Returning to hobby after 10 years...questions
01-28-2010, 08:32 PM
#1
Returning to hobby after 10 years...questions
Hi all! Thanks in advance for tolerating my questions. I'm gonna have many more, as tech has changed much, but here's a start...and I know this is long...maybe pick one? 
1. LiPo: 10 years ago, the quality of your packs re: matching and maxing out 'pushed' capacity was everything. Are things different now with LiPo? I don't see threads about how to cram every last possible bit of performance into packs by pushing them, conditioning them, etc. I'm not asking about care and feeding, I will learn about that by reading existing threads. I'm talking about performance. For racing can you now just read the numbers on the pack, and if it's a pack that suits your needs, you are capable of winning the a main, or is it still an advantage to buy the high dollar packs that are tweaked in some way? Are the days of obsessing over battery minutia in the tireless pursuit of the last .1% of speed over when it comes to batteries?
2. What battery specs go with what classes? I see 5000mah 35c and 40c (I might be a little off I know), and I see 2200mah 20c. I understand that a higher 'c' will discharge at higher rate which is good for speed, but there must be more to it, or nobody would buy anything but the highest number rating batteries. What gives? Is it that for less demanding classes (stock?) you can get 100% of your motor's possible performance with a lesser battery? Whta I mean is, are some batteries just overkill for a given application, meaning that they offer 0 benefit over a lesser model in some case? Back in the day, when racing I would just buy the best possible packs that I was able to find, because it was harder/impossible to compete without doing that. Different now? How to pick?
3. ESCs: from what I'm reading, the ESC is once again an imperfect science as companies scramble to get controllers to deliver maximum power to the newer (brushless?) motors, and LiPo batteries without themselves melting down. Do I have it right? What's going on in the world of ESCs?
4. Brushless motors...do tell. Are we now in a 100% brushless world? How do I compare apples to oranges (brushed specs to brushless)? Do people still tune brushless motors (particularly in stock classes) or are they just drop-n now. Back in the day, a "stock" stock motor would do about 65%-70% of what the same motor would do when you got done tuning it to within an inch of the stock class rules. Is this still the case? Tell me a story about brushless motor tech. Sensor? Sensorless? What's the diff? Is one better? Is one ever required? Does anyone anywhere still race on brush motors, or is that dead tech now?
Ok, that's enough for now. I promise I would not have posted this if I hadn't spend about 6 hours reading the forums first. There are many many specific questions answered, but not much re: background / primer on the technology.
I'd be very grateful if any of you folks love to teach and share enough to answer any of the above. Also, I promise you that in 6 months I'll be answering these questions, not asking them
Thanks!
1. LiPo: 10 years ago, the quality of your packs re: matching and maxing out 'pushed' capacity was everything. Are things different now with LiPo? I don't see threads about how to cram every last possible bit of performance into packs by pushing them, conditioning them, etc. I'm not asking about care and feeding, I will learn about that by reading existing threads. I'm talking about performance. For racing can you now just read the numbers on the pack, and if it's a pack that suits your needs, you are capable of winning the a main, or is it still an advantage to buy the high dollar packs that are tweaked in some way? Are the days of obsessing over battery minutia in the tireless pursuit of the last .1% of speed over when it comes to batteries?
2. What battery specs go with what classes? I see 5000mah 35c and 40c (I might be a little off I know), and I see 2200mah 20c. I understand that a higher 'c' will discharge at higher rate which is good for speed, but there must be more to it, or nobody would buy anything but the highest number rating batteries. What gives? Is it that for less demanding classes (stock?) you can get 100% of your motor's possible performance with a lesser battery? Whta I mean is, are some batteries just overkill for a given application, meaning that they offer 0 benefit over a lesser model in some case? Back in the day, when racing I would just buy the best possible packs that I was able to find, because it was harder/impossible to compete without doing that. Different now? How to pick?
3. ESCs: from what I'm reading, the ESC is once again an imperfect science as companies scramble to get controllers to deliver maximum power to the newer (brushless?) motors, and LiPo batteries without themselves melting down. Do I have it right? What's going on in the world of ESCs?
4. Brushless motors...do tell. Are we now in a 100% brushless world? How do I compare apples to oranges (brushed specs to brushless)? Do people still tune brushless motors (particularly in stock classes) or are they just drop-n now. Back in the day, a "stock" stock motor would do about 65%-70% of what the same motor would do when you got done tuning it to within an inch of the stock class rules. Is this still the case? Tell me a story about brushless motor tech. Sensor? Sensorless? What's the diff? Is one better? Is one ever required? Does anyone anywhere still race on brush motors, or is that dead tech now?
Ok, that's enough for now. I promise I would not have posted this if I hadn't spend about 6 hours reading the forums first. There are many many specific questions answered, but not much re: background / primer on the technology.
I'd be very grateful if any of you folks love to teach and share enough to answer any of the above. Also, I promise you that in 6 months I'll be answering these questions, not asking them
Thanks!
01-28-2010, 09:59 PM
#2
I'm just gonna give my input for the LiPo battery question.
Today's LiPo batteres still come in cells so there is still some "matching" of cells done by the manufacturers. It's important because you cannot discharge individual cells in a LiPo pack beyond a certain voltage unlike in the old days of NiCD packs. Nowadays balance charging individual cells is the equivalent of cell matching to keep the battery performing consistently.
In terms of discharge rate, yes it does make a difference to some extent however that really depends on what the ESC and motor is capable of drawing. If your ESC/motor is only capable of drawing X amps continuosly it wouldn't make much sense to have a battery with 3 * X amps dishcarge rate. Of course the burst rate is important too so you'd have to factor that in as well.
As far as high dollar LiPos vs cheap ones well that depends on the company really. Many companies just rebadge someone elses LiPos and then mark up the price by 2-3 times. LiPos also have a limted shelf life whether you use them or not so if you buy a cheap LiPo it could've been sitting on the shelf for awhile.
Today's LiPo batteres still come in cells so there is still some "matching" of cells done by the manufacturers. It's important because you cannot discharge individual cells in a LiPo pack beyond a certain voltage unlike in the old days of NiCD packs. Nowadays balance charging individual cells is the equivalent of cell matching to keep the battery performing consistently.
In terms of discharge rate, yes it does make a difference to some extent however that really depends on what the ESC and motor is capable of drawing. If your ESC/motor is only capable of drawing X amps continuosly it wouldn't make much sense to have a battery with 3 * X amps dishcarge rate. Of course the burst rate is important too so you'd have to factor that in as well.
As far as high dollar LiPos vs cheap ones well that depends on the company really. Many companies just rebadge someone elses LiPos and then mark up the price by 2-3 times. LiPos also have a limted shelf life whether you use them or not so if you buy a cheap LiPo it could've been sitting on the shelf for awhile.
01-28-2010, 10:35 PM
#3
Hi all! Thanks in advance for tolerating my questions. I'm gonna have many more, as tech has changed much, but here's a start...and I know this is long...maybe pick one?
1. LiPo: 10 years ago, the quality of your packs re: matching and maxing out 'pushed' capacity was everything. Are things different now with LiPo? I don't see threads about how to cram every last possible bit of performance into packs by pushing them, conditioning them, etc. I'm not asking about care and feeding, I will learn about that by reading existing threads. I'm talking about performance. For racing can you now just read the numbers on the pack, and if it's a pack that suits your needs, you are capable of winning the a main, or is it still an advantage to buy the high dollar packs that are tweaked in some way? Are the days of obsessing over battery minutia in the tireless pursuit of the last .1% of speed over when it comes to batteries?
If a Lipo pack is from a reputable company and it has the numbers you need it will be ALL that you need. Lipo does not typically benefit from any "special" charging or cycling tecniques that I have heard of. The main reason I believe that they are all the rage now is because they are easier to maintain and you get consistent performance run after run. The high dollar packs are just assurance that the numbers you are buying is exactly what you are getting. They also use matched cells. This is far from the benefit of Nimh matched cells though; it simply keeps the packs balanced better. If you do not run your packs past the recommended cutoff points then most decent packs will stay balanced anyways, and its recommeded to use a balance charger, so this is a non-factor for most. Many people are winning races with Hobbycity Lipos which are a low cost battery. Just treat them with respect and they perform just as well as any on the market.
2. What battery specs go with what classes? I see 5000mah 35c and 40c (I might be a little off I know), and I see 2200mah 20c. I understand that a higher 'c' will discharge at higher rate which is good for speed, but there must be more to it, or nobody would buy anything but the highest number rating batteries. What gives? Is it that for less demanding classes (stock?) you can get 100% of your motor's possible performance with a lesser battery? Whta I mean is, are some batteries just overkill for a given application, meaning that they offer 0 benefit over a lesser model in some case? Back in the day, when racing I would just buy the best possible packs that I was able to find, because it was harder/impossible to compete without doing that. Different now? How to pick?
Obviously the MAH rating is picked by how much runtime you need/want. The "C" stands for capacity; meaning the number times capacity. This gives you the batteries rated discharge current. ie.--2000mah 20C would be rated for 40 amps discharge. A 2000mah 40C would be rated for 80 amps, so on and so forth. Lower powered motors and lighter cars will need less, while very fast or heavy cars would need more. Typically the most powerful 10th scale setups can benefit up to about 100A discharge. So you can see that even if you want the runtime of a 5000mah pack, a 30C may be overkill for you. But if you can get by with 3000mah for runtime, you may need 35C to keep the discharge rate high enough. Overkill will never hurt anything; except that the packs usually weigh more.
3. ESCs: from what I'm reading, the ESC is once again an imperfect science as companies scramble to get controllers to deliver maximum power to the newer (brushless?) motors, and LiPo batteries without themselves melting down. Do I have it right? What's going on in the world of ESCs?
The brushless ESC is one amazing piece of equipment. Castle Creations and Tekin are the most popular from what I can tell. They both win tons of races and have nearly infinite adjustability. Adjustable timing boost seems to be the latest rage. Although not as important with modified motors since they are all fast anyways, stock and spec racing has almost gotten too fast for some people with these advancements. I have a few models from both brands and I love them both. You really cant go wrong.
4. Brushless motors...do tell. Are we now in a 100% brushless world? How do I compare apples to oranges (brushed specs to brushless)? Do people still tune brushless motors (particularly in stock classes) or are they just drop-n now. Back in the day, a "stock" stock motor would do about 65%-70% of what the same motor would do when you got done tuning it to within an inch of the stock class rules. Is this still the case? Tell me a story about brushless motor tech. Sensor? Sensorless? What's the diff? Is one better? Is one ever required? Does anyone anywhere still race on brush motors, or is that dead tech now?
It should be a 100% brushless world in my opinion. Brushed motors can still compete with an experienced tuner, but brushless does not need tuning at all. A quality brushless motor that is treated with respect will perform the same on its 100th run as it will the day you open the package. I have heard of some guys opening the cans and compacting the windings a bit to make them tighter, but I am honestly unsure if there is any real benefit. I know many top level drivers that win main events with "out of the box" motors. Definitely a far cry from brush/spring tuning and comm cutting. The sensored/sensorless answer I give will surely start a debate, but it is a worthy argument nonetheless. In my opinion sensored motors were a must for racing 2 years ago. The sensorless controllers simply could not start a motor smoothly enough for reliable operation when you needed it most. Jerky starts and abrupt power delivery were common occurrences that could not be avoided. Since sensored motors tell the controller the position of the rotor at all times they could operate much smoother under any circumstance. There is however more detailed and fragile parts to malfunction in a sensored system. Now I believe the tables have turned. Sensorless controllers have improved the operation to the point that the difference is nil. As a big fan of sensorless designs I can admit that an improper setup can still cause rough starts and jerky operation; while sensored motors will be smooth in just about any situation. But, it is important to note that the same sensored setup in the same improper setup will likely not last very long, even if it is butter smooth.
I am certain you will get a plethora of responses going both ways on this subject, and I hope you get a chance to drive several setups before you make a decision one way or another.
Ok, that's enough for now. I promise I would not have posted this if I hadn't spend about 6 hours reading the forums first. There are many many specific questions answered, but not much re: background / primer on the technology.
I'd be very grateful if any of you folks love to teach and share enough to answer any of the above. Also, I promise you that in 6 months I'll be answering these questions, not asking them
Thanks!
1. LiPo: 10 years ago, the quality of your packs re: matching and maxing out 'pushed' capacity was everything. Are things different now with LiPo? I don't see threads about how to cram every last possible bit of performance into packs by pushing them, conditioning them, etc. I'm not asking about care and feeding, I will learn about that by reading existing threads. I'm talking about performance. For racing can you now just read the numbers on the pack, and if it's a pack that suits your needs, you are capable of winning the a main, or is it still an advantage to buy the high dollar packs that are tweaked in some way? Are the days of obsessing over battery minutia in the tireless pursuit of the last .1% of speed over when it comes to batteries?
If a Lipo pack is from a reputable company and it has the numbers you need it will be ALL that you need. Lipo does not typically benefit from any "special" charging or cycling tecniques that I have heard of. The main reason I believe that they are all the rage now is because they are easier to maintain and you get consistent performance run after run. The high dollar packs are just assurance that the numbers you are buying is exactly what you are getting. They also use matched cells. This is far from the benefit of Nimh matched cells though; it simply keeps the packs balanced better. If you do not run your packs past the recommended cutoff points then most decent packs will stay balanced anyways, and its recommeded to use a balance charger, so this is a non-factor for most. Many people are winning races with Hobbycity Lipos which are a low cost battery. Just treat them with respect and they perform just as well as any on the market.
2. What battery specs go with what classes? I see 5000mah 35c and 40c (I might be a little off I know), and I see 2200mah 20c. I understand that a higher 'c' will discharge at higher rate which is good for speed, but there must be more to it, or nobody would buy anything but the highest number rating batteries. What gives? Is it that for less demanding classes (stock?) you can get 100% of your motor's possible performance with a lesser battery? Whta I mean is, are some batteries just overkill for a given application, meaning that they offer 0 benefit over a lesser model in some case? Back in the day, when racing I would just buy the best possible packs that I was able to find, because it was harder/impossible to compete without doing that. Different now? How to pick?
Obviously the MAH rating is picked by how much runtime you need/want. The "C" stands for capacity; meaning the number times capacity. This gives you the batteries rated discharge current. ie.--2000mah 20C would be rated for 40 amps discharge. A 2000mah 40C would be rated for 80 amps, so on and so forth. Lower powered motors and lighter cars will need less, while very fast or heavy cars would need more. Typically the most powerful 10th scale setups can benefit up to about 100A discharge. So you can see that even if you want the runtime of a 5000mah pack, a 30C may be overkill for you. But if you can get by with 3000mah for runtime, you may need 35C to keep the discharge rate high enough. Overkill will never hurt anything; except that the packs usually weigh more.
3. ESCs: from what I'm reading, the ESC is once again an imperfect science as companies scramble to get controllers to deliver maximum power to the newer (brushless?) motors, and LiPo batteries without themselves melting down. Do I have it right? What's going on in the world of ESCs?
The brushless ESC is one amazing piece of equipment. Castle Creations and Tekin are the most popular from what I can tell. They both win tons of races and have nearly infinite adjustability. Adjustable timing boost seems to be the latest rage. Although not as important with modified motors since they are all fast anyways, stock and spec racing has almost gotten too fast for some people with these advancements. I have a few models from both brands and I love them both. You really cant go wrong.
4. Brushless motors...do tell. Are we now in a 100% brushless world? How do I compare apples to oranges (brushed specs to brushless)? Do people still tune brushless motors (particularly in stock classes) or are they just drop-n now. Back in the day, a "stock" stock motor would do about 65%-70% of what the same motor would do when you got done tuning it to within an inch of the stock class rules. Is this still the case? Tell me a story about brushless motor tech. Sensor? Sensorless? What's the diff? Is one better? Is one ever required? Does anyone anywhere still race on brush motors, or is that dead tech now?
It should be a 100% brushless world in my opinion. Brushed motors can still compete with an experienced tuner, but brushless does not need tuning at all. A quality brushless motor that is treated with respect will perform the same on its 100th run as it will the day you open the package. I have heard of some guys opening the cans and compacting the windings a bit to make them tighter, but I am honestly unsure if there is any real benefit. I know many top level drivers that win main events with "out of the box" motors. Definitely a far cry from brush/spring tuning and comm cutting. The sensored/sensorless answer I give will surely start a debate, but it is a worthy argument nonetheless. In my opinion sensored motors were a must for racing 2 years ago. The sensorless controllers simply could not start a motor smoothly enough for reliable operation when you needed it most. Jerky starts and abrupt power delivery were common occurrences that could not be avoided. Since sensored motors tell the controller the position of the rotor at all times they could operate much smoother under any circumstance. There is however more detailed and fragile parts to malfunction in a sensored system. Now I believe the tables have turned. Sensorless controllers have improved the operation to the point that the difference is nil. As a big fan of sensorless designs I can admit that an improper setup can still cause rough starts and jerky operation; while sensored motors will be smooth in just about any situation. But, it is important to note that the same sensored setup in the same improper setup will likely not last very long, even if it is butter smooth.
I am certain you will get a plethora of responses going both ways on this subject, and I hope you get a chance to drive several setups before you make a decision one way or another.
Ok, that's enough for now. I promise I would not have posted this if I hadn't spend about 6 hours reading the forums first. There are many many specific questions answered, but not much re: background / primer on the technology.
I'd be very grateful if any of you folks love to teach and share enough to answer any of the above. Also, I promise you that in 6 months I'll be answering these questions, not asking them
Thanks!
Good luck with your quest, and I hope you are out there blasting around your local track soon!
01-29-2010, 07:11 AM
#4
I'm gonna chew on all of that fo a while, and use this excellent primer as a backdrop for me to gather more info by surfing the forums. But, I do have one follow-up question...ok, two.
1. re: motors - let's say I'm gonna go race stock sedan and stock 12th, both on road. What brushless motor is that? I don't see 'stock' anywhere, just numbers like 17.5 etc. Is there still one specific motor spec that is "stock?"
2. re: sensor v. sensorless - Is the extra complication/failure aspect the only reason to avoid a sensored setup, or is smoothness v. reliability the only differentiator. In other words, are there straight up performance differences between the two, or no? As a followup, I'd ask what is it that you have now that makes sensorless as smooth as sensored these days, or is there more (is this found in careful programming of the ESC, for example)?
Thanks again for all of that great info. I can't wait to see how fast 'stock' racing is these days. I know this will sound lame to current racers, but I thought a well-tuned stock class sedan was pretty freakin' fast (not like a mod, but still) in 2000...if they're way faster now, that's pretty awesome.
Also, thanks for that response above re: the batteries...also very helpful!
01-29-2010, 10:20 AM
#5
I believe ROAR rules have 17.5 as stock. This can vary from track to track though; it would be wise to check where you plan to race.
The difference in sensorless startup came with improved programming of the controllers. Which reminds me of another great point about the Tekin and Castle Creations ESCs; They both have free firmware upgrades. Simply hook them up to your computer and update to the latest model instead of buying the "hot" new controller every month. Frequent updates give improved adjustments, efficiency, startup, and more.
Sensorless designs tend to have increased efficiency, and more peak power. The differences are pretty small, so its not a big deal. The reliability of sensored systems has not been a big issue. This leaves cost as the main difference, and the gap here is quickly closing as well. My reasons for preferring sensorless is mainly because of reasons other than performance or reliability. Sensored does perform just fine and people use them for years with no problems.
The difference in sensorless startup came with improved programming of the controllers. Which reminds me of another great point about the Tekin and Castle Creations ESCs; They both have free firmware upgrades. Simply hook them up to your computer and update to the latest model instead of buying the "hot" new controller every month. Frequent updates give improved adjustments, efficiency, startup, and more.
Sensorless designs tend to have increased efficiency, and more peak power. The differences are pretty small, so its not a big deal. The reliability of sensored systems has not been a big issue. This leaves cost as the main difference, and the gap here is quickly closing as well. My reasons for preferring sensorless is mainly because of reasons other than performance or reliability. Sensored does perform just fine and people use them for years with no problems.
01-29-2010, 12:19 PM
#6
Great...hey, I can't thank you enough for taking the time to write all that stuff. It really has given me a pretty solid basis upon which to build. Now, when I go out to re-fear myself up, I'll have a clue.
It seems that the focus now might be more on the driver and setup, and less on battery and motor performance these days, which is great. I really enjoyed the tinkering and obsessing over comm cutting, brush cutting, spring tuning, battery pushing, etc. but I'd think the current state of things would make racing more accessible.
I mean...you just buy a motor and drop it right into the car...just like that??? Who ever heard of such a thing?
It seems that the focus now might be more on the driver and setup, and less on battery and motor performance these days, which is great. I really enjoyed the tinkering and obsessing over comm cutting, brush cutting, spring tuning, battery pushing, etc. but I'd think the current state of things would make racing more accessible.
I mean...you just buy a motor and drop it right into the car...just like that??? Who ever heard of such a thing?
01-29-2010, 09:46 PM
#7
I have been racing since the days that 1500mah nicd was the hot new stuff. But I have really enjoyed, and grown accustomed to, focusing on car setup instead of tinkering with motors. It was enjoyable, but the feeling of a 5 year old motor keeping up with the new stuff is quite pleasurable as well. Of course with the PC interface to the ESC there is plenty of tweaking left to do; timing adjustments, punch control, throttle curves, etc......
01-31-2010, 03:48 PM
#8
Ok, I came up with another one that I haven't seen the answer to (but this is an easy one)
Do you still have to cut down your own foam tires for sedan and 12th scale, or do they come pre-cut down now? Gawd that was an annoying for-no-good-reason aspect of tires 10 years ago.
Thanks!
Do you still have to cut down your own foam tires for sedan and 12th scale, or do they come pre-cut down now? Gawd that was an annoying for-no-good-reason aspect of tires 10 years ago.
Thanks!
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