WB projects
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Go with LMT motor or TP power. Depending on the budget but you will get what you paid for with LMT. Shoot for the motor power then look the RPM.
Gearing Up Motors
- Thread starter mham2k
- Start date
WB projects
Active member
It look like you try to go backward of what you need. Set you a goal, find your motor and turbo or procharger at the same time to match, find your ESC to go with the motor, then look for the batterys. Do you need more or less voltage depending of your power and current limits. Now you can look at your charging set up.
For the motor, its simple keep in mind that they are all arround 50k rpm. LMT or TP power
If you want a lot of boost you will probably need a high torq motor so maybe you should look with LMT
For the ESC, user friendly, there's MGM controllers. APD have been tryed and fried. So maybe not for now with APD
Now you know that you can run your motor arround 50k rpm. Do you need to gearing up? So find a compressor that is viably clost to your goal.
For the part of assembling everything, we can't suggest you something because they are all work in progress! So try to see all of our idea and try something new or follow our path.
After that, you can worry about your battery and charging method. You are limited by RPM and not by the battery and charging methode
For the motor, its simple keep in mind that they are all arround 50k rpm. LMT or TP power
If you want a lot of boost you will probably need a high torq motor so maybe you should look with LMT
For the ESC, user friendly, there's MGM controllers. APD have been tryed and fried. So maybe not for now with APD
Now you know that you can run your motor arround 50k rpm. Do you need to gearing up? So find a compressor that is viably clost to your goal.
For the part of assembling everything, we can't suggest you something because they are all work in progress! So try to see all of our idea and try something new or follow our path.
After that, you can worry about your battery and charging method. You are limited by RPM and not by the battery and charging methode
MkngStffAwesome
Active member
Technically 48v is always better than 12v and 60v is always better than 48 and 400V is always better than 60v... The reason why you might chose a lower voltage would be ESC limitations ...(cost)
That battery obviously can't power your system,... well not one of them anyway
Ok, 50,000 rpm is good I will use a larger turbo so I can get more at a lower rpm.
Thanks working on this now
Technically 48v is always better than 12v and 60v is always better than 48 and 400V is always better than 60v... The reason why you might chose a lower voltage would be ESC limitations ...(cost)
That battery obviously can't power your system,... well not one of them anyway
Right lol, yeah I'm trying to figure out what I need to allow my 12v alternator to charge my new and improved 48v battery. Unless you'd going to tell me to convert my entire car to 48vs
WB projects
Active member
I personnaly use a step up plug to my BMS and thats it
you want to look at this motor:
www.castlecreations.com
Castle 1721 Sensored Motor - 2400Kv - LIMITED WARRANTY
Castle 1721 Sensored Motor - 2400Kv - LIMITED WARRANTY
SGL12GUNNER
Member
Hello, new here.. I have been reading a bunch, and I'm a brand new to brushless motors.
I see Alex had a step up, and is now stepping down his set up. I am curious as to how stepping down is going to help.
I understand the motor needs load. I don't see any one here that has stepped up to a ratio of at least 3.0:1.
The issue I see here is you are trying to spin your brushless to max RPM.
RPM and torque are inversely proportional; as one increases, the other one must decrease. So if your step up is so close to 1:1 such as 1.22:1 you aren't putting any more Tq into the impeller at max RPM. So the only thing to do is to go with a larger motor to supply more Tq at max rpm.
I am most likely wrong but it seems to me we should be calculating the most efficient motor and gear for the desired impeller speed. EXAMPLE (Kv × V) / G1/G2 = RPM
(Kv × 48) / (54/18) = 40,000
Kv = RPM x (G1/G2) / V
40,000x3/48 = 2500 Kv
With that knowledge, you are using a larger motor with higher system voltage instead of gearing to get the the supercharger to spin faster
I know I'm missing some other concepts regarding motor load. But I I really think we are missing out on what potential we can achieve by selecting the right motor AND gearing.
One other thing that intrigues me is: The more boost you produce the more load on the motor?
I think we need a "larger" motor, with sufficient system voltage (but not excessive)...and appropriate gearing.
The P2 is nice as it already has a drive with 18 teeth... however... finding a pulley of greater than or around 54 teeth and a belt that will be a slight challenge... but maybe not as challenging as finding a motor that will do the job too... I wish I had more info on the LMT TorQstar3.
@AlexLTDLX I wish I had the means to test my self. But alas I can't. I know you tried the snorklet to simulate load. Perhaps you make a "boost tube" to allow a greater volume to be filled. Have the tube be roughly 2-3 feet long with that 90 off the blower, with the restrictor plate in the end of the tube.
Idk I'm spitballing here. I'm really hoping I'm correct in my thinking. As more boost builds the greater the load on the motor, resulting in being in the motors efficiency range...
School me!
I see Alex had a step up, and is now stepping down his set up. I am curious as to how stepping down is going to help.
I understand the motor needs load. I don't see any one here that has stepped up to a ratio of at least 3.0:1.
The issue I see here is you are trying to spin your brushless to max RPM.
RPM and torque are inversely proportional; as one increases, the other one must decrease. So if your step up is so close to 1:1 such as 1.22:1 you aren't putting any more Tq into the impeller at max RPM. So the only thing to do is to go with a larger motor to supply more Tq at max rpm.
I am most likely wrong but it seems to me we should be calculating the most efficient motor and gear for the desired impeller speed. EXAMPLE (Kv × V) / G1/G2 = RPM
(Kv × 48) / (54/18) = 40,000
Kv = RPM x (G1/G2) / V
40,000x3/48 = 2500 Kv
With that knowledge, you are using a larger motor with higher system voltage instead of gearing to get the the supercharger to spin faster
I know I'm missing some other concepts regarding motor load. But I I really think we are missing out on what potential we can achieve by selecting the right motor AND gearing.
One other thing that intrigues me is: The more boost you produce the more load on the motor?
I think we need a "larger" motor, with sufficient system voltage (but not excessive)...and appropriate gearing.
The P2 is nice as it already has a drive with 18 teeth... however... finding a pulley of greater than or around 54 teeth and a belt that will be a slight challenge... but maybe not as challenging as finding a motor that will do the job too... I wish I had more info on the LMT TorQstar3.
@AlexLTDLX I wish I had the means to test my self. But alas I can't. I know you tried the snorklet to simulate load. Perhaps you make a "boost tube" to allow a greater volume to be filled. Have the tube be roughly 2-3 feet long with that 90 off the blower, with the restrictor plate in the end of the tube.
Idk I'm spitballing here. I'm really hoping I'm correct in my thinking. As more boost builds the greater the load on the motor, resulting in being in the motors efficiency range...
School me!
MkngStffAwesome
Active member
i asked that in the other thread that i think is more appropriate
"why is he now reducing the gearing"
P2 Supercharger Thread
i expect the MGM to just work too.. DID APD replace your ESC's or is that just money thrown away
www.electrifiedboost.com
SGL12GUNNER
Member
I get that, but that is specific to the P2... I'm talking about gearing in general and was referencing his p2 build. Im talking about determining the proper motor and gear ratio for a a desired boost level/compressor RPM.i asked that in the other thread that i think is more appropriate
"why is he now reducing the gearing"
P2 Supercharger Thread
i expect the MGM to just work too.. DID APD replace your ESC's or is that just money thrown away
For the P2 he is using the same motor he used on the Vortech and made decent boost on a V8... Something that is actually really impressive... It could not be replicated on the P2, but it isn't an apples to apples for compressors either. I'm not sure the step up was a hindrance.
While typing this, I kept trying to wrap my head around this ... and I conclude that I am most certainly incorrect. In an engine a step up gearing is needed. In a brushless motor, you aren't as confined to a peak engine rpm of 6-7k , and you don't need the gearing to get the blower moving because the motor has enough Tq ...instantly. Stepping down should actually allow greater efficiency and performance....
MkngStffAwesome
Active member
Well im not sure which discussion we are having in here... you say we are not talking about the P2 but you mention that ?
However you also mention 2500kv which is not realistic with the big motors used on the P2
2500kv * 48v = 120,000 rpm.. that is a very high rpm motor and therefor it's total power handling will be FAR to low to be of any value (compress the air) because it will been to be physically small to be able to maintain that rpm.
Im also not sure where 40,000 rpm came from ?
Im also not sure you understand the need for the high voltage? This is needed because higher the voltage the lower the current for the same power. Buying high current ESC's that actually work seems to be the limiting factor...
However you also mention 2500kv which is not realistic with the big motors used on the P2
2500kv * 48v = 120,000 rpm.. that is a very high rpm motor and therefor it's total power handling will be FAR to low to be of any value (compress the air) because it will been to be physically small to be able to maintain that rpm.
Im also not sure where 40,000 rpm came from ?
Im also not sure you understand the need for the high voltage? This is needed because higher the voltage the lower the current for the same power. Buying high current ESC's that actually work seems to be the limiting factor...
Last edited:
SGL12Gunner - I initially thought exactly the same as you. But I didn't take duty cycle into account. Think of everything in terms of energy. We want to maximize energy in to turn the impeller as fast as possible. For our units of energy, let's use watts. If a brushless motor is running at half speed, then it's only running at half duty cycle. Meaning it's only getting power to the coils in the stator half the time. There's a limit to how much current you can push through the motor before it starts to magnetically saturate and eventually melt down. So let's say our motor is rated for 100 amps. If you're pushing 50 volts into the motor at 100% duty cycle, and the motor's hitting 100 amps, you're pushing 5,000 watts into the motor (and e turbo system). If the motor's spinning at half speed - 50% duty cycle - at the same 100 motor amps, then you're only pushing 2,500 watts into the system. You can think of duty cycle as a voltage multplier. 100% duty cycle = full voltage. 50% duty cycle = half voltage.
Also, the load on the motor affects kv. In my current case, my TP Power motor is rated at 750 kv. Under no load conditions, it's more like 800 kv. Under a heavy load (like running the compressor into choke), it's more like 600 kv (or less). The key is to maximize duty cycle above all else. That's what will maximize overall system power.
Hopefully that helps.
Also, the load on the motor affects kv. In my current case, my TP Power motor is rated at 750 kv. Under no load conditions, it's more like 800 kv. Under a heavy load (like running the compressor into choke), it's more like 600 kv (or less). The key is to maximize duty cycle above all else. That's what will maximize overall system power.
Hopefully that helps.
MkngStffAwesome
Active member
The more i read his post the more i think this is about motor efficiency , which is a conversation i had with me self on the p2 charger thread.
If so then sure having the motor spin faster than the impeller should be more efficient than the opposite.. However that can actually be difficult to find both a high powered motor and high rpm.
If so then sure having the motor spin faster than the impeller should be more efficient than the opposite.. However that can actually be difficult to find both a high powered motor and high rpm.
We may ultimately find that direct drive isn't the way to go for high-powered applications. But I do think for low powered-applications (under 650 hp), direct drive is the way to go. The costs seem to spiral above that magic number. Nevermind that it gets dangerous as heck.
WB projects
Active member
Do you ever do something really fun that is safe? AHAHAH
SGL12GUNNER
Member
It is hard to wrap your head around things when you have nothing in front of you...
The math I provided above is what KV a motor would need to spin the compressor shaft to 40k rpm with a gear ratio of 3:1 @ 48 volts, which was about 2500kv. However this takes nothing else in to consideration. Such as load, in the form of the resistance the compressor faces as it moves more air. Let alone losses from the gearing/belt, Bearings
In a traditional supercharger you have your crank pulley which is rather large and a smaller pulley on the supercharger. That is where we get things mixed up. As the engine is high hp/tq but relatively low Rpm. But we are dealing with low hp and low Tq - High RPM electric motors that make their TQ instantly and as RPM increases the motors Tq decreases.
But look around in the real world applications. Now I don't know why I didn't think of this earlier, but if you look at Tesla and their drive unit, they are geared down not onec but twice. To the tune of around 9:1 depending on which revision you look at.
Take a look at any older AHU for a building HVAC system and those are also geared down. The pulley on the fan is larger than the pulley on the motor.
Now by gearing down you are limiting the final drive rpm. But your allowing more work to be put into moving the air.
By gearing up you maximize rpm to be put into the impeller shaft but it seems that the power isn't there. I don't think the TP power motor is good for anything other than direct drive. If we had a low rpm (relatively speaking) high tq and Hp motor then gearing up would likely work. Far better. But we don't have that.
The largest motor we have (to my knowledge) is the LMT 30100... which does have some power! Also has a really high price point...
... but the jury is still out for me weather this motor would benefit from gearing, or is this motor still best suited for direct drive.
Given the price of that unit, unless you could get 9psi out of the P2 on the v8, it just plain costs too much to e-charge. But that is for another topic...
The math I provided above is what KV a motor would need to spin the compressor shaft to 40k rpm with a gear ratio of 3:1 @ 48 volts, which was about 2500kv. However this takes nothing else in to consideration. Such as load, in the form of the resistance the compressor faces as it moves more air. Let alone losses from the gearing/belt, Bearings
In a traditional supercharger you have your crank pulley which is rather large and a smaller pulley on the supercharger. That is where we get things mixed up. As the engine is high hp/tq but relatively low Rpm. But we are dealing with low hp and low Tq - High RPM electric motors that make their TQ instantly and as RPM increases the motors Tq decreases.
But look around in the real world applications. Now I don't know why I didn't think of this earlier, but if you look at Tesla and their drive unit, they are geared down not onec but twice. To the tune of around 9:1 depending on which revision you look at.
Take a look at any older AHU for a building HVAC system and those are also geared down. The pulley on the fan is larger than the pulley on the motor.
Now by gearing down you are limiting the final drive rpm. But your allowing more work to be put into moving the air.
By gearing up you maximize rpm to be put into the impeller shaft but it seems that the power isn't there. I don't think the TP power motor is good for anything other than direct drive. If we had a low rpm (relatively speaking) high tq and Hp motor then gearing up would likely work. Far better. But we don't have that.
The largest motor we have (to my knowledge) is the LMT 30100... which does have some power! Also has a really high price point...
... but the jury is still out for me weather this motor would benefit from gearing, or is this motor still best suited for direct drive. Given the price of that unit, unless you could get 9psi out of the P2 on the v8, it just plain costs too much to e-charge. But that is for another topic...
MkngStffAwesome
Active member
It is hard to wrap your head around things when you have nothing in front of you...
The math I provided above is what KV a motor would need to spin the compressor shaft to 40k rpm with a gear ratio of 3:1 @ 48 volts, which was about 2500kv. However this takes nothing else in to consideration. Such as load, in the form of the resistance the compressor faces as it moves more air. Let alone losses from the gearing/belt, Bearings
In a traditional supercharger you have your crank pulley which is rather large and a smaller pulley on the supercharger. That is where we get things mixed up. As the engine is high hp/tq but relatively low Rpm. But we are dealing with low hp and low Tq - High RPM electric motors that make their TQ instantly and as RPM increases the motors Tq decreases.
But look around in the real world applications. Now I don't know why I didn't think of this earlier, but if you look at Tesla and their drive unit, they are geared down not onec but twice. To the tune of around 9:1 depending on which revision you look at.
Take a look at any older AHU for a building HVAC system and those are also geared down. The pulley on the fan is larger than the pulley on the motor.
Now by gearing down you are limiting the final drive rpm. But your allowing more work to be put into moving the air.
By gearing up you maximize rpm to be put into the impeller shaft but it seems that the power isn't there. I don't think the TP power motor is good for anything other than direct drive. If we had a low rpm (relatively speaking) high tq and Hp motor then gearing up would likely work. Far better. But we don't have that.
The largest motor we have (to my knowledge) is the LMT 30100... which does have some power! Also has a really high price point...
Given the price of that unit, unless you could get 9psi out of the P2 on the v8, it just plain costs too much to e-charge. But that is for another topic...
yes this i all true and has been discussed before