Originally posted by

**VicRC**View PostDon't get your shorts in knot, I am not making fun of you. But a 75C battery is impossible, and is pure marketing genius. You pay an extremely high premium having 75C printed on that battery. You are being ripped off.

If you want to know the True C-Rate of a RC LiPo battery, you can measure it if you have a charger that reads the individual cell Internal Resistance. If you have one you are in for a Hell of a Shock.

Here is how you do it. I will use your battery as an example.

1. 6 watts x mah / 1000 = 6 x 1500 / 1000 = 9 watts. All you are doing here is finding a thermal mass limit of your cell of 6 watts per Amp Hour of a individual cell. You have a 1.5 AH cell x 6 watts is 9 watts.

2. Now is simple Ohm's Law. Use the highest Resistance cell of your 4 cells. If your battery is in excellent shape and new will bee roughly .006 Ohms or 6 milli-ohms. Once you have that you find the maximum current your cell can safely dissipate using Ohm's Law of the Square Root of Power / Resistance. So ^2 of 9 watts / .006 Ohms = 38.7 Amps.

3. Now you find the True C-Rate for your battery and you will not be happy. C-Rate = Max Amps / mah x 1000 = 38.7 / 1500 x 1000 = 25.8C. Far from 5C you paid for..

I have only been in the hobby now for about 4 years. But after working with batteries for 40 years I knew C-Rates were complete fantasy. Every manufacture lies big time. It took me a while to find engineers that make LiPo's for RC and they gave me the Formula I just shared with you. That formula of 6 watts for every AH is ridiculous. If you were to actually run your battery at 38 amps means the battery is burning 9 watts x 4 cells = 36 watts smoking hot.

There is also a web site with a data base from users measuring Real C-Rates. No on the face of the earth has ever measured one greater than 30C. 75C is impossible. I run 25C cells and most are around 18 to 20 C. I do have some rated 45/90C Turnigh Nano's but their real C-Rate is 23 to 26 brand new.

Here is something else to consider. I bet if you measure the Internal Resistance of your cell they will be roughly .007 Ohms or 20C. 20C on a 1500 mah battery is 30 amps. That means each cell looses .3 volts per cell or 1.2 volts for a 4S pack. Again you can do the math 1.2 volts x 30 amps = 36 watts of hear cooking your battery. That is why the puff up.

Give you a hint. Buy a Gens Ace or Thunder Power 4S 1500 mah 25C battery will perform just as good as your 75C battery and only cost half as much.

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