Reply from tech support

[tibalotte]

Hi guys.

First of all I have to say that I appreciate CC support. Already used it for my mamba monster and been satisfied of the answer and support they gave me.

But friend of mine received a weird reply from a CC tech and I would like someone at CC or someone else explain it to me. I have some knowledge in electronic and electricity but I can't understant this reply from castle about his failed ESC:

The ESC failed because of running inadequate batteries. The minimum battery for the Monster system is a 5000 mah 25c or better battery. 2600 mah will kill and did kill the ESC. We will replace it once assuming using those batteries was a mistake but if the replacement is run on them, when it fails we will not cover replacement.

Friend's setup:

Buggy: Team Associated RC8
Pinion: 13T
Motor: CC 2200KV
ESC: Mamba Monster
Battery: 2X3s (6S) 2650mah 30c Turnigy

Every major components are checked after each race. No anormal heat. 5 race later ESC died. That happen 3 times...

What is that "minimum battery" requirement .... I can accept that these lipo are cheap and maybe overrated but let say I'm the cheap guys running on nicad or nimh.... those pack would deliver less power than thos Turnigy pack no? Would it failed my ESC and void my warranty for that?

What do you think about that reply... ?? Am I missing something. If someone could explain it to me I would be pleased to inform my friend.

Thanks

[BrianG]

Lower quality batteries have higher internal resistance, which causes ESC-damaging ripple currents at high current draw. A sort-of bandaid approach would be to add some capacitors to the input power lead (make sure they are 105*C low-ESR, 35v+, and 1000uF+). This also creates a larger hook-up spark so be prepared to replace connectors a little more often.

[TexasSP]

You do realize that the pack you have is only rated for 78 amps? On the MMM you should at least have packs capable of 100 amps continuous. I am not surprised the ESC blew on those. I would also not be surprised if the cells are now damaged as well.

[Thomas Porfert]

That setup is geared for ~55-60 MPH, the amp draw will easily exceed the capability of those batteries. We recommend as an absolute, bare bones minimum a 5000mAh with at least a 20C continuous discharge; which is good for 100 amps based on the C rating, the minimum we recommend for most setups. For a hot setup like this, you would want a 25 or 30C continuous. We have to account for manufacturing tolerances, battery wear and sometimes just blatantly false C ratings. We recommend removing ~20% from a batteries ratings and still shooting for 100 amps; so a 5000mAh at 25C would yield 125 amps, and 100 amps removing ~20% would be a much safer bet. There's no such thing as too high of a discharge, but there certainly is such thing as too low. You cannot run NiCd batteries with any of our systems, and NiMH's are only good for conservative setups. And they must be the highest quality NiMH cells and be assembled correctly (IE battery bars).

If this were setup to go 35-40 MPH, you might just get away with those batteries; but even then, there is some potential risk involved with that low of a continuous discharge. If you were to go to a 4s setup, or preferably switch to the 1512/1.5Y (1800kv), I would feel a lot more comfortable with that setup; but I still urge extreme caution using those batteries with a Monster setup, they really aren't powerful enough for these types of vehicles. A battery rated for 79 amps, and 63 amps removing ~20%, is a cause for concern; and if I understand correctly, this has happened 3 times before? Multiple failures on the same setup generally indicates a problem with the setup; or some of the worst luck ever, and in that case, go buy a lottery ticket and remember who told you to go get one when you win. :)

As BrianG mentioned, you can "band-aid" slightly inadequate batteries with extra caps, but it doesn't fix the underlying problem. If you were to gear a bit more conservative (drop the pinion, increase the spur) and add the caps, you have a much higher chance of success.

Thomas Porfert
Castle Tech Support

yup, too low of mah. i run 5000mah at 35c in a 11lb truck geared for 40.

but sounds like CC is going to do their awesome thing and replace it for him anyways.

[Pdelcast]

Originally Posted by TexasSP

You do realize that the pack you have is only rated for 78 amps? On the MMM you should at least have packs capable of 100 amps continuous. I am not surprised the ESC blew on those. I would also not be surprised if the cells are now damaged as well.

QFT -- the MMM can draw upwards of 400amp surge, and 90-100 amps at full speed. You need a pack rated for 100A minimum.

[tibalotte]

Ok guys. Thanks for all these great answer. I didn't know that it could exist minimal requirement for this kind of setup and that weak battery could be harmful for the esc.

Good to know

[BrianG]

Originally Posted by Pdelcast

QFT -- the MMM can draw upwards of 400amp surge, and 90-100 amps at full speed. You need a pack rated for 100A minimum.

Patrick, how about adding a brief not-too-techy note on your site explaining this? I've seen many many people who do not understand how much current these setups can pull (especially those guys who gear their E-Revo for 90mph and wonder why things blow). Maybe even some graphs for logged runs as proof of typical real-world setups? It would probably be good to note that some loggers can't measure the full current bursts because they are limited to their rating. Also, there seems to be a thought that since the ESC is rated for ~150A, that the ESC will only pull 150A whether you are gently driving a moderate setup or mashing the throttle on an aggressive setup. I guess what is needed is "layman's electronics 101".

[JThiessen]

Originally Posted by BrianG

Patrick, how about adding a brief not-too-techy note on your site explaining this? I've seen many many people who do not understand how much current these setups can pull (especially those guys who gear their E-Revo for 90mph and wonder why things blow). Maybe even some graphs for logged runs as proof of typical real-world setups? It would probably be good to note that some loggers can't measure the full current bursts because they are limited to their rating. Also, there seems to be a thought that since the ESC is rated for ~150A, that the ESC will only pull 150A whether you are gently driving a moderate setup or mashing the throttle on an aggressive setup. I guess what is needed is "layman's electronics 101".

Great idea - or how about a calculator similar to the ones you have Brian?

[BrianG]

A calculator can only be used as a rough estimation. There are simply too many variables for accuracy. I think as long as the issue is explained in a manner that can be understood by most people, there will be fewer problems. Sure, this kind of info can be found here and many other forums, but it would lend it credibility to be on the site of a company that makes the product.

Brian, you making the assumption that those people who really need to, would take the time to read it. They don't even read what's up now. Though it's a great excuse for getting the ones who do care, more info :)

This goes along way to answering alot of questions, I see everyday. http://www.castlecreations.com/suppo...ing_guide.html

[simplechamp]

I agree Asheck, a lot of people won't read directions or follow suggestions no matter what you do. OTOH if putting that extra warning/explanation out there even convinced a small percentage of people get better, more capable lipos, it would be good for Castle in terms of a few less warranty replacements to dole out (especially since using poor lipos shouldn't really be covered by warranty anyway, Castle is just that good to their customers that they give them the benefit of the doubt the first time around).

[TexasSP]

I don't know how much it would help as most of the people I have seen blowing out there MMM's and other ESC's seemed not to have read the instructions. Especially the savage flux guys who go to 6s and don't even bother to change the gearing as the manual states to do.

[suicideneil]

When the inevitable does happen though, and the user answers the question 'what batteries were you using & what gearing/ vehicle?', just tell them 'sorry, the manual clearly states that you mustuse sufficient lipos and dont gear for in excess of xxmph with xx vehcile'. I took the time to read the manual & leaflet ( care & feeding of your monster ), so anyone who doesnt should be puni$hed.

[redshift]

I feel the need to play moron's advocate. What about the ones who do read the bottom of the MMM itself where it says "max input 18 nicad/nimh, 6S lipo"

Now I know better, but if you really don't want the MMM being used with nicads, or lesser nimh packs, why include that info at all? The less experienced user will likely assume that any nicad/nimh cell count up to 18 will suffice. And if they in fact read the manual, they might find some conflict between what is stated in the manual versus the info on the esc. We're at the point now lipos are A. cheap enough and B. pretty well known and used in the hobby. I do think it may be wise to remove any mention of nicad use ANYWHERE in brushless, and have at least stronger warnings about nimh use, if not removing reference entirely to those as well.

Not trying to ruffle feathers, just pointing out....