Razor MX500 36V Lithium Battery UpgradeLuna Cycle 36v 18650 20ah Ebike Battery Pack[UPDATED FUTURE UPGRADES AND CHARGING SECTIONS WITH INFORMATION ON 52V PACK NEWLY AVAILABLE FROM LUNACYCLE AND CLARIFICATION ON CHARGING - 2016-01-09]
Hey guys! I just got done putting this Razor MX500 back together after upgrading the battery to Lithium Ion but before I did I made a quick video and wrote everything up to help anyone else that has been searching for a Lithium battery option for the Razor. I'm sure I'm not the first person to do it but when I was looking for myself I couldn't find anyone that has done it and posted about how they did it and the results after the upgrade. Also note that this should work great on a Razor MX650 as well.
Over 10 years ago my Dad picked up this Razor MX500 for about $30. It was really cheap because the bike was missing the rear wheel and didn’t have a battery charger. He gave it to me as something to tinker with.
I found a new rear wheel for $55 and a new charger for $30. After installing the rear wheel and charging the battery the bike ran great. At one point the bike was being stored on a covered but open air balcony not being used so it did pick up a little rust. In particular on the lower shock tubes and the front disc brake mounting plates but I have cleaned that up with a dremel in preparation for delivery to my 4 nieces for Christmas. It’s not perfect but it looks much better now. All things considered the bike survived pretty good.
Front Shock and Brake Caliper Mount After Cleaning With DremmelUpgrading the Battery
The battery has been dead and bloated for years so it hasn’t been running. With the stock battery, the power light on the throttle would turn on but the low power light would be on and the bike wouldn’t move at all. You wouldn’t even hear any relays clicking. Checking the voltage with a meter and the pack is only at about 4 volts. The two batteries that were on the bottom shelf are also stuck together and one battery has some burn marks on one of the terminals.
Stock Sealed Lead Acid Batteries Bloated and Stuck Together
My sister’s 4 girls are old enough to ride it now so I decide that it’s time to revive the MX500 and put it to good use. You can buy a replacement 12Ah battery pack of three Sealed Lead Acid (SLA) batteries for around $80. You can upgrade to a 15Ah battery pack for around $100. I looked for a Lithium battery pack option but couldn’t find any out of the box solutions specifically designed for the Razor. I found that some people have used RC Lithium battery packs but those require the use of more than one pack and a balance charger. I haven’t seen anybody who has used the RC packs report performance so here are the lessons I learned while searching for a suitable Lithium battery for the Razor MX500 and the resulting performance improvements from the upgrade. After doing tons of research I considered building a custom pack but I finally settled on a Lithium Ion battery pack assembled by a company called Luna Cycle. The battery pack is designed for use in electric bicycles and it works great in the MX500!Size and Weight
The Razor MX500 comes stock with three SLA batteries. I weighed the pack and all three batteries weigh a combined 26lbs. The Lithium battery pack weighs just 10lbs for a 16lb reduction. 16lbs may not make much difference for an adult like me that weighs 180lbs but for a kid that weighs 120lbs or 100lbs or less, the weight reduction will make a difference.
In addition, the weight is now all down on the bottom rack inside the frame keeping the center of gravity low. You can see in the picture showing the foam blocks in the bottom rack where the stock batteries would have gone. Two on the bottom rack and one up top. Now the entire pack occupies approximately the same space as the two stock batteries on the bottom rack but weighs less than just those two. The new pack is about 5.5in wide x 8.6in long x 3.1in tall or 140mm x 220mm x 80mm. It’s just barely too long to fit in the bottom tray. I used these foam blocks which are taller than the edge of the tray and then zip tie the battery in place. The stock batteries are held in place by these metal brackets. I tested it and the zip ties do a great job holding the battery in place. Between the low weight of the battery and the shock absorption you get from the foam blocks the zip ties hold it in place without any issues. I had the bike laying sideways in a car while transporting and I even jumped the bike several times off some stairs and the battery pack didn't budge and the zip ties didn't break. You will need to wrap the zip ties around the pack from front to back in order to be able to put the plastic back on. Luna Cycle does sell another pack that is more expensive that is physically slightly smaller but it’s still the same capacity. That pack uses cells that are slightly more energy dense so it doesn’t need as many cells which is why it can be smaller but still have the same total capacity. That pack might actually fit in the bottom tray and allow you to use the factory brackets to hold the pack in place. This pack is so close to fitting. When I measured I thought it was going to make it but it’s literally like a millimeter or two too big. If I had known I would have spent the extra money for the other pack.
Razor Bottom Rack with Foam Blocks
Luna Cycle Lithium Battery Pack Installed in Bottom Rack on the Razor MX500Capacity
The Razor MX500 stock battery pack uses three 12 volt SLA batteries with 12Ah of capacity. The Luna Cycle battery pack is a 36 volt 10s10p Lithium Ion battery pack. 10s10p is 10 series 10 parallel so that’s 100 lithium ion batteries total. The pack is made using 18650 2500mah cells for 20Ah total or 720Wh.Connecting the Lithium Battery Pack
The Razor MX500 stock battery pack has a harness with a 4 pin connector and a fuse holder with a 30 amp fuse. I reused the connector, fuse holder and fuse to create a harness that adapts the XT90-S connector that comes on the Luna Cycle Lithium battery pack to the 4 pin connector on the Razor. Even though the Lithium battery has a built-in BMS I still used the 30 amp fuse. The BMS on the Lithium battery pack will allow the battery to provide up to 80 amps burst and 50 amps continuous. While the battery pack may be able to withstand that amount of current, the wiring, motor controller and motor on the Razor MX500 isn’t designed for that much juice. Using the 30 amp fuse will protect from damage to these other components.
Lithium Battery Pack Connected to Razor MX500 Using Custom Built HarnessCharging [UPDATED]
I never measured the voltage of the stock SLA pack but based on my research it looks like it would be 39-40V fully charged. The Lithium pack from Luna Cycle measures 41.3V fully charged. The built in BMS means you don’t have to use a balance charger like you would if you were using RC packs. Instead, I was able to keep all the stock wiring and use the stock charger. The charger just plugs right in like normal using the XLR plug.
It takes FOREVER to fully charge the Lithium pack using the stock charger. Using the stock 1.5 amp charger plugged into the XLR charging port on the side of the MX500 takes 8 hours to charge the stock 12Ah SLA battery pack (12Ah/1.5A = 8 hours). Using the stock charger to charge the 20Ah Lithium pack takes 13 hours (20Ah/1.5A = 13 hours).
One alternative would be to use a fast charger. I didn’t buy one but found a really nice fast charger made by a company called GRIN. The charger is called the Satiator and it will charge the pack at 8 amps instead of the 1.5 amps the stock charger provides. Using the Satiator would cut charge time down to just 2.5 hours (8A x 2.5hours = 20Ah). During winter when the bike is not being used the Satiator can be set to keep the voltage at 75-80%. When temps outside go up and you want to ride you can top off in a few minutes. Using the Satiator could extend battery life to 1400 to 1600 cycles.[UPDATE 2016-01-09]
In the video I created I said the battery doesn't charge through the controller connector labeled 'charger' but that isn't correct. Using the stock wiring the battery does charge through this connector. If a quick charger is used, the controller may limit the amps that it will flow through to the battery. This might limit the ability to use some chargers at full power without taking advantage of the direct connection to the battery pack using the XT-60 connector.Cost
Replacing the batteries with new SLA batteries costs about $100. You can find them for cheaper depending on brand and capacity. Assuming you want the best quality with the highest capacity then just say $100. The Lithium battery pack from Luna Cycle costs $300 so if it lasts three times as long as the SLA pack then the total cost is the same. SLA batteries are good for 200-300 charge cycles. Assume best case, 300 cycles. A Lipo with a good BMS can get 800-1000 cycles. So it will last 3 to 4 times as long as the SLA pack.Battery Management System (BMS)
The Luna Cycle Lithium pack comes with a built-in Battery Management System (BMS) which protects the pack from damage during charge and discharge. This BMS also has temperature protection to keep the pack from getting too hot. It is a high power BMS which will allow the pack to put out 50 amps continuous (1500 watts) and 80 amp bursts (2500 watts) although Luna Cycle advises that running this much power (2500 watts) will drastically reduce pack life expectancy so they recommend to not run your battery too hard if you expect it to last over a couple hundred charges. The Razor MX500 with a stock 500 watt motor and 36V controller will never even pull 50 amps let alone 80 amps. In addition, the BMS will balance the individual cell voltages to keep the individual cells and the pack from getting undercharged (voltage too low) or overcharged (voltage too high) to help maximize the life of the pack. Its possible to have a pack without a BMS but that requires that you pay a lot more attention to the batteries while charging and requires regular monitoring to ensure things aren't getting too far out of alignment. A good BMS will do that for you and is a great thing to have to prevent overheating and possible fires when the battery is going to be in a kids toy.Digital Volt Meter
I added a digital volt meter to the bike so that you would have a better idea of how much ride time you have left when you are riding or how much longer you have left to charge when charging. The throttle on the MX500 has two lights for battery power. A ‘Full Power’ light and a ‘Low Power’ light. The Lithium battery pack can still provide a lot of ride time after the ‘Low Power’ light goes on. The digital voltmeter tells you exactly how much charge you have left which can be used as a much better indication of how much ride time you have left.
Digital Volt Meter Installed Next to ‘Gas Cap’Performance
Razor claims the MX500 is good for 40 minutes or about 10 miles of ride time on a single charge. They also claim a top speed of 15mph. I have ridden the MX500 with the stock batteries but I never performed any controlled tests or collected any data to verify. At 180lbs, I doubt I was ever able to ride it for 40 minutes or go 15mph. Using the Lithium battery pack from Luna Cycle I was able to ride for 1 hour 37 minutes and went 23.56 miles. In addition, I was able to hit 17mph on flat ground, I went a max speed of 21.5mph going down hill and averaged 14.44mph for the duration of the 1 hour 37 minutes. Not too bad considering all I did was replace the battery! Keep in mind that I weigh 180lbs and I kept the throttle wide open the entire time. A kid that weighs 120lbs or less should see even better performance especially if they aren't riding at full speed the entire time!
Test Result Stats From 23.56 Mile Trip
The main test I performed was at a park with a 5.5 mile bike path that loops around the park. I only stopped a couple of times (total trip time was 1 hour 38 minutes) and kept the throttle wide open the whole time. The elevation changes by more than 150 feet during the course of the loop and there 3 large hills that each have a long steep grade. On the first two laps with the Lithium battery pack the MX500 barely slowed down going up the hills and was able to maintain almost 15mph. The stock SLA batteries would never be able to provide the current required to do that. When I performed the test the starting voltage of the Lithium battery pack was 41.2 volts and ended at 31.9 volts.
Test Result Chart From 23.56 Mile Trip
I also performed some off road tests on grass and in mud. The MX500 with the Lithium battery pack handled both with ease climbing hills with ease in both the grass and mud. However, what I was most impressed with was how long the battery was able to provide high power. Notice the red line drawn through the points where the bike was working the hardest during each lap. You can see that with the Lithium battery pack the bike is able to maintain almost full performance for over 20 miles. As the voltage drops while you use it, the battery has to provide more current to provide the same power. But as the voltage drops and more and more current is required to make the same power, the battery struggles to provide the increasing amount of current. The stock SLA battery is not able to keep up with the increasing demand of current very well and this results in full performance for a short period of time and then slowly degrading performance as the battery drains. So even though the battery may last for 40 minutes or 10 miles, the second 20 minutes is not nearly as much fun as the first 20 minutes. With the Lithium battery pack from Luna Cycle, full performance is maintained for a much longer period of time because it is able to provide higher current at lower voltages than the SLA pack.
Tomorrow I will be giving the bike to my nieces for Christmas, I will update this post with the results from a kid rider.Future Upgrades [UPDATED]
I have found examples on YouTube of people that have upgraded to a 36 volt 750 watt motor and a 48 volt controller. They added a fourth SLA battery to get the pack voltage up to 48 volts. Luna Cycle sells a 48 volt 20Ah Lithium battery pack that will easily fit in the lower rack on the Razor MX500. If fact, the 48V pack is physically smaller than the 36V pack I used but actually provides 1000Wh. Luna Cycle also sells a 52 volt Lithium pack that could be used with the 750 watt motor and 48 volt controller. Overvolting the stock Razor to 48 volts while keeping the stock 500 watt motor and 36 volt controller seems to be a popular mod for the Razor MX500 so bumping up to 52 volts using the 48 volt controller and 750 watt motor seems like a natural progression. However, the Lithium battery pack is capable of providing far more current than the motor and controller are able to draw so the advantages will be reduced and the 52 volt Lithium pack is physically large and getting it installed will be more challenging than using the 48 volt pack.[UPDATE-2016-01-09]
Lunacycle has just started selling a 52V 20Ah pack using the same Panasonic NCR18650b cells used in the 48V 20Ah pack. The 52V pack is small enough to fit in the lower tray on the razor without any modification. At 8x6x3.3 it is actually slightly shorter but slightly wider and taller than the 36V pack I used and will be really close to fitting without the need for any foam blocks to keep the battery from sitting on the side rails. The only question is the 6in width which is the exact width of the lower tray....it might fit but it might be just too big....interesting. I'm not sure you would get much speed or acceleration improvement between the 48V lithium pack and a 52V pack but with 1100Wh the 52V pack would definitely increase range. However, with a current price of $640 it isn't cheap!
Here is a list of the [UPDATED]
components I would buy to maximize performance without having to make any physical modifications to fit a motor bigger than 750 watts.
- Luna Cycle 52V Panasonic NCR18650b 20Ah Battery $640
- Satiator Charger by GRIN $295
- 48 Volt Controller from TNC Scooters (Model: MX4830-5) $40
- Twist Throttle with 48 Volt LED Meter from TNC Scooters $25
- 750W Motor - 36 Volts (Style: MY1020) from TNC Scooters $119
I decided to go with the 36 volt Lithium pack and the stock 36 volt controller and 36 volt 500 watt motor because I think my sister would kill me if I gave my nieces an electric dirt bike that could go over 25mph….maybe when they get older and they have a few years experience with the bike they way it is now.
Razor MX500 reassembled and ready for Christmas delivery!!