EMMO Proton Shunt Mod?

Joined
Nov 27, 2020
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62
Good evening everyone.
I'm a bit new to the ebike scene and I'm trying to squeeze a little extra top end out of my proton GTS.

I've heard that the shunt mod is the way to go to get what I'm after but my first attempt yielded literally zero results I've come looking for some more advice.
The controller has 4 shunt wires and space for a 5th, so I took some 14awg solid wire and soldered it in the empty place but didn't get anything more when I propped it up on a stand and went full throttle.
should my next step be just throwing solder on and wrapping wire around the current shunts to get as much metal on there as possible?

Here is the shunt configuration. This is the picture before I added the extra wire in the middle
20201127_181835.jpg
 
I have, I tried adding solder with no wire but didn't get any results. Exact same top speed. I'm having trouble getting the solder to bond to the circuit board though, I think my iron just isn't hot enough. I'm guessing this is likely my issue.
 
Millhouse_5 said:
I have, I tried adding solder with no wire but didn't get any results. Exact same top speed. I'm having trouble getting the solder to bond to the circuit board though, I think my iron just isn't hot enough. I'm guessing this is likely my issue.

The shunt mod affects the max current values of a controller. In general, increasing the max current (phase and battery) will not give you more speed except for maybe up a steep incline where the controller is hitting max current levels. You also have to have a battery pack that can handle the increased current draw.
 
Modding the shunt will increase the current limit but may do nothing for top speed. But you should reach the top speed faster and have better acceleration. If increasing the current limit doesn't change the top speed, then your only options are to increase the voltage or change the gear ratio. If you have a direct drive hub motor, the only ratio change is to use a larger tire.
 
I haven't had it on the road to test out acceleration lately, but I've heard of these bikes going significantly faster than what I'm getting out of mine. I'm not looking for highway speeds exactly, but I'd like to not be "that guy on a motorcycle that is going 10 under the limit for some reason"

If at all possible I'd like to not have to swap out the controller
 
You may also want to ensure your controller doesn't have a speed limit set. For instance: in Canada many ebikes (like EMMOs) come from the factory with a 32 km/h limit for legal reasons. Some also have 3 speed switches to go beyond the limit. I don't know what setup your Proton may have but I bet you can find some info on that.
 
There is a limiter on this bike and is easily disabled by pulling a single connector. I'm not worried about the legality because there are a ton of well managed paths and trails around where i live. I can take an ATV path nearly all the way to work. Some guys even take a snowmobile in the winter.
in low it hits 32k, medium 42k, high 52k.
I just want to hit 60, that's it. I got the upgraded lithium (not 18650) battery that came with the bike (35Ah LiFePO4) so I know its not the weight that's holding me back. I'm only 160lb as well.
With the bike on a stand and at full throttle I'm getting a no load 56k.

I'd like to avoid getting a new controller because I really don't want to rewire my bike this winter. But if that's what I need to do I'm open to recommendations.
 
Millhouse_5 said:
There is a limiter on this bike and is easily disabled by pulling a single connector. I'm not worried about the legality because there are a ton of well managed paths and trails around where i live. I can take an ATV path nearly all the way to work. Some guys even take a snowmobile in the winter.
in low it hits 32k, medium 42k, high 52k.
I just want to hit 60, that's it. I got the upgraded lithium (not 18650) battery that came with the bike (35Ah LiFePO4) so I know its not the weight that's holding me back. I'm only 160lb as well.
With the bike on a stand and at full throttle I'm getting a no load 56k.

I'd like to avoid getting a new controller because I really don't want to rewire my bike this winter. But if that's what I need to do I'm open to recommendations.

In that case:

fechter said:
Modding the shunt will increase the current limit but may do nothing for top speed. But you should reach the top speed faster and have better acceleration. If increasing the current limit doesn't change the top speed, then your only options are to increase the voltage or change the gear ratio. If you have a direct drive hub motor, the only ratio change is to use a larger tire.

pwd said:
The shunt mod affects the max current values of a controller. In general, increasing the max current (phase and battery) will not give you more speed except for maybe up a steep incline where the controller is hitting max current levels. You also have to have a battery pack that can handle the increased current draw.

One other option is to get a motor with a higher rpm/volt. As stated above; changing the motor controller will not affect your top speed.
 
I just got my load meter installed but, its still raining here so I dont really want to take the bike out to check how much current it's pulling.
The controller is rated at 45 amps and my battery is 72v so some quick napkin math puts me over 3kw at max load. I doubt I'm pulling that at 52k which is why I'm expecting the controller is limiting me in some way.
 
What legalities are you worried about? If its wattage then don't worry at all. No one can tell the difference between 250W or 2500W, seriously no one can, unless theres a neon sign sticker on your hub/controller in plain sight. Grab some hallographic stickers that say 250W and stick them over your 1 mega watt engravings.

32k, medium 42k, high 52k.
so thats gotta be kph, totally reasonable, depending on what you got. I've done 60, not my cup of tea.



Millhouse_5 said:
There is a limiter on this bike and is easily disabled by pulling a single connector. I'm not worried about the legality because there are a ton of well managed paths and trails around where i live. I can take an ATV path nearly all the way to work. Some guys even take a snowmobile in the winter.
in low it hits 32k, medium 42k, high 52k.
I just want to hit 60, that's it. I got the upgraded lithium (not 18650) battery that came with the bike (35Ah LiFePO4) so I know its not the weight that's holding me back. I'm only 160lb as well.
With the bike on a stand and at full throttle I'm getting a no load 56k.

I'd like to avoid getting a new controller because I really don't want to rewire my bike this winter. But if that's what I need to do I'm open to recommendations.
 
yeah, the "k" is for kph. no way am i expecting to pull 50-60 mph out of this little bike without some serious modification.

The main/only reason i want to hit 60kph is to not have traffic confused when I do have to drive down the one road in town with a 60k limit. Otherwise I'm perfectly happy with how the bike performs.

I've held up traffic before by having people refuse to pass me when I'm driving my "bicycle" all the way over on the side of the road.
 
If your top speed on the road is about equal to the top speed with the wheel off the ground, there is likely some limiting going on in software.
 
So my shunt mod worked really really well. I took the bike out for a test run and noticed right away that acceleration was more instant, and the regen braking was super strong and really irritating.

Turned out that when I was giving it full throttle it was pulling a peak of 103 amps!

Super hard on my components and I pulled back on the throttle very carefully to get home without pulling too much power.

I removed my entire extra conductor and as much solder as I could and ended with 52 amps at peak acceleration which I'm ok with.

As for my top speed, it was 50kph at 2.1kw (roughly 30a at 70v) so I know there's room for more power somewhere. If anyone has any ideas what could be holding this bike back I'd love to know.
Voltage sag seems to be a real problem though. Anyone here know how much a fully charged 72v nominal (84v peak) battery normally sags.
 
Millhouse_5 said:
......Anyone here know how much a fully charged 72v nominal (84v peak) battery normally sags.

Depends on the kind of chemistry your battery is, the type of cells and how thick your power and phase wires are. A lot of variables.

:D :bolt:
 
You're lucky you didn't blow anything up. That's a good sign.

Can you measure the no-load speed? With my bike, the speedometer pickup is on the rear wheel so I can just lift the wheel off the ground and give it full throttle.

I'd guess either there is some electronic limiting going on in software, or the motor kV just won't pull enough amps to go above that speed, in which case you'd need more voltage or a different motor wind. If your top speed riding is almost exactly the same as the no load speed, it would indicate software limiting.
 
No load speed stock was 56 and after the super shunt mod it was also 56.
I haven't tested it again since I took the shunt down but I can only assume it will still be 56. If it didn't change with double the current limit then it might be limited by my voltage. I just gave the bike a fresh slow charge overnight and I'm going to see what it does this morning.

Cell chemistry is lithium phosphate and I can at least say that the wires coming off the battery are 10 awg. Not sure how far that goes, but I would hope it doesn't go any thinner than that.
I'm using a 72v Luna charger peaking at 84v. Stock charger is also 84.0 so there's no difference there.
 
Changing the current limit won't have any effect on the no load speed.

It sounds more like the motor speed is being limited by the available voltage and the motor windings. Either more voltage or a different motor wind are about your only options for more speed.

One other possible option is to replace the controller with one that can do field weakening.
 
Managed to get an answer from QS motors themselves. According to the people who I'm sure want to sell me a new motor, the 12" 1500w v1 motor (which the proton has stock) will simply not reach 70kph. My current draw seems to support this as well. I was able to hit 53 the other day with a slight downhill and a small tail wind. I was max throttle while slowly dropping wattage to around 1,600. The motor is just out of rpm at that speed.

QS was able to give me a quote on a 3kw motor but the shipping was almost the same price of the motor so I'm going to be trying to source something from north america. Anyway, my chasing speed with simple mods I think is over, now I guess I'll have to move on to some real upgrades if I want to get anything else out of it.
 
If you're cheap and have lots of spare time, you could rewind the motor with fewer turns. If you're lucky, you might even be able to change it from wye to delta without much work. This assumes it is wye to begin with. I think this approach may require changing the hall sensor positions or wiring.

I've rewound a few motors before. It's a lot of work but the cost of the wire isn't much compared to a new motor.
 
Wow, I like fiddling with electronics, but I think re winding a motor is beyond my ability and my free time. If I can find a buyer for my old motor I can likely save a few bucks on the upgrade. The quote I got from qs directly was (in usd)
240 for the v2
270 for the v3
300 for the v4
Plus around 125 shipping

The v1 will bairly go faster than my current setup so it's not worth the investment, these all hit around 90-100kph but the newer ones are just more efficient and run a little cooler. I'll probably end up with the v3 because I want the new magnet design but don't need the current capability of the v4

Current plan is to swap the motor with the stock controller and see what I can get out of it. If it doesn't meet my needs then a new controller is in my future.
 
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