Help! Shengyi DGW07 solder looks to be 'crumbling' inside motor

[jimbobbikeboy]

After 4 years use and 6000km I started to have issues with my Dillenger 250 Watt front hub conversion suddenly cutting out under load when climbing a hill near my house and all power ( including to the display being lost ). I now think this is probably battery related and plan to take the battery apart later today looking for a faulty cell - but as part of troubleshooting I took the DGW07 front hub motor apart and noticed the solder appears mis-shappen and almost looks like it has 'run' or 'crumbled' on one of the sets of wires feeding the motor windings.

Having never taken the motor apart before I have no idea if this has always been like this or is a sign the motor is on the way out. Anyone recognise this type of issue? Only one out of the three sets of wires feeding into the motor exhibit this issue which is the set of wires at the bottom of the photo.

I typically run the motor flat out at maximum assistance levels and it will have been working hard during its life but I have stuck with the supplied Dillenger controller and 36volt battery so haven't done any 'hot-rodding' of it.

 

[Woosh]

the 'crumbling' you see on the circuit board is dirt and rust deposit where humidity attracts dirt and rust. You don't have to do anything to them because the board is varnished, thus protected against humidity. The surface of the solder will lose its initial shine but functionally, it won't be affected by a bit of dirt and rust. You can clean the little deposits with a brush if you like.
Your bike has done 6000kms, it's time to change its ball bearings. New ballbearings reduces running noise and friction.
Your problem can be in the battery like you suspected.

 

[jimbobbikeboy]

thanks for the reply Woosh!

Good call on the bearings BTW - I just changed in the rear wheel ones last month as the wheel was running very badly!

 

[Nealh]

The solder points are for the sensor wires and not motor windings, the latter are imbedded elsewhere.

As to replacing any dodgy cells, it isn't worth it on an aged battery. One simply can't test cells which are all connected by welded buss bars. All on ecan do is check voltages but even worn cells will show up good a good voltage, it is the internal resistance one needs to test but to do so would mean testing every cell individually.

Battery wise one will have to bite the bullet and buy a new battery or get it recelled.

 

[jimbobbikeboy]

The solder points are for the sensor wires and not motor windings, the latter are imbedded elsewhere.

As to replacing any dodgy cells, it isn't worth it on an aged battery. One simply can't test cells which are all connected by welded buss bars. All on ecan do is check voltages but even worn cells will show up good a good voltage, it is the internal resistance one needs to test but to do so would mean testing every cell individually.

Battery wise one will have to bit ethe bullet and buy a new battery or get it recelled.

I took the battery apart this morning and as you said - no way of testing individual cells due to the buss bars!

I am going to gamble on a new battery and see if that fixes things, thanks again

 

[Nealh]

One can check the parallel cell groups for volatage to see if one shows up an issue.
Also did one look to see if a fuse is present ?

 

[jimbobbikeboy]

I did look to see if I could get a reading across the two 'halves' of the battery pack but it was difficult without partially dis-assembling it and stripping back some insulation so I gave up.

The only reading I have been able to get is fully charged the whole thing is 40v.

 

[jimbobbikeboy]

Issue solved with a new battery pack! I'm delighted to be back in business on the ebike! The cutting out under load was the BMS cutting off the power as it detected the battery was dropping below 30v.

The easiest battery replacement option was to spend £400 on a dillenger battery pack but that seemed a bit excessive and I went for a £250 Green Power pack of the same capacity off Amazon.

However, the old Dillenger battery pack mounting contained the controller for the motor and this wouldn't work with the new Green Power battery as it was the wrong shape and had the wrong power connectors. After discovering I would need to potentially spend £80 for a new controller and compatiable display, I decided to keep with the Dillenger supplied controller and display but did some moding so I could mount the existing controller on top the battery - with an air gap beneath it to stop it overheating......

original Dillenger controller top which 'mated' to the battery




My modified controller top with the top bit that 'mated' to the battery cut-off, with new clear plastic cover made from an old ice cream tub and with newly soldered connectors for the 4mm bullets on the new battery




And in situ on the battery.



I ride all year in all weathers so additional silicon and weatherproof tape will be liberally applied before I go out in the rain!