MrDude_1
100 kW
ElectricGod said:
I know from experience that it is really easy to step over the gearing limit.. you can keep inching up on more speed, more speed, and then its like it fell off a cliff.. it suddenly doesnt work well anymore.
My kick scooter project
- Thread starter ElectricGod
- Start date
I know from experience that it is really easy to step over the gearing limit.. you can keep inching up on more speed, more speed, and then its like it fell off a cliff.. it suddenly doesnt work well anymore.
ElectricGod
10 MW
MrDude_1 said:
Limit...yeah...play around and get close or a little under to the sweet spot and stay there. There are limits to "more is better".
MrDude_1
100 kW
I think of it as a limit..
What I noticed was if I overgear it, it will keep pulling more amps, usually maxing out the controller, while not going as fast as it did previously with "slower" gearing.
So I have to lower the gearing down until I get a high top speed. its counter-intuitive.
Then I of course try to run a higher voltage to raise the motor RPM for more speed as well... but you will reach a motor RPM that if you exceed it, it will start building heat in the motor (for mine its around 7700RPM)
If I run the motor at 66v (my max voltage) in open air with no load, it will turn 9000 RPM and in 10 seconds of no load running, it is over 100*F. the stator is saturated, so its just making tons of heat.
So you can raise the voltage making the no load RPM number overspeed and then gear it so the load always keeps it safe. if your controller has a RPM/speed limiter of some kind, I would set that too.
but you're already beyond all that.. you have your voltage and motor set.
speaking of motor cooling though... I 3d printed some impellers to cool my motor. If you have a rear shaft, you could try that method on your motor. it works well.
What I noticed was if I overgear it, it will keep pulling more amps, usually maxing out the controller, while not going as fast as it did previously with "slower" gearing.
So I have to lower the gearing down until I get a high top speed. its counter-intuitive.
Then I of course try to run a higher voltage to raise the motor RPM for more speed as well... but you will reach a motor RPM that if you exceed it, it will start building heat in the motor (for mine its around 7700RPM)
If I run the motor at 66v (my max voltage) in open air with no load, it will turn 9000 RPM and in 10 seconds of no load running, it is over 100*F. the stator is saturated, so its just making tons of heat.
So you can raise the voltage making the no load RPM number overspeed and then gear it so the load always keeps it safe. if your controller has a RPM/speed limiter of some kind, I would set that too.
but you're already beyond all that.. you have your voltage and motor set.
speaking of motor cooling though... I 3d printed some impellers to cool my motor. If you have a rear shaft, you could try that method on your motor. it works well.
ElectricGod
10 MW
MrDude_1 said:
I don't have a rear shaft on my motor, but I could add one easily enough. It would be great to reuse a little motor RPMs for a blower, but I think a seperate blower motor is better since it keeps air pushing through the motor whether I'm stopped or moving. I do have RPM control in my Kelly. My motor free wheeling doesn't get hot at maximum RPM's. It just gets hot under load which is way less RPMs. I need to buy a tachometer and don't currently have one so I can do real measurements of RPMs. I don't think I'm normally running into saturation issues. IMHO, its the fact that it is a 2000W in-runner designed to run at 60 volts that is running at 2800-2900 watts and 72 volts. I'm pushing it and it has less than wonderful ventilation anyway.
I noticed the same behavior...lots more amps and no more speed with the 15 tooth motor sprocket. Since I have bumped back to the 11 tooth sprocket I am still pulling about the same amount of current as I was before this radical gearing change, but I am doing 37mph. I was pulling the exact same amount of current and getting up to 40mph with the 4.27:1 ratio, I'm definitely going to change out the 11 tooth sprocket for the 13 tooth sprocket (4.92:1) and see how it goes. Worst case I go back to 64/15 sprocket set (4.27:1) which was working well already.
Air will exit out of the sprocket end and be forced in on this end. I haven't done it yet (hopefully this week...the blower arrives today), but I will make an end cap that covers those holes and mates to the blower motor and forces air into the motor. I'm pretty sure that I will cook the motor if I don't do forced cooling.
ElectricGod
10 MW
Blower development is coming along nicely. I have a 12v blower fan now and have decided to try making an end cap to go over the end of the motor out of wood. I've glued up several layers of plywood into a block and then, I'll rough round the corners off on my table saw and then turn the block on my wood lathe into a hollow cap. Once it is the correct size I'll impregnate the wood with epoxy to make it resilient. A little more lathe work and sanding and it will be like it was made out of reinforced plastic. Then comes the minor fitting details of getting it to fit around the motor bracket and some kind of opening for the blower to mate up to. I'll open up the motor bracket a little so the motor vent hols that are currently covered are free for air flow again. I want to push air into the motor everywhere I can. I also have some slim heat sink strips that I have cut to the length of the motor. I know passive cooling is less effective, but if it helps keep the motor cool, well then it's worth it. The strips will be held down via 3 large hose clamps. The aluminum is pretty thin so putting a slight curve in them to match the curvature of the motor can should be pretty easy. A little heat sink compound and that's all done.
ElectricGod
10 MW
I pulled the motor out of my scooter today so I could work out the blower adapter manifold and to modify the bracket a little so all the air holes are clear. While I was at it I looked at the vent holes and realized I could mount to them directly. I went to Home Depot and bought 7 brass elbows. They needed to be drilled out a little to increase air flow through the elbows, but that was easy. I also tapped 1/8 NPT threads into the motor vent holes and threaded in the brass elbows. I'll use some clear nylon tubing shoved onto the other end of the elbows and then connect them all together at the blower fan. A small block of wood that fits inside the mouth of the blower with some holes drilled into it for the hoses will do the trick. The air flow through the elbows is narrower than the open vent hole, but this gets 100% of the air forced into the motor with no chance of it leaking out via the many cracks and possible gaps between the wood manifold I was going to make and the motor and bracket. Also, I can easily limit dirt and pollution from every getting into the cooling system via a simple filter on the blower.
This is the brass fittings. I'll attach the hoses later. You can also see the ends of the heat sink strips. I have more of them on the way to fill in that gap on the top of the motor. They go most of the way around the motor with a gap on the bottom of the motor about the same size as the unfilled gap in this picture. I could make the motor bracket taller so I could get the heat sink strips all the way around the motor, but this is passive cooling and not much air flow will get under the motor.
This is the heat sink strips from the side of the motor.
This is the brass fittings. I'll attach the hoses later. You can also see the ends of the heat sink strips. I have more of them on the way to fill in that gap on the top of the motor. They go most of the way around the motor with a gap on the bottom of the motor about the same size as the unfilled gap in this picture. I could make the motor bracket taller so I could get the heat sink strips all the way around the motor, but this is passive cooling and not much air flow will get under the motor.
This is the heat sink strips from the side of the motor.
ElectricGod
10 MW
i am building a new charger. THe little 100 watt DC-DC converters worked pretty well at 48 volts. Despite being able to go up to 82 volts, they don't work very well there. I have a lot of spare mosfets and have replaced them in all of these little converters. I am running 6 of them in parallel and I can't charge but 1 or 2 battery packs at the same time or else they burn out the mosfet. I had no issues charging 4 8000mah lipo packs off of 2 of them at 48 volts as long as I used a fan to keep them cool. With 6 of them running at 82 volts and fans they still kill the mosfets. The mosfets don't get hot, they just can't handle the current draw. I have as a result gone with 1200 watt converters. I received one 2 nights ago and now I wish I had just gone with them to begin with! They have an adjustable output voltage up to 88 volts and current limiting. You set the current via a second precision pot. These DC-DC converters have 2 mosfets and a much larger heat sink. The board has places for 2 more mosfets. I think I will add them! who knows why they are not already there. At 82 volts, I was able to set the current to 2 amps and the heat sink got to 80F. Going to 3 amps quickly went up to 100F and so on. I put a fan on the heat sink and ran for 6 hours straight at 3.5 amps and it never got warm. I'll bump the current higher the next time I need to charge and after I get it mounted to my 24 volt, 25 amp power supply. This was a preliminary test and it worked out better than I expected. I'll run 2 of them in parallel so I can charge at 10-12 amps. I used a meanwell power supply. It has overload protection. I know it works because the mosfets on the 100 watt converters would blow and become dead shorts. The power supply would shut off the 24 volt output. All I had to do is remove the blown converter and plug in the power supply again and it was producing 24 volts again. They have a little bit of adjustability to them from 16 volts to 27 volts. Because my fans are 12 volt fans, I am running 2 of them in series and that means the power supply needs to be close to 24 volts out.
This is the DC-DC converter I used. The board dimensions are about 4" by 2" by 2". They are advertised for 1200 watts, but that's not likely. The mosfets would burn out instantly at 14 amps and 82 volts. They are more like 6 or 8 amps at 82 volts or 500 watts. At lower output voltages you can bump the current significantly higher. They have a current handling curve that drops off more quickly at higher voltages. I looked up the mosfets on them and they can handle about 3.5 amps each at 82 volts. The heat sink is pretty large, but it gets quite warm at more than about 3 amps with no fan cooling. The pot next to the coil is the current adjustment. I have a watt meter attached to the output of the converter. It displays voltage, amps, watt/hr and a few other things. I watched the current it displayed to see how much I was allowing through the converter. With my batteries being half discharged, I pluged in a single battery pack. It was sufficient to pull 3 amps. I then watched the converter for a while to see how it responded and then started slowly plugging in more battery packs to see if the current draw went up or not. It stayed right at 3 amps and voltage drop off either. The current limiting on the converter worked flawlessly. Soon I had all 3 LIPO packs and all 7 LION packs plugged in and charging. It took about 6 hours to charge up to 81.7 volts and current draw had gone down to 200mah. Obviously with 2 converters in parallel and bumping the current on each one a little, I can charge much more quickly.
When I am done I will have a completely adjustable charger/power supply good for 36 volts to 88 volts.
This is the DC-DC converter I used. The board dimensions are about 4" by 2" by 2". They are advertised for 1200 watts, but that's not likely. The mosfets would burn out instantly at 14 amps and 82 volts. They are more like 6 or 8 amps at 82 volts or 500 watts. At lower output voltages you can bump the current significantly higher. They have a current handling curve that drops off more quickly at higher voltages. I looked up the mosfets on them and they can handle about 3.5 amps each at 82 volts. The heat sink is pretty large, but it gets quite warm at more than about 3 amps with no fan cooling. The pot next to the coil is the current adjustment. I have a watt meter attached to the output of the converter. It displays voltage, amps, watt/hr and a few other things. I watched the current it displayed to see how much I was allowing through the converter. With my batteries being half discharged, I pluged in a single battery pack. It was sufficient to pull 3 amps. I then watched the converter for a while to see how it responded and then started slowly plugging in more battery packs to see if the current draw went up or not. It stayed right at 3 amps and voltage drop off either. The current limiting on the converter worked flawlessly. Soon I had all 3 LIPO packs and all 7 LION packs plugged in and charging. It took about 6 hours to charge up to 81.7 volts and current draw had gone down to 200mah. Obviously with 2 converters in parallel and bumping the current on each one a little, I can charge much more quickly.
When I am done I will have a completely adjustable charger/power supply good for 36 volts to 88 volts.
ElectricGod
10 MW
I'm using brass nipples on the fan manifold still, but I will probably work out a way to leave the clear tubes unrestricted. The ID of the 1/8" NPT nipples are 1/4". The ID of the nylon tube is 3/8". I'm definitely restricting air flow somewhat with the NPT nipples. You can see that I crammed the ends of each tube into the vent holes in the motor. Right now they are threaded for 1/8" NPT and that's restricting air flow considerably. I think I will drill them out to slightly smaller than the OD of the tubing and then use epoxy to hold them in place. The tubing at the fan mouth needs a better manifold so there's no restriction there too. I wanted to be able to remove the tubing from the fan or motor easily, but the truth is better air flow matters much more.The only way that is going to work is to use a different way to hold the tubes onto the fan and motor. Larger elbows on the motor wont fit in the space where the tubes are so that's not an option. I don't have all of the heat sink strips in place on the motor yet since I'm still waiting for the rest of them to arrive. With no blower and just the heat sinks, the motor ran much cooler than with no cooling. The blower right now makes the motor run reasonably cool for longer duration rides. I just want to get more air into it than I am right now and the blower can definitely do that if it was less restricted. I have the blower hooked up to my 12 volt DC-DC converter. All the electrical system turns on with the key switch. The blower turns on when the key is turned on and runs continuously until the key is turned off. I will later work out a way to run the blower separate from the key switch so that I can run the fan based on motor tempurature. When the motor gets sufficiently cool, the blower will shut off on its own. The idea is that I can get to my destination, turn off the key and the blower continues to cool the motor for several more minutes. I need to get some springs of the right diameter to put inside the tubes or maybe use copper tubing. whatever I do, the bend in the tube needs to not get crimped over and collapse the tube. Copper tube is probably the best option. I can cut the tube on the inside of the bend and then solder it back together. The current method works, but isn't ideal since the tubes partly collapse at the bends. Air flow is king here!
ElectricGod
10 MW
Right now full throttle and accelerating hard pulls 76-78 amps. That lasts about 15 - 20 seconds until I reach full speed and then current draw drops off to 40 amps. Ironically, at full throttle at 48 volts to get 30mph also pulled 40 amps. Now I can do 40 mph at full throttle and pull 40 amps. I will ride for a few days with this setup and then I intend to change the 11 tooth motor sprocket for a 13 tooth sprocket. I was already running with a 15 tooth motor and 54 tooth wheel sprocket and got 44 mph at 40 amps so I know I can tweak a little more speed out of the system with no more current draw. The motor is doing great now that I have implemented active and passive cooling. I know it has a little more in it to give. Right now with the slightly less than optimal gearing, acceleration is really strong. At 15:54 I still had really strong acceleration and topped out at 44 mph. I'm heading back there again. It will be nice to be able to keep up with and pass cars on most of the roads around here. 
ElectricGod
10 MW
I have been running off the 3 LIPO 20S packs and all the used laptop cells. With all those batteries, sag is very small under full load. I still have a 20S2P pack to fill and I have an unknown amount of crappy cells in the mix yet to be eliminated. I'm pleased with the results of the 18650 battery packs so far. I still need to work out charging though.
ElectricGod
10 MW
Today was the first time I have been able to ride into work since I started all these upgrades. The scooter has gained a lot of weight with all the 18650s over the back wheel. I liked the 85 pounds it weighed before and now it's more like 120 pounds. I was curious to see how it handeled stopping and turning and what not with the extra weight over the back wheel. With the hydraulic brakes stopping was fine and in fact...just the back wheel alone stopped me faster than both front and rear did when they were mechanical and the scooter weighed lots less. I noticed a fluid leak at the front caliper. GRRR! I'll have to put my hammer drill on it tonight and hopefully get the fitting a little tighter and refill the reservoir. The passive and active motor cooling worked pretty well. The motor was pretty warm after the 5 miles into work, but not more so than running the old 1500 watt motor hard for 20 minutes. I'll improve the forced air cooling some more and add a few more heat sink strips and then it wont ever get warmer than 150 F. This is a 2000 watt motor and I am running it at 3000 watts typically and when I am accelerating hard that jumps to 5700 watts. LOL! Not bad for a $140 Chinese inrunner motor! It's pulling my 240 pounds and the 120 pounds of the scooter at 40mph and 40 amps. I'm pretty happy with that. I don't need to run at full speed all the time, but it sure wants to get up and go. As expected my used laptop batteries which haven't been vetted yet ran down fairly quickly. Still...I am at 86% full. That's plenty to get me home on and that was after I road it hard last night to make sure everything was working correctly for several miles. I have a paved bike path a couple of blocks away. It's about 1/2 mile long and pretty straight. It was 1:30am so there was no one around. I would kick off from a stop and then go straight to full throttle and let the motor pull as hard as it could. I loved the nice strong acceleration it got all the way up to field saturation. Doing that kind of acceleration means 20 seconds at nearly 80 amps to reach 40 mph. I drained the batteries pretty hard last night and then rode in on the same charge this morning and still have 86% left on used laptop batteries!!! It was soooo worth it to build those battery holder packs. I might make a smaller box over the back wheel and lose some weight. Now that I know I have waaaaaaaaaaaay more capacity than I need...I can reduce my battery capacity some and lose a little weight and not even notice the loss. I was worried that with all the old laptop cells that I would run dry and that totally hasn't happened. Once I get home, the used cells will have had a good solid work out and then I will know which ones to dump. I checked the temperature of the motor controller last night after doing all that hard acceleration and it was running at 80 F. It's mounted to the steel wall of the battery bay and has heatsink compound under it too. The controller despite having zero air flow around it stays nice and cool. I was concerned that my LIPO packs would get hot from the controller. I think it's actually the other way around. The LIPOs heat up the motor controller.
My trip to and from work can be done on main roads or neighborhood streets. I usually take the neighborhood streets which means a few more stops and slower speeds, but zero traffic. This morning I never went faster than 30 mph. I'll have to try the main roads again and then I can go full speed and keep up with or pass the cars. LOL! I'm loving all the improved performance. My efforts over the winter doing the various upgrades I did were really worth it. During this upgrade process I have been looking at possible 3000 watt inrunners for the next bump in performance. I'm not sure I should ever do that now. With slightly lower gearing I can get another 3-5mph with the same current draw. How scary fast do I need to go on a moped designed for 25 mph? 40 mph already feels really fast on it.
My trip to and from work can be done on main roads or neighborhood streets. I usually take the neighborhood streets which means a few more stops and slower speeds, but zero traffic. This morning I never went faster than 30 mph. I'll have to try the main roads again and then I can go full speed and keep up with or pass the cars. LOL! I'm loving all the improved performance. My efforts over the winter doing the various upgrades I did were really worth it. During this upgrade process I have been looking at possible 3000 watt inrunners for the next bump in performance. I'm not sure I should ever do that now. With slightly lower gearing I can get another 3-5mph with the same current draw. How scary fast do I need to go on a moped designed for 25 mph? 40 mph already feels really fast on it.
LockH
1 PW
ElectricGod said:
Hi again eGod Guy. Yah know, it occurs to me your kick scooter is pretty much a "kick" scooter in name only? You almost nEVer tap here about kicking it at all... except from stops? Watt I figure is useful anyway to shave peak battery discharge at zero RPMs. BUT. In my use of a tiny stand up kick scooter I got tired of banging my ankles against the back end of the deck, and my "Dray" design intentionally narrowed the deck for that reason. To make the back end as small and as skinny as possible (EVen shrank the diameter of the wheel(s).)
And you're mounting a basket back there??? Guess, you're riding a "kick scooter" in name only? Kick from stops pretty much only and not for example when misjudging distances rolling up to a stop? I was using the kicking not only to extend ranges per charge but also for warmth and exercise. (And to maintain the pretext of traveling by non-motorized vehicle. Hehe)
And I went front wheel drive. Same as a lot of cars do, but also my last trike was a front wheel hub motor. No thoughts about switching the drive from back to front? I figured by powering the front wheel instead of the back/rear, no chance any "wheelie" could flip the rider over backwards.
Thanks
L
(PS. Oh yeah. Got enough drink holders on there?)
ElectricGod
10 MW
I got the rest of the heat sink strips on Friday, so I now have enough to surround the motor with them. I then bent a curve in them so they fit around the motor better and put heat sink compound under each strip. That's about the best passive cooling is going to get without putting a fan on it too.
On active cooling...My original blower connections via nylon tubing worked OK, but then on the way home it started falling apart. A couple of the tubes came out of the back of the motor and a couple of them started collapsing since they were bent over at a right angle. As a result I decided to go a much more permanent route...something that minimizes air flow restriction from the fan and into the motor. I had some 3/8" ID copper pipe so I started messing with that last night and it worked pretty well. It had much better air flow and the copper pipe wont have problems with heat. By cutting the pipe at angles and soldering it back together I was able to maker a compact manifold that fits snuggly up to the back of the motor. I drilled the holes in the back of the motor out to fit the pipe. I used several pennies as copper washers so the copper pipe couldn't go inside the motor too far. I then soldered them about 1/8" from the end of the pipe. The pipe sections seal up pretty well to the back of the motor. I can't detect any lost air out the back of the motor and pretty much all the air I am blowing into the motor comes out the sprocket end of the motor. The copper manifold stays on the motor just by friction because its a really close fit.. Then when the motor is installed in the scooter, the manifold is trapped by those 2 blue vertical parts and the blower is also screwed to the frame. There's 3 screws in the side of the blower that secure it to the copper manifold. If I unbolt the motor from the frame and take that one screw out of the blower, I can completely remove the manifold. I flattened the two layers of copper pipe part way so there is a very small gap between the manifold and the blue vertical parts. With this copper manifold, I can use a much larger blower too.
On active cooling...My original blower connections via nylon tubing worked OK, but then on the way home it started falling apart. A couple of the tubes came out of the back of the motor and a couple of them started collapsing since they were bent over at a right angle. As a result I decided to go a much more permanent route...something that minimizes air flow restriction from the fan and into the motor. I had some 3/8" ID copper pipe so I started messing with that last night and it worked pretty well. It had much better air flow and the copper pipe wont have problems with heat. By cutting the pipe at angles and soldering it back together I was able to maker a compact manifold that fits snuggly up to the back of the motor. I drilled the holes in the back of the motor out to fit the pipe. I used several pennies as copper washers so the copper pipe couldn't go inside the motor too far. I then soldered them about 1/8" from the end of the pipe. The pipe sections seal up pretty well to the back of the motor. I can't detect any lost air out the back of the motor and pretty much all the air I am blowing into the motor comes out the sprocket end of the motor. The copper manifold stays on the motor just by friction because its a really close fit.. Then when the motor is installed in the scooter, the manifold is trapped by those 2 blue vertical parts and the blower is also screwed to the frame. There's 3 screws in the side of the blower that secure it to the copper manifold. If I unbolt the motor from the frame and take that one screw out of the blower, I can completely remove the manifold. I flattened the two layers of copper pipe part way so there is a very small gap between the manifold and the blue vertical parts. With this copper manifold, I can use a much larger blower too.
ElectricGod
10 MW
ApacheXMD said:
I rigged up something like that, but it leaked air too much so I abandoned it for this idea. Also, the copper tubes are no where near capacity. The blower can't put out enough air to max out the copper tubes. I'm thinking a much bigger blower is a good idea.
ElectricGod
10 MW
I've built a new charger...
I used a meanwell 24 volt 25 amp power supply and 2 1200 watt DC-DC converters. The converters have current limiting built into them so I can control charging rates or keep the converters from burning out. I have the output voltage set to 82 volts. I think this is pretty close to the final product. It charges all my batteries in about 3 hours. The little LED display shows the output voltage of the power supply. It never dips below 24.7 volts. The watt meter shows me charge voltage, current draw, watt hours, charge time and percent full. The power supply never gets warm and two fans keep the DC-DC converters nice and cool too. I might add a switch or jumper or something so I can disconnect the DC-DC converters. With them in parallel all you see on the watt meter is there aggregate outputs, but not their individual outputs. I suppose I could run two watt meters in parallel. That would get me current output, but not voltage.
I used a meanwell 24 volt 25 amp power supply and 2 1200 watt DC-DC converters. The converters have current limiting built into them so I can control charging rates or keep the converters from burning out. I have the output voltage set to 82 volts. I think this is pretty close to the final product. It charges all my batteries in about 3 hours. The little LED display shows the output voltage of the power supply. It never dips below 24.7 volts. The watt meter shows me charge voltage, current draw, watt hours, charge time and percent full. The power supply never gets warm and two fans keep the DC-DC converters nice and cool too. I might add a switch or jumper or something so I can disconnect the DC-DC converters. With them in parallel all you see on the watt meter is there aggregate outputs, but not their individual outputs. I suppose I could run two watt meters in parallel. That would get me current output, but not voltage.
ElectricGod
10 MW
I suffered a burn out of sorts. My field wires are ideally too small for 3000+ watts I am now running at and they got hot and melted my lighting wires together. The scooter still runs, just no lights or horn. There was no other damage to anything other than melted wiring. Since I'm having to replace a lot of wiring. I'm also rearranging the rest of the wiring. I'm losing about 14" of motor phase wire by making them exit out of the back right corner rather than the back left corner. I'm also replacing the 12 awg phase wires with 8 awg wires. That should solve the hot wire issue! I am also redesigning my lighting wiring significantly. The old way was a bit of a hodge podge so now everything will all work the same way and will be done with heat resistant wiring. The new wire withstands soldering without melting the insulation. The old stuff had vinyl insulation and it melted much too easily. The field wires didn't get uber hot, but enough to melt together the crappy vinal coated wiring.
ElectricGod
10 MW
I'm mostly done with the rewire...just waiting on the 8awg feild wires to get here from China.
ElectricGod
10 MW
Minor changes to my charger, but this is the final product. I added some diodes to the outputs from the 2 DC-DC converters to isolate them from each other. Their input side already has large diodes on the heat sink that isolate that side. The watt meter shows total current draw, watt hours, charge voltage, etc. The 3 digit LED shows the power supply output voltage.
Ianhill
1 MW
- Joined
- Sep 25, 2015
- Messages
- 2,872
That scooter must be a rocket ship.
Well done tap on back the charger setup seems to be coming along nicely i use lipo at moment but when I can afford lifepo4 cells or equivalent I will be moving to something like this for ease of use. I have three 4s 16ah to charge so i can charge in under two hours in theory but I only have a 10s charger so I just individual balance charge that takes around 5hours but bit of a potch taking the lid of and having to series them up with xt90 to run it and your battery's display looks ace I only have a volt and ammeter with shunt to see volts sag and work out my watthour on the run 3000max I get on a 15khz brushed setup bit shudery at low revs and only gets moderately warm and keeps up with 30mph traffic nicely with bit if reserve so must do 35mph I bet yours tops 50mph it must.
Well done tap on back the charger setup seems to be coming along nicely i use lipo at moment but when I can afford lifepo4 cells or equivalent I will be moving to something like this for ease of use. I have three 4s 16ah to charge so i can charge in under two hours in theory but I only have a 10s charger so I just individual balance charge that takes around 5hours but bit of a potch taking the lid of and having to series them up with xt90 to run it and your battery's display looks ace I only have a volt and ammeter with shunt to see volts sag and work out my watthour on the run 3000max I get on a 15khz brushed setup bit shudery at low revs and only gets moderately warm and keeps up with 30mph traffic nicely with bit if reserve so must do 35mph I bet yours tops 50mph it must.
Ianhill
1 MW
- Joined
- Sep 25, 2015
- Messages
- 2,872
For a PSU I have a HP c7000 unit from a server they are very cheap easy to get running and supply 12v at 2250w 187amp single rail my charger can not budge the input voltage with a 300w sag it just laughs at it so 2 more icharger 1010b for me possible to charge 6 packs at a time then make around 30miles or so fun time. And all that in under 2 hours
ElectricGod
10 MW
Ianhill said:
I don't know what my current top speed is, but it will do 40mph+ on level ground. I need to tune my gearing a little more, but I think 45mph is full out.
Ianhill
1 MW
- Joined
- Sep 25, 2015
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I think the natural poor aerodynamics of a scooter and its riders position do not help achieve high speeds, upto 20mph there's not to much are resistance other than gusts of wind after that the power increases for each extra 5mph are a lot if I can reach around 30mph with 3000watt that extra 15mph or so you make takes a big jump up in watts with your efficiency increases been brushless say 300% more power needed so a 10kw setup will crack 50mph say but makes sence really but nice too know that as you go up the speed the watts needed increase exponentially.
ElectricGod
10 MW
Ianhill said:
Wattage is definitely higher now. I typically pull 2800 watts to get 40+ mph now. The scooter weighs more now and the increase in speed both weigh into that increase. With my old motor and 48 volts to get 30mph was around 1900 watts. I ride standing up as little as possible to minimize wind resistance. My experience is that wind resistance between standing and squatting down costs or gains me 1-4 amps. That's pretty negligible. I suppose some kind of wedge on the front of the scooter to cut through the air would do more. I haven't finished tweaking my gearing. I was running at 4.27:1 and got 43mph and about 40 amps draw at 72 volts with the 64 tooth/15 tooth combination. I am currently running at 4.9:1 and top out at 39mph and still pull 40 amps which is 54 tooth and 11 tooth. I haven't tried it yet, but I want to try 4.15:1 (54:13) to see how that does. If I can stay at about 40 amps and get better than 43mph, well that will be about perfect. I have tried 3.6:1 (54:15) and I drew 60 amps and barely got to 35mph. The gearing ratio was just too excessive for the motor and load.
Here's my sprockets. I have a lot of combinations I can try.
64 and 54 tooth rear sprocket
9,10,11,12,13,15 tooth motor sprockets
3000 watts ought to get you LOTS more than 30mph. My current inrunners are not the best. I know other inrunners are more efficient than these are, but hey they are really inexpensive so I'm not complaining. I think a better inrunner would pull less current and give me similar torque. If you can't get 40mph out of the 2000 watt motor I am currently using, well you are doing something wrong.
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