XM-3500Li Performance

jdh2550 was reporting about 50MPH actual in some thread, but he was going to verify it and never saw a reply from him on it.

John - were you ever able to get an accurate read?

Hi,

I don't have an independent speed reading yet. I'll be using a radar gun for that (I'll just wait until the cops set up a speed trap... JUST KIDDING! Erik has a couple of radar units).

On my way to work today I figured that my odo is 12.6% optimistic. My commute is 12.3 miles and the odo measured it as 13.9 miles. Bear in mind that Henry calculated an 18% optimistic rate (over on the long thread).

IF my speedo and odo are off by the same amount (not guaranteed, but not unlikely either) then:

50 --> 44
51 --> 45
52 --> 46
53 --> 47
54 --> 48
55 --> 49

Anecdotally that matches my real world experience. On a stretch of 50mph limit road cars do pull away from me but not all that quickly. I could imagine them doing 55mph and pulling away from me at a difference of 5mph to 6mph.

I'll post better numbers when I've done the radar gun tests.

Do you have any subjective sense for how linear your speedometer is? Any subjective issues with the brakes? Have you tried a "panic" stop or similar?

If you get a chance, can you compare the handling/riding experience between your XM-2000, XM-3000 and XM-3500? How do you decide which one to ride?

Speedo seems linear to me. Brakes have a softer feel than the XM-3000, i.e. you have to pull the lever in further to get the same amount of stopping power. HOWEVER, the brakes are more than adequate for a quick stop. Haven't tried a true panic stop yet. The ride on the XM-3500Li is too harsh - but I'm confident we can tweak the suspension to get around that. The pickup on the 3500 is much, much quicker than the 3000. The seat is really high on the 3500 and it's kind of hard too - I'm more comfortable on the 3000.

All this and more will be a part of the 5 way review (which is turning into more work than I expected - oops!)

As to which I ride it's usually a tossup between the 3000 and the 3500. If the 3000 had quicker pick-up, LiFe batteries and another 5mph top speed then I'd likely ride it all the time for my commute. "Small is beautiful" :-)

I don't ride the 2000 at all anymore - I'm supposed to be selling it - but I've never quite gotten around to advertising it yet. I'm basically a hoarder...

Hi there,
I'll add a few cents here...
I just offloaded my scoot from the truck today and am back from my first ride on some rural roads.
I took the Tom-Tom along and the iPhone with DynoLicious; yes, holding them in one hand whilst driving, really dumb, especially since I just finished my Motorcycle Safety course last weekend!
Anyways, the speedo seems pretty linear,as far as I took it;
Speedo GPS
20kph 9mph
30kph 14mph
40kph 20mph

On the way home I realized I had forgotten all about the Hi/Low Speed Switch, and had been a little disappointed with top speed, until I flicked it into high for a bit, ahh.
I only tested in the low range as my road is too rough for much speed on the 3500 due to the harsh suspension mentioned by jdh above. The GPS would have gone flying from my hand if I went any faster on my debt-stricken California washboard back-road.

I thought the braking was quite solid. I did a number of emergency stops from around 30mph and feel that it stops quickly, and only skidded the rear wheel only once.

I'm a big guy, 6'4", 240# and feel pretty comfortable with the sizing of this scoot; my knees aren't hitting the handlebars, my feet don't feel scrunched and the seat was pretty comfy for the 35 minutes I was out, though I kept sliding more forward than I would have liked.

The molded plastic around the handlebars is rotated to one side, offset from the handlebars themselves, indicating a direction in which you will not really travel.

I expected it to turn a little tighter; just my expectation.

I mentioned the DynoLicious/iPhone combo, with which I ran some Acceleration tests, but the results made no sense, giving me top speeds of 3.5 mph, Horsepower=1KW, etc., so I canned it for this session. Will have to contact the developer.

I look forward to getting out on a smooth flat road Thursday for some higher speed tests, hopefully with the GPS and DynoLicious duct taped to me or the bike.

Anyway, a fun ride, probably better suited to smooth urban streets than rural lanes, though at low speeds, either could be very pleasant.

I really enjoyed hearing the leaves blow in the wind as I passed under them too, wow.

R

Hi Ross,

Congrats on the new ride. I think they put that low speed button on there to trip up every new rider! ;-) I know it caught me out too (on my first XM-2000).

Well it turns out I have a dead cell. After a 12 mile ride all my cells except 2 were at 3.29V - 1 was at 3.28V however the other one is at zero! I'll open up a ticket with X-Treme this evening. Obviously I need to hold off the top speed testing until I have a full compliment of cells...

Hey John - that makes two dead cells on a fairly new bike (henry with the other). Ask API what they think; are they going to get a BMS into the 3500LI with a retrofit kit for those that shipped already or are they going to accept replacing LOTS of batteries? I sent them an inquiry and never heard a word...they should also know they will probably be loosing sales bcasue of this (if I knew then what I know now I might not have purchased it; luckily being a power electronics engineer as my job I can undertake some of this but I am not happy about it).

I am not taking my 3500LI out for any riding until I get the quasi-BMS done with a Paktrakr for alerts. However, this "BMS" I am making is crude and actually inefficient and adds cost as far as electricity to charge the bike. A much better way can be done but it is expensive (and something I thought I was getting for the $4K I put out for the 3500LI). Grumble, grumble, grumble...

JDH,
Yeah, you've got to be careful not to switch to 'High' with the throttle twisted as it could 'Buck' one right off the back if not paying attention.
Sorry to hear about the battery. I guess I better get real and start measuring mine.
I couldn't wait and post-charge went out to a flat spot and did some DynoLicious testing.

Here's what I got:

Accel
Run#1(hi) Run#2(hi) Run#3(low)
0-10mph 3.59sec 14.5 3.1secs
0-20mph 13.39s 16.6 8.44
0-30mph 20.99s 18.3 n/a
0-40mph 26.17s 20.7 n/a
0-49mph

T-elapsed 60' 5.2s @ 11.8mph 11.8 @ 2.3mph 5.2 @ 13.3mph
330' 15.8 @ 21.9 20.9 @ 38.7 13.3 @ 28
1/8m 23.7 @ 33.5 25.7 @ 46.5 21.78 @ 25.3
1k' 29.4 @ 45.6

Max Speed 49.0mph 48.0mph 29mph

Max Accel. 1.58G's 1.76G's 1.53G's

Peak HP 6HP 9HP 4HP

As you can see, there are some anomalies in the data, and obviously I couldn't Grok the Table tag ;)
For those who missed it, DynoLicious is software for der iPhone which uses the accelerometer and GPS within to measure this stuff. It doesn't ask for rider weight, just vehicle weight, so I'm assuming they meant it for auto use where driver weight is relatively insignificant compared to car weight. They'll have to change that me thinks!
The top speeds seem to jive with my TomTom, though it was vibrating and jumping ALOT at 49mph. I stuck the suction cup mount for it over the left-hand Tachometer blank.
The rest of the info...grain of salt.

BTW, I found it climbs pretty niceley, though I didn't want to push it too much so kept the speed down.
That small of a front wheel seems just slightly unstable to me cornering at 35+. Maybe I just need to get used to it.

Scoot gets a thumbs-up from me.
The 49mph will just meet my needs for the most part, though I'll have to take a back road home rather than the highway which has a long, steep hill that would probably drop me to 15mph; I'll have to try it at 3AM some morning to know for sure.

cheers,
R

The electric motorcycle racers in Santa Rosa (Thunderstruck motors)used to be a dealer for those same batteries they are putting in the 3500, but they told me they had almost a 10% defective rate on brand new cells, so they stopped carrying them. Something to be aware of.

If the Thundersky battery has something around a 10% defective rate, would a BMS even help? I suppose it would make it easier to detect that one battery simply isn't performing like the others, but I don't see how a BMS could keep a bad battery from eventually failing entirely.

A known sample of 2 out of over 200+ isn't that bad! (there are 10+ bikes out there).

We just don't know at this stage whether the cells were bad from the start or became bad because of out of balance usage.

Anyway - at least we get a chance to test out X-Treme's battery replacement warranty!

The way around this issue long term will be a pre-delivery inspection that tests the cells (and conditions them too). That way bad cells will be replaced before the customers receive them - and if it is indeed true that balanced cells stay balanced then the reliability will be improved as well. Alternatively, we find that the inclusion of a BMS will prove to be mandatory.

Hmmm, I wonder if anyone who's planning on starting a dealership is thinking of doing this? (hey, ross - perhaps you should too! ;-) )

Are these 19 Battery 3500s or the newer 20 battery version? Here are two photos, 1st is 19, 2nd is 20.
Notice that the 19 battery version only has 3 cells in the 1st row. The 20 cell version has 5 rows of 4.

The 10% dead cell LFP battery due to the quality control when output. They come from disfigurement production.I have remind TS many times....

These batteries dead as soon as discharged occurred,even BMS can't save these 10% any more.....

Other cells who can get over the beginning would be self-balance all the time.

Xtreme will definitely compensate the dead cell,we have shipped 20 cell of brand new battery 2nd container to replace the dead one.

jdh,
Yes, I agree....best way(and least expensive) is to perform impedance & other tests on the batteries before install at the factory and reject them early in the process. Are the known duds just being "eliminated" by sending them here? ever heard of externalizing costs?
If Extreme or the dealer is having to test them, it's too late in the process and too costly; will drive the prices up alot.
And, customer perceives it as the quality control issue it is.

R

Hi All - battery balance update:

I went 22 miles of very steep up/down riding today and the fuel gauge is still "just" above full but would drop to 2/3 going up a 20% slope. I then measured the cell voltages and they were all 3.31V +/-20mV, so pretty damn close.

I did notice before riding the fully charged cells ranged from 3.81V to 3.38V, so a shunt style BMS during charging should allow better over-all pack charge efficiency by getting the lower cells charged more and keeping the higher cells off the non-linear part of their charge curve. I have $80 worth of parts (including perf board) ordered to build a 1.5A shunt per cell activated at 3.65V on and then release at 3.55V.

I also noticed the charger cycles on/off and gets the most charging done with the first cycle and then slowly brings the pack up with the following cycles (it cycles about 20 min off and then on for shortening times as the cycles continue). The first cycle got the pack to 70V and by the end of the fourth it was up to 73.2V and the on-time was only about 1minute. I think the BMS shunt circuit will work well with this scheme since it will slowly discharge the higher cells during the off period of charge (and the BMS is designed to release when the cell drops below a set point) and the following charge cycles will bring the cells into balance to get an optimally "full-tank" of fuel.

I also wired in a wiring harness connected to a 25-pin D-Sub connector mounted near the charger input connector to easily connect the Paktrakr and BMS when I have them. The D-sub is rated for 3A per pin so more than adequate. I will send pictures when I have everything done.

P.S. My wife rode it finally and says it is better than she thought it would be (she is comparing it to a 50cc Honda Elite scooter she has rode in the past). I am also quite content the more I ride it.

P.P.S. Anyone teetering on their decision to get one of these (based on the battery discussions) should go ahead as the battery situation seems manageable. Range, top-end speed, and power also seem good and I agree with other posts on these parameters. However, this is just my opinion! ;)

I also wired in a wiring harness connected to a 25-pin D-Sub connector mounted near the charger input connector to easily connect the Paktrakr and BMS when I have them. The D-sub is rated for 3A per pin so more than adequate. I will send pictures when I have everything done.

Ya know, I really like the idea of using a DB-25 connector. I know they are good for the voltages we are interested in (3-5v), but are you sure they can handle the amperage?

For the DB-25, if it has the metal shell and the gold plated contacts, the rating is 3A per contact. Being a power engineer I like to limit my designs to 50% of max rating for continuous use so I am fine with the 1.5A BMS (I would probably not push a D-sub above 2A per contact). As far as the BMS, the worse case situation is if every other BMS is on. If two adjacent BMS are on, the middle leg between them will actually have 0A as one is "pushing" and the other "pulling" the same amount and the current just flows from one to the other and does not go back to the cells.

Also, for just monitoring cells, it is great.

Z20b Wrote:
What was the indicated speed when you hit 49 mph on your Dynolicious testing? 98 kph?

...........

You know, I had one hand on the throttle, one holding the cell phone, watching driveways for car pull-outs, 49mph, so I totally ignored the speedo!

I just divide KPH by two and call it good; it's within 1 MPH.

Ross

Yes, that, I expect, would be 98kph on the speedo at 49mph via gps.

Does anyone know how to get the batteries out of the XM-3500LI? They appear to be stuck and I do not want to apply pressure without knowing if they are attached in some other way or not.

:? Henry42, After you open the byke up and disconnect the wire jumpers between each batch of 4 , remove the spoung and slide NO. 1 back , move batch No. 2 half way and using a length of masons string make a loop tie the ends togather and slide the string past the alluminum tubes , USE Gloves , lift the middle so each side lifts into the other !! remove the second one first and you will have room to get them all Altho I have not yet tryed a removal, I had looked at the probublem when I took it apart to find out "HOW" LaTeR

The top speed I get out of my XM-3500Li with a 66V pack (20 cells charged to 3.3V) is 41.8mph measured by my Garmin GPS. The indicated speed is 55mph.

That's a massive 31% inaccuracy in the speedo.

I apologize that it took me this long to get around to doing the test - I first got this figure yesterday and thought "no, that can't be right". I then retested today and got the same results.

I apologize to my customers - you should have just received an email from me with the same info and suggesting that you consider if you want cancel or not.

Yes, this is very disappointing.

While I was at it I tested my XM-3000. It has an actual top speed of 40mph with 45mph indicated on the speedo (a 12.5% inaccuracy).

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?

Yea, that can't be right.

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?

I tested twice and I also tested the accuracy of my GPS against my Subaru speedo.

The Subaru and GPS matched practically exactly (maybe a few 10ths or as much as 0.5 mph difference - remember the speedo is analog and the GPS digital).

So, unless the XM-3500 speedo or the GPS is screwed up in some "interesting way" I'm confident that 55mph indicated = 42mph actual. I've never had my bike past 60mph indicated (down a long enough hill I can nudge up to 60). To get a real world speed of 55mph one would have to get an indicated speed of 72mph.

I'm more concerned about the inaccuracy than the top speed. It's possible I might need to inflate my tires, or I had a head wind or I was going uphill - but none of those things affect the indicated speed.

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.

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.

Comparing the price of the XM-3000 and XM-3500 and saying that the only difference is the increase in speed isn't really accurate. One has SLA's the other has LiFePO4's - one is suitable for the 6 foot plus crowd the other is much smaller. Not excusing anything just pointing out the differences. There's a small chance someone might want an XM-3500Li even at the lower speed. It's there choice.

If you want to go the XM-3000 route and upgrade the batteries then I know someone you can buy one from.

Also, one could probably add at least a couple more cells to the XM-3500Li - perhaps even take it to 24 cells before any releasing any of the magic smoke. Cells are $68 each from Elite Power. However, that would void the warranty. I think you might get 50mph at that point (42 * 1.2). It seems that top speed is volts limited not amps limited on this bike - because on first accel the volt meter dips and then after you achieve top speed and finish accelerating the volt meter rises. This tells me the load is reducing and the system is demanding less amps.

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?

Ross is using a program called Dynolicious on his iPhone. It uses the accelerometer. Doesn't that mean the device needs to be mounted solidly to the vehicle to avoid extra forward movement creating a higher reading? Ross held it in his hand.

My readings were taken with a Garmin iQue and then the Garmin readout was verified by comparing it with the speedo in my Subaru.

So, unfortunately, I think Ross' readings are more suspect than mine.

But.. a GPS estimates speed by looking at the signals it gets from satellites. What would be most accurate is to get a Cycle Analyst or other 3rd party speedometer which reads directly off the wheel and into which you can program the wheel size.

FWIW I too spent awhile driving around with a GPS and being wowed about how accurate it appeared to be. But it strikes me it might be most straight forward to have a normal speedometer on the bike.

It's such a shame these companies can't deliver speedometers that work. It's not like it's rocket science.

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 ;-)