Dawes Swift

DJG

Pedelecer
Jun 27, 2020
26
1
I have a Dawes Swift with the Dapu centre motor and LCD screen controller, the battery is charged and there is power to the connector at the screen and switch but it will not power up or work in any way. Am I right in thinking that the fault lies with the screen and switch if so where can i get another original or will any five wire unit work?
 

RoadieRoger

Esteemed Pedelecer
Nov 8, 2010
621
109
Check the gap between the sensor on the rear frame and the magnet on the wheel spoke . If it`s too wide nothing happens . I have the Pro Rider` Flare` which is the same . I experimented by repositioning the magnet onto another spoke and found this out . The gap has to be pretty small to work .
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
1,435
287
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Some bikes have sensors in the brake levers, tthere to sense braking and to then turn off the motor when braking, also a source possibly of an inactive motor, if the first tip above did not help.
Unplugging the electric wires going to the brake levers, will usually allow the motor to run, if thats the problem.
Measuring the battery voltage accurately and posting the result here, is the next best move I feel, once the previous tips have been checked out.
Best of luck.
Andy
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
11,180
4,315
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West Sx RH
If the Dapu is MD250 mid drive, PAS will be internal .
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
11,180
4,315
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West Sx RH
Check the gap between the sensor on the rear frame and the magnet on the wheel spoke . If it`s too wide nothing happens . I have the Pro Rider` Flare` which is the same . I experimented by repositioning the magnet onto another spoke and found this out . The gap has to be pretty small to work .
Any rear wheel magnet will be a speed sensor and not PAS sensor.
 

DJG

Pedelecer
Jun 27, 2020
26
1
Some bikes have sensors in the brake levers, tthere to sense braking and to then turn off the motor when braking, also a source possibly of an inactive motor, if the first tip above did not help.
Unplugging the electric wires going to the brake levers, will usually allow the motor to run, if thats the problem.
Measuring the battery voltage accurately and posting the result here, is the next best move I feel, once the previous tips have been checked out.
Best of luck.
Andy
I have measured the voltage at the five pin connector close to the display and it was 38.4 volts, the bike doesn't have brake sensors and the display does not light up at all.
 

DJG

Pedelecer
Jun 27, 2020
26
1
I have measured the voltage at the five pin connector close to the display and it was 38.4 volts, the bike doesn't have brake sensors and the display does not light up at all.
 

Andy-Mat

Esteemed Pedelecer
Oct 26, 2018
1,435
287
73
I have measured the voltage at the five pin connector close to the display and it was 38.4 volts, the bike doesn't have brake sensors and the display does not light up at all.
Then I would hope that it is nominally a 36 Volt battery, somewhere in mid charge, (between 30 and 42 Volts), which of course would be working exactly as it should.

If the battery is nominally a higher voltage, say a nominally 48 volt battery, then the battery is IMHO, probably fully discharged, which might explain the problems you are having.
I do not myself (sadly!) know the nominal battery voltage for any/all e-bikes.
But when a Li-ion battery reaches a certain level of voltage, generally around 3 volts per "series" cell, then the Battery Management System kicks in to prevent a further loss of capacity.
If the charger is attached, but the LED indicator stays green, implying fully charged, then further charging is most probably being prevented by the BMS.
If this is a 36 volt Battery, then it should simply take a charge at the voltage you mentioned IMO.
I am sure someone here will know your bike and its voltage. Most are 36 volts nowadays.
If you need anything explained further, please just ask.
Andy
 

DJG

Pedelecer
Jun 27, 2020
26
1
The battery is a 36V10.4Ah (375Wh), PANASONIC SANYO cell 2600 which appears to be almost fully charged from the led display on the battery. As there is power across 2 of the wires that go into the LCD display does this mean that the fault of the display not turning on or operating any of the motor features lie in the display and handlebar switch unit?IMG_6031.JPG
 

DJG

Pedelecer
Jun 27, 2020
26
1
Thanks for the link to the bike manual, that is the correct one for the bike and comfirms that I am using it correctly but still does not operate the display or motor.
 

sjpt

Esteemed Pedelecer
Jun 8, 2018
1,705
1,134
Agreeing with what Andy-Mat says above. If the battery is only showing 38.4v at full charge it is probably nearly dead. It should be around 42v. Even some pretty dead batteries can manage 42v at full charge, it's just when you start to use it that the voltage drops right down very quickly. The led display on the battery may not be very accurate; do a full charge and measure the battery.

You should not do this regularly, but leave it on charge a few hours after the charger light goes green. That might be able to balance the battery and bring up and cells that have dropped a lot.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
4,875
1,753
Basildon
The switch unit identifies the LCD as a Bigstone one, but the layout doesn't tie up with standard Big stone LCDs, so it's probably a special one for Dapu.

In principal, they all work the same and they work independently from the rest of the electronics.

They have 5 wires, normally:
Red battery positive
Black ground
Blue battery voltage that's switched on when the LCD is lit. This wire powers the motor controller.
Two data wires Tx and Rx that communicate with the controller, which can be any colour.

When you press the power button, the CPU latches it on to power the LCD and the blue wire. When you press it again, the CPU latches it off.

If the LCD doesn't switch on, it's because:
There is no battery voltage coming to it. Bad connection of the head unit if removable or interrupted red or black wires.
The switch doesn't work. Wire pulled off the LCD's PCB. Broken or worn out switch. Damaged connecting wire.
Damaged circuitry on the PCB. Water ingress. Corrosion. Wire pulled and shorted. Wiring messed with and battery wire connected to wrong position.

Whatever the cause, it should reveal itself if you can open the LCD and do some simple voltage testing.
 

DJG

Pedelecer
Jun 27, 2020
26
1
The LCD is a sealed unit so can only test the wires at the 5 pin connector just before it, I will give it a charge and see what the voltage reads afterwards.
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
4,875
1,753
Basildon
I'm pretty sure that you have an Ananda controller. that's what Dapu used to use and it looks the same. Probably any Bigstone LCD will work.
 

DJG

Pedelecer
Jun 27, 2020
26
1
Thanks for the E Kit link I have asked for a quote for the switch and display as they look identical to the one that I have fitted. Given that the handlebar on/off switch doesn't power on the display or the motor functions is it reasonable to assume that a new one will rectify the problems?
 

vfr400

Esteemed Pedelecer
Jun 12, 2011
4,875
1,753
Basildon
Thanks for the E Kit link I have asked for a quote for the switch and display as they look identical to the one that I have fitted. Given that the handlebar on/off switch doesn't power on the display or the motor functions is it reasonable to assume that a new one will rectify the problems?
I can't really say without testing anything. Ananda controllers are normally full of hard jelly stuff, do you can't even test in there.
 

DJG

Pedelecer
Jun 27, 2020
26
1
Are there any tests that I can do on the wiring in and out of the control unit to verify if the display unit and handlebar controller are faulty?
 

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