Just got my XM-3500Li

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zarlor
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Points: 146

Well, my XM-3500LI just arrived yesterday. The box and pallet had pretty extensive damage. Large rips on the box and quite a few slats were out on the pallet. One of the tie-downs on the rear wheel wasn't tied down to anything (although it didn't look broken, just not connected to the frame.) The metal frame seemed to be OK, if a tad lopsided, though. The bike itself had some damage on either side of the front cowling and the bottom right (from the driving perspective) plastic piece was somewhat damage and mostly broken off. Also the lower right foot rest was missing one of the screws and I noticed, after removing that plate, that that lower plastic panel was also missing at least one of the screws that would normally hold it in place. One of the headlights didn't work on low beam, but I later took it for a spin, just around the block, and it came on during the ride. I guess the bit of vibration from that reseated it properly (unless it was a power saving thing?) It also has the brake chirping on at least the front brake and I'll try to take a closer look at the back brake a bit later as well.

I opened a ticket with Xtreme about those issues, and if the experiences of others recently reporting on such things is any indication, then it shouldn't be a problem getting those basic body parts that were damaged. (The brake thing I'll just have to see what I can work with thanks to some of the other posters here.) None of them prevent the scooter from running, but I definitely need to look at fixing the brake problem before I feel comfortable using this as a commuter. And I do want to do some of the recommended battery conditioning recommendations others have claimed by riding it a few miles, then a few miles more and so on with recharging in between.

Unlike some of the other folks who reported that their bikes were pretty much fully charged, this one registered a very low charge on the gauge on the display panel. It pretty much took a good 3-4 hours before the charger finally turned off when I started charging it up, so I think it was definitely low. I don't know if that is any indication of anything, mind you, as I don't know if they are being shipped that way or what.

I've not found a good way to mount the bicycle speedometer I bought, either, but subjectively it has pretty good pickup (although this was only on little neighborhood streets with stops at every corner and at a guess I never got it about 25-30 mph.) The throttle is going to take some getting used to. It picks up and goes pretty quick and it's very hard to fine tune a cruising speed with it. I find it's a lot of throttle on/throttle off to try and maintain a speed, but we'll have to see later how that translates on some of the roads I'll be driving that have longer stretches on them.

The scooter was also a little heavier than I expected and the overall frame feels pretty sturdy to me. I'll look at taking off the body panels and tightening everything down before using it as a commuter, though. I noticed several of the screws and such were a tad loose so I'd like to make sure nothing important is loose.

Now I just need for my helmet to finally get in, get the paperwork from Xtreme (that's requested in my ticket as well... I wish they would just automatically mail that to you when they ship the bike or something. It's very frustrating to have to wait to get the needed paperwork like that!) and take a look at doing the rest of the basic setup. I'm thinking I may also just have to go the GPS route, too, since the bike speedometer doesn't look like it will be too easy to mount (at least not for me.)

Sorry for not having much to add on the riding or performance data points. Hopefully I'll have everything in place to really start using this in a few weeks and can provide some more information then.

__________________

Lenny Zimmermann
Metairie, LA

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zarlor
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Points: 146
Re: Just got my XM-3500Li

I finally got the paperwork on Friday and got this puppy registered today. I've been doing short, with progressively longer, runs a bit in the meantime to follow the advice of someone on these forums for battery conditioning. So 2 miles, then 4 and such on back streets didn't give me much opportunity to open it up.

Today I did, though. THe best speed I could get, according to a Garmin Zumo 450 GPS, was 40.4 mph. I'm 6'1" and 200, so not a small guy, but still I was really hoping for a bit more. At LEAST the 42mph, especially since the acceleration between around 25 up to 39 (which is what I can normally maintain as a standard Max speed) is a bit slow. Has anyone made any progress on figuring out if this thing really is speed limited in some way and if we can remove that?

Overall it's a bit shaky and one of the plastic bits that you have to install over the rear sidebars broke as soon as I hit a dip in the road. You definitely will want to at least take out the screws you can see and put some Loktite (super-glue) on them to help hold everything down a little, IMHO. However my tires were, like many others, well overinflated (around 48psi) so we'll see if dropping them back down to 33 or so will help with that. I'll take this thing in for the full commute to work tomorrow.

I decided not to work on the brakes any. The instructions posted here were just shy enough on details that I decided I didn't really want to risk experimenting with it. The chirping has already worked itself out of the front brake, but the brakes definitely chatter when applying them. I expect that with a bit of wear on them that will work itself out some, but probably not as much as I would like. I may take it to a motorcycle shop and see if they have any ideas. I may be bringing it there anyway to actually hook that Zumo 450 into the power of the bike and I'm just not too positive where to splice the leads in for the proper power levels needed for it.

At any rate, that last run was about 8 miles (the trip to the office in the morning will be 12 and, hopefully, I can charge there.. after that I'll probably do the the round-trip before charging again which will probably be my standard, so approximately 24 miles between charges from that point on.) After doing a full charge (once the charge stops and both lights go green it is charged, right?) I measured the batteries with a voltmeter. Here's what I got, and any comments on these numbers would be appreciated. They are definitely not level, though.

Layout is from front-left (from the seating position) on the back reading right to left.

3.71 3.56 3.43 4.25
3.38 3.57 2.48 3.37
3.75 3.45 4.15 3.99
3.38 3.58 3.39 3.43
4.29 3.42 4.01 3.42

I suppose I should get a PakTrakr to make tracking these easier, but then again there's not much I can do about those readings anyway (at least not without a BMS) and they are so darned expensive! Unless someone can really convince me it would be worth it.

Thanks for any feedback!

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Lenny Zimmermann
Metairie, LA

zarlor
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Re: Just got my XM-3500Li

Oh, one last thing on the speed. For wind it was fairly calm (slight, maybe 1-3 mph winds) and living in the New Orleans area means it is flat, flat, flat. So no hills to affect the numbers. I did try doing a little bit of crouching, but I don't think I improved my speed by more than maybe 1 mph doing that.

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Lenny Zimmermann
Metairie, LA

zarlor
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Re: Just got my XM-3500Li

I drove it on the normal commute this morning, 12 miles of almost all flat (except for one bridge over a canal). I'd say the average top speed was 39mph, it was dropping down to 37, though, where there was a little bit of a headwind along the lake shore (yeah, I have a fairly scenic drive in for about 1/3 of the way ;)), which also meant going up that little bridge dropped me to 34, but it picked up to 42 going down the other side. It was also still dark when I rode in and I can definitely say that the dashboard light is garbage. Not enough light from it to read the speedometer. Luckily the GPS I ended up mounting on the handlebar (had to do some slight modification to the plastic surrounding the handlebars to do it) is lit up so I still had an easy readout for speed when I needed it.

Deflating the tires to the recommended levels did help to soften the ride a little. It can still be a little shaky, especially with how so many of the roads are around here, but so far I think it's working out fine. Now if I could only get a little extra speed out of it and maybe see if someone could fix what I think is a warped disk on the front brake we'd be in good shape.

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Lenny Zimmermann
Metairie, LA

ratatouille
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Re: Just got my XM-3500Li

Thank you Zarlor for your reports.

You confirm the disappointing top speed :(

There is a switch on this scooter for 2 speed settings : "eco" and "fast". Do you confirm the 42mph are reached with the "fast" mode ?

Thank you,

Jean-François

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Jean-François

zarlor
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Points: 146
Re: Just got my XM-3500Li

Oh, absolutely. The low speed setting tops out at around 26 mph sustained. (And that 42 in high was downhill. Sustained it stays around 39-40 mph, for someone of my size anyway, and barring any headwinds.)

However, to add another oddball datapoint to all of this... driving home from the office today it was light enough outside that now that I've moved the GPS I can read the speedometer. Oddly enough the speedo was pretty accurate to what I was getting on the GPS, no more than 2-3 mph difference, but that was with variable speeds and the GPS has a few second delay. One straightaways at full throttle I was looking at a GPS of 40 and a speedo right at the 40 mph marker. If anything a good deal of the variability showed slower on the speedo than the GPS was showing (which could be accounted for to some extent by the GPS dealy, but it still seemed rather odd.) Indeed it's almost the opposite of what so many folks here have already reported.

I'll keep an eye on it and report later if that variability changes any. Could there be differences in the batches to account for this or even between bikes? Maybe Mountain Chen has been able to better calibrate the speedos or did I just get lucky?

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Lenny Zimmermann
Metairie, LA

zarlor
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Re: Just got my XM-3500Li

Oh, I also had a motorcycle mechanic look at the brakes for me and he just tried shooting it with brake cleaner. A lot of black "dust" did come out and the chatter was reduced a good bit, so maybe the disk isn't warped after all. He did say that if the chatter is still there (and that it's not uncommon on a lot of bikes, maybe I just notice it more because the bike is so quiet otherwise) we could just try something with the pads, but I forgot what he said, now. Another guy there also suggested replacing them with ceramic pads as another possibility.

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Lenny Zimmermann
Metairie, LA

sparc5
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Re: Just got my XM-3500Li

Just out of curiosity, has anyone tried to increase the controller's amp limit to affect speed? Its controlled by a bridge; accessible by removing the screws to the back plate (closer to the rear tire).

__________________

XM-3000...
-DC-DC converter replaced with a Dell D220P-01 power supply.
-72V mod
-Expensive bank charger until I come up with something better... Still trying.
-Headway 10Ah LiFePO4 cells 24S2P, pack in parallel once the item above is ready.
-KEB72801 300A 72V 8.0KW (Enormous EV grin)
-DPDT relay to use throttle to control regen and to invert break/kickstand input.

zarlor
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Points: 146
Re: Just got my XM-3500Li

Let's see if I can do this.

Here is the back of the controller, the sticker on it has handwritten 60V80A (it's overexposed in this pic so it just looks like a wite rectangle):


Click image for larger view.

And here it is with that back removed:


Click image for larger view.

What is the bridge part there and what would I do with it?

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Lenny Zimmermann
Metairie, LA

rossasaurus
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Re: Just got my XM-3500Li **Lenny, Lenny **

Lenny, Lenny,
I'm really concerned by looking at your cell voltages!

I figured something was up with your pack when you mentioned a top speed of only 40mph, as you're lighter than me.

I see you have one cell at 2.48v...dat no good braddah.

Very basically, what happens is the charger keeps pumping until your overall pack voltage hits a certain preset voltage, let's say 72v, then it shuts down to avoid pack overcharge.

In your case, with your low cell at only 2.48v, this means the charger keeps pumping current into the pack, and since there are some cells at 3.8, 3.6, whatever, the voltage on those cells will continue to climb to compensate for your low cell until the pack preset voltage is reached; unfortunately, those higher cells may enter an overvoltage condition, while your other cell(s) may continue to be left behind, voltage-wise. Both high and low conditions can be worrisome.

In other words, your pack is ....unbalanced.

Someone correct me if I'm wrong, but I think 2.5v is generally considered the point a Lithium-Iron cell should never go below, risking permanent damage.
It's like the DNE speed(do not exceed) speed in an airplane 'cause the wings they break off.

I hate to be the bearer buddy, but I'd stop riding your 3500 Lenny until you address the imbalance.

At the very least, you need to get the voltage of that very low cell back up through single-cell charge, and you need to check all your cells until you get a handle on what's going on.

I'm concerned as well that some of your cells are headed for overvoltage and swelling, possibly failure.
I'd recommend getting your high cells down to 3.7v or so; you can jumper cell by cell to a standard household light bulb if need be, or run the headlights, or the motor, but monitor your low cell while discharging the high cells, so it doesn't go below 2.5v
Guess what Lenny? YOU are now the BMS!

Step by step:

• charge your low cell only, to 3.7v(unless it's dropped even lower than 2.48v; it's hazardous to charge cells which have dropped too low; I don't know what the "too low" voltage is). Anybody? I kinda remember reading if it drops below 1v, forget about it, it's dead meat and dangerous to try and recharge.

Assuming low cell is still good;
• run the motor or lights until highest cell drops down to 3.7v
• charge cell-by-cell until all are up to 3.7v
• you could now run the charger on the whole pack; it shouldn't take too long to hit full charge.
• measure cell voltages again
• do all you can to always keep cells between 2.6v and 4.1v
• once you do this, there's a better chance the cells will track each other, assuming there was no damage done, but you'll still need to measure every cell often until you're confident you know what's happening cell by cell. The charger may indeed be said to have a BMS inside, but the Management is ineffective at balancing all cells in our packs. Do not trust or expect it to care for your cells properly.

• It'll help during this special period of learning if you go light, keep your speeds under 30 or 35 and don't ever let your "fuel gauge" really a voltmeter, drop below 50%. I know the voltmeter doesn't mean much, but it's all we got for now, so call it a limit.

Hope this helps and I haven't freaked you out.

It's pretty much what I went through, ahem, am still recovering from. I'm still waiting for my replacement cell from X-treme and, come to think of it, acknowledgement that they received it ;)

Cheers,
Ross

zarlor
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Re: Just got my XM-3500Li **Lenny, Lenny **

Ooops. That was a typo. It's actually 3.48, not 2.48. Sorry about that. I would have noticed that big of an outlier right off the bat. Sorry for the confusion. Still good info, though. Thanks!

I agree that it is odd that I'm not getting the 42mph plus levels that other folks ahve reported of not too dissimilar size from me. I've tried a bit of crouching (but really getting low just make me feel a little stupid so I haven't tried something like sitting on the back seat and getting really aerodynamic) but what little I've done doesn;t seem to make much difference. I did do some conditioning runs, first for around 2 miles, then 4, and 6, all below 30-35 mph before I got it registered and recharging in between. Then I took out for 8 miles on that first run I was able to get it up to 40 initially and recharged. Yesterday it was 12 miles to work and I charged up there, with 12 miles back charging again last night. Today I'll run a full 24 mile commute before charging again at home.

I think this time I'll try to measure the batteries when I get home tonight before I charge them up again and see what the levels look like after a run. But overall after a charge they appear to be within.. let's see low of 3.37 high of 4.25, .88 volts of each other. I'll let folks know what I see on it tonight. And again, sorry for the typo on the 2 volt one.

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Lenny Zimmermann
Metairie, LA

sparc5
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Re: Just got my XM-3500Li

Lenny,

The bridge are those two staples you can see sticking up from the board. Probe it with a continuity tester to make sure they are indeed connected, if yes, it's safe to attempt to make them more conductive. The more conductive it is, the more current the controller allows go to the motor. Try bridging them with something metal temporarily, and seeing if your top speed increases. If the continuity tester says they aren't connected, abort mission.

Now let me warn you, this is only an experiment, and a risky one. By raising the current limit of your controller you risk overheating your motor. You would have been the first to attempt this, so there could be unforeseen consequences.

__________________

XM-3000...
-DC-DC converter replaced with a Dell D220P-01 power supply.
-72V mod
-Expensive bank charger until I come up with something better... Still trying.
-Headway 10Ah LiFePO4 cells 24S2P, pack in parallel once the item above is ready.
-KEB72801 300A 72V 8.0KW (Enormous EV grin)
-DPDT relay to use throttle to control regen and to invert break/kickstand input.

zarlor
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Points: 146
Re: Just got my XM-3500Li

Hmmm... if I remember it looked like that was two or three "staples" (sure enough, that is what they looked like) all soldered together at the ends. So it looked something like [I] (but the lines on the I were connected out wiht what just looked like solder.) I knew I should have gotten a picture from more of a top-down angle. So I'm pretty sure they are all connected, but I'll try to take a look again and maybe post another picture.

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Lenny Zimmermann
Metairie, LA

zarlor
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Re: Just got my XM-3500Li

First off, here's a pic of the bridge (or at least what I think you're talking about is the bridge, it's a bit blurry, but the best I could get with the crappy camera I've got at the moment.):

Click image to see a larger view.

All soldered together, so unless the solder just has some extra impurities in it, it should be passing current between all 3 strips.

For today's battery report, I drove it 24 miles without recharge (and it was a bit windy today, so top speed in some spots was only 36 mph with that headwind... that's getting a bit hairy dropping that low in some of the traffic that surrounds me out there). Measuring the batteries after that run they are all very consistent, within .02V of each other. Here's the graph:

3.27 3.27 3.27 3.27
3.27 3.26 3.27 3.26
3.27 3.27 3.27 3.27
3.27 3.27 3.27 3.27
3.28 3.28 3.28 3.27

So I don't think I have any bad batteries from the looks of it all so far and they leveled off pretty well once running, it seems.

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Lenny Zimmermann
Metairie, LA

zarlor
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Points: 146
Re: Just got my XM-3500Li

One other addition, I think I mentioned above, but the "fuel gauge" doesn't work on mine. It looks like it's plugged in at the dash, but I'm not sure where it connects down at the other end. I did recieve the new front cownlings and the bottom faring that were damaged in shipping, so maybe I'll try to take it furhter apart and trace the wire down a little better. I don't expect to ever put more than maybe 30 miles on it between charges, though, so I can't say that having it working is much of a priority for me.

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Lenny Zimmermann
Metairie, LA

sparc5
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Re: Just got my XM-3500Li

Ok Lenny,

Now that I see they are already soldered, I feel much better suggesting you experiment making them more conductive. My main concern for the short run was you'd short something that shouldn't be. Now my fear is more limited to overheating the motor on extended runs.

It's a long shot, but I don't know what else to suggest besides adding more batteries or rewinding the motor. So far no one is in a hurry to reverse engineer that controller.

__________________

XM-3000...
-DC-DC converter replaced with a Dell D220P-01 power supply.
-72V mod
-Expensive bank charger until I come up with something better... Still trying.
-Headway 10Ah LiFePO4 cells 24S2P, pack in parallel once the item above is ready.
-KEB72801 300A 72V 8.0KW (Enormous EV grin)
-DPDT relay to use throttle to control regen and to invert break/kickstand input.

PJD
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Points: 1238
Re: Just got my XM-3500Li

I would still be concerned about battery balance.
When discharged anywhere from 70% to 30%, the cell voltage under no load will typically be about the same, so partially discharged cell measurements don't reveal a lot unless a cell is completely shot. However, based on your voltage when finished charging, some of the cells are probably getting a bit overcharged. Try checking, the cell voltage when charging. 3.7 volts per cell is ideal for cell life.

A BMS is a must. A do-it-yourself version (PC board plus bill of material for parts) for up to 24 cells is soon to be available as discussed here:

http://endless-sphere.com/forums/viewtopic.php?f=14&t=5416&st=0&sk=t&sd=a&start=450

Whatever happened to eped's charge-balancer?

zarlor
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Re: Just got my XM-3500Li

Thanks, I'll try to track that thread to seea bout doing that. I'm a little torn on the whole BMS thing only because John Harding (at least I thought it was John) was saying something in a previous thread that adding a non-Thundersky BMS (and it's not like I've seen anyone mention one available from them) would void the 2-yr warranty on the batteries. So the question I keep mulling over is should I wait 2 years and then get a BMS, just in case something happens to them in the meantime, or should I just bite the bullet now in the hopes of extending their life some significant amount more. I just don't know how much more battery life being on the BMS will get me over that time.

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Lenny Zimmermann
Metairie, LA

zarlor
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Re: Just got my XM-3500Li

If we're REALLY lucky, maybe Mountain Chen can jump in on this and let us know. Considerig I'm getting a bit lower top-end than others are reporting I can't helpo but think maybe adding more juice won't affect the motor. If nothing else I can say that the bike probably isn't going to be ridden more than about 12 miles between charges anyway, which might give it less time to overheat, but probably 9 of those miles will be at top speed. So maybe that wouldn;t buy anything.

At any rate, if I wanted to mess with that what would I need to do to try to improve the conductivity?

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Lenny Zimmermann
Metairie, LA

PJD
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Re: Just got my XM-3500Li

Lenny,

There is no reason for X-treme to ever know you had the BMS connected - which cannot in any way harm the cells. The fact that X-treme has a warranty for the cells should be of little comfort as the electric motor scooter world is littered with out-of-business importers who got buried by warranty claims and the Chinese manufacturer refusing to honor the claims.

Sorry to say, but for now, anyone who buys a Chinese electric motor scooter should consider it more of a kit-project than a turn-key product.

As far modifying the bridge (current measuring shunt resistors), it is a good idea in "moderation". But one way to see if the current limit is what is limiting the speed would be to measure the the pack current while riding. Check the maximum current when under full-throttle acceleration (or full throttle up a hill - probably hard down there in the Big Easy). It should hit the controller's current limit and go no higher. Then check the current at top speed, on level ground, no headwind. If it is the same value, than the controllers current limiter is limiting the speed.

If the controller is really putting out 80 amps, I doubt the current limit is what is limiting the speed unless the motor/wheel diameter combination is wrong - i.e. the motor is "lugging" inefficiently at too low an RPM range. My 60 volt e-max draws only about 53 amps at 45 mph, level ground.

I made a cheap high-range ammeter using a shirt-pocket-size multimeter and exactly 11 inches of 10AWG medium-coarse stranded automotive wire. Ring terminals are put on each end of the wire (11 inches butt to butt), with small gauge wires also attached to the ring terminals. These wires run to the voltmeter mounted at a safe readable location while riding. The ii inch piece of wire is connected between any two cells in the string. This wire has about one milli-ohm of resistance so the voltage measures between the end will be one millivolt per amp of current, so you can read the mV on the meter as amps while riding.

If you are going to modify the shunt resistors in the controller, I'd do it in a calibrated manner using a fourth resistor made from steel coat hanger wire, as discussed way back in this forum:

More E-max Controller Mods - Shunt Resistor Trick

I have spreadsheet to calculate the steel wire length for the current increase you want. You can PM me for it.

- Paul D.
Pittsburgh

Mountain chen
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Re: Just got my XM-3500Li

TS batteries already have angency in USA,see http://visforvoltage.org/forum/4750-thunder-sky-40-ah-lifepo4039s-elite-power

Any broken of LFP battery from Xtreme scooters within warranty could be replaced in Elite or Xtreme stock.

But if the battery are damaged by using unstable BMS or bad workmanship connection of BMS (so many wiring from any kind of BMS),it would beyond warranty.

zarlor
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Points: 146
Re: Just got my XM-3500Li

Thanks, Mountain Chen. Can you provide us with any insights on the controller? Is there anything we might be able to do to knock up the top end speed? I just need to get a little more out this scoot as I was really, really hoping to have had some of the same speeds other folks on the forums here have reported. Even 2-5 extra mph would help a good bit for me.

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Lenny Zimmermann
Metairie, LA

sparc5
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Re: Just got my XM-3500Li

Chen,

Can you please give us any information how to raise the top speed?

__________________

XM-3000...
-DC-DC converter replaced with a Dell D220P-01 power supply.
-72V mod
-Expensive bank charger until I come up with something better... Still trying.
-Headway 10Ah LiFePO4 cells 24S2P, pack in parallel once the item above is ready.
-KEB72801 300A 72V 8.0KW (Enormous EV grin)
-DPDT relay to use throttle to control regen and to invert break/kickstand input.

PJD
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Points: 1238
Re: Just got my XM-3500Li

To clarify, the only way a BMS is going to ruin a cell is if it discharges the cell. The only way the Goodrum/Fetcher BMS design would fail would be simply to go open-circuit. So, the use of a BMS can only improve battery pack performance. The existing setup on the 300Li is no charge management and no individual cell low voltage cutoff. This is probably going to result in premature cell failure and a lot of expense and headaches, leading to most poeple assuming the whole idea of electric vehicles is nonsense, putting their scooters out for the trash pickup and setting us back another couple decades.

As far as extra speed, it will probably require adding extra cells and raising the voltage, but if someone can obtain the performance data for the hub motor (current/RPM, torque) there is a chance some improvement can be obtained from changing the tire size. From my calculations with my e-max, you need to overcome about 38-40 pounds of drag and rolling force, while obtaining the necessary motor RPMs, to get to 45 mph.

BTW, it is always a good idea to keep the tire pressure as high as you think is safe to minimize rolling friction. About 5 to 10% overinflated is OK with quality-brand tires.

eped
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Re: Just got my XM-3500Li

My BMS is working great. Note I have added a BMS, over inflated tires by ~10%, and added an additional cell for 21. These three mods have gotten me an additonal 6.5MPH top end (at 49.5 now and was about 43 when I first tried the bike without doing anything). The BMS added about 2.5MPH (yes, it does help since the lower SOC cells will have a lower voltage under load due to increased internal resistance and lower charge capacity), the extra cell about 2.5MPH (basically a 5% gain going from 20 to 21), and the over inflation about 1.5MPH (lower rolling resistance but a "harder" ride).

I have also thought about the reported 52.5MPH on the Martin EVD and I did a quick caluculation assuming the 60AH batteries have a lower internal resistance than the 40AH of the 3500LI. The EVD has 21 cells and what appears to be a similar motor, so the 52.5MPH and my 49.5MPH (with 21 cells) both make complete sense if I assume 75mohms total resistance for the EVD and 120mohm for the 3500LI and a draw of 80A. Thus, I have put about $200 extra into my 3500LI and getting close to the EVD (which costs $1700 more) and I don't have that honkin' controller sticking out the side of my bike ;)

EDIT - I have to add another $50 for the DC/DC that failed since it did not like the additional battery voltage when I added one cell :(

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Green electric power and use thereof; what more do we need?

PJD
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Joined: 11/22/2006
Points: 1238
Re: Just got my XM-3500Li

eped,

This is good news.

Are you still use the original charger with the extra cell?

The Fetcher/Goodrum BMS has a circuit to "throttle" the charge current proportional to the duty cycle of the cell voltage shunts. But if you are using a CC-CV charge with the CV voltage nearly the same as the BMS's shunt regulator voltage, your solution looks like the better one.

This is the first I have heard of the R Martin Product. It looks good, but considerably more expensive (21 60AH Thundersky's aren't cheap) and still doesn't have a BMS.

Johnny J
Johnny J's picture
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Joined: 07/08/2008
Points: 323
Re: Just got my XM-3500Li

Eped!
Finished soldering my BMS today and got it to work!
At 3.7V it wakes up and draws 1.75A with the 2.2Ohm 10W resistors.
Seems like some bad soldering caused the problems before...
I used 2.2KOhm resistors instead of 2.21 since I couldn´t find any here.

Will try it out on the bike tomorrow.

Thank you very much for sharing your work!

Johnny

eped
Offline
Joined: 06/13/2008
Points: 126
Re: Just got my XM-3500Li

PJD wrote:

eped,

This is good news.

Are you still use the original charger with the extra cell?

The Fetcher/Goodrum BMS has a circuit to "throttle" the charge current proportional to the duty cycle of the cell voltage shunts. But if you are using a CC-CV charge with the CV voltage nearly the same as the BMS's shunt regulator voltage, your solution looks like the better one.

This is the first I have heard of the R Martin Product. It looks good, but considerably more expensive (21 60AH Thundersky's aren't cheap) and still doesn't have a BMS.

Thanks PJD. Yes, I am using the same charger. I reverse engineered it to scale its charge profile for 21 versus 20 plus I tweaked it so it is pretty much just entering the CV portion when the BMS kicks in and it does great. Here is the post on the charger mod.

http://visforvoltage.org/forum/4844-thundersky-tsl6010-xm3500-charger-mod-21-cells

The Martin EVD does look good, but also does not have the BMS as you mention. I also don't know if you looked at the post but the controller is huge and sitting out to the side (otherwise it looks good and pretty much the same as the 3500LI; I do like the dash on the EVD versus the 3500LI). Here are some posts;

http://visforvoltage.org/forum/4841-evd-3000w-wlithium-batteries
http://visforvoltage.org/forum/5016-evd-lfp-impressions

Thanks

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Green electric power and use thereof; what more do we need?

eped
Offline
Joined: 06/13/2008
Points: 126
Re: Just got my XM-3500Li

Johnny J wrote:

Eped!
Finished soldering my BMS today and got it to work!
At 3.7V it wakes up and draws 1.75A with the 2.2Ohm 10W resistors.
Seems like some bad soldering caused the problems before...
I used 2.2KOhm resistors instead of 2.21 since I couldn´t find any here.

Will try it out on the bike tomorrow.

Thank you very much for sharing your work!

Johnny

Hey Johhny - this is great! Please keep us posted on how it works and note how the charger LED and the BMS LEDs track (the charger goes from CC to CV mode when its LED changes color from Red to Green). Hopefully you will get most if not all BMS LEDs lit with a few barely just starting when the charger goes to green. If this is your first time running a balance, you will have some cells fire the BMS early and may not have a good portion light at all before the charger goes green and then turns off (the BMS shunts a good portion of current but not all so the full cells will still increase a little and the charger will see the pack full). But if you do this charging several times they will come into balance eventually. Monitor your cell voltages as well and report your results!

Thanks

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Green electric power and use thereof; what more do we need?

Mountain chen
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Joined: 09/05/2007
Points: 318
Re: Just got my XM-3500Li

Speed is not decided by controller,it is decided by solution of cooper winding,change into more speed,the torque and accelerating would be reduced.

zarlor
Offline
Joined: 07/03/2008
Points: 146
Re: Just got my XM-3500Li

Thanks again, Chen. Any ideas on why mine might be running 3 mph slower than what others of similar size to me are getting?

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Lenny Zimmermann
Metairie, LA

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