ESC Questions--protection and recommendations??

[rdlb23]

Hello... I fried my LRP Quantum Sport ESC. There were actual flames. This happened because I stopped very abruptly. I hit a pole. SO the motor sends a shock back to the ESC right? How do I protect the ESC from this shock? Also, any recommendations for a new ESC forward/brake with strong brakes? How do you even measure brake strength?  Thanks.

[steviedee]

i swear by mtroniks all the way, less expensive then others but i have yet to break one

[MikeT]

I like MTroniks too, one broke on me and i sent it back, payed a small charge (£10 ) and they sent me a replacement!

TOP CUSTOMER SERVICE

 

Mike

[rdlb23]

I was thinking about mtroniks for my buggy because its waterproof.  But how are the brakes?/ Do you guys have any other escs that you can compare them to?  For the buggy it'll be f/r but for a raod car I want brakes, really good brakes.

[rhenbelz]

I've never used an Mtroniks personally, but supposedly they are all waterproof which is always a plus.

The best ESC I've ever had for reliability and all is my Traxxas XL-10 (10t limit). It's been in a Clod running dual motors, in a drag car running an 11T, and several other cars. It never heats up. It's been wet often and won't shut down without a fight, and when it does it works fine after an hour drying out. It has been run over by a 1:1 car and still works fine.

And for brakes, it is currently in my XC and I can assure you it has great brakes. I use them a lot.

Second best ESC I've had is a tie between two of my Futaba ESCs. Just good reliable ESCs, but not as capable as the XL10 and haven't been abused as much so I don't know about strength.

[Backlash]

Hello... I fried my LRP Quantum Sport ESC. There were actual flames. This happened because I stopped very abruptly. I hit a pole. SO the motor sends a shock back to the ESC right? How do I protect the ESC from this shock? Also, any recommendations for a new ESC forward/brake with strong brakes? How do you even measure brake strength?  Thanks.

 

Manufacturers dont often advertise "brake strength" as a rating. I would say that it would be safe to assume that an ESC would have sufficient "brakes" to stop or slow whatever the ESC's rated motor is.

One important factor that you are overlooking here is the motor that you are using. A car using a standard 540 "kit" motor will not stop as well as the same car using say the TZ / BZ Motors, or a 27 turn rebuildable stock motor, as the magnets in the TZ / BZ and rebuildable stock motor ar just better that that fitted to the kit 540.

[rdlb23]

Awesome thank you for answering my opriginal question!!!!  Braking strength is related to the motor, not the ESC.  Thanks for clearing that up!!

[Backlash]

No, please dont get me wrong. The ESC braking ability, will and does play a part in how well or quick the car stops, but I seriously doubt that you would notice that much of a difference between the different brands of quality ESC's.

Obviously the brake transistor(s) in an unlimited ESC would have a higher rating than those fitted to say, the Tamiya 101BK, but the unlimited ESC may have to slow a car down running say an 8 turn motor, whereas the worst the TEU 101BK has to contend with is a Sports tuned.

The motor you are using, and the gear ratio you are running will however will play a greater part.

Cheers.

[rhenbelz]

Don't forget that it's also about number of braking transistors. It's similar to reverse; a single one can only do so much work. It's why a lot of old ESCs with only one brake transistor have difficulty slowing down. My Novak 828 is great in every way except it has only two small brake transistors, so slowing down my massive TXT takes a while.

Has anyone pried off that black lid on the TEU-101BK? I would bet there's not much under there.

[Backlash]

Don't forget that it's also about number of braking transistors. It's similar to reverse; a single one can only do so much work. It's why a lot of old ESCs with only one brake transistor have difficulty slowing down. My Novak 828 is great in every way except it has only two small brake transistors, so slowing down my massive TXT takes a while.

Has anyone pried off that black lid on the TEU-101BK? I would bet there's not much under there.

The reason why a lot of older ESC's have poor brakes, is the same reason why they also have a poor motor limit. The FETS (transistors) have a much lower current rating than the ones used to make modern ESC's. Its really that simple, it all comes down to advances in technology.

Also have you considered the fact that your TXT weighs about 5KG may have something to do with why it wont stop as well as a 1.5KG touring car.

Do you actually know how the ESC's brakes work?

[rhenbelz]

Relax, buddy.

It's a combination of both, that's why I said also. You're right in saying that the transistors handle more current. But ESC design has a part in it too.

I did consider the weight issue, I'm no idiot. However, it was stated before that the motor used has an effect too. Correct me if I'm wrong but if I'm running twice the input voltage (14.4v), two motors, and two brake transistors, then it's not a bad comparison to a touring car to use as an example of what happens if you have too little braking-dedicated hardware for what you're trying to stop.

And to your final question, I'm not sure, and I'm reading this thread with interest. I know that on brushed plane ESCs, when the motor is turning but there is no power applied to it, the motor is acting as a generator. Shorting this back current makes the motor do much more work to try to generate the same voltage across the short. The ESC is making the short.

I would assume brushed car ESCs are the same, but I'm not 100%. If you know how the brakes work, please enlighten us because I don't see an explanation in any of your posts in this thread.

[rdlb23]

So... can I assume that lower gearing will provide better braking, and since technical tracks need both better acceleration and braking at the same time everything works out. I just ordered a used Q2 Competition from ebay for well under 100 dollars.  The ad said it was for carpet racing for 3 months so it shouldn't have gotten too abused.  This thing is apparently way more capable than I'll ever need it to be and it apparently charges the battery under braking.  Probably not much but that may offer some insight into the generator question.   Lets keep the discussion going.  I want to learn how all this stuff works!!!!!

[rich_f]

If by lower gearing you mean lower top speed / high gear ratio (small pinion, large spur), then yes, this will provide the best possible braking force, because it means the motors shaft will be spinning faster than lower ratios for a given road speed. The faster the motor is being turned (like a generator or dynamo) the more voltage is produced. When the brakes are applied, the esc directs this to the batteries to recharge them.

[Backlash]

It's a combination of both, that's why I said also. You're right in saying that the transistors handle more current. But ESC design has a part in it too.

And to your final question, I'm not sure, and I'm reading this thread with interest. I know that on brushed plane ESCs, when the motor is turning but there is no power applied to it, the motor is acting as a generator. Shorting this back current makes the motor do much more work to try to generate the same voltage across the short. The ESC is making the short.

I would assume brushed car ESCs are the same, but I'm not 100%. If you know how the brakes work, please enlighten us because I don't see an explanation in any of your posts in this thread.

Look I dont want to turn this into a slinging match, nor do I want to hijack rdlb23's thread, so lets just keep it professional.

The braking process used by ESC's is known as "Dynamic Braking", and yes, your explaination is a good basic description of how it works. 

Using your explaination, and still keeping things simple, there are two things that can affect how well the brakes work. One is the generator (motor) itself, where a generator that is spinning faster, and with stronger magnets will generate more voltage. The other is the the amount of load that the ESC can place on the generator, and this load is measured as resistance. The lower the resistance, then the greater is the load.

MOSFETS (FETS) in ESC's are rated in a few ways, but what is of interest to us is their "maximum current" rating, and their "ON resistance".("ON resistance" is the resistance of the MOSFETS when they are turned full ON). ESC manufacturers rarely advertise the ON resistance for the brake circuit, however it is common practice to do so for the foward steps, so the only rating we have to use when comparing the effectiveness of an ESC's Brakes is the current rating.

Now, I understand what you were saying when you said "Don't forget that it's also about number of braking transistors". For a given time period, say the early 90's, well this would be true, but when your comparing old and new ESC's, it doesnt work. Advances in technology have just made the MOSFET ratings better.

You say that your Novak 828 has 2 brake fets, but its Brake current rating is only 50A according to Novak's website. I have an Mtroniks unlimited ESC in my touring car that's brake circuit is rated at 60A, and it only has 1 brake fet. Now would you say that the amount of fets the ESC has is maybe not as important as the rating of the FETS??

The other thing is that a lot of modern ESC's dont have TO220 packaged MOSFETS, where the tops of the fets stick out through the case. Most now have been made using surface mount devices, and without pulling the ESC apart, we will have no idea how many FETS are contained inside the ESC's case.

Cheers.

 

[Lonestar]

Funnily enough, no one has yet mentioned that the limiting factor to "strong" braking often is the tires loosing grip... not the ESC.

 

Paul

[Backlash]

A very fair comment.

Although, in a 4wd car,  Ive never seen an ESC / Motor combination where the brakes were that good that they could lock the wheels, well not in the way you can with a gas car. A 2wd, with worn tyres on dirt, well this is a different story.

Maybe when rdlb23 gets his new ESC, this may be the title of his next thread.

Cheers

[rdlb23]

I would love it if I could lock up the wheels!!!! Like a real racecar.    The Q2 has inital brake settings that allow you to change the arc of the brake control so it can be maxed out well within the trigger pull.     I'll post some braking info on the Q2 using a p2k2 , tamiya silver can, and tamiya sport tuned.   I don't have any crazy mod motors to test.  Maybe I'll put together a little test video. I can measure braking distance from a set speed.  I'll have to take off work for a week...

[Lonestar]

The thing is, most (hi-end) esc's are designed to PREVENT wheel lock, as this undoubtedly is the most inefficient way to brake

Anyway - take any tamiya basher with an old msc, get your rig to full speed, and yank the throttle to full reverse... not only will the wheels lock, but they will also turn in reverse in most cases, even with a silver can... which proves that locking the wheels IS easily doable

 

 

I recently picked up a moped V16R off ebay for 35bucks incl S&H, it has a 15T motor limit... for bashing around it's awesome. Only shortfall (for me who's a picky competitor who wants the best even in his bashing toys, in this cas a Kyosho trail blazer, motorized by an oldie but goodie Trinity Paradox and powered by a 7 cell pack - did you say "sick fast"???) is that it has auto brakes, ie at neutral brakes are applied and there's no timing to go to reverse. But I'd recommend it, can't beat it for the price. the workaround against the auto-brake feature is just a tod of forward on the throttle trim

 Hope this helps,

Paul

 

[rdlb23]

I got a lrp Q2 Competition and installed it but I'm having interfernece issues.  A jittery Servo that becomes more jittery at higher rpms.  Not good.. If you guys have any suggestion I'd appreciate it .  I started another thread for this in the electrics forum.

[Lonestar]

most of the times the ESC isn't the culprit, but rather the motor and/or the overall electronics setup. Make sure it's been on a lathe lately, that the anti-glitches cap are on, and the adequate shottky's on the motor. Also check that you have an additional cap on the ESC, and also look for any plug/wire that might be on the damaged side and get the Rx as far from the motor and speedo as possible... if you follow all this you should have a glitch free car. Again, changing components is rarely the solution, it's more a matter of overall maintenance

Paul

[rdlb23]

Capacitors and Schotkys are all where they are supposed to be.  I'm trying to find time to replace the aerial in a forward location so we'll see.  THanks everyone