New warning insert in MMM box: "DO THE MATH!"

[pasan]

I use the (in)famous blue packs from the far east, and have had no problems so far, they are rated between 20C-30C. However, the talk is that the first few batches came from surplus cells used to make another popular and 3x as expensive brand of LiPo. I'm inclined to believe those claims because two of my packs are slightly puffy as a result of me plugging them in the wrong way (big spark and badly burnt 6.5mm connector), but they're still going strong in my E-Revo. And I do drive like a total tard, I broke my E-Revo the first time 15 minutes after I had unpacked it.

On another note, can anyone make sense of the "new" rating system Maxamps is using and how it translates into real world usage? They're throwing around the term "surge watts" quite casually, and it seems to me like a blatant attempt at misleading people. And the fact that they're refer to the maximum constant output rate of a cell as "arbitrary" only more so, since there's nothing arbitrary, to me at least, when it comes to figuring out the minimum resistance you can put between the terminals before the cell self destructs.

[jpoprock]

There is thread somewhere called" New Maxamps 60C packs?" or something like that. It's quite a hot nugget of info!

[TexasSP]

Maxamps is a marketing machine and nothing more. From their advertising in RC rags to their web page to the way the present themselves in RC forums it is blatantly obvious. I believe that the new rating system is simply a ploy to gain sales in a weak economy (you can't tell me being some of the most expensive packs around that sales aren't hurting). I also believe it was by intent designed to further confuse unknowing people. While the C rating method is not uniform across companies and there are issues, it is what we have and does work for the most part. I would like some things standardized and cleaned up about it but as far as the basic principles it makes sense.

As for me based on my experience in the past and this new rating system as an indication of the way MA does business I will be staying away from them, forever.

As time goes by, the internal resistance of lipo batteries will increase.
Even a decent battery will become inappropriate for MMM eventually.
How do I tell it is time to dispose of the battery?
From the battery IR. measurement of chargers? or from the increasing temp of the battery?
I was told to use an eagle tree to measure the volt spike. Is there any easier way?

[jpoprock]

Where does one just "buy" and Eagle Tree? Are they expensive? Handy to have for the weekend warrior? Overkill?

[shaunjohnson]

eagle tree's are perfect for selecting your NEXT battery.
you can see how much power you are using then give it 50% more in the battery and you are SET

[suicideneil]

You can get an Eagletree from most 'upmarket' retailers- hyperion website has them I believe, or google for them.

I got that flyer in mine when they first had the refurbs earlier in the summer for $100.

Originally Posted by TexasSP

Maxamps is a marketing machine and nothing more. From their advertising in RC rags to their web page to the way the present themselves in RC forums it is blatantly obvious. I believe that the new rating system is simply a ploy to gain sales in a weak economy (you can't tell me being some of the most expensive packs around that sales aren't hurting). I also believe it was by intent designed to further confuse unknowing people. While the C rating method is not uniform across companies and there are issues, it is what we have and does work for the most part. I would like some things standardized and cleaned up about it but as far as the basic principles it makes sense.

As for me based on my experience in the past and this new rating system as an indication of the way MA does business I will be staying away from them, forever.

Though i've never owned them, i've heard enough negative things about them to never recommend em

[littlegiant]

Originally Posted by Pdelcast

Because during braking the ESC has to dump power back into the battery. Packs with poor C ratings have high internal resistance, so to get the power back into the battery the voltage has to rise. The lower the internal resistance of the battery (higher C rating) the lower the voltage drop during accelleration, and the lower the voltage rise during braking.

Will bigger capacitors help prevent damage then?

[shaunjohnson]

caps are for huge amps for split seconds. acceleration can go on for more than a few seconds.
hence a good battery is needed.

[NIX]

Originally Posted by fastbaja5b

And this is why on 4s the failure rate for the MMM is far lower than on 6s, greater difference between the pack voltage and fet rating... right?

MGM compro did testing on voltage: http://mgm-compro.com/pdf/en-motor-braking-050409-g.pdf It is quite interesting to see what the effect is of using breaks over the ESC. It is quite some info but the same voltage problems when braking can occur in all on the market available ESC's. Principles are the same. It can cause quite some troubles/failures in setups but with this knowledge one can prevent problems to occur.

If you want to run your ESC's bullit proof a few conclusions I took myself after discussed this with Grisa of MGM is:
1. Use a ESC that is rated for 2s higher than you are running. So a 6s when running a 4s setup, 8s when running a 6 setup etc..
2. Rating of ESC's max A draw is given for certain temperatures. A lot of setups (bad ones..) give higher temperatures and by that inner resistance will go up and max amp draw capable to handle will be lower (much lower). For that take a margin of 30 - 50%.
3. Use a good akku. Rating continuous should be 50% higher than the continuous rating needed for the motor you use. Especially with when you use packs that are branded with just 'marketing/making sales' in mind. Maxamps isn't the only one who is 'confusing'......
4. A BEC gives extra temperature in an ESC. Using a ubec makes a big diffference!! The castle creations UBEC is lightweight and can make real difference in temperatures you are measering. The temperature loss on a BEC (switching and linear are both very big, so it are small heaters on should get rit of in the system).
More on cooling /temperatures of ESC's:http://mgm-compro.com/pdf/controller...n-models-h.pdf

A well balanced setup can run cool without fan's etc. If a setup needs to be run with a fan for cooling down the elements it is a no good setup. A MMM can do a good job to without its fan if one plans it setup.

I think that a lot of the new 4s ESC's coming on the market (LRP etc) will give a lot people headaches.... Also marketing specifications....

MGM compro will come out on a short time with 'controlled breaking resistors' break device that will prevent problems caused as described. So no problems anymore with 6s esc's run on 6s.
They also have introduced a ESC that is completely waterresistant (you can even run under water).... For US buyers these might be quite expensive but on the european market the price difference is at the same level as the there to highly priced MMM v3.