt and split form heat/current.
 
Last edited:

Popps

Finding my (electric) wheels
Jul 31, 2019
6
0
Thanks for getting back to me Nealh. Donne as suggested, almost impossible to get voltage readings through double insulated cables. Anyway, the hall sensor is working, led flashing as passage of each magnet, 12 magnets on the disc. Distance seemed OK, but I moved it closer at 1 mm. While the bike was inverted and slow moving of the cranks, I could feel and hear the motor coming on intermittently. I them checked all the connectors, unplugged and reconnected them. Switched everything on and still inverted ( no load), cranked the pedals again the motor did attempt to start but only a few times and intermittently. I then decided to remove the battery, controller and wiring off the frame and reconnect everything back so that I could easier wiggle the connectors to check for bad connections. Things improved, I could fairly consistently get the motor running, but not every time, and I suspect that if I put everything back into the frame, I would be back to square one. The controller seemed to be getting very warm and I wasn't even riding the bike, also the led display was all the time flashing on the"high" led. What do you think, perhaps the controller has had it. I checked all the cable for chaffing and they looked OK. The only place where I couldn't check thoroughly is where the cable passes into the rear wheel spindle and the hub. This could be a problem area I suppose. What are your thoughts. Could the overheating controller be a sign of it's demise, or a problem with the motor?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
16,975
6,636
59
West Sx RH
You can carry out checks to see if the controller Mosfets have an issue, the controller gets hot due to faulty Mosfets . Faulty Mosfets cause lack of or no power.

Remove the battery to test the controller Mosfets resistance.

Set your meter to 200 ohms and probe between Black/Gnd and each of the three phase wires , you should get three readings the same in the region or 7 -14k. If any differ then the Mosfet is no good.
Do the same for the Red/V+ and three phases, the three readings should all be the same. They might be in the 7 -14k region or they might all read 1/infinity, If any read 0 or non are the same then Mosfet is no good.
If a Mosfet has failed then other PCB damage may have occurred and replace said Controller.
 

Benjahmin

Esteemed Pedelecer
Nov 10, 2014
2,035
1,398
68
West Wales
My controller was overheating (admitedly under load) when there was one very poor/resistive phase connection at the motor connector. Made the motor very noisy, lots of vibration. Worth a check for signs of heat damage at the motor connector.
 

Popps

Finding my (electric) wheels
Jul 31, 2019
6
0
Hi Nealh, thanks for the pointers. I disconnected and took off the controller and loom and carried out measurements as directed. The loom comprises of the power cable from the battery ( 2 pins ), the cable to the drive motor ( 8 pins in a circle, 1 pin in the centre,) 3 pins are larger than the rest, so I presume they are the phase wires, 1 cable from the brake levers and 1 cable from the Hall sensor. I measured between the + 38v to each to each of the phase wires is 22 Kohms and rising constantly to 40 or 50. The -38v to phases is 19.8 Kohms and staying constant. I repeated this a number of times, always the same. What do you make of it?
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
16,975
6,636
59
West Sx RH
Usually when I test, I get a static 9.9 - 10 ohms for the Gnd to phase, though 19.8k seems quite high though they are all the same.
The V+ to phase again appear good all being the same.

What I don't know is when a mosfet gets warm/hot is how much the heat damages them and if it affects their resistance/performance.
 

Popps

Finding my (electric) wheels
Jul 31, 2019
6
0
Getting back to where the problem lies, controller, motor or wiring, does anybody knows or has any information on the circuitry of the wiring of the Carrera crosscity E. Also of the controller Tianjin Santroll WZKD3613KA-FSDWM28-FI, 36V 6 amp. , motor Bafang 8 FUN 36vdc 250w model BF1704H60027-1. Any diagnostic/testing info on the controller and motor would be greatly appreciated.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
9,822
3,950
Basildon
The wiring is absolutely standard and the same as any similar ebike. Santroll controllers work exactly the same as any other make.

Every check you've done confirms that things are working as they should. Your problem must be caused by an intermittent connection between the controller and the motor. Look at the cable where it comes out of the axle to make sure it's no nicked, and make sure that you pushed the 9-pin motor connector all the way to the line.
 
  • Like
Reactions: Thorls1

thenuns

Finding my (electric) wheels
Sep 30, 2021
5
1
Getting back to where the problem lies, controller, motor or wiring, does anybody knows or has any information on the circuitry of the wiring of the Carrera crosscity E. Also of the controller Tianjin Santroll WZKD3613KA-FSDWM28-FI, 36V 6 amp. , motor Bafang 8 FUN 36vdc 250w model BF1704H60027-1. Any diagnostic/testing info on the controller and motor would be greatly appreciated.
Did anyone get back to you with wiring details at all? my Crosscity E is not producing the correct speeds, 3/5/7 rather than 6/11/15. I'd appreciate any help testing the controller