Wow, first thanks to all the forum posters here. Many of the articles on controller modifications and learning about brushless DC motors helped me with this modification.
The scooter is fantastic to drive now. The acceleration is great and I am going an unconfirmed 42 miles an hour. It's unconfirmed because it's hard to tell how fast your really going with the gauges.
First, I picked up this scooter used, very cheap at ($200.00). This included a brand new 48 volt charger. Given my current financial state I could not afford to drop thousands on a new electric scooter.
I could only acheive a top speed of about 28 m/hr. This was disapointing as most of the roads I need to drive on the speed limits are 45 to 35 m/hr.
I went about taking the controller apart and making the following modifications:
1.) Add a 1.5 inch length of pollished "coat hanger" to the current shunt.
2.) I added solder to the positive and negative traces that feed the FETS to add to their current carrying capacity.
3.) I replaced the capacitor across the FETS.
4.) I added an additional wire to the positive and the negative input DC power wires. This was to increase current
carrying capacity and reduce voltage drop.
After making the modifiation to the current shunt I noticed a wonderfull increase in acceleration. I would highly recommend this modification to anyone interested in increasing acceleration.
I was very concerened about the trace thickness and their ability to supply adaquate current to the fets and not burn up a trace when excessive current is present. It is imperitive that if you make the shunt modification that you check to see if the traces can handle it.
In the 60 volt mod of the Panterra Freedom the FETS are only rated for 75 volts. Your charged battery voltage is around 66 volts and all brushless DC motors have a certain amount of back EMF (Electromovive Force). This is esentially Enery in the motor winding that is released and can cause a voltage spike across the FETS and damage them.
In order to be sure my FETS rated at only 75 volts were not damaged I replaced the 63 volt 2200uF capacitor with one much, much larger. A 100volt 15000uf cap. This cap is physically much larger and had to be mounted outside the controller.
The DC power wires of the controller that supply the 60 volts and current to drive the motor are very under sized. The wire from the batterys is a legitamate 10 gauge stranded, but the wire going into the controller would be lucky to be a 14 guage stranded. I added a wire to the positive and negative input, thereby increaseing the current capacity and reducing voltage drop.
In this cheap scooter it is essential that wire guage be increased and connections be improved with solder and elimination of high voltage loss connectors. Voltage = speed = RPM's. Minimizing voltage drop is key.I believe the large capacitor is also providing a valuable service to the controller by providing the quick energy needed so the contoller can quicly respond to throtel demand and provide excellent protection to the FETS when running so close to their rated maximum voltage.
This scooter flys now and is usefull to me on the busy streets. It is a testiment that you don't have to buy an expensive scooter, but definattly need to know how to modify one.
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Jerod
So can you give us any more specs? How fast does it go now at max speed? Did you lose any of the range with the modifications? If I understand correctly, and you added a battery, which kind? Where did you put the extra battery?
Excellent job! You are right in that not only the Panterra, but all the Chinese scooters so far need work and mods. to obtain an acceptable level of performance and reliability.
I didn't know the Panterra'a were brushless.
Stay in touch and tell us how it holds up.
Well I must say, the speedometer in this scooter is very, very inacurate. It reads both in Km/hr and Miles/hr. The speedometer only goes to 30 miles/hr. Before the modification it showed a top speed of around 28 Miles/hr. After adding an additional 12 volt battery to take the system from a 48 volt system to a 60 volt system, the speedometer now is pegged as far farward as it will go. It looked as if I could easily be going over 40 miles/hr. However due to the seriouly inaccurate speedometer my current speed test showed a top speed of about 33 to 35 miles/hr after the 60 volt modification.
I placed the new battery under the seat in the same compartment that houses the circuit breaker. As for loss of range, I cannot speak to this as of yet. Does anyone have any information about reduced range with an increase in voltage?
I must say that I have not replaced all the batteries in this scooter and 3 of the 4 batteries are the orignials.
This scooter uses a 18 Amp hour battery. They are smaller than a regular sized car battery.
I must also say that anyone attempting this modification need know that the DC to DC converter will not survive the 60 volt modifiation. It's max voltage is 63 volts and because it is an encapsulated control no modification is possible. I am currently looking for another DC-DC converter but until I find an affordable one with the acceptable input voltage range, I have just tapped off the first battery to power the 12 VDC circuits of the scooter. The disadvantage to this is all the current comes from the first battery so this battery is more depleated than the others and at night, the lights may dim slightly as the scooter accelerates. But it works, for now.
One other important note, the controller, it has two positive power wires going into the control. One is the "on" lead that powers the internal switching power supply. This must be kept at 48 volts. This is so the internal power supply for the circuits will not get hot and burn out. The other is the main power wire that feeds the FETS and therby feeds the motor. This is now set to 60 volts.
I have put about 60 km on this scooter since the modification and everthing is great so far.
I am serioulsy thinking of replacing the FETS on the controller to 100 volt parts and going to a 72 volt scooter. :)
Jerod
Hi,
Just curious as to how you kept the input voltage on one wire 48v and the other wire has 60v? Did you run extra wires to your batteries to make 60v for the second wire? I'm not sure how you can separate voltage from a pack of batteries.
Keep the rubber side down and the shiny side up.
Jerod,
After reading you recent modification to the Panterra Scooter I found one on craigslist in my local area and purchased it. I am interested in more detailed instructions about this modification. I would also like to try the same. I have 2 new 12v 20ah batteries here that I would like to apply to this if you can help me I would appriciate it you can email me if needed at jeffroig [at] yahoo.com. Thanks and happy scootering.