Are Zippy Lipos safe with a Castle MMM Speedy?

[Pdelcast]

Originally Posted by Jabe

Ill like to protect my controllers, so i was thinking about adding this little component and capacitor parrel to my battery connectors, to protect esc from voltage peaks and drops.
Im using batterys that should power my system in theory, 240A (in theory) continous should be enough.
What castle has to say about that? Would it be good idea?

Already a TVS on the Mamba Monster. The TVS on the Monster is rated for over 2000A -- but it's the total power that is the limitation. You can't put a thousand watts into a 1 gram device and expect it to survive more than a few thousandths of a second. We are talking SERIOUS power here. The Mamba main FETs themselves can stand about 12000A of avalanche current -- but that's instantaneous current again. For four seconds of normal braking power (if the battery refused to take the power back) you can expect about 2000-8000 watt seconds of power that needs to be dissipated. There IS silicon that will take that kind of power -- but the chips are the size of hockey pucks.

[BrianG]

Patrick, when the TVS fails, does it fail open or closed? Meaning, will the user be able to tell it has gone bad? I'm just thinking that if it was forced to dissipate too much power without sufficient cooling interval, it might pop and then allow the large spikes to get to the battery.

[Pdelcast]

Originally Posted by BrianG

Patrick, when the TVS fails, does it fail open or closed? Meaning, will the user be able to tell it has gone bad? I'm just thinking that if it was forced to dissipate too much power without sufficient cooling interval, it might pop and then allow the large spikes to get to the battery.

Usually, they fail closed for about 1/100th of a second, then they fail open. Seriously.

[MrMin]

Cool down..This is a heated thread! I've built a couple of 6 x 4700uF 50v SuperLowESR audio grade capacitors(thats 24mF 50v cap.) and placed then across mmm input. That should help the poor little ESC with its ripple current problem, maybe. Whats your throw on that one patrick? Kind of "band aid" - like BrianG said, but I've did it already a week ago. Not run it yet.. (have family) :-). Maybe some vendor will start selling big caps like for car audio for eg....

[BrianG]

Originally Posted by MrMin

...Maybe some vendor will start selling big caps like for car audio for eg....

Mike does carry some low-ESR caps in his store already: http://www.rc-monster.com/proddetail...=35vcap&cat=21

[MrMin]

hee hee. I mean much bigger caps. Like the 1-2 Farad monsters for car.. coupled with low ESR they will cost more than the batts....Hey Mike, monster opportunity.. if you put a sticker on it, you can sell it for double the price and have some nice flashing leds on it...

...I think my overkill 23mF low esr should suffice - did not do the math - off the batt(pun intended :-) ) what do think brian?

[Pdelcast]

Originally Posted by MrMin

hee hee. I mean much bigger caps. Like the 1-2 Farad monsters for car.. coupled with low ESR they will cost more than the batts....Hey Mike, monster opportunity.. if you put a sticker on it, you can sell it for double the price and have some nice flashing leds on it...

...I think my overkill 23mF low esr should suffice - did not do the math - off the batt(pun intended :-) ) what do think brian?

It would be hard to find room for a 1-2 farad 35V capacitor in an 1/8th scale.


But yes, extra capacitance cant hurt, and in some cases will be a very good thing.

HOWEVER, using it as a band-aid for insufficient batteries isn't a good idea -- just get batteries that can handle the load (better fix...)

[BrianG]

Thanks for the info. So, the user might never notice it when driving around if it happens to go bad. They should be designed to emit red smoke or something equally cool and visible.

And yeah, a 1F cap would be "slightly" large and heavy. For the weight, might as well add more cells...

[MrMin]

Just triple up on caps. BTW: If you look at the specs, the ripple current of about 3A per 3300uF Cap 50V.... And if that does not work, use a bigger hammer. How much ripple-C are we expecting, patrick, brian??

No Really...1F is just a joke. red smoke is a good idea and TVS Transient Voltage Spikes are are real problem. That is why patrick said DONT USE THE NO SPARK THING.

Wink Wink Brian

[Pdelcast]

Originally Posted by MrMin

Just triple up on caps. BTW: If you look at the specs, the ripple current of about 3A per 3300uF Cap 50V.... And if that does not work, use a bigger hammer. How much ripple-C are we expecting, patrick, brian??

No Really...1F is just a joke. red smoke is a good idea and TVS Transient Voltage Spikes are are real problem. That is why patrick said DONT USE THE NO SPARK THING.

Wink Wink Brian

The better the battery, the less ripple current ... so what we do is size the capacitors to something that is reasonable, and use a high switching frequency to optimize the capacitance (higher switching = lower ripple current.)

But, the enemy is ripple voltage -- and the better the battery, the less ripple voltage.

[Pdelcast]

And for those who are interested...

We've been struggling with whether or not to release a version of software that actually measures voltage ripple, and limits performance based on how the batteries perform.

On one hand, it would prevent a lot of damaged ESCs, and batteries -- when users are pushing batteries insufficient for the application.

BUT, on the other hand, a lot of people who are running "marginal" systems will see a performance decrease, and might yell "FOUL!" at us for releasing software that would actually lower the performance of their system.

As it is, very few controllers actually get damaged by ripple voltage/current -- but the people who damage controllers this way don't just do it once and then learn a lesson. They tend to destroy controller after controller with the same bad setups. And then they blame US for making a defective product.

Brian, and others, I'd be interested in hearing your thoughts on this...

Originally Posted by Pdelcast

And for those who are interested...

We've been struggling with whether or not to release a version of software that actually measures voltage ripple, and limits performance based on how the batteries perform.

On one hand, it would prevent a lot of damaged ESCs, and batteries -- when users are pushing batteries insufficient for the application.

BUT, on the other hand, a lot of people who are running "marginal" systems will see a performance decrease, and might yell "FOUL!" at us for releasing software that would actually lower the performance of their system.

As it is, very few controllers actually get damaged by ripple voltage/current -- but the people who damage controllers this way don't just do it once and then learn a lesson. They tend to destroy controller after controller with the same bad setups. And then they blame US for making a defective product.

Brian, and others, I'd be interested in hearing your thoughts on this...

An optional software updated for that would help the people who pay attention to their rigs know if they need to upgrade or not

The stubborn people will argue that their 2C 500mAh batteries can handle their 1/8th scale no matter what

[BrianG]

Originally Posted by Pdelcast

And for those who are interested...

We've been struggling with whether or not to release a version of software that actually measures voltage ripple, and limits performance based on how the batteries perform.

On one hand, it would prevent a lot of damaged ESCs, and batteries -- when users are pushing batteries insufficient for the application.

BUT, on the other hand, a lot of people who are running "marginal" systems will see a performance decrease, and might yell "FOUL!" at us for releasing software that would actually lower the performance of their system.

As it is, very few controllers actually get damaged by ripple voltage/current -- but the people who damage controllers this way don't just do it once and then learn a lesson. They tend to destroy controller after controller with the same bad setups. And then they blame US for making a defective product.

Brian, and others, I'd be interested in hearing your thoughts on this...

Yes, I'd definitely like this. And I'm sure it would help reduce warranty claims (and lost revenues on your end). Just be prepared to increase manpower on your tech support lines because I have a feeling there will be an influx of calls!

Seriously though, this IS a great idea!

One more suggestion; when the ESC limits performance because of ripple, have the LEDs blink some kind of error code so the user knows what to watch out for. And while you're at it, add similar error codes for temperature extremes, and any other condition you can measure. These codes should "latch" so that the code remains (even if the condition goes away) until the ESC is unplugged. It would be like a car's CEL.

And while you're in a receptive mood for suggestions, here is another thread to ponder over: http://www.rc-monster.com/forum/showthread.php?t=18832 After all, gotta give your firmware developer something to do!

[sikeston34m]

Originally Posted by Pdelcast

And for those who are interested...

We've been struggling with whether or not to release a version of software that actually measures voltage ripple, and limits performance based on how the batteries perform.

On one hand, it would prevent a lot of damaged ESCs, and batteries -- when users are pushing batteries insufficient for the application.

BUT, on the other hand, a lot of people who are running "marginal" systems will see a performance decrease, and might yell "FOUL!" at us for releasing software that would actually lower the performance of their system.

As it is, very few controllers actually get damaged by ripple voltage/current -- but the people who damage controllers this way don't just do it once and then learn a lesson. They tend to destroy controller after controller with the same bad setups. And then they blame US for making a defective product.

Brian, and others, I'd be interested in hearing your thoughts on this...

Hi Patrick,

IMHO, Batteries with poor quality ALREADY limit performance. Releasing a new version of software that measures this and protects the ESC is a great idea if you ask me.

If I understand what I'm reading correctly, this could actually lead us to match our systems better based on what the ESC can do safely.

How would it limit performance though? Acceleration isn't where the damaging ripple current occurs, is it? It's during braking.

I can only imagine what happens when all of that inertia from HARD acceleration, and a motor that's suddenly turned into a generator, comes crashing back through the ESC. With a poor quality battery, it just isn't going to accept the current. Things get critical.

If only Batteries could charge as quickly as they discharge.

Thanks Patrick, for giving me a better understanding of what's going on. I really do appreciate it. You have a way with words. A good teacher.

Even someone who does understand, and doesn't present it in an understandable way, only leads people to confusion or false assumptions.

i like that feature in a set up. It would be AWESOME if the user could choose to run it on or off