New PowerPlant for Mugen Seiki MBX6T

[MallyMal]

What's up to all here, I'm new to the forum and my first interest or advice need would be my Mugen Seiki MBX6T electric conversion. I had an older Mamba Monster 2 1515 2200kv setup mostly ran on 4s (5000/6000 mah) 100c. the pinion/spur setup was 14/46 I'm pretty sure (brought used). The motor is uncensored and still in good shape, ESC is bad, so keep in mind I've already got a Castle 1515 2200kv but i think i want lower kv like 1700 or so. My question is what's a good 6s truggy setup for 1/8 scale truggy for general bashing/street stunting? I'm sure you guys have a lot of great advice and experience for me to learn from and thanks in advance.

 

[DavidB1126]

Nice. An older race kit. Seems to be discontinued now. A race kit built up for bashing. I had been looking at the 1/8 teknos just for bashing.

For electrionics. Idk much about 1/8 electronics. @bill_delong races 1/8.

I would suggest a Hobbywing max8. The max8 can do 6s on 2400kv motors or lower.

 

[bill_delong]

For bashing around I would definitely stay away from sensored motors.

HobbyStar makes a great sensorless motor and I would consider this 1500KV motor here for 6S:
https://www.rcjuice.com/motor-esc/b...s-motor-temperature-protection-1-8-truck.html

As far as ESC's go, I would consider the Hobby Wing 8 BL 150 which is waterproof and currently on sale:
https://www.hobbywingdirect.com/collections/quicrun-brushless-system/products/quicrun-wp-8bl150

 

[DavidB1126]

For bashing around I would definitely stay away from sensored motors.

What's the pros and cons for sensored motors for bashing?
I was looking at the new max10 G2s for my 1/10 bashers. I really only want it because its smooth at low RPMs. Also I do track days with them so thats a plus. If I convert my slash into a drag slash, the sensored motor might help a little with a better launch.

 

[Sixtysixdeuce]

Why 6s?

A 2200 KV SD motor with a 19t pinion in my TRF 801Xt turns the AKA City Blocks into pizza cutters on 4s without overheating the motor or the HW Xerun 150A ESC.

What's the pros and cons for sensored motors for bashing?
I was looking at the new max10 G2s for my 1/10 bashers. I really only want it because its smooth at low RPMs. Also I do track days with them so thats a plus. If I convert my slash into a drag slash, the sensored motor might help a little with a better launch.

It really depends on the system. Most sensored systems aren't waterproof, and a lot of the motors are really open.

I run sensored on some stuff that I bash, but with sealed up cans.

 

[bill_delong]

What's the pros and cons for sensored motors for bashing?

Sensored electronics provide extra precision in the throttle response to improve timing for jumps and cornering on a race track. Most bashers are mashing the throttle and aren't "feathering" with any finesse so they have no need for this extra precision which also adds cost and maintenance where sensor wires go bad and sensor boards tend to fail which add more costs for an unnecessary feature to a basher.

Why 6s?

6S will drastically improve efficiency which will reduce temps and increase run time, plus it will extend the longevity of the batteries making the long term expenses of maintaining the system far more economical

The key is to reduce the KV with the following math

2200KV/6S * 4S = 1467KV

The means that a 1500KV motor on 6S will produce nearly identical speeds as a 2200KV motor on 4S, however the 6S setup will run cooler and offer longer run times. The 6S battery will also run cooler which will offer longer run time and longer battery life.

 

[KnowAir]

Sensored electronics provide extra precision in the throttle response to improve timing for jumps and cornering on a race track. Most bashers are mashing the throttle and aren't "feathering" with any finesse so they have no need for this extra precision which also adds cost and maintenance where sensor wires go bad and sensor boards tend to fail which add more costs for an unnecessary feature to a basher.


6S will drastically improve efficiency which will reduce temps and increase run time, plus it will extend the longevity of the batteries making the long term expenses of maintaining the system far more economical

The key is to reduce the KV with the following math

2200KV/6S * 4S = 1467KV

The means that a 1500KV motor on 6S will produce nearly identical speeds as a 2200KV motor on 4S, however the 6S setup will run cooler and offer longer run times. The 6S battery will also run cooler which will offer longer run time and longer battery life.

Good stuff. I have been running my 1/8 kronos xtr and a stretched MT410 on 4s. Both with the same Corally 6s system on truggy tires(Losi XTT). The Tekno does great but the heavier kronos is putting up alot of heat by comparison. I think I need to drop the motor kv and pick up some 6s packs to try..

 

[Sixtysixdeuce]

Sensored electronics provide extra precision in the throttle response to improve timing for jumps and cornering on a race track. Most bashers are mashing the throttle and aren't "feathering" with any finesse so they have no need for this extra precision which also adds cost and maintenance where sensor wires go bad and sensor boards tend to fail which add more costs for an unnecessary feature to a basher.


6S will drastically improve efficiency which will reduce temps and increase run time, plus it will extend the longevity of the batteries making the long term expenses of maintaining the system far more economical

The key is to reduce the KV with the following math

2200KV/6S * 4S = 1467KV

The means that a 1500KV motor on 6S will produce nearly identical speeds as a 2200KV motor on 4S, however the 6S setup will run cooler and offer longer run times. The 6S battery will also run cooler which will offer longer run time and longer battery life.

If your power system is getting hot at the speeds you want to run on 4s, then it makes sense to change. But watts are watts; a 6s 5000 mAh has the same total power as a 4s 7500 mAh pack, and is going to be physically about the same size. So longer run times, no, not when you compare apples to apples, or watts to watts as it were.

 

[bill_delong]

If your power system is getting hot at the speeds you want to run on 4s, then it makes sense to change. But watts are watts; a 6s 5000 mAh has the same total power as a 4s 7500 mAh pack, and is going to be physically about the same size. So longer run times, no, not when you compare apples to apples, or watts to watts as it were.

I'm glad you brought Watts into the discussion because the physics behind it supports my claim that 6S is more efficient using Watts Law:

WATTS = VOLTS x AMPS

Since we are effectively pulling the same WATTS, we are increasing VOLTS which in turn reduces AMPS. The flow of current (AMPS) is what generates heat due to INTERNAL RESISTANCE (IR) which is directly proportional to AMPS. So 6S pulls less current and generates less heat which in turn puts less stress on the battery compared to 4S... going 6S is a WIN-WIN no matter which way you look at it

 

[Greywolf74]

I'm glad you brought Watts into the discussion because the physics behind it supports my claim that 6S is more efficient using Watts Law:

WATTS = VOLTS x AMPS

Since we are effectively pulling the same WATTS, we are increasing VOLTS which in turn reduces AMPS. The flow of current (AMPS) is what generates heat due to INTERNAL RESISTANCE (IR) which is directly proportional to AMPS. So 6S pulls less current and generates less heat which in turn puts less stress on the battery compared to 4S... going 6S is a WIN-WIN no matter which way you look at it

I concur with this statement

 

[Sixtysixdeuce]

I'm glad you brought Watts into the discussion because the physics behind it supports my claim that 6S is more efficient using Watts Law:

WATTS = VOLTS x AMPS

Since we are effectively pulling the same WATTS, we are increasing VOLTS which in turn reduces AMPS. The flow of current (AMPS) is what generates heat due to INTERNAL RESISTANCE (IR) which is directly proportional to AMPS. So 6S pulls less current and generates less heat which in turn puts less stress on the battery compared to 4S... going 6S is a WIN-WIN no matter which way you look at it

Voltage is pressure. Resistance is a product of conductor efficiency and length.

Higher voltage allows the wattage to be carried by smaller conductors, which is an important consideration with long distance power transmission or systems with a lot of wiring due to weight and cost. If our main powerlines were all 230 volt instead of running as high as 765,000 volt, they'd be the size of spillway tunnels. Transforming substations and then single transformers at output points are a lot more cost and weight effective. There are, of course, downsides to higher voltage, namely arcing and EMI. Those aren't really an issue when you're talking RC car voltages, of course, though 10 or 12S is at the point where it can conduct through "dry" skin, about a 40V threshold, and DC is way worse than AC with shock/electrocution risk.

But anyway, really not a big deal to run a few inches of larger gauge wire from battery to ESC and ESC to motor. At these lengths, you're talking weight in grains/milligrams and mere pennies in cost between 8, 10 and 12 AWG. Probably gain more weight with the necessarily larger pinion than you'd save shrinking wires. The resistance difference at such lengths is also barely measurable, couple milliohms.

Point being, if you're buying components anyway, sure, 6S is a worthy consideration. Little more expensive, but not awful. However, I just can't see spending several hundred dollars to swap a good running 4s system for 6s on the notion that you'll gain something in a kit where 4s operates well within temperature range and has ample power & speed. If it's just about run time, go with higher mAh packs.

 

[Lukedavis]

I concur with this statement

Me too

Voltage is pressure. Resistance is a product of conductor efficiency and length.

Higher voltage allows the wattage to be carried by smaller conductors, which is an important consideration with long distance power transmission or systems with a lot of wiring due to weight and cost. If our main powerlines were all 230 volt instead of running as high as 765,000 volt, they'd be the size of spillway tunnels. Transforming substations and then single transformers at output points are a lot more cost and weight effective. There are, of course, downsides to higher voltage, namely arcing and EMI. Those aren't really an issue when you're talking RC car voltages, of course, though 10 or 12S is at the point where it can conduct through "dry" skin, about a 40V threshold, and DC is way worse than AC with shock/electrocution risk.

But anyway, really not a big deal to run a few inches of larger gauge wire from battery to ESC and ESC to motor. At these lengths, you're talking weight in grains/milligrams and mere pennies in cost between 8, 10 and 12 AWG. Probably gain more weight with the necessarily larger pinion than you'd save shrinking wires. The resistance difference at such lengths is also barely measurable, couple milliohms.

Point being, if you're buying components anyway, sure, 6S is a worthy consideration. Little more expensive, but not awful. However, I just can't see spending several hundred dollars to swap a good running 4s system for 6s on the notion that you'll gain something in a kit where 4s operates well within temperature range and has ample power & speed. If it's just about run time, go with higher mAh packs.

No. What he means is if you have a 6s system that you run on 4s, it will not operate as well as if you ran it on 6s. @Greywolf74 has been doing Lipo tests forever even before I joined the forum and @bill_delong is a professional racer and has been for a while. I would just listen to them because they know what they are talking about (not saying that you don’t it’s just that we don’t know you well enough) and have had many conversations about this very topic. I have experienced the same thing comparing 2s to 4s in the same truck with the same c rating and mAh on each battery and by far the 4s ran way longer than the 2s. Both were 5200 mAh and 50C. The 4s battery ran for around 19 minutes and the 2s ran for 10 minutes. That’s real time experience.

 

[Sixtysixdeuce]

Me too

No. What he means is if you have a 6s system that you run on 4s, it will not operate as well as if you ran it on 6s. @Greywolf74 has been doing Lipo tests forever even before I joined the forum and @bill_delong is a professional racer and has been for a while. I would just listen to them because they know what they are talking about (not saying that you don’t it’s just that we don’t know you well enough) and have had many conversations about this very topic. I have experienced the same thing comparing 2s to 4s in the same truck with the same c rating and mAh on each battery and by far the 4s ran way longer than the 2s. Both were 5200 mAh and 50C. The 4s battery ran for around 19 minutes and the 2s ran for 10 minutes. That’s real time experience.

Of course a 6s system will be underperforming on 4s, since it's designed for higher voltage with the motor and gearing used. I never suggested running a system designed around 6s on 4s.

As for a 90% increase in run time on equal capacity packs at 2 and 4s, that anecdotal experience actually suggests that 2s was more efficient in your case. Doubling the physical pack size and voltage would have more than doubled your run time if it were performing more efficiently. Of course, we have to consider the other variables, such as you probably didn't gear it down to have the exact same top speed. But with an incomplete data set, we can't effectively & accurately assess it.

High voltage conducts power more efficiently, but the actual power consumption of the system will be the sum of the resistance (electrical power turned into heat) and the work done. When the conductor size and material is correct for the application, the differences to perform the same work would be so minuscule you'd need lab equipment and methods to detect it. The efficiency of higher voltage is all in conductor size, weight and cost. This goes well beyond the RC world with applicability in AC and DC systems from micro to gigantic. I've personally put together and maintained power systems using transformers, motors & converters as high as 60 horsepower and 440VAC all the way down to 4mm can diameter PMDC stuff. Conductors of steel, aluminum, copper, brass and gold, both mechanical relay switching and solid state semiconductor. Also have 31 years of hobby grade RC experience and currently run & maintain 36 brushed, brushless and nitro ground vehicles from 1/5 to 1/36 scale.

It's conservation of energy. While I am in full agreement with Bill that heat is the enemy of efficiency in an electrical system, we diverge where the effects and mitigation of that variable are concerned. Again, watts are watts, and if your system is designed correctly for the power used at the voltage it will be supplied, the watts will be equal for the work done. It's when the demands of the system are greater than the components, including the wire conductors or the boards, semiconductor parts, resistors, capacitors, etc inside assemblies, were designed to supply that the efficiency suffers due to turning more of those watts into BTUs. And that holds true whether you're trying to draw too many amps or push too much voltage, though excess voltage usually just kills components in the same way that excessive mechanical pressure will cause a hose/tube/vessel/seal to fail.

 

[Greywolf74]

High voltage conducts power more efficiently, but the actual power consumption of the system will be the sum of the resistance (electrical power turned into heat) and the work done. When the conductor size and material is correct for the application, the differences to perform the same work would be so minuscule you'd need lab equipment and methods to detect it. The efficiency of higher voltage is all in conductor size, weight and cost. This goes well beyond the RC world with applicability in AC and DC systems from micro to gigantic. I've personally put together and maintained power systems using transformers, motors & converters as high as 60 horsepower and 440VAC all the way down to 4mm can diameter PMDC stuff. Conductors of steel, aluminum, copper, brass and gold, both mechanical relay switching and solid state semiconductor. Also have 31 years of hobby grade RC experience and currently run & maintain 36 brushed, brushless and nitro ground vehicles from 1/5 to 1/36 scale.

It's conservation of energy. While I am in full agreement with Bill that heat is the enemy of efficiency in an electrical system, we diverge where the effects and mitigation of that variable are concerned. Again, watts are watts, and if your system is designed correctly for the power used at the voltage it will be supplied, the watts will be equal for the work done. It's when the demands of the system are greater than the components, including the wire conductors or the boards, semiconductor parts, resistors, capacitors, etc inside assemblies, were designed to supply that the efficiency suffers due to turning more of those watts into BTUs. And that holds true whether you're trying to draw too many amps or push too much voltage, though excess voltage usually just kills components in the same way that excessive mechanical pressure will cause a hose/tube/vessel/seal to fail.

Your example is correct but only because Bill Delongs statement is true. Wattage can be high voltage low amperage wattage (high efficiency) or it can be low voltage high amperage watt (low efficiency). Your example of why power lines are high voltage is a perfect example of this.

Another example, lets use a TP 4080-CM (2022KV, 8S) motor as an example. its 6000W motor. At 34V (8S max voltage) it will draw about 176.5A. Thats a nice healthy load on an appropriate ESC like say a Castle XLX2. Now if you take that same set up and run it on 2S. Now your pulling 715.25A which will fry your ESC, your wiring, and probably damage the battery too. Its still 6000W whether you run it on 8S or 2S so I reject your notion that "watts are watts". The watts may be equal but the amperage/efficiency is not.

 

[Sixtysixdeuce]

Your example is correct but only because Bill Delongs statement is true. Wattage can be high voltage low amperage wattage (high efficiency) or it can be low voltage high amperage watt (low efficiency). Your example of why power lines are high voltage is a perfect example of this.

Another example, lets use a TP 4080-CM (2022KV, 8S) motor as an example. its 6000W motor. At 34V (8S max voltage) it will draw about 176.5A. Thats a nice healthy load on an appropriate ESC like say a Castle XLX2. Now if you take that same set up and run it on 2S. Now your pulling 715.25A which will fry your ESC, your wiring, and probably damage the battery too. Its still 6000W whether you run it on 8S or 2S so I reject your notion that "watts are watts". The watts may be equal but the amperage/efficiency is not.

Again, the efficiency is only in terms of conductor size, weight & cost.

Low voltage systems are not electrically inefficient. But they may be space and weight inefficient if the power demands force large & heavy conductors.

Conversely, high voltages force a different type of semiconductor due to leakage and arcing not present at lower voltages. Also true of mechanical relays & contactors.

It's all about matching the system components to the requirements. There are a lot of different analogous ways to look at it, but the point is that system efficiency has to take all the variables into consideration. You certainly could run your 6kw motor at 8.4 volts with the same electrical efficiency as at 33.6 volts, but the physical efficiency of your system components would be poor, requiring massive conductors and transistors to handle the high amperage. So we wouldn't do that. Conversely, there's no reason to utilize the better insulated and lower leakage but more expensive solid state components and run the higher voltage on a small system with 1/10 or 1/20th the power requirements.

There's a reason that low voltage systems exist. High amperage requires more substantial conductors, but high voltage requires insulation and isolation that precludes it's practical use in many applications. What balance is appropriate just depends on the application. If higher voltage is always the answer, why stop at 22.2v? Let's do 50v, 100, 200....

Go spend some time looking at component MSDS, specs and pricing at digikey.com. it will help you understand why high voltage is not panacea.

 

[Greywolf74]

Again, the efficiency is only in terms of conductor size, weight & cost.

Low voltage systems are not electrically inefficient. But they may be space and weight inefficient if the power demands force large & heavy conductors.

Conversely, high voltages force a different type of semiconductor due to leakage and arcing not present at lower voltages. Also true of mechanical relays & contactors.

It's all about matching the system components to the requirements. There are a lot of different analogous ways to look at it, but the point is that system efficiency has to take all the variables into consideration. You certainly could run your 6kw motor at 8.4 volts with the same electrical efficiency as at 33.6 volts, but the physical efficiency of your system components would be poor, requiring massive conductors and transistors to handle the high amperage. So we wouldn't do that. Conversely, there's no reason to utilize the better insulated and lower leakage but more expensive solid state components and run the higher voltage on a small system with 1/10 or 1/20th the power requirements.

There's a reason that low voltage systems exist. High amperage requires more substantial conductors, but high voltage requires insulation and isolation that precludes it's practical use in many applications. What balance is appropriate just depends on the application. If higher voltage is always the answer, why stop at 22.2v? Let's do 50v, 100, 200....

Go spend some time looking at component MSDS, specs and pricing at digikey.com. it will help you understand why high voltage is not panacea.

I get that high voltage isnt always the answer but the guy is running a 6S system so why would you not run it at 6S? You're arguing semantics.

 

[Lukedavis]

I get that high voltage isnt always the answer but the guy is running a 6S system so why would you not run it at 6S? you're arguing semantics.

That’s exactly what I said

 

[Sixtysixdeuce]

I get that high voltage isnt always the answer but the guy is running a 6S system so why would you not run it at 6S? You're arguing semantics.

He's running a system that is maxxed at 6s with the max KV motor for it and stated that he's been running 4s and considered switching to a lower kv motor for 6s.

I asked why he wanted to do that, OP hasn't answered, but the rest of you chimed in with a reason that isn’t actually valid per se, requires further input from the OP to make that determination. If the car is fast enough and temps aren't running high, there's no good reason to buy a new motor and batteries as well. If OP just wants longer run times, higher mAh packs get you there without motor replacement. If the electronics are getting too hot or more speed is wanted, on the other hand, then 6S is the solution.
There was, of course, this in the OPs post:

"so keep in mind I've already got a Castle 1515 2200kv"

There are definitely times when it makes sense to up the voltage. I'm getting things too warm on my Kraton 8s with the stock electronics but a change from 23T to 28T pinion gear, and I still want more speed. So it's gonna run on 12S with a Max 4 ESC and 870 KV Leopard 58113 can. But that's over $800 worth of electronics with just one pair of batteries, not something for most of us working class folks to be cavalier about. Unless someone says or implies that big spending is not a problem, I'm mindful of most people not having oodles of disposable income to throw at these toys when I make recommendations.

And on that note:

https://www.merriam-webster.com/dictionary/semantics

There's no mincing of words or lexical gymnastics on my end, just some conflating of different forms of efficiency in electrical systems by others.

And with that, I'm disengaging until we hear from the OP. No point in further discourse without additional input from him.

 

[bill_delong]

Here's a related example from my TEKNO SCT410.3 build thread where I was having temp issues with a 4300KV motor on 2S, you can see where too much current was causing the battery terminals to melt:

https://www.teknoforums.com/threads/build-review-sct410-3.1389/post-14872

The cost to convert to a budget 3S brand with a new 2500KV motor was less expensive than the price to replace the 2S name brand battery. I was effectively pulling the same WATTS and yielding the same top speed, but I discovered that my 3S battery was averaging 15 min run times to LVC where 2S was lucky to hit 10 min runs!

Eventually I would go with a 1800KV motor on 4S which yielded a 20 min run time which I raced alongside with the nitro buggies where I ran my SCT on a single battery charge where my motor temps came off the track at 120°F after 20 min compared to 180°F+ with the 4300KV motor on 2S after just 10 min.
https://www.teknoforums.com/threads/build-review-sct410-3.1389/post-22242


This is all the same principles that we're discussing with the OP to help improve efficiency