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MX500 48v Speed comparison question

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48v mx500
11K views 19 replies 9 participants last post by  HubbaBubbaDenCo 
#1 ·
Ok, I converted my son's MX500 to 48V to help him compete with some MX650s. I am undecided on what to do next to achieve the best results. He is 60lbs. and rides in the grass mainly. So with the listed scenarios, which would be faster?


MX500............................................ MX650
48v batteries only - ..........................Stock
48V and 90T rear - ...........................Stock
48V/750W motor/90T rear -.............. Stock


Where in this scenario would changing the controller help with speed?


TIA
 
#3 ·
He rides in the grass and dirt a lot, from what I have read a smaller rear sprocket would place to much strain on the motor and cause it to burn up.

I like the idea of a bigger rear sprocket for more torque so he has the power to ride in the yard, but I also need it to be faster than an MX650 on top speed; not by much though as he should get the jump due to more torque.
 
#4 ·
They have rear gears w/ 78 plus teeth, you will need a longer chain. I get 10ft. of #25h or 8mm chain, what ever I need. They came w/ 3 master links and cut my own chain to fit. Only takes a few teeth either way to make the chain to long or to short.
 
#5 ·
start out with the math
amps x volts = watts
now if you start moving your numbers around you will see increasing the volts lowers the amp draw equaling the same watts so if you look at the math by adding more battery's to increase the voltage all your doing is extending your run time yes yes I understand you might get a little more power because of the efficiency of the electronics but at the cost of over heating and the possibility of burning up the speed control here lets do the math and see

500 divided by 36 equals 13.9 amps
500 divided by 48 equals 10.5 amps
give or take a bit of rounding
see how the amps go down as the voltage goes up

see the way electric motors work is they are made up of coils of wire making a electro magnetic field pulling the armature along so yes MOD Monsters you can make the 500 watt motor have more power by increasing the pull of the magnetic field all you have to do is change the magnets with some kind of neodymium or some kind of rare earth magnets increasing the efficiency or you can change the windings on the armature re winding it to make it have a higher wattage in the end making it a bigger motor 0

to shorten up this long story if it where me I would just head over to Ebay and grab a 650 watt motor and bolt it in there I have looked at the schematic diagram for both the MX500 and the MX650 and they are both the same even the controllers are the same then when we do the math you will get

650 divided by 36 equals 18.06 amps
650 divided by 48 equals 13.54 amps
give or take a bit of rounding

then your MX500 will be just a little bit faster then a stock MX650 at 48 volts 0 in fact I would try and find a 700 watt motor but I don't think you can push the stock electronics package much more then 700 watts before you have a melt down

with all this said I have one more option you can try go find yourself a 20 amp relay and wire it up so when a button is pressed it completely bypasses the speed control and hooks the motor directly to the battery then any loss in the speed control will be eliminated but your kid will have to understand not to press the button until he is up to speed or it might buck him off the bike
 
#9 · (Edited)
Nice work Mrkitty!

I help teach heavy duty electrical at a local college, and lots of students at the half way mark (2 months into studying electrical) still don't get OHM's law let alone WATTS law, not to mention Kirchoff's laws.

Keep it up!

Your example is easier to understand than ( I x V = P) Current x Volts = Power


start out with the math
amps x volts = watts
now if you start moving your numbers around you will see increasing the volts lowers the amp draw equaling the same watts so if you look at the math by adding more battery's to increase the voltage all your doing is extending your run time yes yes I understand you might get a little more power because of the efficiency of the electronics but at the cost of over heating and the possibility of burning up the speed control here lets do the math and see

500 divided by 36 equals 13.9 amps
500 divided by 48 equals 10.5 amps
give or take a bit of rounding
see how the amps go down as the voltage goes up
 
#6 ·
Thanks for that great response MrKitty!!!

So I could expect good results if I went to a 48V controller and a 800W motor? I found this motor on eBay for $60 and its a direct replacement. I'm also going to order a 90tooth rear sprocket tomorrow as the motor is getting very hot when my son rides in the yard for a short time.

Thanks for the advise!!

Specs:
- 36V DC 28.5 amps
- Max 800 Watt
- Max 2800 RPM
- Chain drive (11 teeth sprocket) #25 chain
- Type of motor: DC, Brush
- Reversible
- 12 gauge leads
- Permanent Magnet
 
#14 ·
I got one of them kits from you a few years ago, but never used it, my OEM battries went dead and I did not want to by new batteries, so I got a new MPR gas 47cc Cagllari Dayona for $169.99. The wiring kits is ready to go w/ all wires & plugs attached, to hook your OEM batteries with a 3rd Lipo battery that the kit plugs into. I just sold all my body & electric PR200 stuff, for a Christmas present for a 4 yr. old girl. Dad had no fairing on the used bike, he is going to use plastic primer & paint and paint it up in one of the 4 Power Rangers colors, I thought that was pretty cool.
 
#17 ·
On the MX650 Mods thread there are 55 pages of folks modding these things. The 48V on the stock controller with the MX500 or 650 seems to be a popular 1st enhancement.

Then you have the 60V crowd, using a different 48 or 60V 1000w controller (or the 24 - 60V YK43B controller) and even running 2 MX500 motors.

Adding a 90tooth Currie or custom rear sprocket seems like a good option for better hill climbing / grass or where you need the torque instead of an eventual high top end runner on a long straight away.

HTH!:)
 
#18 ·
No one successfully runs a yk43b on an mx with 1 motor. Maybe 2. The 100amp draw is too much. Best stock option in to replace the batteries with 5 9ah batteries. Battery shark sells them for 13ea.the stock controller can handle 60v 9ah. If you. Use 12ah you need a bigger controller. Say a 48v 40amp will do. You can mod a 90t currie but you must drill. Bolt holes and you lose your freewheel. You can buy a custom sprocket from rebel gears.com for 50bucks. They do enough mx bikes you can probably forego the schematic and measurements. Some have bought 100t even 120t vs the stock 80t.
 
#19 ·
You can mod a 90t currie but you must drill. Bolt holes and you lose your freewheel.
Not sure about losing the freewheel unless you weld it. Although I have not done this conversion myself yet, basically all you are doing is removing the 4 inner bolts that holds the existing gear plate, making the center hole of the Currie 90T plate the same dimater so it will fit over the existing freewheel & make 4 matching holes for the bolts to go through.

If you get the pre-made one from Rebel Gears.com, again you remove the existing gear plate & bolt in the new one. Does noting to effect the existing freewheel & if you eventually need to get a replacement freewheel clutch, the setup is the same, just bolts pass through holes instead of BMX style gears & you don't need the plate that covers this.

On our MX650 I had to replace the existing freewheel clutch & bolted the existing plate onto it, left off the gear cover plate, no welding needed.

HTH.

This page has examples of replacement freewheel clutches, freewheel plates (stock stype) & threaded (Currie you would need to modify).
 
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