New scooters to modify curtis & s-drive

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New scooters to modify curtis & s-drive

Postby Mkay » 25 Aug 2019, 10:50

Good Morning

So last week I received a mk1 Horizon Aztec and tomorrow I will receive a Vita S. This will leave the old Vita X for experimenting...

The Vita S has the 140amp S-drive controller, first I will try the 200amp S-drive in it to see if it works in that one but if not it will be going and the 140a back in for the time being.

The Aztec has a Curtis 1217-2402 which is a little plastic box and says 200amp max 70amp continuous, it is thrown rather unceremoniously in the rear compartment unsecured and without a heatsink, which I thought a bit poor considering the standard of manufacture of the rest of the scooter.

I dont want any extra speed and I dont want to use momentum to carry me up, I want to modify the components until is it meets (my fairly reasonable) expectations.
Anyway, when testing it has the same problem- when it meets too steep a hill or curb it just fails to move, I think this is what I have heard referred to as Motor stalling.
From here and buggies gone wild I think what I need to do is allow the motor more access to amps, so a more substantial controller, one that offers more continuous amps and longer access to max amps and. larger cables from controller to battery. (as opposed to a new motor)

am I right so far?
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Re: New scooters to modify curtis & s-drive

Postby Burgerman » 25 Aug 2019, 11:03

It all depends...

Also on motor impedance, battery impedance and peukert, and on controller programming. As well.
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Re: New scooters to modify curtis & s-drive

Postby woodygb » 25 Aug 2019, 11:11

I assuming that you mean a Curtis 1227-2402 or 1212-2402 ?
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Re: New scooters to modify curtis & s-drive

Postby Irving » 25 Aug 2019, 11:24

The ability to move is all about torque and torque is proportional to current (A). So, in theory, give the motor more current and you get more torque, more motive force. But that assumes, as BM points out, many things, starting, obviously, with whether the motor can handle more current without burning out - and that depends on the design of the motor, it's electrical resistance and it's ability to shift heat out of the windings.

Even then, being able to handle more current is not the same as being able to provide more current. A better controller is a start, but unless the overall system can step up to the task without the voltage dropping too far (due to internal resistance of the batteries - the Peukert effect - and that of the wiring) which may be unlikely without moving to larger batteries or a different technology and ensuring the wiring is suitably sized.

In short, a change of controller and wiring may help, but equally it may be short-lived as something else gives up the ghost.
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Re: New scooters to modify curtis & s-drive

Postby LROBBINS » 25 Aug 2019, 14:26

Ask yourself first some questions about the batteries. What type are they? How old are they? Have they ever gone more than a few hours (driven much or only a little) without being fully re-charged (with a charger that has the correct output for the battery type, which can be very hard to find)? What is the voltage with the scooter on, but not moving? What is the voltage when moving on a level surface? What is the voltage when trying to go uphill? Are all of the connections battery to controller and controller to motors clean, bright and tight?

If the batteries are poor quality, or "tired", you will not be able to draw enough current no matter how capacious the controller because the voltage will drop more or less severely when they're under load.
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Re: New scooters to modify curtis & s-drive

Postby Mkay » 25 Aug 2019, 15:52

yes woody 1227 2402

would the programming lower torque? I thought that would just effect speed and accel/deceleration

assuming I change the controller24-36vx500a, cables25mm and batteries(low resistance lead)

how do I find out the motor impedance

can I calculate how it will tolerate more amps or do I have to try it and see if it survives(if it doesn't are we talking fire or explosion?)

also there is the option of swapping out a supersport transaxle and motor, the SS has 20"wheels so installing it with 10" wheels should halve the speed double the torque- which I could then compensate for with 32-36v?
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Re: New scooters to modify curtis & s-drive

Postby woodygb » 25 Aug 2019, 16:15

Controller Specs seem more than enough to run a decent motor from GOOD batteries.


1227-24XX 24 v ( nominal ) Current limit = 200 A Current for 1 MIN = 200 A 1 hour rating = 70 A voltage drop @ 20 A = 0.08v under voltage cutback @ 16v


If you know the motors resistance you can find the stall current.

You can measure the motor resistance with a VERY GOOD QUALITY multimeter ...but most meters are crap for accurately measuring very low resistances.
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Re: New scooters to modify curtis & s-drive

Postby woodygb » 25 Aug 2019, 16:29

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Re: New scooters to modify curtis & s-drive

Postby Mkay » 25 Aug 2019, 16:51

I will have to get a d cell.

unless https://uk.megger.com/digital-clampmeter-dcm340 will be sufficient?
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Re: New scooters to modify curtis & s-drive

Postby Burgerman » 25 Aug 2019, 16:57

What you really need is a little knowledge. And some measuring tools.

A basic volt meter to look at battery volts both during charge, and 24 hours after charge. Then the battery volts UNDER STALL LOAD. Remembering that as you approach a low voltage of 16 to 18 volts, the controller reduced the current to prevent this falling further.

So you also need a clamp meter, to watch the MOTOR (not battery) amps under load too. To see if it is your limiting factor.

Now...
If you know the battery volts. The motor volts. And the motor Amps. You can also determine the impedance of the motors too.
For e.g if the controller is at its max 160A, while the battery is at say 24V, and the motor volts are say 12V, then you know that the motor draws 160A at 12V. Ohms law tells you its DC resistance. (impedance is very similar value). It also tells you that the battery was not the problem, and that the motors are of low enough impedance that the controllers current limiting was the limiting factor. And that it was at 50% pusewidth, so that the battery amps were half of the motor amps, and that the only way to increase torque would be a higher amp controller (as long as that dosent smoke the motors) or lower speed gearing. Or both. It also tels you that if there was no controller at all and you were to connect battery to motor directly at stall it would pull 320A from the battery. If the battery voltage didnt collapse, and it will. Your actual figures will of course vary and show you whats happening.
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Re: New scooters to modify curtis & s-drive

Postby Mkay » 27 Aug 2019, 17:50

ocv 26.2v

stall voltage batter 24.3v

stall amp battery 65A


motor volts 25.3v

motor volts at stall 23.5 v

motor amps 193 A
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Re: New scooters to modify curtis & s-drive

Postby Burgerman » 27 Aug 2019, 18:32

ocv 26.2v
stall voltage batter 24.3v

Sounds too high. typically 19 to 22V. Which suggests you were not taking full battery current. Maybe because you waited too long and the controller rolled back power.

stall amp battery 65A

Sounds correct.

motor volts 25.3v

Free running? Sounds correct.

motor volts at stall 23.5 v
motor amps 193 A

If that motor voltage was correct, and I suspect not then motor Amps at 193 means that battery ams at stall would be around the same. And they were 65. So I suspect the correct motor volts at stall is around 193A div by 65A or approx 1/3rd of battery volts.

So your motor should draw 193A at 8V which sounds about what would be expected.
So you will gain some torque by swapping to a bigger Amp controller.
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Re: New scooters to modify curtis & s-drive

Postby Mkay » 30 Aug 2019, 16:40

I will check again, it did start low and then jump up.

If I put in a curtis 1205m 500amp controller will I be able to use the programming to reduce the current until I replace the motor?
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Re: New scooters to modify curtis & s-drive

Postby Burgerman » 30 Aug 2019, 17:22

I would imagine so. But if you go above the manufactrers choice of controller, by more than say 15% you will likely end up burning the motor up if you load it heavily.
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Re: New scooters to modify curtis & s-drive

Postby Mkay » 31 Aug 2019, 10:15

Do they just overheat and die or will it go up dangerously?

There was a thread on building an off road chair in which Shirley was posting images of trans axles with motors on and you pointed out it did not have English translation. I cant remember nor find the thread again? Any idea which it was?
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Re: New scooters to modify curtis & s-drive

Postby Irving » 31 Aug 2019, 11:08

Mkay wrote:Do they just overheat and die or will it go up dangerously?

There was a thread on building an off road chair in which Shirley was posting images of trans axles with motors on and you pointed out it did not have English translation. I cant remember nor find the thread again? Any idea which it was?

Worst case, it will catch fire though there's relatively little flammable material in a motor. Usually something melts and breaks the circuit first. But its a risk.

Another possible issue is the winding gets hot enough (approx 150degC, normally runs <85degC) to demagnetise the magnets which means the motor loses power and that will exacerbate the overheating....

Either way the motor's a goner...
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Re: New scooters to modify curtis & s-drive

Postby Mkay » 31 Aug 2019, 14:14

Ok, small fire extinguisher needs mounting..

What are the important specifications to look at for a scooter? Scooter motors are all to small and golf cart motors to big.I found some go cart motors but they are all pancakes I tried d&d in the states but they are slow getting back and I hear very pricey. I would rather spend big money on big calb cells.
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Re: New scooters to modify curtis & s-drive

Postby Irving » 31 Aug 2019, 15:59

You could look at rewinding the existing motor. How practical that is depends on its internal construction. And the only way to determine that is to open it up.
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Re: New scooters to modify curtis & s-drive

Postby Burgerman » 31 Aug 2019, 18:45

Also brushes. Weak point. Increase current and they burn.
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Re: New scooters to modify curtis & s-drive

Postby Mkay » 01 Sep 2019, 08:35

If I did open up the original motor and posted photos of the wind ings would this be enough information to determine whether improvement is possible?

BM you have said before that a good motor is better than a big motor.. If I am to have one rewound (potentially) would it be better to start with a larger motor?
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Re: New scooters to modify curtis & s-drive

Postby Burgerman » 01 Sep 2019, 09:50

Rewinding isnt practical. For several reasons. If you want more torque, you need a better battery system, a more powerful controller, heavier wiring, more substantial motor internals inc magnets, commutator, brushes, cush drive, gearbox internals etc.

Or you need a gearbox with half the mph, at double the voltage to get the same speed as now which means a different controller.
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Re: New scooters to modify curtis & s-drive

Postby Mkay » 01 Sep 2019, 10:05

Do you have any guidance on how to identify a good motor? Meeting the specs you mentioned
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Re: New scooters to modify curtis & s-drive

Postby Burgerman » 01 Sep 2019, 10:21

Physical size, so strength in gears etc, high current capabiity, high stall current, low gearing, and above all low impedance.

If you want a substantial performance increase you are going to need to break a few eggs. Basically a mobility vehecle has the wrong everything to stand much chace of being useful off road.

I would not really consider electric power in any eal off road capable device because even if you build something with adequate brushless, high power motors etc, and figure out how to do a high voltage brushless controller system, then its still going to be a little battery limited.

Wills 48v BRUSHLESS lithium, low geared, low impedance setup, is basically as good as you will do and headed in the right direction. Thats the sort of thing you must be looking at for any kind of sensible off road use.

Have a read of wills thread, and he roboteq brushless stuff in the roboteq thread etc. To get some idea what we are talking about.
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Re: New scooters to modify curtis & s-drive

Postby Burgerman » 01 Sep 2019, 10:24

Physical size, so strength in gears etc, high current capabiity, high stall current, low gearing, and above all low impedance.

If you want a substantial performance increase - and you do - you are going to need to break a few eggs. Basically a mobility vehicle has the wrong everything to stand much chace of being useful off road. It doesent much matter which parts you upgrade individually. The whole system needs to be different to see any major advantage.

I would not really consider electric power in any real off road capable device because even if you build something with adequate brushless, high power motors and higher voltage setup etc, and figure out how to do a high voltage brushless controller system - not simple, then its still going to be a little battery limited for REAL off road/steep slopes etc. A petrol powered lighter solution makes way more sense. And 10x cheaper. Theres lotsof stuff available cheap.

Wills 48v BRUSHLESS lithium, low geared, low impedance setup, is a wheelchair, needs to go indoors so batteries make sense. It is basically as good as you will do and headed in the right direction. Thats the sort of setup/thing you must be looking at for any kind of serious off road use. It works because higher voltages and slower hearing increases efficiency enormously. And lithium can then cope.

Have a read of wills thread, and he roboteq brushless stuff in the roboteq thread etc. To get some idea what we are talking about.

viewtopic.php?f=2&t=8845

And take a look at his website. He needed to do this because like you he wnted more off road capability. And small incremental improvements are pretty much a waste of effort and $$$ when you look at the system as a whole. Will did this as he lives on a farm, works hard in both engineering and his home. A standard brushed 24V powerchair doesent cut it.
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Re: New scooters to modify curtis & s-drive

Postby Mkay » 02 Sep 2019, 14:55

Will do cheers. That's the plan, 36v 200ah calb, 500amp controller and 25mm cables, just going to do it in stages.going to post and see if Shirley remembers those ev axles he posted.

Tried using ice vehicles but got fed up of being shouted at and threatened. Spoils every day out.
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