Bafang G062 / G063 Info

This is the 45 amp controller, the dunes are just the right size that I don't risk overheating anything and can use full power even though the sand is quite a drag on the bike, running sensorless on a cheap Chinese controller, it works fine, only loses track once every few rides and I am always pushing it to the limit.

That looks like some fun riding! Curious what brand 45a controller you are using that is running "well" sensorless?
 
That looks like some fun riding! Curious what brand 45a controller you are using that is running "well" sensorless?
25 quid eBay version, it seems very hit and miss, I had the exact same one on another bike and it would lose the fields multiple times every ride, resulting in a buzzing lockup, you had to drop the throttle down and up, but by then you had lost all your speed.
 
25 quid eBay version, it seems very hit and miss, I had the exact same one on another bike and it would lose the fields multiple times every ride, resulting in a buzzing lockup, you had to drop the throttle down and up, but by then you had lost all your speed.
Ok I have a theory.

If you use a multimeter on the lowest ohm setting, and you attach one prong to one of the 3 phase wires on your motor cable, and the other prong to your axle, it shouldnt have a reading, it should be an open circuit (no circuit). If you get a resistance reading, it means theres a short where a wire (probably in the windings) has shorted to the stator. Its a super easy test to do, takes just seconds.

My guess is that you have a short on that motor. Its a small enough short that you probably dont notice it when you ride, but its a big enough short that its throwing off the sensorless controller- causing it to buzz out at times (high amp draws). Thats my current (no pun intended) working theory.
 
Dyno session is finally done 😃
Modified G062 motor running 60v (16s) 90A Battery DC (114A 2-3sec peak).


Dyno run was done at (pratkapaja.fi) on DynoJet 250i inertia dyno.
Because of dyno setting stall torque was not measured but run started at about 120rpm. As inertia dyno measures power output from which torque is calculated, motor low speed efficiency does not enable low rpm stall torque measurement. Stall torque can be estimated though to be in close agreement with Grin motor simulator that estimates the value to be approx 190nm.
In all Grin simulator predicts very close to true measured figures in area where both data are available.
Measured input power 5418w
Motor simulator estimate 5285w
Measured output 4042w
Motor simulator estimate 4092w
Measured torque at 215rpm 154,4Nm
Motor simulator torque at 215rpm 153,6Nm
 

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though i have little trouble with a fair amount of math graphs elude ,found out i could do some pretty esoteric things if i really applied myself,however i need someone to decipher graphs for me,have picked up some pretty good ideas from this thread though.
 
Good grief, what an amazing application of inginuity for a problem probably no one asked 😂.
Incredible.
Next of course is a piped heated jacket.
 
Hall sensor board delete- to increase airflow by 20%+ and reduce "hot spots" hidden behind the board
High Temp Insulation Varnish brushed on windings
Oversized Vent holes 2-3x larger than before on both sides
8-10ML ferrofluid on magnets
Custom Hub sinks re installed
22.7" OD tire (low gearing, but not too low, "optimal" gearing for 30mph and below @ 72v)
Stainless/Nylon gears with oversized Stainless Drive Key (5x5x12mm) standard is 5x5x10 low carbon

Stator is ready for new windings- internally coated with high temp insulation, just waiting on the 180c rated copper, I went with higher gauge .81 mm and will attempt the same cross sectional area as the 6t motor (7 strands @ .81), with higher temp coating, higher gauge and 7 turns. Will probably upgrade to 12awg phases as well. - Just waiting on the copper in the mail

Gonna test this out and see what difference it makes to winding temps, then the new wound motor after.
Okay so the verdict on custom winding: No go.

I tried 3 different wire sizes, oem ~.5mm, larger .65mm, and much larger .81mm. The larger wires dont wind as well, the OEM sizing seemed to work best.

The oem motors are tightly wound, they seem to be wound very well. Atleast with my winding skills, I was not able to fit any more copper than the OEM motors come with. Additionally, I tried drilling out the stator. I tried drilling out the stator with diamond grinding bits. I tried using an angle grinder and dremel to widen the stator gaps to fit more copper. None of it helped much, and it damaged the laminations in the process. I also had significant issues with stator shorts when winding, especially when trying to cram in more copper.

I was able to wind a couple successful motors, but they are approximately the same spec as OEM, no improvements.
 
Okay so the verdict on custom winding: No go.

I tried 3 different wire sizes, oem ~.5mm, larger .65mm, and much larger .81mm. The larger wires dont wind as well, the OEM sizing seemed to work best.

The oem motors are tightly wound, they seem to be wound very well. Atleast with my winding skills, I was not able to fit any more copper than the OEM motors come with. Additionally, I tried drilling out the stator. I tried drilling out the stator with diamond grinding bits. I tried using an angle grinder and dremel to widen the stator gaps to fit more copper. None of it helped much, and it damaged the laminations in the process. I also had significant issues with stator shorts when winding, especially when trying to cram in more copper.

I was able to wind a couple successful motors, but they are approximately the same spec as OEM, no improvements.
Pretty much what Justin (Grin) said about these windings. The new style stator on G063 looks bit more favorable in this sense.
Btw what type of damage you got on the laminations?
 
Pretty much what Justin (Grin) said about these windings. The new style stator on G063 looks bit more favorable in this sense.
Btw what type of damage you got on the laminations?
Did Justin do a writeup on this motor, if so I totally missed it, got a link by chance?

Good info on the G063- I'll have to take a look at some pics again. The copper fill from the pics that I have seen looked weak, I'll take another look.

Laminations- All kinds of damage. Drilling (even with a smooth diamond bit) x 18 slots, the vibrations separate the laminations making them much thicker. The motor only has a tiny bit of clearance on each side between the covers and it reduces the clearance. Enough vibrations actually separate the laminations where they can split and fall off entirely as well, losing some of the laminations. Dremels, Angle Grinder also do the same thing with vibrations. All of the tools also seem to burr/nick/bend the laminations or unintentionally make it have sharp edges making stator shorts more common. A professional machine shop could probably do a better job, but I tried on 2 or 3 different stators and didnt have particularly good results either way.

New MXUS GDR19-FAT is here- I'll be testing out this motor starting today on the other thread!
 
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