This is where the lipo industry has gotten ugly in the flight side of the hobby, and unfortunately it's fixin' to get ugly here with cars as well.

Firstly lets define "C" rating:
Oh wait - that's right, no one has a standard definition of what that number means! (seriously)

To ME: The C rating means that the pack can output "X" many amps for the duration of it's capacity WITHOUT doing either of two things: 1) dropping below 3.0v/cell, and 2) heating up beyond 140degF (max safe lipo temp).

The C rating comes from the following math, again using the CORE pack as an example:
First, you must actually have and use some serious discharging equipmnet including voltage and current monitoring/reporting along with a temp gun. Hook up the pack, and throw a load on it. The CORE 5000's were reportedly 20C packs, so I conservatively threw 80A at one to see what happened to the voltage and temperature for the first discharge cycle.

5000mah of capacity, so again /1000 to equal 5 amp hours of capacity.
Find the maximum amps you can discharge with (for the whole capacity) without dropping voltage below 3.0v/cell or the pack heating beyond 140degF. In this case we'll use 100A as that figure for round #'s (it was a touch higher in actuality).

5 amp hours divided by 100Amps of discharge capability = 20"C".

Again: that's MY OWN definition of what C rating means. Unfortunately, most packs out there DON'T live up to the ratings given for them, according to my my own definition/testing/determination.



And here's where the problem lies (whoops - did I just say lies?).
1)Not many folks have access to 100A+ discharging equipment.
2)From the simple answer above - if you have the choice between two packs with the same Mah capacity, and one was 20C and the other was 23C, everyone would buy the 23C pack.
3) There's no real testing/performance standard either in the lipo industry, or the hobby industry.

So when you add up all three of the above items, you begin to realize what the consumer is really facing right now. What does 15-20-25-30C really mean???? By what (and who's) definition was the C rating determined? Were packs actually discharge tested? Are the brands just using what the factories tell them the C rating is? (and again - by what standards are the factories using?) Are they just flat making up numbers higher than anyone else's just to sell packs?

When it comes right down to it - If I wasn't restricted by my own morals and professional integrity, I could advertise the CORE pack as 35C and probably sell 10x more than we already are. Think about it - WHO out there is an unbiased party and has discharge equipment capable of 175 amps to prove my claims wrong?

So the moral of the story here is a repeat of what I've already said should be important to the consumer: Do you trust who you are dealing with? Do they have years and years of application and industry experience with the products they're selling? Do they really know everything about it in order to support you with accurate advice and safe usage guidelines? Personally, I think these reasons plus a good dose of honesty are :-)
Shawn Palmer