4000w model from Mountain Chen?

We have rewired the 3000w and improved only from 40 mph to 42mph. So we dove into our Liberty EM3500 (made by Mountain Chen) and took 4 cells from another EM3500 to increase by 12 volts our 3500. We increased the speed slightly. Our 240lb. technician went from 37mph to 43mph. I who weigh 180 only went up to 44 mph even after boosting it to 23 packs.

We really want to get to 60mph...what we were told it could go... we we feel that even if we try 84 volts, we won't get there, as there is just not any ability to get there.

we tried the upgrade to 72v on our 3000w, same as yours, but ES3000 from Liberty. We got up to 43mph. We took the EM3500 (made by Mountain chen also) and added 4 more cells of Li and increase the speed slightly at 72v. We are trying to get to what is not a hazard to other traffic at 60mph, as we were told. we are wondering if it is really possible with hub motor.

A lot of people speculate that if a hub motor goes highway speeds the magnets will be subject to tremendous stress, particularly while turning. This is why the Vectrix didn't go with a hub motor.

On the other hand, we know the XM-3000 reaches low highway speed with the 72V mod. If RPMs could be held constant, with a larger diameter tire, each round would cover more distance. You just need to bring in more amps to compensate for the increased torque demand. The next problem you have is heat. Some people have put cooling fins on the wheel at the expense of some drag. So if you ask me, a hub motor should be able to go quite fast. I know a few teams working on cars that use hub motors for their highway capable EVs.

We have rewired the 3000w and improved only from 40 mph to 42mph. So we dove into our Liberty EM3500 (made by Mountain Chen) and took 4 cells from another EM3500 to increase by 12 volts our 3500. We increased the speed slightly. Our 240lb. technician went from 37mph to 43mph. I who weigh 180 only went up to 44 mph even after boosting it to 23 packs.

We really want to get to 60mph...what we were told it could go... we we feel that even if we try 84 volts, we won't get there, as there is just not any ability to get there.

Kurt,my charger is limited for 20cell LFP and you can only charge up to 69V even with 24cell LFP,so that voltage and speed is the same even you add it to be 24cell LFP.

Contrary,the controller low voltage protection is only 52V, 52V/24=2.16V,this way would damage your LFP battery very soon.Pls stop modify my scooter. Be patient and we will upgrade 24cell LFP with related controller and DC converter next year.

Mountain,

Nice to hear from you...
Sure we know this, so we do the following:
1. OUr tests are a mile or less so we never get close to low voltage
2. we always check voltage of each cell after our tests and never low
3. We place the cells back in the other 3500 to recharge.

Obviously, this takes time for our staff, but since we were told they were 60mph and our tests show they are 40-42 mph, we are working on developing something truly 60mph . We are getting our next 40' container of 3500 this week and we are only seeing if we can bring our samples up to speed. So we are trying to see if we really can work with your 3500 or if we must work on developing something else. I may see you in a few weeks, when I visit again.

Kurt

If you want one that goes close to 60 MPH, these guys have one. They run a 6 phase motor with Lithium batteries.

http://www.rmartinbikes.com./evd-electric-motorcycle.html

If you want one that goes close to 60 MPH, these guys have one

Be really careful when you write something like this. Are you driving this bike now and is 60mph your experience personally? Even RMartin admits the 60mph was "on a slight decline". My XB-600 will go 60mph down the right hill (welcome to colorful Colorado).

I would have said "If you want one that claims to go close to 60 MPH, these guys have one."

we are wondering if it is really possible with hub motor.

Kurt - the answer of course is it depends on the hub motor. Basically the bikes coming out of the two factories (EFun & ERider) come in both high torque or high speed form. ERider has opted for high torque (good accel, better hill climbing) whereas EFun has opted for high speed (better top speed). They both have access to the other motors (note that the RMartin website talks about the higher-torque in the EFun VRLA version and I've seen discussion about a similar situation for ERider).

In your experiments with your 3500 you might want to replace the controller as well as upping the volts. Or at least measure the amps being consumed and see if they're being limited by using the same controller.

Or, you can do as the manufacturer says, just wait for him to address it.

I'm going to start another thread on speed vs. torque.