Lipo ''C'' rating debate

VillageIdiot · #1 08-01-2012

As all are aware many top brands and others offering performance lipos CLAIM to have high C ratings, 60, 70, 90, even 150.

When parting with £100 per Lipo shouldnt we be expecting them to provide evidence of there testing and results in their so called TRUE rating? this would make a huge inpact in the decent lipos and the ones with false ratings trying to shift lipos on false statements.

Ive just come across a lipo manafacture that ive never heard of, and on the resellers website goes like this....

KYPOM KT7000XP70 LiPo 7.4V 7000mAh 70C Hard Cased.

Latest 2012 technology
7000mAh capacity.
70C rated - TRUE rating. Lowest resistance.

Firstly whats this 2012 technology? secondly they claim TRUE rating.

Is there a way that the end user could measure C rating for themselves accuratly and then compare lipos on the market?

Rant over, Discuss.......

RudolfXC · #2 08-01-2012

Quote:

Originally Posted by LIP

Firstly whats this 2012 technology? secondly they claim TRUE rating.

Is there a way that the end user could measure C rating for themselves accuratly and then compare lipos on the market?

Rant over, Discuss.......

You can check the internal resistance with some chargers but to check the 'C' rating you would need a dyno. There are non for brushless motors but old ones can be adapted using a brushless speed control and servo tester. I'm considering doing this with a Tekin dyno and using my LRP Touch charger to control the speed controller and read out the revs from the sensor board.

SDARCY118 · #3 08-01-2012

i had something said to me yesterday that makes perfect sense..

"its very hard to get any more than 60C from a lipo cell...and even if you get 60C from a Lipo cell.. you cant use it to it full..because of the internal resistance from the 10 gauge wiring you use"

so basically unless you use 0 gauge wiring which no body going to use in a radio control car lol...you never get the absolute full potential from your lipo pack.

SlowOne · #4 08-01-2012

Spot on! And even if you did have 0 gauge wiring, the wiring in our motor isn't, and in the end that would become the limit! Buy to quality and ignore the numbers. Thunder Power and SMC are the only ones that give you anything like their numbers, along with the reliable 'labels' - Orion, Reedy, Losi, etc. Anything else treat with a large bag of salt!

It hasn't changed since we started measuring cells back in the early 1980s. The numbers on NiCad and NiMh cells were closer to the works of Hans Christian Anderson than anything else, and it seems the LiPo numbers are just another chapter in that fairy story!

MattW · #5 08-01-2012

The battery game has been the biggest load of BS in racing for as long as I can remember. It's even worse with LiPo than it was with NiMh IMHO. At least with NiMh you often got a label with some actual cycle results. These were often manipulated by the matcher it's true, but if you actually knew what you were looking at it was possible.

With LiPo, anyone can write "200C" on their label - and all it proves is that they've had a software upgrade on their label printer!! The reality is that there aren't all that many (I'd be shocked if you'd need more than 1 hand to count them!) actual LiPo manufactures. There are a lot of companies that make boxes and print labels, but ultimately the majority originate from similar sources.

Do you really believe that one company has worked out how to make 90C batteries, but the others can only make 60? Well I don't anyway. What they have done, is worked out a different way to measure it.

Fact alert - 60C with a 6000mAh battery is 360Amps. How many people believe their car is able to pull 360A - i'd like to see it.

What is true is that development takes place, and generally year on year the batteries get better. So the source that is quoting "2012 technology" is effectively indicating that these batteries are only recently available to market. Quite shortly, you'll see all the major battery sellers refresh their battery offerings with the "latest" cell from the manufacture in the far east.

VillageIdiot · #6 08-01-2012

some very very good comments here, i'd love to name and shame these companies and have somewhere all the new racers who join can see so as to not to get ripped off by the C rating, after all that exactly what maxamps have been doing for years, ripping off people.

would be nice to see a dedicated thread with testing of all major lipos and report the result.

I am also not convinced of orions 90c lipos, BUT i am sold on them and swear by them for being a very very good lipo, ive driven them side by side with other lipos even my orion 45c lipos and the difference was massive and the car was more drivable and responsive.

badger5 · #7 08-01-2012

The only time I have seen the max C rating being tested was on the GiantCod forum, http://www.giantcod.co.uk/forum/view...p?f=121&t=7579

It makes for an interesting read.

Perhaps it's time that we had some more real independent tests like this and real world blind driving tests carried out so people can see what is hype and what's real in respect to C ratings and capacity and what really matters. It would be nice to see how the cheaper and mid road brands compare to the expensive stuff, do we need 90 or 150C and do the claims stand up.

VillageIdiot · #8 08-01-2012

totally agree, if I wasnt going away for 3 months shortly I would be willing to do this and test as many as possible. put some sort of equipment together to ensure equal testing.

what equipment do I need and how would it be wired up?

mark christopher · #9 08-01-2012

to be blunt C rating is bollocks, no real way of measuring it, this is why you will notice all packs on the 2012 list HAVE to have thier watt hours shown on the pack.
there is new technolgy in certain packs, i had a quick discussion with a company, basically as technology moves forward its moves to products, much like speedo technology

VillageIdiot · #10 08-01-2012

Ive been doing some research and have also noticed it appears that the watt results appear to be a good way to measure a good lipo and not. the link above, whats required to get those results with graphs and evidence to show the results? and whats required to test and measure this wattage?

CrashBangWallop · #11 08-01-2012

Could you use a Trakpower charger for the data logging ?

Great post though, as this thread has played out some great information has come out of it.

mark christopher · #12 09-01-2012

Quote:

Originally Posted by LIP

totally agree, if I wasnt going away for 3 months shortly I would be willing to do this and test as many as possible. put some sort of equipment together to ensure equal testing.

what equipment do I need and how would it be wired up?

Quote:

Originally Posted by LIP

Ive been doing some research and have also noticed it appears that the watt results appear to be a good way to measure a good lipo and not. the link above, whats required to get those results with graphs and evidence to show the results? and whats required to test and measure this wattage?

ill say it one final time
2012 cell have to have watt hour rating and this can be proven.....

if you dont know how to test it 1/ why bother? 2/ who will believe you?