XM-3500Li Performance

It really is a shame that a lot of the scooter manufacturers put lousy speedometers in the bikes. I don't own and XM3500 but I own an trike manufactured by EVT.

I have taken the trike past a "your speed is" display and gotten a reading from it after several passes and I have found my speedometer to be about 16% fast.

When the speedometer was reading about 26MPH the sign indicated 22MPH.
When the speedometer was reading about 38MPH the sign indicated 32MPH.

It's a shame since a good speedometer can be gotten at most inexpensive stores for about $20-$30. This doesn't seem like a big adder considering the costs of these bikes.

GPS is plenty accurate enough for this purpose. There's no way Garmin puts out a product that's 30% off...

Yea, the GPS is going to be accurate to a fraction of a MPH, no question about that. While the absolute position error from GPS is usually in the range of 15-20', the change in error over time is extremely small, so measuring the delta position/time is extremely accurate.

But Ross' posts mention both a GPS and Dynolicious, so he should have been able to get a reading that was pretty accurate. I'm suspicious that you both took accurate readings, but your bikes aren't behaving the same. Can we get a 3rd measurement from yet another bike?

Ok, let me re-phrase: I'm hoping that it's a problem with just one bike, rather than a problem with the design. I've got a short commute with fast traffic, so top speed is more important to me than range. After waiting all this time I'm reluctant to cancel my order, but I'm afraid I wont be satisfied if John's measurement is representative of what I'll be getting.

I do not have a GPS or iphone but have riden a bit and had my wife follow me. As far as I can tell the speedometer follows the "50% of KPH = MPH". I have had it up to 100KPH indicated and I was just pulling ahead of traffic in a 45MPH zone (this speed was on a flat with no wind; please make a note by ducking down and lowering the wind drag makes a difference). I have also found going out with a fully topped off charge seems to give a little more top end, but the cells drop off quick to their plateau voltage of 3.4-3.3V and then the speed remains consistent.

I am thinking of adding one cell and then set my BMS for 3.45V per cell and using the existing charger. Then I will have 5% more "main plateau" stack volatge to draw from and this might get me the slight improvement I want. After that I might take the charger apart and figure how to tweak the upper voltage cutoff limit up so it runs the cells to ~3.5-3.6V.

P.S. If I remember the 4000W design of this scooter Mountain Chen is doing uses 21 cells and the same motor; wonder if this is a coincidence? :?

I would like to hear from Mountain Chen his thoughts on all of this please. Thanks.

Also, does anyone know what the 3500 does to limit its top end? I have measured the voltage the throttle puts out to the controller and found the motor RPM stops increasing before the throttle output voltage stops, so something beyond the throttle control is doing this.

Also, it might be there is a variation bike-bike on this and it would help to know how it is done and if it can be tweaked.

P.S. The throttle is using a ratiometric hall sensor and the speed limiter switch changes the input voltage to this device. I thought maybe you could increase the voltage out of the throttle to get more top end but it appears the top-end stops while the throttle output is still putting out more beyond about 3.2V (it continues putting out to 3.7V but the motor does not go any faster after 3.2V, so increasing the input voltage to the hall sensor will not do anything). The "off voltage" out of the throttle is ~0.8V and the motor does not start to spin until ~1.2V, so the range is 1.2-3.2V from stop to top-end (this is all no-load rpm with the bike up on its stand). If the motor controller responded all the way to 3.7V, this would be an increase of 25% in no-load RPM and would be great! Even if this was a "loaded rpm" increase of 10% that would put it near where I think it should be (and I will take the resulting loss in range since I can still get good range running slower) but I want about 10% more top-end speed/torque.

For the actual top speed, does it matter if the rider is not 5'2"@90#? How can the speedometer be that far off?! 30%? Something's amiss.

For Chen: http://www.mr2ownersclub.com/converter.htm

This has been going on for a long time...

For some history lessons go to this yahoo!group: http://groups.yahoo.com/group/EVespaCloneClub

Back in 2002-3 we were making the same complaints just the manufacturer names differed. Some found that certain brands of bicycle computer could be programmed with a small enough wheel size for the 10" wheels common on these scooters. But FWIW I never did that on my EVT 4000.

That is some rough news, but 42 may still at least be workable for me. One thing we haven't accounted for in differences in speed, though, is the added weight on the bikes and the heights of the drivers. (I'm assuming, here, that a comfortable, somewhat upright, riding position is the norm during these measurements.) Once mine gets in I may see if I can rig up one of those bicycle speedometers and see how that does for me. If nothing else it may give me a more permanent and accurate reading of speed.

Still, what other options do we have here that might increase top speed? The blurb on the scooter suggests that top speed was limited down to 55 to increase range. Can we remove the limiter somehow? (Presumably that would void the warranty but it may be worth it to do for some of us.) What about changing out for a different tire size? What about adding batteries? (And how could that safely be accomplished for those of us who are not electronics experts, capable maybe, but not expert by any means.)

I saw a blurb at http://www.scootersupport.com/performance#TURBO (I think maybe John actually pointed out that link a while back) for making some kind of circuit to boost performance. I think i would need to see the thing on an actual green board or something before having any chance of making it, and I'm not positive if it would work for this care or not anyway, but maybe someone with some skill at such things could take a look and see if it applies?

a) I'll do another odo test - my guess is my first report is wrong (sorry about that). I agree with you that it would be strange to have such a large difference between odo and speedo.
b) I borrowed a cell from the E-FunD - they both use TS 40Ah LiFePO4's. I should be getting my replacement cell in a week or so - they're expected in on September 15th.

Note that "real speed is approximately equal to KPH divided by two" would mean that my indicated 55mph is 88kph which would equate to 44mph. My measured top speed was 42mph. To me that's actually consistent because 44mph is approximately equal to 42mph to the casual observer of the speedo in the car and the speedo on the bike. Furthermore 55mph indicated / 44mph actual would give a 25% overstatement. 25% isn't that much different than 31% when you take into account one is more subjective and the other is measured.

But, hey, I still hope I'm wrong! But no one has convinced me yet.

I just ordered a Topeak Panoram V12 12 Function Cycle Computer, which will be the wheel-mounted magnet kind, so once that and the scoot arrive I'll see if I can post some findings using that. I'm sorely tempted to buy the Garmin Zumo 450 Portable GPS Motorcycle Navigator and see how that matches up as well. Maybe next month I'll buy that, but I'll let folks know if I do.

Here are the results of the speedometer test I just did. The speedometer read 80 kph, GPS read 39.7 mph. The 60 kph and 40 kph had the same ratios. Remember I am using 19 batteries (one is bad), so 80 kph is the maximum. Here is what I did. I drove my 1995 Escort on a known flat, straight road and used the VZ Navigator Version 4.1.0 Build 60 (from Verizon) to get the GPS readings. The GPS matched the Escort's speedometer within 0.3 mile an hour (as far as I can tell, the speedometer is analog and the GPS is digital to the 10ths). When I have driven past the "speed trap" units, the speeds always matched. (e.g. unit indicates 40 mph, the Escort's speedometer indicates 40 mph, 60 is 60, etc.)

I have ridden the XM3500 a total of 912.1 kilometers so far. I have recorded the kilometers along a path that is known to be exactly 10 miles and using the formula kilometer times 0.62137 to get miles and then multiply by 0.815, I get 10 miles. I do not know how consistent other odometers/speedometers. These are what I observed on mine.

HTH.

Another note from my testing - I am running the tire pressure just above the max rating so I may be getting "closer" to actual since my tire diameter will be larger. Additional notes are that I am 5'6" and 160lbs so I am shorter than most and have less wind drag (my weight is probably average for what a typical user of average height would be).

Thinking about this, when I duck down I get slightly more speed. I wonder how Xtreme tested their claims? A small, short person could make a significant difference, but I am not overly concerned about X-treme's claims anyway (I really want a bike that can handle 45MPH zones with some incline and 30MPH zones with ~15degree slope).

okay- after i did my 72 volt mod- i was very happy- and still am happy-
but, after reading what is going on with the mph- i had to spend the $2.99 for my VZ Navigator Version 4.1.0 for 1 day on my cell phone GPS- AND it works great- tested with my car first.

so after a 8 mile ride. the top speed that i hit was 48.1 miles per hr. but that was not for long at all. the normal speed for the trip was 45mph avg. and this is with 6 batteries NOW. SO with 5 batteries the speed will be lower then 40 mph. on my xm-3000.

it looks like 53mph on the speedometer.so i guess its about 8 mph off at higher speeds.

FYI - speedometer cable broke internally today just below the speedo. I took the front off the 3500 and found they had a pretty hard bend in the cable where it broke internally. I am ordering a speedo internal cable replacement kit from JCWhitney for $15 versus trying to get this from Xtreme (even though it is under warranty). If you ever have your front off, check this to make sure it is not bent too tightly.

i checked the odometer. with the mile marker signs on the side of the road. the km is off by .2 KM per KM/per mile... so at 1 mile the odometer should show 1.6 per mile. but shows 1.8 per mile.

Yea, that can't be right.

Among other things, that's paying 60% extra for a 5% increase in top speed. That's either a seriously defective product or some serious marketing balls. Not to mention that I think a speedometer error of 30% is probably illegal.

If these numbers represent the design, rather than a single defective instance, then I just can't see paying $4k for the 3500. I'd rather spend the extra $$ and move up to the Vectrix, or buy a XM3000 and turn the cash savings into battery modifications.

Can we get a confirmation on the top speed from someone else with a 3500? Or a statement from Mountain Chen? If not, I'm afraid my order is getting canceled.

Edit: hold a sec, rossasaurus above tested and got a top speed of 49mph, which is much more plausible. That leads me to think you've got a defect. Perhaps the speed limiter is cutting in too early?

All users of XM3500li,I appologize for the big difference between Speed meter and GPS,but the price difference between XM3500li and XM3000 is no only speed,they have exactly different battery equipment and different quality/performance motors.

XM3500li is much expensive lithium battery which bring longer range and life cycles and lighter weight for easily handling.

Most of all,XM3500li have much bigger torque than XM3000,its climbing is very good,that means good accelerating too,which is very important for saftey on road of heavy traffic.

And XM3500li have bigger motor which is much less overheat than XM3000,even though bigger AMP output. This will ensure longer life of motors.

And XM3500li have bigger tyre,more comfortable riding for most of the big USA guy.

Don't expect 3500W motor would be much quicker than 3000W motor when its torque already so big. Remember Watt= speed x torque.

Yes,Since motor is built ourself,we can adjust speed of XM3500li to be 60mph as my vedio http://www.youtube.com/watch?v=z_HJhNYs34g ,but its torque would be even less than XM3000 and accelerating would take very long time.which would bring a lot of dangerous on real world riding.

Next year we will upgrade XM3500li to be 4000W power by 72V (24cell) battery so that speed would be increased and don't reduce torque,but the price would be more expensive too.

And our new production in Oct would use a new plastic panel supplier who has much better quality and accurate speed meter.

GPS is plenty accurate enough for this purpose. There's no way Garmin puts out a product that's 30% off...

However, I'd love for someone to prove me wrong. Someone should go out and find a speed trap ;-)

When we were doing EEC type approval for XM3500li,the European engineer said that commerical GPS is not accurate at all,in case military GPS,so they didn't use GPS to test the speed of my scooter.

By the way,don't just screw on GPS and speed.......John,pls tell people on forum your real world feeling of XM3500li compare with Efun D and XM3000,not only speed,but also accelerating,climbing,and comfortable factors....etc.

It really is a shame that a lot of the scooter manufacturers put lousy speedometers in the bikes. I don't own and XM3500 but I own an trike manufactured by EVT.

I have taken the trike past a "your speed is" display and gotten a reading from it after several passes and I have found my speedometer to be about 16% fast.

When the speedometer was reading about 26MPH the sign indicated 22MPH.
When the speedometer was reading about 38MPH the sign indicated 32MPH.

It's a shame since a good speedometer can be gotten at most inexpensive stores for about $20-$30. This doesn't seem like a big adder considering the costs of these bikes.

Raise speed on Speed meter is not only happen in china,but also in Taiwan, Everyone so doing,we have no choice,all parts come from Petrol scooters and no parts suppliers would like to modify based on our hundreds pcs small order.

When I was deciding to choose the 3000 or 3500 I was looking at speed and range. The 3000 did not quite have enough power and range (battery) so I chose the 3500. Once I received the 3500 and starting using it I was pleased with the performance. (Yes, I am new to riding cycles. This is my first.) The most severe test (for me) is actually the last 1/4 mile of my commute. The commute is 20 miles and the last 1/4 mile the elevation raises 70 feet (sorry I do not know what that translates to in degrees or grade). I have to back off the throttle to safely go up the curved hill. The fastest I'm willing to go is 20 mph (real speed). I'm not willing to find out (at this point) what the top speed is of the 3500 going up the hill.

I think that the speedometer being off is a plus for me. The main display is in kph. In order for me to know the real speed I divide the kph by two. Much like I do when I have to have a splitter to measure volts or amps. Maybe I would see it differently if the main display was in mph. To attempt to figure speed (kph times .62) with everything going on in traffic is too complicated for me.

When is comes to what can the top speed can be for an electric motorcycle check out "Scotty Pollacheck's 6.95 sec 195 mph pass" http://www.youtube.com/watch?v=-Ev72ppww7Q&NR=1 I am not able to afford a motorcycle like that, maybe I'll win the lottery.

I appreciate all that Mountain Chen is doing to bring the 3500 to market. I knew this was a new product when I ordered it. Having experience with manufacturing companies, it seems that many new products have there share of issues. Some are minor and some are major. The issues I have experienced are minor (meaning correctable), and yes that includes the speedometer being off and no BMS. I check the batteries frequently and have found the more they are used the more they approach the same voltages. (except for the one battery, that I have mentioned before.)

The one item I was planning to purchase and have not yet is a solar power supply (to power the battery charger) Then the 3500 will be completely off the grid (no gas, no electricity).

Don't expect 3500W motor would be much quicker than 3000W motor when its torque already so big. Remember Watt= speed x torque.

Yes,Since motor is built ourself,we can adjust speed of XM3500li to be 60mph as my vedio http://www.youtube.com/watch?v=z_HJhNYs34g ,but its torque would be even less than XM3000 and accelerating would take very long time.which would bring a lot of dangerous on real world riding.

So it sounds like you already knew that the 3500 would be barely faster than the 3000, that this was a deliberate design decision. I'm ok with that.

But this brings up a very different issue: I expected the 3500 to be faster because it's being advertised as being faster. The published specs indicate 55mph. The published specs appear to be simply false, and it looks like you are saying that you knew it.

This is after learning that the specs indicating regenerative braking and a BMS were also incorrect. Again, I understand that there are reasons why regen might not be needed, and that BMS isn't reliable. But again, this seems to be a case of the advertised specs not being matched by the bike as delivered.

Look at the detailed page at X-Treme:
http://www.x-tremescooters.com/electric_mopeds/xm-3500li/xm-3500li.html

It very clearly says:
"Top speed at 55 MPH - Tested to 63 MPH.
De-tuned to 55 MPH for increased range."

But it appears it was actually de-tuned to 42 or so, not 55.

This may be an honest mistake, a series of poor communications, but it's a damn poor business practice. This type of discrepancy will lose you reputation, lose you customers, and possibly result in someone getting pissed enough to file a lawsuit.

GPS is plenty accurate enough for this purpose. There's no way Garmin puts out a product that's 30% off...

However, I'd love for someone to prove me wrong. Someone should go out and find a speed trap ;-)

When we were doing EEC type approval for XM3500li,the European engineer said that commerical GPS is not accurate at all,in case military GPS,so they didn't use GPS to test the speed of my scooter.

Well - my Garmin GPS matches with the speedo in my Subaru Legacy station wagon which matches with the drive by radar signs they put in place from time to time. But, if you wish to hold onto the fact that GPS "isn't accurate" by all means do so.

Rather than vaguely question the accuracy of GPS how about you tell us the top speed of the bike as supplied to Alpha Products International and sold via the X-Treme brand name? You're the manufacturer - why not go on record and quote a speed?

By the way,don't just screw on GPS and speed.......John,pls tell people on forum your real world feeling of XM3500li compare with Efun D and XM3000,not only speed,but also accelerating,climbing,and comfortable factors....etc.

As pointed out by others speed is important because it's so marginal for use for day to day commuting requirements. It's different for everyone (take Henry42 for example). This thread is also about performance, not about the complete package. However, if someone asked me to rank the XM-3500Li, XM-3000 and EFun-D I'd rate them as follows for performance and comfort for my intended use. I am 5'6" and 150lbs and have a 12 mile commute one way. I ride half city, half country, about 1.5 miles is on a dirt road. Max speed limit of any road on my commute is 50mph. I can charge at work.

First Place: XM-3000
Second Place: XM-3500Li
Third Place: EFun-D (I don't know if RMartin's bikes have a better motor but the 3000W EFun-D is not as strong as the XM-3500Li)

I have now canceled 6 out of rEV's 11 orders for XM-3500Li's. None of my 14 XM-3000's owners canceled - although 3 have come close. rEV can't sell EFun-D's.

I still maintain that either the XM-3000 or the XM-3500Li make a reasonable purchase - as long as you educate yourself as to what you're getting. As such, I still sell both models - and I own both models. I ride the XM-3000 more than I ride the XM-3500Li.

Tracy (and those that read his forum - where I can't post) - there's no disservice being done by me. 6 out of 11 canceled because I contacted them with the info. I thought about stopping selling the XM-3500Li entirely - however my site now lists the correct information so if folks buy through me then I'm not sure why they'd feel like they need to return it.

As far as your new found desire to "protect" Mountain Chen - I suspect that has more to do with your business dealings with him than a new found desire to right the wrongs of the world. Simple, straightforward sharing of information shouldn't be seen as putting someone on the spot. If Mountain chooses to comment with actual data then great, if he wants to continue to redirect that's his prerogative too.

As you note there's a chain of folks involved in this situation. I've dealt with my portion in a way I feel is above board and fair. I have no idea why you'd consider that I'm playing a "shell game". I leave it to the other two parties in the chain (and other third parties like myself) to proceed how they see fit.

This is Randall with R Martin Limited.

I wanted to post at this forum about our new EVD with 60ah LFP batteries. We just received them Tuesday and have finished our testing. The lithium EVD charges to 73 volts. It uses the Thundersky batteries and Thundersky charger. It has excellent acceleration and will reach 60 mph (tested with a GPS). Our speedometer is accurate.

Our VRLA EVD with the 50ah BB batteries will reach 50 mph (GPS Tested).

We have these in stock and ready you ship. The lithium models have limited availability (our dealers are taking several of these). Call or email us about shipping. We are offering free shipping to many areas.

www.rmartinbikes.com
www.electricbikedistributor.com

Randall

Who do you get your EVD's from, Randal?

Karen,

Our EVD is built by Efun. We have been working with them for about a year. Together, we have been able to make many improvements that increase the performance and reliability of the EVD product.

We are a licensed distributor and sell through licensed dealers. Our business model is to provide fully supported and warrantied products.

Randall

Randall - a few questions/comments;

1. Looking at this bike it has 21 cells so should hold a decent voltage provided it has a BMS - does it?

2. You mention a 30% slope - what speed and load? I assume this is with your higher torque motor...

3. It appears you offer two motor options for high torque or high speed; what speed does the higher torque get and what slope can the higher speed handle?

I also see the expected price for the LFP version is $5599 so a fair amount more than the $3990 I spent on the 3500. Otherwise it looks identical to the 3500 from the outside.

I am adding an additional battery to my 3500 which, according to some back of the envelope engineering, should get the 3500 close to 55MPH with decent torque since the plateau voltage will be better positioned for what the motor is demanding. I also consistently hit near 50MPH now with the BMS circuit I designed as it gets a good full charge across all cells versus having a couple run up to the 4V level and stopping the charger from running to get the others completed. If this works I will have ~$200 additional cost into my 3500 and it will perform close to the original stated spec (BMS, range, speed, climbing capability), so overall a good deal except I had to do some work to get there (which I happen to enjoy as this is a hobby as well as a mode of transportation).

P.S. I reverse engineered the TS charger to figure out how to scale the output to work with 21 versus 20 cells. I'm now just waiting for the battery as they are back ordered.

I also consistently hit near 50MPH now with the BMS circuit I designed

Is it the indicated speed or real speed (GPS or other) ?

Thank you,

Jean-François

I've started a new thread for discussions of the EVD w/Lithium batteries that Randall is announcing....
EVD w/Lithium batteries

I have calibrated my speedo so I figure 1/2 of KPH is MPH. I have my tires over inflated so I believe this is correct. By consistently hitting "50MPH", what I mean is 100KPH indicated on the speedo.

Please note after riding at this speed for about 4-5 miles the top end starts to drop. After riding 10miles I can only get 90KPH indicated which correlates to a decrease in the battery pack voltage.

Eped,

Thanks for your questions. I will answer these as best as I can. I am the sales manager so I will have to defer some of these to our techs.

I will also copy this to the new R Martin w lithium board....thanks MikeB.

1) We use 21 TS 60ah cells without a BMS. A BMS addition is a great upgrade to any DC system and we may offer it in the future.

We have previously tested 40ah lithium cells in series in ouer EVD. The 21 40ah cells in series would charge to slightly varying voltages depending on the temperature and how far they have been run down. Sometimes they would charge to slightly over 80v and other times they would only reach around 75v. The 40ah EVD always runs fine. We did not sell it because there isn't much performance difference over the VRLA model. We also use 21 cells because the performance is better. We expect the 60ah cells to show similar characteristics.

2) The 30% slope figure is from the manufacturer. Like all electrics, the EVD will slow on hills but we have never encountered a hill that the EVD will not make it up. We have had customers test on some really steep ones. Today, I was testing the lithium EVD and was able to accelerate while going up a slight hill at around 40 mph. This is pretty darn good for an electric in my experience.

3) We have two VRLA EVD+s with the higher torque motors in stock. The higher torque has a top speed of 40 mph. The higher torque helps at slower speeds on steep hills. It has not proved to be a big advantage. The regular VRLA EVD works fine on hills as described above. One advantage of the higher torque model is a longer range since the top speed is less. The higher torque is achieved with more windings in the motor.

Our lithium EVD uses 60ah instead of the 40ah cells. They are quite a bit more expensive. We also use 21 cells. We have a 6-phase motor and controller. Our disk brakes have been changed to a Taiwanese supplier with a better product.

This and the fact that we are a licensed distributor is reflected in the pricing. We are required by law to honor the manufacturer warranties. We also have a complete stock of EVDs and all spare parts in our warehouses.

Where we don't currently have dealers established, we will offer a significant discount - with the understanding that you will self maintain the product. We will provide warranty on the batteries, motor and controller. Please contact us at admin [at] electricbikedistributor.com if you want more information.

One more thing....the top speed of 60 mph was on a slight downhill. The bike will maintain 55-57 on flat ground.

Randall

I have calibrated my speedo so I figure 1/2 of KPH is MPH.

What speed reference did you use to calibrate ? Car speedo, GPS ?

I was a potential buyer but the top speed issue is not acceptable for me (lot of highway in my driving habits), if it is confirmed.

Jean-François