inconsistent power from 72v Enduro style ebike

[TommyofAstora]

Hello I've got a 5kw 72v Alibaba ebike running a QS style motor and generic 80a controller.

Overall it's a very enjoyable machine and gets absolutely insane range but the power delivery is weird and inconsistent.
Sometimes it has a ton of torque and really wants to rip up to about 35mph, then it will sometimes hit a wall and hold speed for a little before blasting off with more power up to 50mph. Other times it will rip right up to 45mph before showing any signs of power reduction. Then randomly I'll hit this wall at 30mph in the middle of hard open throttle and I'll lurch forward a tiny bit because the change in acceleration is out of nowhere. Other times it seems to have low/random power at low speed too...

wondering if this could be my generic controller or maybe the gauge of my wires? I don't really know the exact models of anything, just hoping the symptoms of my issue will help someone push me in the right direction.

I balance the cells before my rides and I've only ever gone about 20 miles which brings me to 75% voltage so it's not that my battery is ever running too low

 

[Chalo]

Who did you persuade to insure your motorcycle?

 

[TommyofAstora]

Who did you persuade to insure your motorcycle?

Currently insured with liability from BOFA but I'm considering other options at the moment

 

[brazilianboy]

Sounds like controller issue. How many amps is your battery pack rated for?

 

[TommyofAstora]

Sounds like controller issue. How many amps is your battery pack rated for?

Thank you. Yes, I ended up pulling the battery out and found that it has a 150a rating on the sticker. So that's my bottleneck then, right? I'm only pulling a maximum of 80a with my controller.. I guess that explains the extreme range. This mismatch isn't straining my battery right? Also would a future controller upgrade mean having to change other components like the display? Thanks

 

[brazilianboy]

Thank you. Yes, I ended up pulling the battery out and found that it has a 150a rating on the sticker. So that's my bottleneck then, right? I'm only pulling a maximum of 80a with my controller.. I guess that explains the extreme range. This mismatch isn't straining my battery right? Also would a future controller upgrade mean having to change other components like the display? Thanks

If your battery can provide 150A and your Controller will pull only 80A, That's perfectly fine! Should Always be this way.
It cannot be other way around! Big No-No.

The controller I recommend is FarDriver. Check on their website the power levels for your battery but regardless, it's configurable. So you can get a powerful controller now, Tune it down to 120 battery amps for example and when you get a better battery, Bring the power up.

There are many videos on youtube teaching how to configure FarDriver.

 

[TommyofAstora]

Great info thanks so much!

 

[bengxe]

It sounds like the controller is hitting a limiter, so its possible that if it has one of those 3 speed switches its going bad. But replacing the controller would have a lot of other benefits. Post a picture of your controller/ display if you want help with that.

 

[Chalo]

Currently insured with liability from BOFA but I'm considering other options at the moment

Interesting, I would expect to have to go with an offbeat provider like pedicabbers have to do. Thanks for the info.

 

[TommyofAstora]

It sounds like the controller is hitting a limiter, so its possible that if it has one of those 3 speed switches its going bad. But replacing the controller would have a lot of other benefits. Post a picture of your controller/ display if you want help with that.

Sorry for the unhelpful pic but the controller was listed in the specs as "generic 80a" and it's just a heatsink with a black housing... can't see any wording anywhere. Here's the display too. Definitely open to suggestions about better controllers

 

[99t4]

... power delivery is weird and inconsistent.

Don't rule out throttle/wiring/connector faults. Can you get another throttle to test with? Actually not a bad idea to have a spare on hand anyway.

And,

Is the inconsistent performance consistent across varied battery voltage conditions? (i.e. same behavior whether fully charged or near LVC?)

 

[TommyofAstora]

Don't rule out throttle/wiring/connector faults. Can you get another throttle to test with? Actually not a bad idea to have a spare on hand anyway.

And,

Is the inconsistent performance consistent across varied battery voltage conditions? (i.e. same behavior whether fully charged or near LVC?)

Yeah, I think I've only ran the bike down to 60-70% voltage but It does seem like that "2nd power band" decides to kick in less when not at full battery. Feels a bit like there's a 0-35mph mode, then a 35-50mph mode may or may not decide to kick in while the throttle is fully open for a few seconds.

I'll try to run the bike down to the lower end of it's battery to see how it behaves but it's prob gonna take a few days. I've got to be under utilizing this battery to get 30 miles out of 30% LOL. No way to test the throttle but that's definitely something to look at.

This is my first PEV like this so it's hard to tell if It's an issue or I'm crazy so I appreciate the help

 

[99t4]

Might help also to clarify what you are meaning when stating "75% voltage," "60-70% voltage," "30%," etc. Is that simple calculated between battery HVC and LVC values? Or reading from the display? Or?

"This is my first PEV like this so it's hard to tell if It's an issue or I'm crazy so I appreciate the help"
The way you are describing it, it appears to be some kind of intermittent failure or impediment.

 

[TommyofAstora]

Might help also to clarify what you are meaning when stating "75% voltage," "60-70% voltage," "30%," etc. Is that simple calculated between battery HVC and LVC values? Or reading from the display? Or?

"This is my first PEV like this so it's hard to tell if It's an issue or I'm crazy so I appreciate the help"
The way you are describing it, it appears to be some kind of intermittent failure or impediment.

Yeah sorry about that I'm talking about the voltage reading from the display, which could be entirely off. I use one of those charts to determine the percentage of battery the display says I have left. I took the bike out around the block today and had a noticeable throttle cut out right as I was accelerating out of a banked turn. I'm gonna double check all the connections tonight

 

[bengxe]

The controller looks like a votol, maybe an em100. Just to eliminate them as problems, I would see if you can ride it with the display and/ or the pas unplugged. And you probably want to try a new throttle.

 

[TommyofAstora]

The controller looks like a votol, maybe an em100. Just to eliminate them as problems, I would see if you can ride it with the display and/ or the pas unplugged. And you probably want to try a new throttle.

A few people saying throttle now and I just looked them up. At only 20$ I might have to grab one just to know it isn't the problem.

Anyway I tried disconnecting the display at the pin connector and the bike won't start at all. I opened up the case to find the PAS wire but it seems to go into a big harness? There's essentially the big grey plug harness that has everything and a small yellow accessory plug for the headlamp I think. Either way I wasn't confident I could easily disconnect it for testing without ripping the entire controller out.

I'm really in love with this bike, it's so crazy solid without a single squeak and super comfortable so I think upgrading to a Fardriver controller seems like the way to get everything out of my 150a BMS without breaking the bank. I'm willing to bet it will solve my issue and if it doesn't that new throttle will be ordered amazon prime

 

[TommyofAstora]

Have I supplied enough info for someone to give a good Far-driver recommendation?
There's so many different models on their website I don't wanna screw this up lol

The info printed on my battery is
72V40ah
84V
40Ah/2880Wh
20 -150a
21700

Motor says QS motor & looks like the 205 50H but the model # is weird.
Seems decent though even pushing it hard after long rides it barely gets warm

Thanks for the patience I'm still learning about these things

 

[bengxe]

I have no experience with either of these, but it looks like the nd72300 will do up to 100 battery amps and the nd72360 will do up to 190. So if that BMS is rated for 150a continuous you may be able to get more power out of the 72360. If you're not sure whether its a continuous or peak rating, or if you're happy with the current power, you probably want the 72300.
It looks like you have to buy the throttle separate from the fardrivers, so you still may want to try that first.