What's inside! .. ?: Razor E300 Scooter

[eccerr0r]

Well, I was working on an Razor E300 scooter and first off the batteries were dead. Well duh, that would explain why it won't work. However what was interesting is that I noticed a heatsink on the control module... I wonder if I should open it and would anyone notice...

Anyway I did see videos about the E100 scooter which has two relays. From what I gather, it seems that one relay is to turn on the motor, but the other one I'm not sure about. Whether this translates to the E300 I don't know. The heatsink seems to indicate it has transistors, alas it still has at least one relay as it clicks.

I was also wondering if it were possible to add regenerative braking for riding it in hilly places, but that got quickly dashed by the ratcheting mechanism of the rear wheel. Oh well. The newer direct drive units seem to be the way to go, and not this chain drive ⅓HP motor...

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I thought I found a reason to open the box but turned out to be due to the charger circuit telling the scooter to not go when it's plugged in. Drat. Thought I was getting somewhere when I got the batteries to read out 13.x volts but nope. So with the charger disabled, it ... well ... tries to power the motor, alas unsuccessfully. Battery voltages plunges like a rock, so we know the batteries are still sick, though at least it's still drawing some current while charging...

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

Wow. I see spinning. Yep the batteries were completely gone, though I somehow got enough charge into them to finally get the motor to spin. About 200mA is charging through now, though at 200mA and 7Ah is a long time to charge.

Seems like this cheap crap scooter has a 1-speed on/off "throttle" - now, I don't get what's with the heatsink, now I'm *really* wondering what's in the box... There's definitely a relay but relays don't dissipate much heat...

7Ah * 24V = 168Wh... hmm... store energy...

[Curious.George]

Re: What's inside! .. ?: Razor E300 Scooter

Seems like this cheap crap scooter has a 1-speed on/off "throttle" - now, I don't get what's with the heatsink, now I'm *really* wondering what's in the box... There's definitely a relay but relays don't dissipate much heat...

It's a PWM controller. The throttle controls speed by altering the duty cycle. As the MOSFETs are eitehr full on or full off, the amount of power dissipated there is "manageable".

7Ah * 24V = 168Wh... hmm... store energy...

60AHr * 24V = 1440WHr in my electric wheelchairs (many have even bigger power packs... and that's before changing battery chemistries!)

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

Ouch batteries are really shot. As of right now, each battery pack OCV is ~11.8V and DC ESR is almost 1Ω estimated. Seems the expectation that the ESR should not be above 300mΩ or so.

Seems speed control is nonexistent or at least not normally accessible. Might have to hack in something to allow easy speed control. I suspect that using this thing at 5mi/hr is probably not very practical, and people would rather just it go up to the maximum speed of 15mi/hr.

Wonder if it's worth to mod for another battery chemistry to do away with SLA, and perhaps with those it might be worth to figure out how to temporarily lock the chain to the tire so that some regenerative braking solution could be made.

I also wonder if regenerative braking is more valuable for heavier people. For me with the scooter's limit of 220lbs, I could carry a few extra battery packs without issue...

Next problem is that there's no theft prevention for these things. Nevermind one could just lift it up and dump it in a car, one could just joy ride it away as long as the battery pack has charge...

Hmm... The practicality of these things...


Hooray found a picture of the guts so I don't have to tear it apart!

https://hackaday.io/project/9941-the...-e300-overvolt

[Curious.George]

Re: What's inside! .. ?: Razor E300 Scooter

Seems speed control is nonexistent or at least not normally accessible. Might have to hack in something to allow easy speed control. I suspect that using this thing at 5mi/hr is probably not very practical, and people would rather just it go up to the maximum speed of 15mi/hr.

Speed control is only obvious for "lightweight" riders. Motor torque drops with speed so heavier riders effectively only have one choice: full throttle (cuz the motor is undersized).

I've rescued and refurbished 6 of them. Found homes for 4, so far (two more in the garage waiting for parts). As they are most useful for lighter/younger kids, I've found parents aren't keen on having their kids able to run "flat out" (as the kids lack the skills to evaluate their risks in doing so). So, I modify the scooters to set an artificial upper limit on their speed -- a simple hack.

[Sadly, it's not practical to harvest parts from smaller scooters as they, too, are sized to JUST accommodate their intended riders. So, I just let the smaller ones go directly to "scrap". Unfortunate, for me, as providing fresh batteries, labor/knowhow AND having to purchase replacement parts out of my own pocket tends to disincentivize me from refurbishing every scooter that comes along (if I could salvage parts from the smaller scooters then I wouldn't have that last expense!)]

Wonder if it's worth to mod for another battery chemistry to do away with SLA, and perhaps with those it might be worth to figure out how to temporarily lock the chain to the tire so that some regenerative braking solution could be made.

I also wonder if regenerative braking is more valuable for heavier people. For me with the scooter's limit of 220lbs, I could carry a few extra battery packs without issue...

Don't bother. If you want to make a scooter for "heavier people", then start from scratch. You'll find that the frame, tires and motor aren't really appropriate for an "adult".

Next problem is that there's no theft prevention for these things. Nevermind one could just lift it up and dump it in a car, one could just joy ride it away as long as the battery pack has charge...

As they are small and lightweight enough, there's no real reason you'd need to "leave it" unattended. Just carry it into the store (or wherever) with you.

My electric wheelchairs are similarly "unprotected". Yeah, I can shut down the system ("lock it") but anyone with any experience would know how to UNLOCK it! The thinking being that you're likely IN the chair if you need a $40K chair and not likely to leave it sitting, unoccupied, outside the store! :-/

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

While this doesn't handle the lift and go theft, I wonder if faking a dead battery is sufficient as a deterrence. Say it has a bluetooth or nfc module and looks for your phone. If not present, drive at 1mi/hr and conk out in 10 feet.

Well this was an old fashioned car theft deterrent where one could let the engine start and only run for 5 seconds and stall... making a thief's life miserable, hopefully abandoning the car and looking for an easier target to move...

[Curious.George]

Re: What's inside! .. ?: Razor E300 Scooter

While this doesn't handle the lift and go theft, I wonder if faking a dead battery is sufficient as a deterrence. Say it has a bluetooth or nfc module and looks for your phone. If not present, drive at 1mi/hr and conk out in 10 feet.

A would-be thief who THINKS would realize that having the scooter WITHOUT THE CHARGER makes the theft meaningless; the only value would be if a NONTHINKING "customer" could be found to take it off his hands.

I refurbished a heavy duty, extra wide electric wheelchair some years ago. TWO people could sit side-by-side on this one! (intended for very FAT users!).

One evening, it was left in an unprotected area. Someone cut the chain link fence and drove it off the property (batteries were installed and charged).

The only "loss" was the materials required to repair the fence; the chair had been donated so didn't represent any out-of-pocket costs. Nevertheless, I wasn't happy that my time had been wasted!

OTOH, the thief would find -- in a day or two -- that the batteries would need a charge. And, he'd NOT have a proper charger to do this. So, now he'd have a very large, bulky, HEAVY (several hundred pounds) chair that he'd have to figure out how to discard! No, you're NOT going to lift it onto the back of your pickup truck! And, as the batteries are flat, you'll have to PUSH it to <wherever>...

Anyone THINKING about stealing a scooter would find themselves in a similar situation; once the batteries go flat, you've got a piece of trash on your hands!

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

Awesome! Got the batteries to charge enough to run the motor at nearly full speed when lifted off the ground! Need to check OCV and ESR again but at least the scooter does somewhat try to get away from me when operating the throttle. Whether the batteries are still good enough to carry someone around is another story, and I'm curious what the current current draw is -- originally it probably was around 10 amperes steady state, which would mathematically make sense for a ⅓ HP motor. (also I wonder how much more current it draws/mechanical power it creates while accelerating, or is this ⅓ HP rating was meant only during acceleration and not during cruising.)

At least this scooter seems to be quite sturdy, though unfortunately at a cost of weight. Pretty much all steel design though still "light" enough to be a victim of lift and go. I do wonder about the hackaday page overvolting the motor - whether or not the motor actually will overheat being driven more than ⅓ HP, though it would be nice to have more reserve power versus additional speed.

That and having a different charging system, looking at how the circuitry is wired, unfortunately 10 hour charge time is indeed the limit of how the wiring is done. Might have to figure a way to charge them directly to reduce charge times - charge at C/3 instead of C/10, though not sure what impact faster charge rate has on lead acid.

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

Excellent! I forgot I had a 0-20A ammeter that I was using with my solar experiments that maxes out at about 6A. So this ammeter is better suited for the scooter.

Again the scooter does try to get away from me when turning it on so that's a good sign, though unsure what it will do with my weight on it. Anyway I did see it drawing 5A when the tire is lifted off the ground. I also see it drawing about that much if I jammed the scooter so that it wouldn't move (should this be possible in a properly working battery system?). Perhaps it is trying to ensure that it doesn't waste energy/burn up motor if it's stuck, but then there's also that circuit breaker that would be redundant. Maybe just to lessen the chance of the scooter running away without the person on it. Uh, no idea.

Needs a test drive soon, though wonder how far I can go and not have to walk home with it. So much for bottom of the barrel, there's no battery state monitoring at all.

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

Hmmm maybe expectations here...

It seems to struggle to move with me standing on it, though it does move slowly. Maybe we're not supposed to make these skateboard with a stick scooters start from dead stops and just use good old foot power to start it going, then only use the motor for steady state? Then again the owners manual seems to indicate it should be able to start from a dead stop...

I'm surprised it seems to be a lot easier to balance upon than a regular bicycle, most likely due to its wider wheels. At least it's sort of possible to somewhat stay upright on it while still (though better to still have a foot on the ground) unlike bicycles where you need to be moving to keep the inverted pendulum upright...

Need to get with the times I suppose... ?

[petehall347]

Re: What's inside! .. ?: Razor E300 Scooter

you could check battery voltage whilst setting off to see where it drops to .

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

Yeah, need to somehow jury rig a way to monitor battery voltage while standing/riding it. Especially dangerous as the rider should be looking ahead and not down at the meter...

Still seeing 7 amperes peak while trying to get it going from a dead stop, staying around 5 amps. Current draw is only 3 amps or so when the tire is lifted from the ground.

At least the batteries still could be used for something other than the scooter, not completely useless yet.

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

Hmm... proper words used to move one of these "skateboard with a steering stick" scooters appears to be "kicking" them from a "kick scooter," though this electric one isn't going to be pleasant due to its weight from the steel frame... Don't care if you're a soccer player or whatnot, kicking 50+ pounds is not going to make it go very far.

However due to the ratcheting chain drive, "kicking" is still very possible, though it would be nice if it could be locked to the chain and hence have the ability to charge the battery. Because of the ~2:1 gear ratio, yes "kicking" the scooter with the chain bearings, motor bearings, and passing over magnetic regions (even worse if it's generating electricity), yeah it would not be pleasant if that needs to be overcome along with the weight. Still if the battery's low and after you "kick" it up a hill, that other side of the hill would be nice to get bit of that energy back...

Incidentally, despite the virtually useless for emergency C/10 charger, I wonder if one should carry it with them when using electric scooters. As an aside it seems the one I'm working on, there's a residual charge current at about 200mA after the pack is full, which is lower than C/20 which should be "okay" for SLA but probably not healthy for them long term...

[stj]

Re: What's inside! .. ?: Razor E300 Scooter

what type of motor is in these things then?
3phase?
brushed?
are they fixed magnet type or with outer aux coils?

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

It's a brushed DC motor. Whether it has a PM or electromagnetic stator I don't know...

[stj]

Re: What's inside! .. ?: Razor E300 Scooter

brushed is too bad.
if it was multi-phase you could use predictive vector-drive to push the torque through the roof.

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

Seems people have been simply increasing voltage to bump up the torque/speed as the webpages listed above. But if it's an electromagnetic stator, it will be trouble trying to get power output from it as there's only one pair of wires on the motor.

Apparently the controller does try to limit current, if I try to hold back the scooter it will grudgingly go, but if it gets a little movement, it seems to really want to go. Not sure if this is expected behavior however.

Unfortunately I'm not versed in scooter riding so it'll be a while before I can figure out how fast it goes and whether it's up to spec or not. Probably will need to use a GPS or time out a mile or something, then perhaps I can use that data and count wheel rotations to have its own speedometer. Alas kicking a 50 pound piece of steel and lead down the road for a mile (worst case) will not be fun if the batteries run out before the testing completes.

[stj]

Re: What's inside! .. ?: Razor E300 Scooter

it may be an intentional restriction for legal reasons.

electric start is an electric vehicle,
but if you have to kick off then it's classed as electric assisted.

[Curious.George]

Re: What's inside! .. ?: Razor E300 Scooter

Yeah, need to somehow jury rig a way to monitor battery voltage while standing/riding it. Especially dangerous as the rider should be looking ahead and not down at the meter...

There is a crude (full/low) battery gauge on the throttle. Though I can't recall the trip point for "low" (if it winks while trying to get moving, it would suggest the batter is drooping significantly)

Still seeing 7 amperes peak while trying to get it going from a dead stop, staying around 5 amps. Current draw is only 3 amps or so when the tire is lifted from the ground.

It's only a 250W motor so you won't see more than ~10A.

Note that you should double-check all of the wiring connections as I've found scooters with large losses in the "ties".

[eccerr0r]

Re: What's inside! .. ?: Razor E300 Scooter

What the heck. Seems like older E300s had a battery gauge, and the newer ones omitted them. Weird.

Plus it's a 4-wire throttle cable, of which is connected to an on-off switch - like the older ones. What's really weird is that the intermediate versions have 5-wire throttle cables.

I wonder if the battery information is still coded in the wire somehow and just simply not displayed due to the lack of LED hardware...