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Discussion Starter #1
Hey,
I have done as much reading as possible but cannot find the answer I am looking for so hopefully the forum can help me out. We are running a PR200 with 3 12v 12AH into a 36v 500w universal controller using the factory motor and sprockets. The rider weighs about 127lbs. We just ran a GPS speed of 19mph. We are looking for some more speed. What would be the next step if it was your choice for the money? If we went with sprockets, what would be the best combo for a faster speed? I would assume the next motor would be the 500w. I would rather just change sprockets without having to pull out the welder. I realize the factory motor can only handle so much, but I have 2 back ups on the shelf so I would like to try and get close to 25mph with the existing motor. Thanks in advance for your time and thoughts.
 

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Hello <---the song I'm listening to this second too!

Hmm, how is the low end take off, good and "fast enough" ??

If it is, can you count the teeth (or do you know) Pinion and sprocket please... that will tell us what setup you have, for the most part, yes, if there is "enough power" to be had (there should be with that battery setup) 1 tooth larger on the front pinion would be a nice upgrade, it is roughly 10x per tooth ( 7-70 front - rear) is normal on some pocket bikes, so 1 tooth change up front is = 10 teeth at the rear, 1 tooth change up front, and I bet the chain still fits, 10 teeth at the rear and it might be some serious slack.

Front Pinions: more teeth = more top speed
Rear Sprockets: less teeth = more top speed

Good luck, and have FUN!!! :thumbsup::):thumbsup:
 

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So their are some very cheap ways to get your bike up to 25 mph I would wire a turbo bypass and change the sprockets or add a 4th 12 volt battery.The 4th battery would get you up to 25 and you probily will not have to change controllers.For the sprockets as Nick stated above that dropping sorockets in the front would be the best but you will lose speed on take off or you might not hit the speed your looking for so I would wire a turbo bypass.A turbo bypass bypasses the controller letting the motor have more amps but this is a little bit like nos would be on a car so you can only use it for about 30 seconds to 2 mins and if you use it for 2mins the motor could possibly get dammaged.Here is how to wire a turbo bypass first you need to get this switch Northern Tool because this can handle lots of amps.After you get the switch if you do not have 12 Gage wire or below you need to get some,you need to take the wire and soder it to one side of the switch and soder another wire to the other part of the switch then you need to put the 1 strait wire to the positive side of the battery to the negative side of the battery,and do the same in vise versa.Once you hit the switch you will have massive acceleration and you will gain some mph on top speed.Never have the bike on at the same time you hit the switch for the turbo bypass.
 

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Also I have never done this but you could posibly add more volts when you hit the turbo bypass like you could wire in a rc car battery,12 volt battery or a 6 volt battery would do you well.For me this worked small scale but I have not tried it on my pocket bike yet.
 

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Discussion Starter #5
Nic,
Thanks for the quick response, I am running stock 11/55 the next aval. sprocket for the motor side is 13. This might make it tough to come off of the start, and if that is the case I will get a 65 wheel to even things out.

Haydendlp,
LMAO it never amazes me how guys can figure out a way to get more power out of anything. I like the idea but realize the damage that it may cause long term. A turbo switch....tooo funny.

ok, a few more questions please, We had a MX500 controler on originally until some damage was done to it (long story) so I went back to the vendor to get another one and they were out of stock but they suggested I get a universal one. 36 Volt 500 Watt Universal Speed & Voltage Controller
So now the bike seems to be faster (by my sons perception)compared to the mx 500 controller. Why would this be?
The specs state that it can handle a Max of 14 amps...how is this related to performance?
Last question, my batteries are rated at 12 12ah, I got the 12ah only because I was told that it would make the rides last longer per recharge. Is there anything else that this rating would mean relating to performance?

Thanks again for the quick responses.
 

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No Problem, it was FUN!

Batteries, YES, I have been in love with batteries since 1985 <---my first Flashlight <---I am a really weird dude! hahh

12Volt, automotive, diesel, marine, motorcycle, we all "mostly" use 12v the 12v is the "possible" potential of the battery (water tank)

Amps, Moving amps is the flow of electrons, the actual "Labor" of work, 12v pushing through 6 Ohms, should create a 2-Amp draw (Ohms Law) <---anyone wanna become an electrical engineer by reading 2 pages I would be more than willing to "Write-up" for you all?

Amp hours, (AH) How many amps can the battery flow for 1 amp (Hour) <--just a fancy word to say 1 amp load for 60 minutes = 1AH

the more AH, the longer.... the rides! YES! and the charging, NOOOOO!

These small batteries can only be charged at slow and low amperage settings, not like the 12 amps I hit my Optima's with!

But, the stock chargers play a silly trick on us (usually) <---here it comes!

If they can "Trick Us" into charging at a ridiculously slow charging rate, they wont have to warranty batteries for us so often <---That is mean!

The super sweet, top secret, OEM un-approved procedure.

Google! type in the battery stats, and a + charge rates, watch how much faster these guys are charging their batteries.

But, the "packs" <---groups of batteries will last a bit longer when "trickle" charged.

I employee the how hot does this sucker feel trick, I watch them charge the first few times I am "playing" with charge rates, and feel it every 10 minutes or so, all over, just not the terminals !! :p as another member said last night, "I Don't Want To Burn The House Down!"
 

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Discussion Starter #7
Wow,
You do like batteries! So basically what your saying is I bought long running batteries that take a long time to recharge, but they do not add any more performance than say a 12v 7ah battery.?.? Great. I still am confused about the "max 14 amps" on the controller? How much amperage are my batteries putting out? I am cluless on this electrical stuff but I am a quick learner.
thanks for the help
 

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Wow,
You do like batteries! So basically what your saying is I bought long running batteries that take a long time to recharge, but they do not add any more performance than say a 12v 7ah battery.?.? Great. I still am confused about the "max 14 amps" on the controller? How much amperage are my batteries putting out? I am cluless on this electrical stuff but I am a quick learner.
thanks for the help
Well 12 volt 12 amp batteries preform better because they allow more current to go threw but they only add like 1-3 more mph but you can not realy notice the little extra performance.Well the controller that says it is rated for 14 amps does not make sence at all because 14 amps means the controller will alough the motor to pull 14 amps but that is not right or the controller does not have a amp cut off so it can pull more amps but it could possibly damage the controller after a couple of months of hard riding but I do not know if this is the case.The mx500/650 controller is a good controller mine is very slightly modded but that controller you have seems like a good controller.
 

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Wow,
You do like batteries! So basically what your saying is I bought long running batteries that take a long time to recharge, but they do not add any more performance than say a 12v 7ah battery.?.? Great. I still am confused about the "max 14 amps" on the controller? How much amperage are my batteries putting out? I am cluless on this electrical stuff but I am a quick learner.
thanks for the help

Yes, but I suck at MATH!

Here is some more of Ohm's law "put to work?"

12v at 14amps (Wide open throttle) = 168 watts, so, by my math 14amp max is shooting you in the foot, unless you are running a motor that only wants 150 or so watts. (14 amps is the max the controller can handle without overheating)

3 x 12v = 36 volt when it is in Series, so, since you (probably) are hooked up in "Series" you would be running 36v, ah ha, 504 watts now, 36v at 14 amps = 504 watts.

so if the motor wants 500 watts, at 36 volt, you will be using 14 amps per hour? now, if this is all correct, that would be a 12 amp hour total (because we are in series) which should be 30-45 minutes on a full charge.

Electrical can be EASY as PIE!

Ask me more, I'll show you some of my cool Fluke meters!
 

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Discussion Starter #10
alright Nick since you are willing to teach,

36v (3 x 12v in series) = 504 watts....how is this determined? (I don't understand how watts is related to volts and amps.)

Ratings...

a 24v 250 watt rated motor being pushed to 36v means that RPMS are being pushed to a higher than rated output with more torque or just more speed?


If I were to change out the 24v 250Watt motor with a 36v 500watt motor. What could I expect for performance compaired to the 250 watt motor, More torque but at the 500w rated RPMS or more speed as well?

let's say for learning discussion, we are running at wide open throttle. If I was at top speed with existing equipment, then let off throttle and pushed a bypass button to hook the motor directly to the batteries would I see or feel any more performance at the consequence of over pushing the equipment?

thanks again
 

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No Problem, I've got around a year of electrical training under my belt!

I'll slow down a little bit, so everyone on the forum can keep up with us, this post is going to need more words though, so I hope you are ready to read.

**this is ALL off the top of my head, and could be wrong** <---not much of a chance of that but who knows!

12 volts, pushing 1 amp, is 1/3rd as "Strong" as 36v pushing the same 1 amp, they all match up, so, 12 volts pushing 3 amps would be close to 36volts pushing 1 amp.... <---**** you math! hahah

The controller, I did not know you were at 24 volts, sorry! lets do some more math.

24 volt pushing 12 amps = 288 watts, watts are a form of power measurement, like HP kinda, the rating is like this, voltage times amperage = wattage, I think that was the math :p

Batteries (series vs parallel) series, positive to negative to positive to negative to positive to negative (in a row) each time the voltage will jump up, 12 + 12 + 12 = 36, Now, 12 AH batteries, in series, will still be just that, 12 AH, series kicks up voltage for us, but all the amp hours wont help performance, just run-time.

500watt, going from 24 volt (12 x 2) up to 36 volt (12 x 3) should be 1/3rd more powerful, but, you would want to up the watts of the motor too, otherwise it will fry out on you from overheating. most motors are rated to 12v or 24v or 36v or 48v, and they can freak out if you "over-volt" them.

a 24volt 250 watt going up to a 36volt 500 watt, this starts to get a bit tricky, 24v to 36v = 1/3rd more volts, 250 watt up to 500 watt is literally double the power, but to flow enough amps to make 500 watts WILL drain the batteries even faster! <---where is that Energizer bunny when you need him!

The old Turbo button, yes, more power <---Tim the tool-man hahah

But, it would be all or nothing, and could create some weird sparks, that could freak out the controller, but if lots of "Dudes" are doing it, it may work out just fine, the controller is there to protect the motor and the batteries, so I would not just go around bypassing it, everything I wire, gets a fuse, think of the controller as a nice "Smart" fuse, just get a controller that can do more amps / volts, but make sure the batteries can keep up!

Ask me more, this is STILL fun for me! <---I like to talk! I have lots of stuff to say, and it is almost always nice or funny or both!
 

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Discussion Starter #12
Hey Nick,
I have done a bunch of reading since this morning so I think I am begining to understand the principles of electricity.

So right now, I am running 36v through a 36v 14 amp max controler to a 24v 250 watt motor. SO how can I figure out how many amps this setup is pushing?

If I strait wire the set up and run 36v 12 ah batteries to the 24v 250 Watt motor, how many amps will the current be?

By over volting the 24v 250 watt to 36volts am I must be gaining rpms on the motor based on the higher running speed. Will I loose the rpms when I replace the 24 v motor with the 36v 500w motor?


I plan on getting a 44 tooth sprocket for the wheel and a 13 tooth for the motor. I am hoping that the speed will increase with the existing setup. However if the motor cannot push the gears I am prepaired to get the 36v 500Watt motor. I am trying to get into the mid to high 20's that is fast enough for a bike this size. Anything faster will need to be done on the go-kart (31mph).



thanks again!
 

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If you didn't already order anything, get the 500watt 36volt motor first, that will hook you up, it's almost like you have a fuel injected, nitro enhanced turbocharged fuel system, and my 1.5 liter Hyundai engine trying to suck up all that power, not a "match made in "heaven" :D:thumbsup:
 

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I don't know a lot, so I'm not going to waste your time, but here are a few pointers I have learned along the way that may help you.
this links rocks;
Speed Calculator For Go Karts and Mini Bikes
you need to figure your rpms...to do this find the KV(kilovolt) like the rating of hobby motors in rc stuff.
to do this take the rated rpm of the motor(2650rpm for 24v 250watt) divide that by the motor voltage(24v) you get a kv of 110 or so. Next multiply the kv by the voltage you intend to run....(36v) you get a rpm of roughly 3900rpm.
now your gearing and wheel size are the remaining factors in calculating speed. you won't be swapping tires, so it's the gears you're concerned about.
so for example you want a 44/13 and that gives you 20mph, but a 44/25 gives you 35mph....that's all fine and good, but it's going to take a lot of strain on the motor and a looooong stretch of road to get to that speed.
The key here is to gear for speed, but factor in load on the motor...electric motors are designed to run load free at top speed. the reason they are rated at 2650rpms is the max...they won't go any faster. They will also do what it takes to get to that speed. So the more load on the motor, the more heat. This is why you don't want to run straight amps to battery unless you are already moving pretty fast.

The next key is your controller, it is more like a gateway...limiting current from the batteries. so I really only focus on its amp rating. yours is 14amps so that means(in my experience) that you're popping the breaker going up hills and when the batteries are low. I'm surprised it doesn't trip just from sitting on it and hitting the throttle. Can it handle take off from a dead stop?!
My razor controllers are 30amp, and that is just fine for me. You can pick up a generic version for $20-$24. mine runs just fine on five 7ah batteries.
my 1st mod was a razor vespa style pocket mod. I removed the 250watt replaced it with a 1k watt 36v motor, 36v 30amp controller, 44t rear on 12in tires. The speed calc said 35mph on 48v. I ran it on 24v for awhile and it went around 15-18mph, but it took forever to pick up speed.(gearing) I ran it on 48v and got 26mph out of it. I bought a 60v controller (100amp) and added a 5th battery. I burned my motor up! black smoke, burnt copper smell! So I messed with the controller. I ran 48v on my MX650, it accelerated so fast it popped wheelies, it climbed hills! but again, smoke! and HEAT! So I ran 36v on my MX650...no smoke, no hill climb, just fast accel and lots of HEAT.
So I asked and asked what was the problem?! I was told that the 44t on 12in tires was too small...the motor couldn't spool up as fast as the controller was dumping amps into it. So my MX has 16in tires, but even the large 80t sprocket is too small. but they don't make larger sprockets! So I put it on my MX500 with TEN batteries! 2 parallel packs. Because I was told that larger capacity batteries were the 2nd key. I would only accel slowly, and I still burned it up.
So the controller is rated up to 100amps, but that doesn't mean it is throwing 100amps all the time, or even at all. But even if it's throwing 50-80amps that is apparently enough to burn up the motor.
High load(take off) and wide open throttle are the 2 situations where there is high amp action, this will 1.drain the battery quickly, and 2.burn up the motor. The motor is like a sponge, it will soak up all the amps it can from the battery, but if it cannot spin freely, that extra battery juice turns into heat. That heat radiates through the copper coils and to the outside of the motor case. So when you feel the motor is "hot" that energy is already passed through the motor. Now the copper wires have a coating on them to protect from heat, but when you overvolt, that heat is enough to burn the coating and damage the motor. So a controller with a high amp output will "dump" amps to the motor faster than they can be used.
The lesson I learned? the 30amp controller will let me hit 24mph on a 650watt motor just as well as the 100amp controller.
I acidently figured out I could run 60v on a 36v controller...I have a pile of dead controllers to prove it.
It is like running 36v 50amps I've been told, but I'm skeptical. the 50amps give you way more torque for quicker take off, but you could also gear to do that and not suffer the heat damage. I figure 36v is still only so much rpm. The low amp with high volts ensures high rpm which is more top speed. So your low amp controller is actually preserving your battery. I can't see how it is faster than a 30amp razor.
As I was saying about the batteries...you already know a larger amphour is just a way of saying more available power. I have run 4 12ah batteries on the same system as 4 7ah and my top speed was about 2-3mph faster. That should mean that the motor is actually getting more amps, but less than 30amp or my fuse would blow right?! I don't know about calculations, but if you look at lipo batteries for instance they have a 'C' rating for constant and burst rates...what this means is that they are able to run 25c constant or put out 25% of thier capacity on demand and 50c burst would be short term...like 3sec of top power under a dead stop. (this is all rough terms here) So again with the turbo button...what you are doing is going direct battery to motor...meaning there is no controller; no gateway. You can actually "shock" lower capacity batteries if the load is too great. Meaning the burst rate will be exceeeded and you will actually overdrain the sla battery and render it unable to hold a charge. See you can only use 20% of an sla's charge MAX before you have to recharge it. That's why the controller has a lvc(low voltage cutoff) this will slow down your scoot and even shut it down if you continue to use it. My old 24v razor could run until it barely crawled because there wasn't too much demand on the battery with a 24v system...that how they claim you can run for 40mins....the last 10minutes you're going 2mph! when you overvolt to 36, 48, 60v, you get about the same 20min run time for all of them, but the higher the volt, the quicker the cutoff. on 36v I could get home when I hit 'low' before I'd have to push it home. on 60v it runs just fine until it hits 'low' then it instantly cawls. If I'm too far from home, I'm not making it back. and that is voltage sag or the throttle demand on the battery. the throttle's saying more juice! the battery says I have a shelf life!
larger capacity battery lets you run a little longer, but not much in the long run because of all the extra weight.
so why not go lipo?! too expensive and prissy! I'd LOVE to, but you really have to baby those bad boys! especially if you're piecing hobby grade lipos together. You could essentially get 6s batts ...22.2v 5ah for $50each....4 of them would get you 44.4v 10ah for around $200, plus harness, charger, etc....$300tops would get you a very nice lipo set, but you really have to watch them when riding AND especially charging! Especially charging them all on the same charger. You're almost better off getting 4 chargers, but at $40 each that's not cheap. That's just too much money for me.

If I wanted to tweak my vehicle to perfection I'd get a 50amp controller(lb 37) 5 12ah batteries and a 48v 750watt motor. that should get me around 28mph on my MX650....right now it's running 60v on 7ah batteries and hit about 23-24mph....slow until I hit gravel then it's reallll squirelly! It's enough for a 10min laugh and a 3hr recharge. it is what it is and I've decided I've gone far enough.

hope this helps.
 

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I don't know a lot, so I'm not going to waste your time, but here are a few pointers I have learned along the way that may help you.
That last post looked like allot to me! <---Give yourself MORE Credit bassiclyloudog!

:p:thumbsup:
 

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Discussion Starter #16
Wow,
Great stuff Bassiclyloudog and Nick. Well over the weekend I cleaned up the install, tightened the batteries, welded them with 10awg (instead of cheap fittings), pumped up the tires 5lb over and sent my son out with my GPS speedo app running on my phone. We to my surprise, he cam back and told me wow this thing is much faster. I didn't believe him until I looked at the phone. He rode it for 3 miles and top speed was 23mph! This was great data compared to our last run of 19mph.

Bassiclyloudog, it seems as though you have been down the road that I am wanting to experience. We live on flat ground, there are no hills where we live so wind is our only resistance other than weight. I had an MX500 controller prior to this latest rebuild but could never get it to the speed that it is doing now. I am only basing the controller amp rating off of the specs on the website. I am tending to believe it give all that the mx500 controller gave and possibly more. I do have a 30amp fuse in line and have never popped it either. I think the Turbo button is crafty but I would hate to see my 9yr old son get burned if the load was too much or that he hits the throttle and the button at the same time (blowing up controller).

With all of the help that you all have given me, I think I will be ordering a 500w motor 44/13 sprockets and 1 more 12v 12ah battery. I have many fabricating tools, skills, and experience (with cars). I'm thinking we will leave it as is for now but when it gets cooler out in the fall we will. strip down the bike, design a way to make the bike more comfortable for my son (he is big for his age), tuck in another battery and weld in mounts for the new motor. This should allow a safe design with a pretty good run time in the close to 30mph range. My son is fearless, but wiping out going much past 30mph might change that in a hurry. Honestly he just wants to beat the new gassers (49cc pocket bike) in the neighborhood. I am a speed junkie and he gets it from me.

BTW I have done something that I have not seen anywhere in these forums that is a simple way to add length to the bike and add room for a 12v 12ah battery under the faring/tank. I took a sheet of 3/4 plywood and fabricated a extention under the faring. It allows the faring seat to sit 3/4" higher and about 4 inches back from the handle bars. This gives my son a little more room in the cockpit and allows me to mount the 3rd battery under the gas tank/faring works like a champ. If you did not know what you were looking for you would think that the faring is in the factory spot.I'm going to need to brake out the welder for the 4th battery. When I decide to pull the trigger on the rebuild I will be sure to post some pics.

Thanks again for sharing the knowledge
 

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I too have been scouring these threads for the last 3 days and am still unclear on an actual controller recommended for a 36v setup. any suggestions guys?
 

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I too have been scouring these threads for the last 3 days and am still unclear on an actual controller recommended for a 36v setup. any suggestions guys?
It just depends on what you want to spend, and how you want to ride.
 

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Ok let's say under !100 around $50 if possible. How I want to ride? Not looking crazy. Gonna run stock 200 watt motor on my pr200 for a couple months then looking at a 700-800 watt replacement. Going to stay at 36volts. Suggestions?
 
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