E-max accelerating over 40mph

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Kmullee
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E-max accelerating over 40mph

Well the sun came out today and I finally got a hold of a video camera so I decided to take a video of my scooters speed like a said I would. It’s kind of hard to see the GPS because I don’t have a camera mount yet so I was holding the camera in one had and driving with the other but if you look closely you can see I made it up to 40.6 mph on level ground. I’ve made it up to 42 mph on a fresh charge before but holding the camera I couldn’t crouch into as much of an aerodynamic position and I was also wearing about 20 lbs of winter riding gear. Anyways here it is.

http://video.google.com/videoplay?docid=6885764429943799951

if you stop the video at 42 seconds you can see the top speed readout on the gps.

Gman
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Kmullee, Nice vid, I didn't

Kmullee,
Nice vid, I didn't know they could go that fast. What model is that?

Peace Out,
Gman

Please stop by the V Refuge for the latest news about the V is for Voltage Recovery effort and status.
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Kmullee
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It's an E-Max Sport but I'm

It's an E-Max Sport but I'm running it at 60 volts. I had posted all the mods on the old V forum, I'll transfer everything over here if this form becomes our permanent forum.

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

PJD
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Battery mamagement?

Keith,

How do you manage the batteries with the 60 volt setup? Since the battery gauge and the controllers over-discharge protection are designed for a 48-volt pack, isnt it easy to over-discharge the pack?

Paul D.

JDELUNA
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Nice Video

Was that accelerating with or without the TURBO button ?? Please post your instructions on how you made it run on 60 volts, as I would like to do the same too.

Also I have always wondered if adding a windshield would help with the speed. Here is one I was thinking of adding to my E-MAX.

http://www.gmimotorsports.com/parts.shtml

Kmullee
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Yes, I was using the turbo

Yes, I was using the turbo button during that run, it will creep up to those speeds without it but it just takes longer. I was also looking at that windshield they are great for cold and rainy weather but in my experience with ICE scooters they will hinder your top speed as they add a lot of wind resistance. I’ll post some more instructions soon.

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

Kmullee
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Yes you can easily over

Yes you can easily over discharge the batteries of you don’t watch it and I did accidentally extremely over discharge the extra hawker battery the first time I tried it but luckily hawkers are rugged batteries and it recovered fine.

My current setup at 60 volts is a 28ah hawker odyssey (less with Peukert effect) in series with the 40ah E-max pack so the hawker will always drain first if both are fully charged, I have a switch that disconnects the e-max battery gauge when I’m running at 60 volts and have a multi-meter measuring the hawker and I just make sure I stop before it reaches about 10.05 volts under load, I’m currently getting about 15mile per charger before the hawker is drained under normal usage.

I plan on using a better battery monitoring system when I get a more permanent 60v battery arrangement. I’m currently looking at my li-ion options because I think the e-max would perform awesome with a light weight 60v pack.

I now feel that with the replacement caps you can run it all day every day at 60 volts with no problems and if I could find replacement Fets with the same specs and in the same package but with a higher voltage I think it cold be run at 72 volts. The controller has a separate voltage input for the logic and you could use a dc-dc converter to step down the voltage for 72 volts but it accepts 60 volts with no problems.

Anyways here is a video of my setup I took before the other video. If you look at leg shield storage area you can see I have a multi-meter there for monitoring the hawker.

http://video.google.com/videoplay?docid=-4196113627723851364&hl=en

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

PJD
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The FETS?

Keith,

As yu've read, while I am upgrading the caps on the controller for my two scooters, currently I'm content with upgrading the amperage rather than voltage. (My bigger tires give me an honest 35-37 mph - fast enough). More torque means faster hill climbing (or climbing some at all) so it means a lot more speed in my hilly neighborhood.

I'd like to see the data sheet for the FETs. Do you recall the number on them? I'd like to see whay kind of current they can accept...

Thanks,

Paul D.

Kmullee
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Yeah, I saw that it looks

Yeah, I saw that it looks really cool and I think I may try that and use larger tires later but it may be pushing the motor if your controller mod is putting out 100 amps at 60 volts that would be like 6 kw but imagine the performance! But anyway those FETs can handle a good amount of current their part number is IRFP2907 Id is 209 amps;

http://www.irf.com/product-info/datasheets/data/irfp2907.pdf

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

PJD
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Benefits of more power

So that 209 amps per FET - and each phase uses four in parallel - not even close; but presumubly more amps means more amps of ripple, so it may be hard on the capacitors.

Going out to lunch just now, I ave it a bit too much throttle on a particularly steep (maybe 20%) hill and momentarily reached 190 amps - yes, even up this hill, it was accelerating. With this unlimited-amperage controller, I have been riding over my regular routes to feel out the maximum amperage I need without being "greedy". I will then redo the mod. for a new, higher-than-stock amperage limit setting. Right now I'm thinking 100 amps. In cool weather higher amperage would probably be safe, but I've got to keep hot summer days in mind.

One thing that isn't an issue is battery range. By simply being moderate on the throttle, I can get about the same range. Safety is enhanced too since the throttle now works like a real throttle - no annoying preamature acceleration "wall". I don't have to ride right up on the rear bumper of a slowing car to keep momentum up in uphill traffic.

I agree that both a voltage and amperage upgrade would probably be puhing it.

rgx
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input and output currents are not the same

Keep in mind that the input current is not directly related to the output, it will depend a lot on the characteristics of the motor. I will try to make a very simplified example. Let's say the max input current is 72A at 48V, that makes 3456 W. Lets also say the controller has no losses, it's 100% efficient.

Max peak-to-peak output voltage is a few volts below the input voltage, lets say 44V. So peak output voltage is 22V, and RMS value is 15.6V. With 3456W total, or 1152W per phase, that means RMS current per phase is at least 74A. Probably more, depending on the power correction factor. (Actually, neither current nor voltage are sine wave for a PM motor, so RMS calculations are simplified as well.)

At speeds below top speed, power will be around maximum in a wide range, but motor voltage will be lower, and motor current higher. Current could be several times 74A, at low speeds. At very low speeds, the controller will probably limit the output current, and power will decrease. I think we have seen and felt this effect around 15 km/h. Basically, the e-max will climb a hill at at least 10-15 km/h, or not be able to climb it at all. Max torque is usually directly related to max current.

This means we can't assume we're safe as long as input current stays below 209A. On the other hand, there is some kind of limiting mechanism on output current which might be independent on the input current limiter, saving the FETs anyway. Not sure how the controller does this. I also remember seing something that looked like a temperature sensor on the heat sink for the transistors, guessing that it is protecting the transistors from overheating.

Regards,
Rolf

PJD
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...

...at any rate the FET literature has this footnote to the Id value:

"Calculated continuous current based on maximum allowable junction temperature. Package limitation current is 90A."

Deafscooter
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Deafscooter READ your 40 mph on 60 volts But Craig's done 58 Mph

This is Craig ( Deafscooter ) Read your video ( hard to read the GPS )

His Emax run on kph ( Kilo per Hour ) 73 Kph on your speedo meter

Deafscooter own EVT Special Edition it Actual 58 MPH and 93.3 KPH

there only 48 volts ( four 12v batteries packs ( not 60 volts version )

Craig Uyeda
Deafscooter

Check out Picutre of my original Asian version E Scooter

this my EVT Special Edition, still current is 5,437 Miles old
http://www.austinev.org/evalbum/popupimg.php?5240

Here is Show 50.9 MPH on road test then Stripped to pieces
http://www.austinev.org/evalbum/popupimg.php?5244

deafscooter

Gman
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I'll transfer everything over here if this form

Kmullee,
You might as well start transferring it.

Peace Out,
Gman

Please stop by the V Refuge for the latest news about the V is for Voltage Recovery effort and status.
http://autos.groups.yahoo.com/group/VRefuge/

Peace Out, <img src="http://tinyurl.com/ysafbn">
Gman

Kmullee
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Yeah I am, it was suggested

Yeah I am, it was suggested that I start a blog about it, but I'm going on vacation for a couple weeks and I've been getting ready for that so I'll probably finish it up when I get back.

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

Kmullee
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Ah thanks I hadn't noticed

Ah thanks I hadn't noticed that.

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

PJD
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correction...

To correct the comment below (dumb me) the brushless commutation requires a pair of FETS per phase to switch between plus and minus polarity. I just realized that's why each phase has a pair of wires coming off the PC board - one for the negative commutation - and one for the positive commutation. They could have put this on the PC board but didn't for some reason.

At any rate, the important thing is that this leaves just two FETS in parallel, for an absolute maximum continuous drain current of 180 amps. But any given FET is "on" a maximum of only one third of the time (1/3 minus the PWM duty cycle). So the actual maximum current is higher. But I'll take 180 amps as the maximum.

Rolf, I'm not sure I understood your remarks. In a brushless PM DC motor, isn't the current just being switched between three sets of stator windings?

rgx
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input and output currents

Paul, I was trying to make the point that output current can be higher than input. The switching does two things, it chops up the input voltage, but it also transforms it to lower voltage and higher current. If you measure 10A/48V (480W) on the input, perhaps the controller is putting out 15A/10V on three phases (450W). Or 30A/5V. Or 20A/10V, if current is not in sync with the voltage (the controller probably tries to keep it in sync, to maximise efficency). Note, motor voltage and current might not be sinusoidal, and peak currents are much higher than these RMS values. The FETs will experience the output- rather than input current, but you're right, they will only sense the output current part time. The rest of the time it will be taken up by the other FET in the pair and by freewheeling diodes, sometimes integrated in the FETs - guess that's how it's done in our controllers.

The lower the speed, the lower the output voltage, and the worse the relation between input- and output current. Be careful with the throttle at low speeds :-)

GrooveConnection
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Of course, we know.....

:jawdrop: You never give that up , do you, Mr Hightech-meister???
Smiles for your resourcefulness, though!!

Kmullee
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Guide

Here is the guide I said I would make on converting the E-max to run at 60 volts, sorry it took so long. http://keiths-evs.blogspot.com/

Keith
2006 E-Max sport @ 60v

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

PJD
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Re: Guide

Nice guide. I'm always too impatient to document my work as well as you did.

I have also upgraded the capacitors on my old controllers so I'm ready for such a mod. But, in the old-style controllers with the smaller case, the bigger 100 volt capacitors don't quite fit, unless recesses are ground into the controller cover over each capacitor. You need to put some kind of marking material on the tops of the cap, close the cover, look for marks, grind away, (make sure aluminum shavings stay off the pc board!) recheck, regrind etc - like a dentist does.

But, after all that, after having made the amperage upgrades, I am looking at another approach for more motor speed - keeping it at 48 volts, but rewinding the motor with heavier wire and fewer turns - lower the inductance about 20%, raise the RPM's by 20%. The amperage increase will offset the trade-off in torque.

This is could be simplified because the windings are on the stationary part of the brushless hub motor - no balancing concerns. But, I'm a newbie doing pure experimentation, so I really need a spare E-max motor before I will try this.

I'll entertain offers from any e-max owners or former dealers out there...

PJD
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Re: E-max accelerating over 40mph

Keith or others,

I think the best place for this is in your old thread.

I an interested in a making the 60 volt modification for my e-max user-selectable while riding, while preserving the stock power to the accessories and other features - the charge gauge and over-discharge protection cutoff, the DC-DC converter, the controllers internal voltage regulator.

Because running it at 60 V will be intermittent, I can get away with just one 20AH booster battery and preserve most of the under seat storage. I plan to do it like this:


            Click to Enlarge.

The key-switch circuit which closes the circuit to the red logic wire and relay solenoids is removed for clarity.

I already changed to the 100 amp capacitors when I did my amperage increase modification. The mod makes use of the e-max's existing dual-relay setup one of which is currently unused since changing the battery pack to series-pairs.

My question (primarily for Keith since he has the e-max experience) is, do you think something bad is going to happen if the main power wire voltage is different than that for the red wire which provides 48 switched volts to the whose function seems to be for turning on the controller logic and drivers?

Kmullee
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Re: E-max accelerating over 40mph

That’s a good idea using the extra relay for the 60v selection and I cant wait to hear how your performance is with your larger tires and current mod, I’m guessing maybe 45mph+. The controller logic and the DC-DC converter both run fine with the 60v pack so I have not tried running the controllers logic power form a different voltage but I’ve thought of that when looking at my 72v options and I don’t see why it shouldn’t work as from what I can tell the Logic and the motor power are totally isolated except for where the logic controls the Fets and measures the current and voltage. Also maybe you just didn’t include this but your circuit diagram doesn’t show your key switch so I would probably do something like this;
60VRewire2.jpg

Keith
2006 E-Max sport @ 60v

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

PJD
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Re: E-max accelerating over 40mph

My schematic was just to illustrate the concept but yes, the key switch circuit will be in there.

One thing I've noticed that make me wonder if it will work is that, with the black box eliminated or bypassed, there is this a one-second delay between turning the keyswitch off and "click" of the relay opening. Have you noticed this? I thought it might mean the relay is being kept momentarily closed with stored charge from the big capacitors - via that red wire - meaning they are connected somewhere in the circuit and I would create a 12 volt short-circuit in the controller.

Ideas?

reikiman
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Re: E-max accelerating over 40mph

My EVT4000 has a very similar turbo mode that was built by Todd Kollin at Electric Motorsport. Mine is the only one he did, the 60 volt mod they sell today is a different design. They put in some resistors or something to make sure I couldn't switch in turbo mode until the bike was at around 20-25 miles per hour -- actually, when the power level was high enough, because I can make the turbo mode go on while it's standing still on its kickstand.

From my standpoint there's a button near where the right thumb rests. I twist the throttle, get up to speed, and if I need turbo mode I hit the button. Very simple.

What it does under the hood is switch the power circuit around in a way similar to your diagram. The motor is fed 60v direct from the pack. Which gives the bike a second wind and probably gets up to 40 miles/hr. However the fastest I could register using the GPS unit was 37 miles/hr.

It's useful mostly for those situations where you need a bit of speed to get out of a dicey situation. Or for those days you just want to ride extra fast.

- David Herron, http://davidherron.com/

- David Herron, The Long Tail Pipe, davidherron.com, 7gen.com, What is Reiki
- Electrified Electra To

Kmullee
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Re: E-max accelerating over 40mph

I can't say for sure if wiring the controller in that way would cause problems by causing a short but it does seem to be what they are doing with the EVT 60v mod. As for the delayed relay switching off I believe its caused by the inductance of the relays coil and if you are using a wire wound resistor in series with it for the higher voltages like I have that also adds more inductance.

Keith
2006 E-Max sport @ 60v

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

PJD
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Re: E-max accelerating over 40mph

Update:

I rigged up a booster battery at the relay and things worked well - the battery gauge continued to measure the voltage of the 48 volt main pack. I didn't road test it, but on the stand at open throttle, the rear wheel spun at dramatically higher RPM's.

So I am ordering the 48-60 selector switch. I want a SPDT rocker switch that has a middle off position - to avoid any chance of both relays being momentarily closed, which would short the booster battery. Looking on the Mouser site, SPDT rocker switches are denoted like this:

On-Off-On; or,

(On)-Off-(On);

What does the parenthesis denote? Is the "On-Off-On" switch the one I want?

rgx
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Re: E-max accelerating over 40mph

The brackets only signify that the switch doesn't stay in that position. I guess you want an On-Off-On type of switch. Without brackets.
To compare with the e-max switches, the horn could be described as Off-(On) type of switch. The headlights are Off-On-On.

Kmullee
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Re: E-max accelerating over 40mph

Nice going Paul I’m eager to see your results at 60 volts with your current mod and the larger tires. I have replaced my hawker battery with two BB HR22-12 batteries and was getting about 25-30 miles range at 60 volts and the weight doesn’t seem to be a problem but I probably weigh a bit less then the average rider. I think my batteries are starting to show their age though, I have over 3k miles on them now (witch seems to be the mature age for the e-max batteries) and I’m starting to see a range decrease.

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

Keith
2006 E-Max sport @ 60v
http://keiths-evs.blogspot.com/

PJD
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Re: E-max accelerating over 40mph

Few comments:

My concern isn't the added weight of the batteries as much as the volume. I use the under-seat storage space a lot. On gorcery runs both the trunk and under-seat space get filled.

But, it will take only a screwdriver and a minute or two to add another 20 ah battery if needed.

My silicone pack went downhill at about 3000 miles as well. But only three batteries had degraded to an intolerable level (<10AH at C/4 or so) So, I still have five silicone batteries as spares.

My usable range may always limited to 18-20 miles because of an unaviodable hill climb getting back home from nearly any direction. Curiously, the higher amperage controller setting has had no noticable effect of the range - but has "opened up" access to areas that were inaccesable on just 70 amps!

PJD
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Re: E-max accelerating over 40mph

I completed my selectable 60V configuration today. Works like a charm. Operation on 48 volts is fine most of the time, but if I need more speed or torque, I simple flick the switch. And, I can still fit a lot of stuff under the seat, including my helmet, so this objective was met too.

I'll include some pictures soon.

As far as the new top speed, there are no level roadways in my immediate neighborhood, but on a roadway with a constant slope of about 4%, the speedometer indicated 49 mph going downhill and 42-43 mph going uphill, still accelerating a bit when I had to stop for a traffic light. The speedo error is known to be 1-2 mph fast at 35 mph. so, correcting and averaging, this would suggest a true top speed of 44-45 mph. I will be riding on a nearly-level usually empty stretch of road tomorrow on the way to work tomorrow, so I'll report back.

The combination of the higher voltage and higher amperage limit makes for impressive hill climbing and acceleration - but at 60 volts plus "turbo" mode, it may be a bit "too impressive" as far as being hard on the motor or controller.

My e-max is now a far cry from what came out of the crate 20 months ago. Now, I could only do something about the idiotic mocking from all the young paleo-burbanites here in the "south hills". Boy, I regret moving out of the city. Bet you don't have such problems, even in the suburbs, in a green-progressive town like Portland, eh Keith?

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