Wilderness Energy BD36 running at 48v
If the battery pack is shutting down that's not an issue of the BD36 motor but the pack.
On my BD36 bike I'm using a 36v Ping pack and sometimes the pack shuts down. It's a pain and it has to do with the Ping BMS (I suppose) protecting the pack against an aggressive discharge. It indicates the cells Ping sources aren't high power.
If you were to find a different pack with a different BMS that allowed more power then presumably it would work.
I've seen some describe "bypass the BMS for discharge" and that is one way around this. What that means is to have the power wires connected directly to the + and - of the pack rather than the + and - of the BMS. Ping's instructions are to wire the controller to the + and - of the BMS which is what gives us this situation where the BMS shuts down cutting power to the controller. If you wired directly to the + and - of the pack the BMS cannot interfere with power delivery. It also means the BMS cannot protect the pack.
For example lithium cells, if the voltage goes too low, will be damaged quickly.
obviously my BMS is working. True, there is a way to by-pass the BMS. There are 2 other neg & positive leads, but they would have to be freed via soldering.
I'm going to be using it with my Aotema brushless, sensorless kit. This 48 v 15 ah lithium pack has about 2 hrs run time total. I'm going only a few miles and leaving it
on charger for a very long time ( breaking in pack).
It would be risky to bypass BMS on a brand new pack. Balancing with a new pack may be even more important. This is not a Ping pack. I bought it f/ Ebayer named olympics2000888.
On my brushless, BMS has never shuts down pack. I might sell the BD36
Longevity update: I have about 250 miles on the BD36 at 48v now. No problems so far. The motor still gets hot if I use full throttle for more than a few miles, but I think it would do that at 36v also (maybe not quite as hot). I can keep the speed in the low 20's until that battery runs out, and not much heat in the motor. I think the BD36 controller can handle all I want to give it at 48v.
Richard, any idea how long BD36 motor will last at 36 or 48v? I have observed and read that brushes last about 5000 miles.
Richard, any idea how long BD36 motor will last at 36 or 48v? I have observed and read that brushes last about 5000 miles.
Just changed brushes after 2300 miles. about 1/2 inch of each brush remained. I had to open hub as one of the brush spring was jammed and motor would not work. Maybe running on 48 v lifepo4 makes more arcing etc. This may be what caused brush spring to "jam."
I'm not sure how long the motor will last at either voltage. I have about 300 miles on mine now, maybe 350, only about 60 or 70 of those at 36v, and it still seems to run fine. Lately I have been hearing a bit of a grinding sound when I first start, which almost immediately goes away. I heard that a bit less when the motor was new, then it was mostly gone until recently. If this motor goes bad, I'll go brushless, which actually seems to be the only option now.
Its normal for some noise to be made by a bd36 when getting started. A bike with a fender will make the noise louder. Sometimes called a grunting noise, rather that a grinding, I found with my bike it was loudest when the battery had the most charge. Backing off the throttle and giving the motor less amps starting out would lessen the noise. If this describes the noise, you have no problems.
When I had loose magnets in my bd36, I did hear a scraping, or squeaking noise as the magnet rubbed on the coverplate. This would go away quickly after a few hundred yards, only to return the next time I stopped. This was a very different noise from the grunting, and would sometimes sound like a cricket chirping in the motor. I suspect you are hearing the normal grunt of a motor under a heavy load starting up.
I mostly agree with DogMan. I guess I had heard the occasional grunt if I gave it too much throttle from a dead stop. But if you're hearing a grinding or a scraping sound, I'm betting it's a loose magnet. My interpretation is that when the voltage is highest and you're generating the most torque, that's when a loose magnet can scrape across the rotor. What ultimately happened with my motor is that I began to hear a louder and louder grinding noise culminating in the motor turning minimally and I think my throttle indicator went from green to yellow on a quarter twist. With DogMan's e-assistance, I eventually got it apart to discover that 9 of the 10 magnets had become loose and had basically clumped together on one side of the rotor. My motor has about 2000 miles on it at 48v and the brushes are still about .75 inches long (original brush length unknown).
I had to remove and clean the magnets -- they're painted black and the paint was flaking off covering the stator and created a general mess. I had to clean the rotor, removing the old glue residue while marking the original magnet placements / spacing. Then I had to use a marine epoxy (PC-11) recommended by DogMan to put the magnets back on. Re-assembly without crushing fingers is a challenge. Regardless, the motor works fine now, although I think I over-drained and damaged my SLA pack during the death ride. However, even with stress testing, I have nothing like grinding sounds now.
This is the finished project. Re: above noise, I think more of a grunt. 4 batteries in a DeWalt tool bag. Fenders from eBay. Controller and throttle sealed with silicone sealant. PowerLED headlight from Sigma, very bright.
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I'm very surprised. I thought I'd heard of others using the 48v lifepo4 with the BD-36. My understanding is also that it's possible to modify the BMS to tolerate the draw -- again, it was another thread in which someone communicated with Ping about a similar problem and he was able to fix it.