Need advices for e-Scooter upgrade!

[Edward312]

This is my first post in ES and pardon me for my English!
I have been reading and searching for months before I decided to make this post since I had no knowledge about EV.
So I bought this E-Scooter (From EMMO). Here are some specs:
72v32Ah-Lead Acid.
500watts motor. ( I think it's actually 1500-2000watts from QS motor, they mark it 500w since the E-bikes' laws in Ontario only allow >500w)
Chinese controller rated for 42v-72v (100v caps and mosfets) max Amps draw 50A.
Wheels size 120/70-12.
Weight : 220-240lbs
The torque is decent, I can pretty much catch up with traffic.
Top speed on fully charged(80-82v) is 50-54kph (30mph).
I have recently ordered a Yuyang king controller rated for 72v, 80a.
https://www.aliexpress.com/item/329...chweb0_0,searchweb201602_2,searchweb201603_55
With the hope to get better torque by pumping more current (50a stock to 80a) and achieve higher top speed with the new controller field weakening.
So I need some advices on what should I do to get better performance on this scooter, I'm not quite sure that the new controller can bring me to 60kph with the same battery so I have planned on adding a pack of 12-17v 18650 in series with the lead acid and charge them separately.

This is my sketch on my plan. the switch is original from the scooter, a kill switch. is this set up gonna work?
Also I plan on to change the motor wounding from star to delta. I'm not planning on making a switch since it's too complicated and all I want is more top end speed, I just wanna know if it's worth it? from wye to delta. And what else can I do to improve speed without changing the stock motor out?
I appreciate every comment, thank you very much.

 

[John in CR]

The weight and voltage sag is what is limiting performance. You're talking about adding too much voltage in series. You're correct that more voltage is what you need for more speed, but you have to be careful about the fresh off the charger voltage being too high. Talk with YYK to find out what is the absolute maximum fresh off the charger voltage for that controller, since it may programmed to not even function above a certain voltage. Hopefully you ordered it with the Bluetooth unit so you can change controller settings.

Your long-term plan should include getting rid of the lead pack. Not only is it heavy for the stated capacity, but that capacity is very misleading in our use due to Pukert's Effect. Lead is rated at a 20hr discharge rate, so at about 1.5A current draw. When you draw current faster is has much less energy to deliver. Add in that if you run them down below about a 20% SOC (State Of Charge), lead batteries rapidly deteriorate. That means a lead pack with 34ah is comparable to a lithium pack of less than 20ah and about 1/4th the weight. Once you switch to lithium you'll be glad you did, and your bike will feel and perform very differently.

 

[Edward312]

Thank you so much John.
And yes I did order with bluetooth and I have seen someone running this same controller up to 110v but I’ll keep it under 100v full charged. I’m planning on building a 72v lithium pack next summer when I can test it out ( it’s hella cold here). So after I swap out my controller. Do you think there will be any better in top speed?
Edit: with 72v lithium I’ll see better speed and performance? Is that right?

 

[John in CR]

Sorry I didn't check the link you provided for the controller the first time around. It looks like you got the higher voltage controller, so you should be fine in terms of voltage, so your plan for adding the pack in series may work fine. I hope you do understand the special charging needs of that arrangement. ie 2 separate chargers. Once you get it going, note how much voltage sags down under maximum load (hard acceleration or up a steep hill), which will give you an idea of much the lead batts are hurting your performance. To give you an idea for comparison, my 24s pack of Chevy Volt modules sags less than 3V under a max load of 250A from the battery. If you have no way of seeing voltage while under load, you could easily find out by increasing the low voltage cutoff setting until the controller cuts out when you give it full throttle. The difference between that LVC and the at rest pack voltage shown by the phone app is your voltage sag.

Note that the mosfets used in the higher voltage models make about double the heat per amp compared to those with the lower voltage, so you could run into heat issues depending on the controller mounting position and how high you turn up the settings. The part needing the best air flow is the top face with the 5 bolts in a straight line, which secure the heat spreader block of aluminum to the inside of the controller shell.

 

[Edward312]

That’s brilliant, I have never thought of using LVC.
I’ll mount the controller on a bracket next to the seat. Thank you so much for your replies. Will work on it soon!