nameless china scooter, controller speed limit help required
Hello,
I've got myself some 800w 48v electric scooter a year ago, use it for closeby work and shopping trips, problem is with the 45km/h speed, i'm constantly in the way of traffic and badly need a 5-10km/h boost so that everyone doesnt have to pass me.
I was searching around and found out nice kellycontrollers with regen abilities and all cute configuration optins but thats 200$ that i cant currently afford right away, and hey i've got a working scooter, so maybe somebody knows where and what limits me, took some pictures.
I didnt find anything seemingly simple like jumpers.
i'll upload front and rear view of controller board
is there anything to pass simply or it requires programming thats beyond my tools?
thanks for your time, if you know this stuff.
If closer pictures of details required that can help, please do tell
You probably need more volts, and it would probably cost a lot more than $200 to do it right. At the very least you might be able to add one battery to up the volts, but it might fry your controller or motor or both.
It just seems to me that even on a brushless motor geared for speed, 27mph is fairly fast for 48v. Have you looked into changing the gear ratio in order to sacrifice torque for top speed? That might be an option, but get some1 elses opinion. I'm no expert.
Well i figured that this 45km/h limiter is not just battery power but controller limit too, i would not mind a little range drop for the added speed (when i use it, doesnt mean i must use full throttle, just need it possible), extra battery is good too i'm sure but yeah that again costs a little.
Does the shunts have something to do with limited power sent to motor? i see two with holes for third.. heres a pic
some controllers have an explicit max speed programmed in (basically above this speed, power = 0)
if your controller is programmed this way, either you change the gearing, or ditch the controller and get a new one (the kellys ones are top notch IMO)
if you are limited by back-emf, then you will need a higher voltage battery pack, and maybe a new controller anyway.
most "48v" controllers will run fine with a 60v battery pack. some go snap crackle and pop. YMMV.
my original emax 48v controller i ran at 60v for 15'000km before failing (and even then i suspect the motor failed first causing a cascade failure)
the shunt mod increases the battery side current limit enforced by the controller. This gives you faster acceleration, but has no effect on top speed.
Matt
That looks like a pretty solid controller. Maddeningly, the voltage limits on the caps are not visible in the otherwise tack-sharp picture. If the caps are rated for, say, 100V, then there are just the SCR's to check. You can look the device numbers up and find their voltage rating.
If the components can take it, boosting the voltage shouldn't be too dangerous. (The DC-DC will also have to deal with the higher voltage.)
I've probably got the same scooter as xmasta. 48v 800w. However, my top speed is obviously limited to 25mph.
The speed is the same if I am going up a hill or if there are two people on the scooter, so I do not think 25 is really the top speed. Is there something I can do to remove the speed limit?
I will pull out the controller sometime and take pictures, but it is buried pretty far beneath plastic.
I have never done the voltage upgrade, but there's a fair amount of discussion on other threads on this. There seems to be a lot of overvolting going on without any controller upgrade. There are also controller failures. Where you want to put your money on that gamble is up to you.:
Question 1: Is there a downside if i pull them all off and replace with ow, lets say 100v rated with equal uF ?
No downside at all, as long as the uF are equal. Based on reported EVT controller experience, use some hot-melt glue around the bases to fight vibration.
Question 2: SCR's as i searched up are those rectifiers, all of the black 3 legged ones on my controller? with screwable tail, counting 12 screwed to the cooler and 3 sitting off on board
The ones screwed to the heatsink are the crucial ones. If you can read the numbers on the sides, you'll be able to confirm the voltage ratings.
OTOH, I can pretty confidently answer this part...
about volts and amps stacking, i know i put extra battery in line with other 4 of my batteris that are also connected in line, they are 12v20ah, combined they do 48 and my extra will boost it to 60v, but what of the amps.. i felt about amps like.. stamina of a battery, of how long it can put out its 12v load or.. anyway, point is, i'm not overloading anything with the fifth battery being 43ah?
You'll only be able to get ~15AH from the new battery before the rest of the pack is flat (Why not 20AH? That's another whole discussion), other than that, it will boost your voltage (pressure, affecting top speed) without changing the maximum amps (volume delivered, affecting acceleration and hill climbing).
Mark
Question 1: Is there a downside if i pull them all off and replace with ow, lets say 100v rated with equal uF ?
No downside at all, as long as the uF are equal. Based on reported EVT controller experience, use some hot-melt glue around the bases to fight vibration.
The caps are there mainly to suppress voltage ripple.
Make sure the ESR at the switching frequency is similar to that of the original caps.
If the ESR is higher, either the gates (MOSFets, not SCRs) will suffer "voltage punch through" and fail immediately, or, the caps will overheat during use and fail.
it doesnt matter that much if the new caps have slightly lower capacitance, than the old caps, its the ESR thats important.
Question 2: SCR's as i searched up are those rectifiers, all of the black 3 legged ones on my controller? with screwable tail, counting 12 screwed to the cooler and 3 sitting off on board
The ones screwed to the heatsink are the crucial ones. If you can read the numbers on the sides, you'll be able to confirm the voltage ratings.
The Gates are most likely to be MOSFets, rather than SCRs.
The 12 will be the mainpower stage (2 in parrallel, per direction, per phase)
FWIY, i ran my emax at 60v for 16'000km before the controller failed (and even then i suspect the motor failed first) YMMV.
If you are planning on over-volting, id suggest buying a spare controller just in case.
Matt
you'll love the kelly controller, far more features and usability than any analogue controller.
Its likely the gate drivers (or possible pull down resistors) failed on your old controller. When this happens, both FETs on the same half bridge get turned on causing a short across the battery, resulting in smoke and dead FETs.
The logic section might still be ok, if you would like to learn more about fixing motor controllers.
Ive found that it is much easier to deal with either a well documented controller, or a well supported controller. preferabley both.
Id consider the kelly to be well supported, but definately not user serviceable.
Matt
Well i figured that this 45km/h limiter is not just battery power but controller limit too, i would not mind a little range drop for the added speed (when i use it, doesnt mean i must use full throttle, just need it possible), extra battery is good too i'm sure but yeah that again costs a little.
Does the shunts have something to do with limited power sent to motor? i see two with holes for third.. heres a pic
http://img196.imageshack.us/img196/2386/img4168a.jpg