SVMC7280 - Low amps?

[GiantYukon]

Hey guys, I've recently got myself the 80a Sabvoton.
It feels great, super smooth, but according to the display I'm not reaching the max amps that I've programmed in with the bluetooth app.
No matter how high I set the amps, I'm only reaching 2100w. I've got a 52v battery with 40a constant. So with 45a selected as the dc current, I should be reaching 2300w or with 50a I should be reaching 2600w, but no matter what I select it doesnt go over 2100w.
I've been playing around with all kinds of different settings on there but nothing seems to produce a different result.
Can someone have a look at my settings and tell me if I've missed something obvious?
Thanks

 

[amberwolf]

First, no matter what your settings are, you'll only draw the amount of power it takes to do whatever it is you're doing with it, so if it only takes 2100w to do that, that's all you'll ever draw, even if you have a setup capable of and set to 10,000w.

So...what are you doing to test the power draw, and how much power should it take to do that?


Second, what are you monitoring power usage with? It's possible the measurement is inaccurate, so using a second wattmeter would help confirm that, especially if you've already verified that it is indeed accurate.


Third, your battery voltage will drop as current draw increases. You might have so much voltage drop at the max current that the volts x amps = watts ends up below what you could get if the battery was better able to handle it.

 

[GiantYukon]

Thanks for getting back to me!
For the moment the only way I'm gauging power is from the display showing what the wattage is, and then figuring out from there what the amperage must have been to pull that wattage.
I'm about to head out the door and buy a clamp meter so I might be able to see what amps are actually being used.
I'm sure the battery is capable of more, because with my kt controller when I would go full throttle, the wattage would be 2300, which is about right for 52v and 45a controller. But you are right about a second way to measure, I have no real way of knowing which display was accurate, except that the maths add up for the previous KT controller.
The battery is a 17.5ah 40a constant, Samsung 35E cells.

I guess what I'm trying to achieve is harder acceleration, so I figure if its putting in more amps at full throttle it should give higher wattage and accelerate harder.
The watts on the display dont reflect it, but it does feel like its accelerating harder than the KT, but I have no real way to prove it.
It feels smoother and faster, but I was hoping to have the wattage change accordingly to the changes in amps I put in the settings.

Thanks!

 

[Audisport09]

Can I ask why you went for the SVMC7280? Based on Aliexpress the 72150 is only like an extra £20? Anyway I think you may need more voltage. I tried to run my 72150 on (12s) and it started current limiting big time. 18s is where the fun starts. I'm in the process of going to the full 72 (20s).

 

[GiantYukon]

Can I ask why you went for the SVMC7280? Based on Aliexpress the 72150 is only like an extra £20? Anyway I think you may need more voltage. I tried to run my 72150 on (12s) and it started current limiting big time. 18s is where the fun starts. I'm in the process of going to the full 72 (20s).

I went the 7280 because, I'm never likely to be able to put more than 80amps through any hub that I can fit on my mountain bike.
And I didnt want the controller to be too big, I havn't actually checked but I'm sure the 150 has more size.

I wouldnt mind going 72v, but I havn't really seen many aus sellers, and the ones I have seen start at $1500.
Thats why I thought my best option for acceleration would be to get an entry level sabvoton, keep it at 52v and throw some more amps at it.
But its turning out I can't even make it throw as many amps in as I want it too.

Funny thing on my ride last night, I noticed once I got over 50kmph at full throttle while hitting some resistance, head wind or slight hill, a few times it did throw in a few more amps, I saw the wattage go up to 2200-2300.
Id love to be able to get extra amps on early acceleration rather than at the top end.

 

[GiantYukon]

I'll mention too just in case anyone else has got some experience with it.
The pedal assist has been quite strange, it does all kinds of surging and cutting out when first coming on, especially when on 5 sometimes I'd just have to stop pedaling and then start again and it would be smooth like it should, and if I've got it on pedal assist 1 and I go much faster than the limited speed for that level of pedal assist , I've noticed what seems like engine braking! and the wattage on my screen went up to nearly 200w while not pedaling. I've got regen turned off, so I'm not sure why anything like that would happen.

 

[amberwolf]

Id love to be able to get extra amps on early acceleration rather than at the top end.

As noted before, you'll only see the amps that your system is actually able to draw because of the load on the system.

If the load on the system isn't high enough to draw more amps, it doesn't matter if your controller can supply and is set to send it a million amps, it will still only draw what it draws under that physical load, for that voltage on the system (including any voltage sag), for those components of the system (motor winding, gearing ratio between motor and road, etc).


It may not make any difference to have a higher amp controller, or higher amp settings, if your battery cant' handle the current because it is sagging in voltage enough to cancel out the higher amps (making the same watts but beating up the battery by doing it).

Same if your motor winding and gearing to road vs the physical load placed on it doesn't need more current to do that.


If you have a steep enough hill that is long enough, you can try riding up that at full throttle, and it will show you the max power draw you can achieve with your present system, settings, etc., by forcing the load on the system to be high enough to draw the max power (which you may not be doing under your existing test circumstances).



You can see how this works by setting up various systems in the https://ebikes.ca/tools/simulator.html and placing them under various loads.

 

[GiantYukon]

Id love to be able to get extra amps on early acceleration rather than at the top end.

As noted before, you'll only see the amps that your system is actually able to draw because of the load on the system.

If the load on the system isn't high enough to draw more amps, it doesn't matter if your controller can supply and is set to send it a million amps, it will still only draw what it draws under that physical load, for that voltage on the system (including any voltage sag), for those components of the system (motor winding, gearing ratio between motor and road, etc).


It may not make any difference to have a higher amp controller, or higher amp settings, if your battery cant' handle the current because it is sagging in voltage enough to cancel out the higher amps (making the same watts but beating up the battery by doing it).

Same if your motor winding and gearing to road vs the physical load placed on it doesn't need more current to do that.


If you have a steep enough hill that is long enough, you can try riding up that at full throttle, and it will show you the max power draw you can achieve with your present system, settings, etc., by forcing the load on the system to be high enough to draw the max power (which you may not be doing under your existing test circumstances).


You can see how this works by setting up various systems in the http://ebikes.ca/simulator and placing them under various loads.

Yes, feels like you are right, since I managed to get it to throw in more amps while it was nearing top speed and hitting resistance. Although I have been up some steep hills that slowed my speed down, watts never went over 2100, the only time it goes over is when I'm going over 50kmph.
Would a better hub draw more amps? The hub I'm using is a 1500w voilamart. I've read the csc 1500w hub is better built.

To be honest I thought the whole system was a bit dumber than this, I really thought that if a controller put out more amps those amps go to the hub no matter what the hub wanted or could handle and that would result in a power increase until something popped or got too hot.

Thanks for taking the time to help!

 

[amberwolf]

If it only draws a certain amount of power even up a steep hill, and maintains that power, then that means it only takes that much power to go up that hill. If you have a steeper hill you could see if it takes more power, or use higher speed on that same steep hill. Either of those would take more power.

If no more power is drawn, then the system isn't capable, for whatever reason, of supplying more power to the motor. That can be voltage sag, so that volts x amps = watts is a lower number despite amps being set higher (and in this case, higher amps will usually make the problem worse, and begin harming the battery). Or it can be the controller not providing more amps, either because of physical limitations or because of settings. (sometimes a controller might allow higher settings than it can physically do, but then just still limit to whatever it's hard-coded safety limit is).


But since you are slowing down as you go up the steep hill, then you are probably hitting the limit of what the controller and battery are supplying the motor. If you watch the battery voltage under the varying load, you can note down the voltage you see at max power, vs that you see at lower power levels, and post that up here.

If the battery sags too much, power drops, and the motor has less to work with.

A motor, regardless of ratings, will draw as much power as the system will provide, if the load on hte motor is high enough. That's what causes motor meltdowns.

If the load isn't high enough, the motor won't draw any more power than the load takes to overcome, regardless of what the system is capable of providing.

A bigger motor is usually needed when the existing one overheats under the load it sees. If it's not doing that, a bigger motor won't help, unless you also use a bigger controller and battery.


The simulator at https://ebikes.ca/tools/simulator.html can show you how this works, with reading of the instructions and some experimentation.


If it is a limitation of your controller's settings, I don't know how to get past that. It's even possible that the version of setup software you have isn't fully compatible with your controller...and I don't know which version would then be fully compatible, either. :/

 

[GiantYukon]

Under load I havn't seen it drop more than 2v.
I've had an idea though, I think I'm going to play with wheel sizes in the display settings and see if that will trick it into putting out more power. The only time I've seen it put in more amps is when I've been over 50, so I wonder if changing the wheel size will change the output. I may try the magnet pairs too, when the controller came it was on 16 pairs and my speed was reading alot faster. I might put it back to 16 and see if the power changes.

 

[Audisport09]

Ok fair enough, yes it's a bit bigger. My theory still is that Sabvotons don't like low voltages. Even though they state 48-72v, I feel this is a marketing game to get more customers. It's really a 72v controller. You need to run it as close to that as possible or it will current limit. You will accurate and climb faster I'm sure of it. Do you not have any e-friends with higher battery system to test with or Buy a 6s lipo and serie it with your current battery to test.

 

[GiantYukon]

Ok fair enough, yes it's a bit bigger. My theory still is that Sabvotons don't like low voltages. Even though they state 48-72v, I feel this is a marketing game to get more customers. It's really a 72v controller. You need to run it as close to that as possible or it will current limit. You will accurate and climb faster I'm sure of it. Do you not have any e-friends with higher battery system to test with or Buy a 6s lipo and serie it with your current battery to test.

My cousin has the same battery as me, with csc 1500w hub and 45a KT controller, so I might actually try and organise a ride, have a little race and see what kind of power difference there is, I'm 100% sure its faster now than when I was using that same KT controller, I just think the wattage isn't reflecting it. I'm still yet to play with the wheel sizes to see if that makes a change in the wattage.

I'm a bit of a chicken when it comes to lipos, I've heard stories of peoples houses burning down.
It would be nice to get my hands on a 72v battery, I think there is something in it for sure about Sabs not really being designed for 48v.

 

[GiantYukon]

I can confirm changing wheel size makes no difference. Was a long shot, this controller is smarter than I thought!

I can also confirm I was wrong about voltage drop, with a full battery going full throttle it drops about 4 volts. So I guess thats not great, but I hope thats not enough to stop pulling more amps.

 

[E-HP]

The battery is a 17.5ah 40a constant, Samsung 35E cells.

You need more battery. 5P of 35E cells isn't enough, and I probably wouldn't trust a battery manufacturer that would use a 40A BMS for that configuration.

 

[GiantYukon]

The battery is a 17.5ah 40a constant, Samsung 35E cells.

You need more battery. 5P of 35E cells isn't enough, and I probably wouldn't trust a battery manufacturer that would use a 40A BMS for that configuration.

Thanks for that!
This is the battery
https://caprouge.com.au/collections/52-volt/products/cppolf52-17-5-52-volt-17-5-ah-40a-ds-6-battery-samsung-35e-cells.

Would this battery be better suited?
https://caprouge.com.au/collections/52-volt/products/cptr52-19-2-52v-19-2ah-90a-panasonic-cells-triangle-battery

I spoke to them today and they are making a 72v 50ah, 60a battery soon. Not sure something that big would even fit on my bike, They say their costing would be $1600 for that.

The first battery has worked perfectly at 45a for 200kms without ever getting warm, but now with the Sabvoton I can't even pull 45a. I hear what your saying, but the fact that I had it doing more amps before with no issue makes me wonder. It has never tripped out, or gotten warm. I wonder if I turned up the amps to 80, if I can make more power or trigger the bms.

 

[E-HP]

As the cells age, both the energy capacity and the discharge capacity drops. The pack may work, while the batteries can provide 40A, but the BMS won't be doing anything to protect the batteries when they can no longer produce 40A continuous, degrading the batteries further.
EM3EV uses a more conservative approach, so their 14S5P pack of 35E has a BMS of 25A continuous. I decided on 40A continuous on my 8P pack, following the same conservative ratings. 90A from a 6S pack seems sort of crazy, even with Panasonic cells.

https://em3ev.com/shop/em3ev-52v-14s5p-jumbo-shark-ebike-battery/

 

[GiantYukon]

As the cells age, both the energy capacity and the discharge capacity drops. The pack may work, while the batteries can provide 40A, but the BMS won't be doing anything to protect the batteries when they can no longer produce 40A continuous, degrading the batteries further.
EM3EV uses a more conservative approach, so their 14S5P pack of 35E has a BMS of 25A continuous. I decided on 40A continuous on my 8P pack, following the same conservative ratings. 90A from a 6S pack seems sort of crazy, even with Panasonic cells.

https://em3ev.com/shop/em3ev-52v-14s5p-jumbo-shark-ebike-battery/

Its a new battery pack, I've only had it a month or more, but who knows how old the cells actually are, they do say the test all the cells to a certain standard.
I do have another 52v 14ah pack, which was much more expensive, but only has a 20a constant on it. I guess they have taken the conservative approach.
So it seems the battery really might be the limiting factor here.
If only there were more trusted suppliers in Australia....and reasonably priced

 

[amberwolf]

The first battery has worked perfectly at 45a for 200kms without ever getting warm, but now with the Sabvoton I can't even pull 45a.

Are you measuring the amps exactly the same way, with the same equipment, in both cases?

If not, then there's no direct way to compare the readings, especially if the readings are from the controllers themselves.

If the problem is caused by the battery being unable to support the current draw, then I suspect your previous controller wasn't really drawing 45A either. But you'd have to measure the same way with each controller to find out.

 

[GiantYukon]

The first battery has worked perfectly at 45a for 200kms without ever getting warm, but now with the Sabvoton I can't even pull 45a.

Are you measuring the amps exactly the same way, with the same equipment, in both cases?

If not, then there's no direct way to compare the readings, especially if the readings are from the controllers themselves.

If the problem is caused by the battery being unable to support the current draw, then I suspect your previous controller wasn't really drawing 45A either. But you'd have to measure the same way with each controller to find out.

Yes you are right, it needs to be measured in the same way.
I have a clamp on volt meter, but I'm not sure how I'm going to rig it up to be able to see the screen while I'm full throttle and not crash while I'm trying to look.
I contacted the supplier and they said because its a 1500w motor, that the motor is restricting the controller.
Unless its a super smart controller and it somehow knows its only 1500w, I can't see how thats possible, I'm sure it should just send what its programmed to, and melt the hub when it gets too hot or trip the bms when too many amps are going out.
I'm leaning more towards it being a battery thing, but I just dont know anymore.
I just want more power without having to fork out for 72v.

 

[amberwolf]

I have a clamp on volt meter, but I'm not sure how I'm going to rig it up to be able to see the screen while I'm full throttle and not crash while I'm trying to look.

The only way I can think of would be to extend the battery to controller wires up to the handlebars, and that's usually impractical for various reasons (including excess inductance and resistance that can cause controller issues).

If you have or can get a basic wattmeter with remote shunt ($20-$200 depending on capabilities needed), you can do a lot of troubleshooting not easily possible without one.

I contacted the supplier and they said because its a 1500w motor, that the motor is restricting the controller.
Unless its a super smart controller and it somehow knows its only 1500w, I can't see how thats possible, I'm sure it should just send what its programmed to, and melt the hub when it gets too hot or trip the bms when too many amps are going out.

Controllers' don't "send" power. They supply what is demanded by the load, within their capabilities and settings. If the load isn't high enough, then the controller won't supply any more than the load demands.

So the supplier is *sort of* correct, though it is not likely the motor restricting the controller, but rather the usage scenario.

If you're willing to take the time to learn how the simulator previously linked works, and play with various scenarios and setups in it, you will begin to see how this all works out.

I'm leaning more towards it being a battery thing, but I just dont know anymore.

A battery problem would show significant voltage sag under a load that is too high for it, or else so much sag that the BMS actually shuts off the output. A battery can't directly limit the amount of current a system uses--that's what the controller does.

I just want more power without having to fork out for 72v.

Generally, higher voltage gives higher speed, rather than higher power directly--but it can certainly give higher startup torque (acceleration) *if* the controller + motor combination with that higher voltage causes higher phase currents than the lower voltage did.

 

[GiantYukon]

I have a clamp on volt meter, but I'm not sure how I'm going to rig it up to be able to see the screen while I'm full throttle and not crash while I'm trying to look.

The only way I can think of would be to extend the battery to controller wires up to the handlebars, and that's usually impractical for various reasons (including excess inductance and resistance that can cause controller issues).

If you have or can get a basic wattmeter with remote shunt ($20-$200 depending on capabilities needed), you can do a lot of troubleshooting not easily possible without one.

I contacted the supplier and they said because its a 1500w motor, that the motor is restricting the controller.
Unless its a super smart controller and it somehow knows its only 1500w, I can't see how thats possible, I'm sure it should just send what its programmed to, and melt the hub when it gets too hot or trip the bms when too many amps are going out.

Controllers' don't "send" power. They supply what is demanded by the load, within their capabilities and settings. If the load isn't high enough, then the controller won't supply any more than the load demands.

So the supplier is *sort of* correct, though it is not likely the motor restricting the controller, but rather the usage scenario.

If you're willing to take the time to learn how the simulator previously linked works, and play with various scenarios and setups in it, you will begin to see how this all works out.

I'm leaning more towards it being a battery thing, but I just dont know anymore.

A battery problem would show significant voltage sag under a load that is too high for it, or else so much sag that the BMS actually shuts off the output. A battery can't directly limit the amount of current a system uses--that's what the controller does.

I just want more power without having to fork out for 72v.

Generally, higher voltage gives higher speed, rather than higher power directly--but it can certainly give higher startup torque (acceleration) *if* the controller + motor combination with that higher voltage causes higher phase currents than the lower voltage did.

I'm not really all that keen on more top speed, thats why I went down the 52v route with the hope of throwing in more amps.
I'm really starting to think its the battery now, just went for another test ride and it dropped 5/6v on full throttle.
Maybe I can get more power from a 52v battery, just not with this battery.

 

[amberwolf]

I'm not really all that keen on more top speed, thats why I went down the 52v route with the hope of throwing in more amps.

If under the same conditions you were previously always maxing out the amps on the old controller, then a new controller capable of and setup for higher amps would then be able to provide more power, as long as the battery can also supply the higher amps without sagging in voltage more than it did under the lower amps (more voltage sag means less watts).

I'm really starting to think its the battery now, just went for another test ride and it dropped 5/6v on full throttle.

How much voltage sag was there under the same conditions with the old controller? If it was significantly less, then the amps demanded by the old controller were also probably significantly less. If it was the same, the amps were probably the same, too.

Maybe I can get more power from a 52v battery, just not with this battery.

If you have another battery that is the same chemistry and same number of series cells, then you can fully charge both of them, verify their voltages are the same at that point, and then connect them in parallel, to get higher amp capability with less voltage sag. The better each battery is, the more amps that will be.

The other option is to completely replace the present battery with a bigger / more capable one, if voltage sag under load is the problem.

 

[GiantYukon]

I'm not really all that keen on more top speed, thats why I went down the 52v route with the hope of throwing in more amps.

If under the same conditions you were previously always maxing out the amps on the old controller, then a new controller capable of and setup for higher amps would then be able to provide more power, as long as the battery can also supply the higher amps without sagging in voltage more than it did under the lower amps (more voltage sag means less watts).

I'm really starting to think its the battery now, just went for another test ride and it dropped 5/6v on full throttle.

How much voltage sag was there under the same conditions with the old controller? If it was significantly less, then the amps demanded by the old controller were also probably significantly less. If it was the same, the amps were probably the same, too.

Maybe I can get more power from a 52v battery, just not with this battery.

If you have another battery that is the same chemistry and same number of series cells, then you can fully charge both of them, verify their voltages are the same at that point, and then connect them in parallel, to get higher amp capability with less voltage sag. The better each battery is, the more amps that will be.

The other option is to completely replace the present battery with a bigger / more capable one, if voltage sag under load is the problem.

I know the with the previous controller it did sag, but I wasn't paying close enough attention at the time to know exactly how much.
I spoke with the battery supplier and they say their bms limits bursts above 40a to 3 seconds and then will only put out 40a. Which turns out to be exactly 2100w at 52v. So I guess with all you guys are saying and what the battery supplier says, makes it pretty conclusive.
I really just need a battery that has a higher constant output and more in parallel to lessen any sag.
What do you think of this? Wouldn't run 90a...doubt I'd go over 60, I dont think my hub could handle it.
https://caprouge.com.au/collections/52-volt/products/cptr52-19-2-52v-19-2ah-90a-panasonic-cells-triangle-battery

 

[E-HP]

I went the 7280 because, I'm never likely to be able to put more than 80amps through any hub that I can fit on my mountain bike.
And I didnt want the controller to be too big, I havn't actually checked but I'm sure the 150 has more size.

I wouldnt mind going 72v, but I havn't really seen many aus sellers, and the ones I have seen start at $1500.
Thats why I thought my best option for acceleration would be to get an entry level sabvoton, keep it at 52v and throw some more amps at it.

I think you should play with the simulator as suggested. I was in a similar place, with similar goals, which is more acceleration but with moderate speed expectations. I experimented with various voltages and current limits, and played with the simulator before and after to "see" the effects I was feeling/observing. My main goal was to have good acceleration all the way from stop to my speed expectation, which was around 25mph.

My conclusion after all of that is that to build a bike that accelerates hard to a target speed of 25 mph, you have to build a bike that will go about 30% faster. This is due to how the torque curve peters out as it approaches top speed. It drops off so significantly that the last few mph of acceleration is at a snail pace, at least by the seat of the pant measurement.

Here's a few examples. It's easiest to view, if you turn off the power, efficiency, and load lines by toggling them off at the top of the graph.

This is what it looks like if you stay at 52V, but double the current:
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=B5220_GA&cont=cust_40_80_0.03_V&hp=0&axis=mph&cont_b=cust_80_160_0.03_V&motor_b=Leaf%205T&batt_b=B5220_GA&hp_b=0&bopen=true
Better torque and acceleration off the line, but then by the time you are near target speed, it peters out like the lower amp scenario.

Same current, double the voltage:
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=B5220_GA&cont=cust_40_80_0.03_V&hp=0&axis=mph&cont_b=cust_40_80_0.03_V&motor_b=Leaf%205T&batt_b=cust_104_0.2_20&hp_b=0&bopen=true
Same initial starting torque, but the curve stays flat (maximum acceleration) almost up to the target speed, and even when the curve drops off, you still have twice the torque when reaching the target speed. 104V is pretty extreme though.

Raise the current and voltage (to a reasonable level):
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=B5220_GA&cont=cust_40_80_0.03_V&hp=0&axis=mph&cont_b=cust_80_160_0.03_V&motor_b=Leaf%205T&batt_b=B7223_AC&hp_b=0&bopen=true
This is more or less where I landed. Huge torque gain throughout the band, up to and past the target speed. I set my controller's three position switch to low, which limits the speed and continuous current, but still allows a lot of peak current to flow, so acceleration stays strong. I switch to middle speed if I want to hotrod around, but 99% of the time I stay in low, even on steep climbs, so it's where I want it now.

Here's possibly the scenario that your vendor is talking about. At some point, the motor won't take more current, because it's reached saturation. So even doubling the available amps won't increase the current draw of the motor (curves are idential)
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=B5220_GA&cont=cust_200_400_0.03_V&hp=0&axis=mph&cont_b=cust_400_800_0.03_V&motor_b=Leaf%205T&batt_b=B5220_GA&hp_b=0&bopen=true

Don't forget to turn off the power, efficiency, and load lines so you can more easily compare the torque lines.

The bottom line is you need more battery, and you can decide after playing with the simulator if you need more voltage. The simulator assumes that your battery can supply whatever current the controller parameters are set to.

 

[GiantYukon]

I went the 7280 because, I'm never likely to be able to put more than 80amps through any hub that I can fit on my mountain bike.
And I didnt want the controller to be too big, I havn't actually checked but I'm sure the 150 has more size.

I wouldnt mind going 72v, but I havn't really seen many aus sellers, and the ones I have seen start at $1500.
Thats why I thought my best option for acceleration would be to get an entry level sabvoton, keep it at 52v and throw some more amps at it.

I think you should play with the simulator as suggested. I was in a similar place, with similar goals, which is more acceleration but with moderate speed expectations. I experimented with various voltages and current limits, and played with the simulator before and after to "see" the effects I was feeling/observing. My main goal was to have good acceleration all the way from stop to my speed expectation, which was around 25mph.

My conclusion after all of that is that to build a bike that accelerates hard to a target speed of 25 mph, you have to build a bike that will go about 30% faster. This is due to how the torque curve peters out as it approaches top speed. It drops off so significantly that the last few mph of acceleration is at a snail pace, at least by the seat of the pant measurement.

Here's a few examples. It's easiest to view, if you turn off the power, efficiency, and load lines by toggling them off at the top of the graph.

This is what it looks like if you stay at 52V, but double the current:
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=B5220_GA&cont=cust_40_80_0.03_V&hp=0&axis=mph&cont_b=cust_80_160_0.03_V&motor_b=Leaf%205T&batt_b=B5220_GA&hp_b=0&bopen=true
Better torque and acceleration off the line, but then by the time you are near target speed, it peters out like the lower amp scenario.

Same current, double the voltage:
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=B5220_GA&cont=cust_40_80_0.03_V&hp=0&axis=mph&cont_b=cust_40_80_0.03_V&motor_b=Leaf%205T&batt_b=cust_104_0.2_20&hp_b=0&bopen=true
Same initial starting torque, but the curve stays flat (maximum acceleration) almost up to the target speed, and even when the curve drops off, you still have twice the torque when reaching the target speed. 104V is pretty extreme though.

Raise the current and voltage (to a reasonable level):
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=B5220_GA&cont=cust_40_80_0.03_V&hp=0&axis=mph&cont_b=cust_80_160_0.03_V&motor_b=Leaf%205T&batt_b=B7223_AC&hp_b=0&bopen=true
This is more or less where I landed. Huge torque gain throughout the band, up to and past the target speed. I set my controller's three position switch to low, which limits the speed and continuous current, but still allows a lot of peak current to flow, so acceleration stays strong. I switch to middle speed if I want to hotrod around, but 99% of the time I stay in low, even on steep climbs, so it's where I want it now.

Here's possibly the scenario that your vendor is talking about. At some point, the motor won't take more current, because it's reached saturation. So even doubling the available amps won't increase the current draw of the motor (curves are idential)
https://ebikes.ca/tools/simulator.html?motor=Leaf%205T&batt=B5220_GA&cont=cust_200_400_0.03_V&hp=0&axis=mph&cont_b=cust_400_800_0.03_V&motor_b=Leaf%205T&batt_b=B5220_GA&hp_b=0&bopen=true

Don't forget to turn off the power, efficiency, and load lines so you can more easily compare the torque lines.

The bottom line is you need more battery, and you can decide after playing with the simulator if you need more voltage. The simulator assumes that your battery can supply whatever current the controller parameters are set to.

Thanks for that! That all makes sense! amps take care of wind and weight and hill resistance to a certain point but as it gets to top speed it slows no matter what.
But when you increase the top speed with volts you accelerate harder for longer to get to your "previous" top speed faster.
I found a guy in my city that builds batteries, so I'm going to have a chat with him about what he can build for how much, depending on how that goes for 72v, I might just go the 90a 52v......after I sell a battery or two.