Are Zippy Lipos safe with a Castle MMM Speedy?
 

Was looking at getting a pair of 3s Zippy Lipos for my HPI Flux..
when I came across this thread:

http://www.rctech.net/forum/electric...ml#post5469766


So now I am confused.

Should I not use Zippys in my Flux?

Batteries do not kill speed controll's... operator or manufacturer does.. I have been running a zippy with my 2200 combo for months with no problem...

That guy just doesnt know what he is looking at.

+1....i've been running zippy-h's for a couple months now with my MMM/Neu 1515 1/y/f and it started in my revo, then my 8ight-t, then my e-maxx, then my 8ight, and now i run both in my sc8 and rc8t.....i've recently picked up some of the flightmax 30c lipos and use then in my rc8t and so far the only complaint I have about them is the fact that they so sometimes take a while to get back into balance after being discharged up to the LVC...but thats why i own 2 balancer/voltage testers (from commonsense rc thankyou!)....zippy's have always been great bang for the buck and only once have the soldering jobs on packs been a little loose.... but thats only happened once in the 12 packs i've received.....I've ran each pack down until the LVC and they have each taken a little bit more than 5000mah each time....i say get some zippys...or the flightmax if you can wait...or Mike's lipos! :yes:

As discussed in the thread, a poor quality pack is a huge threat to the life of the esc and that is a fact. That is not to say that the Zippy pack was the cause. There was likely something else leading to the disaster. The fact that the car "seized" during a straight means something more serious. Whatever the cause, these "1 in 1000" scenarios are bound to pop up more often as more escs are sold.

I finally picked up one of the zippy 25C 5000mah 3S packs and used my wattmeter to test and a 120A spike was at 10.13V on an 11.1V lipo. That wasnt a bad number for a battery on a full charge. I was geared for 55mph on an MMM 2200 combo. I had it in 5S config with an 8000mah 15C battery that gave an even higher voltage drop at the same current. I can see these numbers dropping significantly when the packs get discharged a bit, but in general I think all Lipos are overrated. I dont think that pack could see 120A continuous draw much like any other pack could see 120A continuous draw. The packs that claim even higher numbers are just making this stuff up even more.
It sounds like that was a fluke and something besides the battery that caused the failure. I can see a bind in the driveline causing a huge current spike enough to take out the speed control. For the most part though, Its all about C rating vs final speed. Generally if you are geared for around 40mph I dont think you are going to have these issues, but gearing for higher is probably going to tax the speed controller and batteries.
On a separate note, if it was the driveline I can see why Castle might not want to warranty the speed controller. It might or might not be their fault, but if they see a 1000A spike took out the speed controller, they will have to question what happened and ask whether it is truly a manufacture defect or not.

The poster on the rctech thread sounds very bogus to me. It's more of a "Nitro guy converted to Brushless - going back to Nitro" thing to me.

A Bad cell in ANYTHING doesn't surge, it dies a slow death.

If a Lipo can't keep up because of it's "C" rating, it overheats and puffs.

Thats what makes sense and what I thought/think, but the Tekin prez said himself in that thread that they do infact surge? :neutral:

ZIPPY 6S 5000mah flightmax FTW!!!!

I don't see that thing fitting!

Ok, I went back and read what you are referring to that Mr. Tekin Prez said.

They are talking about braking emf forces exceeding the voltage limitations of the caps and fets.

"If a battery is over rated or over stressed the voltage will bounce to very high levels and stress the caps. If the caps blow the voltage spikes can exceed the limits of the fets and the speedo will blow. Many of you are looking at things with data loggers that take 20 samples per second or less. We are talking about voltage ripple that happens in micro seconds that can bounce off the scope thousands of times per second with no caps. The fets are only rated to 30V."

Most Manufacturers allow enough overhead in their fet ratings and in their cap ratings to help compensate for this. They also don't over-rate the ESC, such as amp carrying ability, voltage range, etc. They also use forms of secondary protection in their braking circuitry. Couple this together with some great operating software, and you have a great package.

I've heard alot of really good things about Zippy Lipos and would not hesitate to use them. In fact, I've been thinking about ordering some soon. :yes:

That's garbage. I have smoke several MMM's maxamp on one, TrueRC's on one and Zippy on another....flat BS and CC's attempt to pass off a controller problem to batteries.

Before we assume CC said something, I think we probably should hear their take on this subject from them.

Instead of playing, he said, she said.

Agreed I have fired off an email to Joe Ford about 8 or 9 hours ago, and am waiting on a response, I only asked as I want to get a pair of 3s for my Flux but finding that post and their "alleged" replies from Castle support, I thought it best to check before I throw some coin at it.

the 4s set up I run is 2 * 5000mah hard cased packs at 30C so I am fairly confident in that set up.

Now see, that makes sense. He never said anything about the regenerative braking (I'm assuming thats the cause?) causing the voltage spikes

This proves the point more than it disproves it. None of those batteries are "high end" batteries and would all be prone to exactly what was discussed in the linked thread. Jim (Tekin Prez) made a couple sensible, descriptive posts in that thread regarding the "potential" pitfalls of lower end batteries. It is a fact. I am not here to call out any specific manufacturer or seller, but many packs do tend to be over rated, inexpensive packs that are popular due to their inflated specs, inflated marketing or low price(or combination of the above). Everything has its place. If your particular setup or driving style, etc. allows you to have great success with your particular "low end or mid range pack that happens to be overrated ", but you aren't anywhere near the particular pack's limits, then you got a good value. If you are pushing things, you will not only notice the performance difference with a good pack, but will be less likely to experience failures.

I am not saying the battery was the cause or wasn't the cause of the failure in the discussion - I don't know the guy, don't know the car and wasn't there. I do agree with the logic regarding the pitfalls of lesser quality cells - particularly in 1/8 brushless applications that tend be very hard on equipment. Maybe the pack was the cause. Maybe it was just one of several factors that caused the failure. Maybe it had nothing to do with the failure at all. It certainly COULD have been a major factor in the failure and the advice to use a quality pack is sound advice.:intello:

Here is the problem with that logic. I have used these very same packs with other cheaper controllers (Turnigy 100HV) and as high as 12S and nothing has ever happend to those controllers with huge immense loads when I was doing speed runs. I also run the same exact packs on the HV110, and use to run them on the little old mamba max on 5S. NONE of those controllers have ever given me a problem and still use them on apps when the MMM dies. Now this controller has gone dead 3 times, I swap in my trusty HV110 or mamba max between service times and magically never have any problems. The only common variable being changed is the MMM. The batteries never change....

I was not speaking to any "specific" instance so much as suggesting that the lower quality batteries CAN cause problems. Perhaps the MMM is more prone to this issue than other escs due to lower internal resistance or something else specific to its construction or specifications. That wasn't my point. My point was to state my agreement that better batteries are indeed better. Better performance. Better cycle life. Less likely to cause esc problems(Better). Regardless of how prone any particular esc is to this issue, it will be less prone when quality batteries are used. That is my logic.
So - IF the MMM or any other esc is prone to failure due to lower quality cells, then my "flawed" logic suggests that better batteries lessens the possibility of this happening. The fact that the manufacturer recommends high quality batteries to begin with is no secret, either.
Is this illogical?

To add to the logic - most people report increased power in the otherwise identical setup when switching to the MMM controller(myself included). Perhaps the trade-off is that this more pronounced and available flow of power goes both ways, making the controller more prone to failure due to "issues" more commonly found in lower quality batteries. I am not the manufacturer and I did not join the discussion to offer anything other than my thoughts on batteries causing esc failure - using better batteries will yield better results in all cases.

You just proved the point... The HV controllers are based on 60V processes -- the Mamba Monster is a 40V process.

If there was a problem that was causing voltage spikes during regenerative braking, the Monster could be damaged BEFORE the HV controllers.

That's why the Monster is rated to 6S and no higher. It can take bus surges to 40V.

To add to what Mike has said; The controllers mentioned are either airplane ESCs (HV110, turnigy) or ESCs with a lower current rating (MM). This could be due to FET choice, and/or ESC construction. It has been stated that an airplane ESC is not designed for the burst currents we see in car applications, so they have a higher total resistance (in FET choice, PCB traces, etc) so they tend to not to funnel as much energy as an ESC designed specifically for car use. And lower-current ESCs, like the MM, also have a higher total resistance, which helps to limit the potential current spikes.

An "ideal" ESC would be one that is as transparent as possible to current flow. This means 0 ohms of resistance. While that ideal is not practical, car ESCs designed for 1/8 scale (or larger) vehicles will have less resistance because of the currents they are designed to pass.

Also, lower-end packs tend to have higher internal resistance, which tends to increase the ripple current from a powerful system. I am willing to be that adding a few more low-ESR caps to the MMM when used with lower-end packs will drastically reduce ripple currents. Yeah, it's a band-aid, but not for the ESC, it's to compensate for the lower-end packs.

Patrick, since you're on here, I have a few q's about the MMM:

- What is the voltage rating of the clamping device used in the MMM?

- If the EMF braking spikes are excessive/numeruous enough, is there a chance of that device blowing while not being obvious to the user (which would then allow those brake spikes to now reach the battery)?

- And, which version of MMM was this device added? I say this because my V1 had what looked like such a device added after manufacture.

I'm not sure if the V3 uses the same device or not, but the device in your V1 that was added is detailed here:
http://www.rc-monster.com/forum/show...9&postcount=22

What has me confused is all my race trucks are mechanical brake...reverse and brake are all but disabled.

"all but disabled" or actually disabled? The motor itself has mass and can result in significant back emf when applying brakes to slow itself down(Brian and I discussed this yesterday in fact regarding some tests he performed). IIRC, the motor in question produced nearly 30 volts of back emf when the brakes were applied - using a 4s pack to accelerate. No load other than the motor itself.

Now, that said, ANY battery that is pushed beyond its capabilities can damage an ESC.

Let me say that again:

ANY BATTERY THAT IS PUSHED BEYOND ITS CAPABILITIES CAN DAMAGE AN ESC.

AS CAN BAD CONNECTORS, BAD WIRING, AND BAD SOLDER JOINTS.


We have gotten so oblivious to the fact that we are harnessing thousands of watts in these setups -- any problems in the system can cause problems with other components in the system very quickly.

So we must be VERY careful NOT to push batteries harder than they can handle.
The very same is true of Motors -- and people seem to accept the fact that certain motors can only be pushed to a certain point before they fail.

Why do the same people not understand that a battery pushed beyond its capabilities can damage the ESC?

The ESC relies on the battery to both SOURCE high currents without significant voltage drops, and to SINK high currents without significant voltage rise. If the battery cannot hold the bus voltages within a reasonable voltage, then the setup is PUSHING THE BATTERY TOO HARD.
A battery needs to have the ability to sink braking energy during hard braking, and take that energy back as charge energy. If the battery can't take the energy back quick enough, the voltage on the bus will rise, and eventually it could get high enough to damage the ESC. We do bus voltage monitoring on the Mamba Monster, but if the battery is REALLY bad, the voltage can rise faster than the MMM can respond to it.

It all comes down to this: Don't push any parts in your system beyond what they can REALISTICALLY take. This includes motors, batteries and the ESC.

Just as some motors are better than others, some batteries are better than others. You can't expect a $25.00 Chinese motor and a $250.00 Neu motor to perform on the same level. Same goes for Lipos. There are applications where cheap lipos and cheap motors WORK JUST FINE -- but there are other applications where they may perform below par.

Patrick

LOL, 5 new posts while I was composing that post.... :lol:

lol, Patrick. So, wait a minute, I'm gonna go out on a limb here and assume you are trying to say that any battery that is pushed beyond its capabilities can damage an ESC? :wink:

And, I for one am amazed at the power levels these little devices control.

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. :oh:

Brian, yes - -that's exactly what I'm trying to say. :yes:

Really, if any component in the drive line is pushed beyond it's power handling capability, it can potentially cause damage throughout the entire drive line. For example, if the rear end is pushed too hard and it seizes, that could cause damage to the spur gear, the pinion, the motor, the ESC and the battery (potentially...)

We just need to be careful about how we match components, and make sure that we make careful choices.

For example, I would never run a 6S 1515 MMMM system on a 6S 1200mah Lipo -- I know the Lipo would fail under those conditions (100C+ currents) and might also damage some of the other components in the system (ESC in particular.)

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.

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....

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

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. :whistle:


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...)

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

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. :lol:

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

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. :yes:

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...