XM-3150 72 Volt Mod

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Chasbro
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XM-3150 72 Volt Mod

OK you guys, school me on adding another battery. My XM-3150 runs good, but since when is that an excuse for making it run better. Besides, playing with this thing has become my favorite hobby.

I already have some experience at overvolting. I added a battery to my Currie e-zip 750 and it worked out great. I went from 15 mph at 24 volts to almost 30 mph at 36. I’m not expecting that kind of improvement here but if I can increase the voltage on my XM by 20%, I should see an even larger increase in range because I won’t have to push the batteries as hard.

I’ve already ordered another battery, same size and capacity as stock. My plan going in is to simply add the new battery (in the storage compartment) and wire it in series to the top of the stack. I’d like to leave my stock charger across the first five batteries and charge the sixth battery separately with my little Schumacher 12 volt charger set at 4 amps. Here are some of the issues I see:

I’m assuming the stock controller can handle it. From what I’ve read, most people are getting away with it.

I’m a little less sure of the DC-DC converter. I can think of lots of schemes (like powering it with only the first five batteries) but they involve more complications like how do you turn it on? With a 72 volt relay I suppose. Another possibility is to put the new battery on the bottom of the stack and use it for your 12 volt power supply. It’ll be charged separately so balance shouldn’t be a problem. Or I guess I could add another small battery just to handle the 12 volt needs. You’ll still need a relay to turn it on though. The easiest way is to hope the stock converter can handle it.

The stock voltmeter and my Doc Wattson power meter are meant to measure 55-65 volts. Can I just add a resistor to drop my 72 volts back into that range? I’m hoping so. Of course my power readings won’t be accurate but maybe the amps still will be.

Of course the low voltage cut-off won’t work, but I don’t think that will be a problem for me. If you have any advice let me know.

LeftieBiker
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Re: XM-3150 72 Volt Mod

I think you'll run into several problems. First, the 5th battery should be the same capacity as the other five, and that under-seat compartment probably won't hold one that big. Second, I think you are over-estimating the quality and durability of the XM's motor and electronics, not to mention the basic wiring itself. Last, if you can squeeze a large enough battery in there, you are going to make the scooter heavier. If you are small that isn't much of an issue, but if you are heavy, it will matter.

I hear that the guy who builds ZEVs is doing repairs and mods on XMs as well. One that might interest you is adapting his ZEV motor and controller to fit an XM, via a more robust swingarm...

Chasbro
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Re: XM-3150 72 Volt Mod

Thanks for responding Leftie,
The battery came in today. It is the same capacity as the others - 35 aH. I got it from Battery Mart for $59 (but shipping was another $24). If you buy 3 or more, the price drops to $54. Actually, it fits under the seat rather nicely. The bottom of the storage compartment even has a cut out that looks like it was designed to handle it. I weigh around 175 and the battery is another 25. I took it for a ride (not hooked up yet) and it was slightly perceptable. As far as the wiring, the battery cables are especially thick. I would think the Doc Wattson would be the bottleneck. I'll probably install it this weekend. I wonder if I ought to leave the batteries discharged a little before I turn it on for the first time. I'd hate to blow it up right off the bat.

Charles

LeftieBiker
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Re: XM-3150 72 Volt Mod

I'm not sure that the difference in voltage would be enough, between "full" and "3/4", to save the electronics if they can't take it. I'm sure a lot of us are interested to see what happens, but I'm still picturing the little wires that run down from the charging port on my XM-3000...

Chasbro
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Re: XM-3150 72 Volt Mod

Well, today I set about modifying my XM3150 from the stock 60 volts to 72. I have to admit I was filled with trepidation and I don’t even know what that means exactly. I guess it means my scooter has been running good and why mess with success. Going in I had three main fears: 1. would the controller be able to handle it; 2. would the motor be able to handle it, and 3; would the DC-DC converter be able to handle it. First I disconnected the DC-DC converter to see what all would still function. Answer: the red power LED on the dash still comes on and the motor runs like normal. No other lights work. Then I disconnected the voltmeter lead from the instrument panel, along as well as the voltage feed to the Doc Watson (my power meter). Then I temporarily hooked up the extra battery and turned on the circuit breaker. There might have been a slight soft snap sound, but no other signs of duress. Moment of truth time - I turned on the ignition switch. Again, no problem. I gingerly twisted the throttle. The rear wheel spun like normal. So far so good.

Next I plugged the DC-DC converter in and tried it again. Everything OK. I checked the taillight. The brake light comes on with the side stand - good. I tried the headlight - it works. OK it looks like the controller and the DC-DC converter won’t blow up immediately.

Now I needed to do something about the Doc Wattson and the voltmeter. Before, the voltmeter would range from 65 volts at full charge, 60 volts between the green and yellow, 57 volts between the yellow and red, and 55 volts at the bottom. The low voltage cut-off kicks in at 54 volts. The Doc Wattson was rated for 60 volts nominal - 69 max. I put the batteries back to stock and added a 1000 ohm resistor to the voltmeter supply wire. The voltmeter showed 57 volts - great, adding a resistor works. Or so I thought. Once I settled on what I thought was the right resistor (1200 ohms) I put the extra battery in and the voltmeter read 55 volts, not 65. I measured it with an ‘independent’ voltmeter ahead of the resistor - 64 volts. It should be reading 77 volts ahead of the resistor. The bottom line is I don’t know what’s going on with the voltmeter. Maybe it has a zener diode going on somewhere or maybe the controller calibrates it when it turns it on. Bottom line is that no resistor is needed. I hooked the sixth battery back up and both the voltmeter and the Doc Wattson show normal five battery voltages even though there are six.

I put the dash back together and went about adding the sixth battery permanently. What a piece of cake. You do have to take the storage compartment out (which by now I am pretty good at) to get at the battery cables but it’s very easy after that. I relocated my circuit breaker to the inside of the storage compartment. This allowed me to use the same cable from the breaker to battery number six. All I had to add was a cable from the negative of six to the positive of five. I used another piece of that 10 gauge range cord for that.

Next came the highly anticipated first road test. I took it real easy at first and then started to roll into it like normal. The bike seems about 10% peppier - you don’t have to give it as much gas to get the same acceleration. I’m glad I took care of the throttle response problem before I did this. After about 5 miles I went ahead and opened her up - 51 mph indicated (vs. 47 stock) and it might have had another 1 or 2 left if I had room. I brought it back and felt the motor. It was hot - you couldn’t keep your hand on it for more than 5 seconds. The controller was warm too but you could hold onto it.

I plugged in the chargers which was easy. The stock charger still handles batteries 1-5 and I have a little 2-4-6 amp Schumacher for battery number six. It charged up like normal. You know, with some jumper cables you could even give people a jump off of battery number six. I took it for another ride in the evening - it runs great. The voltmeter doesn’t sag as much and now I get tired of riding it before it does. The motor was warm but not hot and the controller was cooler as well.

Although it still needs long term testing, the 72 volt mod is viable. You get more acceleration, top end, and range. The cons are you lose the storage compartment and you gain 20.8 pounds (I weighed it). If you can keep your throttle hand in check I get the feeling it will last. Just don’t turn your teenage grandson loose on it.

Charles

LeftieBiker
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Re: XM-3150 72 Volt Mod

Thanks for the update. Don't take this the wrong way, but are you *sure* that the extra battery is wired in series with the others, not parallel? If it were in parallel that would account for the readings, and maybe even the extra performance, as the extra capacity would reduce voltage sag and allow the controller to possibly put more amps to the motor. Did you get a 72+ volt reading anywhere, at any time, with any instrument?

Chasbro
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Re: XM-3150 72 Volt Mod

Hi Leftie,
Battery six is in series. The pack measures 77 volts from the negative of battery one to the positive of battery six.
I have no idea why the voltmeter reads 'correctly' at different voltage levels. Maybe they designed it to.
I'd like to range test it. I wonder if the low voltage cutout will function. If it's tied to this voltmeter I think there's a chance it will. My max range before was 26 miles 'real world', not 'easy'.

Charles

Chasbro
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Re: XM-3150 72 Volt Mod

I went range testing today with my 15.6 lb toy poodle Max. I alternated between a couple of easy 10 mile scenic routes - mostly 25 mph although I had juice it a couple of times to get back and forth across the river bridge. Result - 42 miles. That’s an astounding 60% increase over my previous best of 26 miles. What’s equally amazing is the ‘gas gauge’ and the low voltage cut-out work exactly as they did with 5 batteries. I even made a high speed pass at the 38 mile mark - it accelerated to 47 mph. I resumed low speed cruising until it finally started stuttering. I measured the voltage as soon as I got back home. The pack showed 55.4 volts and batt six was at 11.5. The motor was warm (ie you can hold onto it). I’m beginning to think this bike was designed for six batteries and was de-rated to squeeze it under the moped limit in some states.

I think I’ve harvested most of the low hanging fruit on this machine. I would like to have the regen capability, but I’m not going to take that sealed controller apart - its sealed really well. I’ll get back with a final report once I get a few thousand more miles on it.

Charles

LeftieBiker
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Re: XM-3150 72 Volt Mod

That's great news. If I hadn't bought the ZEV (and I kind of wish I hadn't, because I haven't had the use of it and the whole thing has been a huge, expensive hassle because of the shipping damage) I'd consider this mod to my 3000. As it is I enjoy riding it maxed out in Low on country roads, with occasional motorcycle-like excursions at 38-40MPH in High. It's really easy to "shift" on mine, with the switch right on the throttle. I always make sure to change settings with the throttle completely off, though.

It's funny: the top speed is only 43, but that last 3-5MPH or so makes a big difference in power consumption. I can probably go 15 or more miles if I don't exceed 40, and slow down on hills.

Chasbro
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Re: XM-3150 72 Volt Mod

Hi again Lefty,
How's the ZEV doing. Any idea on when they'll ship it back?
That was a bad luck deal with the shipping damage. We all take a risk when we order these things. That should be quite a machine when you get it straightened out. I've had some bad luck in the past too. Back in '78 I bought a Suzuki GS1000 and it came with the cams mis-timed from the factory. It took a long time to get that figured out and spoiled a lot of the initial experience but the bike more than redeemed itself. I'm sure your ZEV will too.

Charles

LeftieBiker
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Re: XM-3150 72 Volt Mod

Latest word is the bike will be shipped on Friday - IF the insurance company waives their right to inspect it first. I work Fri-Sun, so I really hope it ships Friday and arrives early to mid (NOT late) week next week. Just in time for the falling leaves and too-cool temps...

As for shipping damage: I got my Lepton on Ebay. It arrived with a slightly damaged pallet and a chip of paint off the front fender. I was kind of irked, thinking i was unlucky. Then, years later, I bought the XM-3000 on Ebay from a dealer clearing out her stock. I "won" it for about $968, IIRC, plus $50 shipping. When that arrived I made the mistake of trying, after unbolting it from its shipping frame, to put it on the center stand while on it, like I do the Lepton. That scooter's response to that situation is to fall over sideways, and it did - pinning me on the cement against the garage door. (I still have scars.) That was only the beginning: it ran, kind of, but had what I'm now sure was a broken loose magnet in the motor. It died after a few short hops. I got parts for it under warranty (thanks to the nice dealer), but it took most of a year to get it completely fixed, because the wiring was also messed up, and the mechanic I hired to install the parts didn't make things much better - at one point, while I was walking over to him holding a multi-meter, he went ahead and made a connection, and the taillight literally exploded - POW. Anyway, the XM had obviously been dropped in transit, and I've only this Summer started to like it. Then the ZEV arrived partially wrecked.

I figure the next scooter I order shipped will arrive in a big shapeless bag that rattles and leaks electrolyte.

Chasbro
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Re: XM-3150 72 Volt Mod

XM-2000 mile update
I’ve got 2K on the clock and everything’s still going. The 72 volt mod doesn’t seem to have stressed anything. I put a windshield on it. I looked in the Dennis Kirk catalog and found a Prima 17” shield for $129. It was made to fit a Kymco People scooter, but from the picture it looked like it would fit mine. It had one review from a guy who said the hardware doesn’t fit - boy was he right. I had to make my own mounting hardware but it wasn’t that bad. I got some 3/8 aluminum rod from the hardware store and bent it into shape. I borrowed some handlebar clamps from my MotoGuzzi and am pleased with how it came out. It even works with the stock mirrors. The bike is really silent now. I found myself cruising 5 mph faster just because it feels so effortless. It’s a big shield and your so close behind it it’s like the wind doesn’t exist anymore. I’ll see if I can include a picture. The big windshield didn’t help my top speed any. I mounted a GPS unit and the most I can get is 47 mph (with the speedo needle pegged at 51). I also couldn’t resist mounting some “running lights” - you know - those blue LED light glow stick looking things. Don’t tell me you haven’t been tempted to do the same thing. Let’s see - what else. I mounted a “cigarette lighter” out of the way just under the ignition switch. I powered it from battery six (which gets charged independently). That’s about it. I like the bike at this level. I think I’ll leave it alone and just drive it. I’d like to have regen, but that’s going to take several hundred dollars for another controller and I can’t see the return on investment there. When these batteries wear out I’ll look at the alternatives.

Here’s a list of all the major modifications:

72 volt mod ($88 for the battery plus $29 for a small 12 volt charger)
Magura 5K Potentiometer throttle ($50)
Prima 17” windshield ($129 + hardware)
Doc Watson power meter ($59)
Light bars ($12 - Walmart)
H4 55-60 Watt headlight bulb ($10)

Here’s one last tip: don’t get rid of your gas powered scooter - you’re going to need it for all those trips to the hardware store and auto supply while you’re working on your electric scooter.

Charles

Iccarus
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Re: XM-3150 72 Volt Mod

I also couldn’t resist mounting some “running lights” - you know - those blue LED light glow stick looking things. Don’t tell me you haven’t been tempted to do the same thing. supply while you’re working on your electric scooter.

GUILTY AS CHARGED
DSC01369.JPGBill 007.jpg
28cell XM3500li, really the equivalent of roughly a 4500li if they made one. lots of torque
Bill 016.jpgBill 015.jpg

At night you really stand out, I like it, but of it's not for everyone I guess.

2008 XM3500li Mods/Kelly KBL12251/84v 28cell 40AH pack/ Variable regen brake trigger on left brake handle/Givi/Cycle Analyst/Homemade BMS

KMX Typhoon Home build (recumbent pedelec) with two Astro Brushless 3220motors/twin castle Phoenix ICEHV 160/ Cycl

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