What are Cs?

[MagicTrail]

I recently got into this hobby and have learned a lot about it. I still have no idea what the C rating on batteries means. I can't find any good info online about it. I know it has something to do with amps but beyond that I know nothing. Thanks!

 

[Ketchup]

The c rating multiplied by the amperage of the battery is the maximum amount of amps that you can pull from the battery. For example, a 3s 2200mah battery that is rated at 25c can handle a 55 amp discharge because 2200mah is 2.2 amps and 2.2 times 25 is 55.

 

[Merv]

I agree with @Ketchup. You should never change faster than 1 C.
It would be perfectly fine to use the above battery in a plane that used 30 amps but you would damage the battery if you used it in a plane that uses 60 amps.

 

[Hondo76251]

C rating, because Amps, mAh, voltage, and Watts isn't enough ways to describe a battery...

Its not as hard as it seems at first...

Take a quick glance at any pack... the first thing you see is 1800.... 2200... whatever the mAh of the battery is. This is the capacity. It is also the quickest number you can use to know what to rate to charge it it at...
Take whatever the number is and move the (.) to the left... an 1800 could charge at 1.8... 2200 at 2.2...
some batteries CAN charge at a faster rate but its best to stick with 1C...

or 1x(capacity) of the battery...

That "C" rating is also how you figure the max power that battery can deliver.

Again, its C "Rating" times the capacity...
1800 mAh @ 30c is 54 Amps... (1.8 x 30 = 54)

Keep in mind this is MAX... I like fly my models with the motor as the "weak link" My ESC's are usually overkill as are my batteries. If my motor can pull 30 amps I like my battery to handle 50 at least (something in the 150% range)

So a 4000 mAh pack would give me A LOT of flight time and would only need to be rated at about 12c, but this would also be very large and heavy.
To get the same "Punch" from a battery of a lighter weight (say something in the 2000 mAh range) I'd need to look at batteries that are capable of at least 25c...

If I've got a model where I am really concerned about keeping the weight down, and still needed the same 54 amps we've been talking about, I might even end up with something in the 800mAh range... in which case the battery would need to have a C rating greater than 65 to ensure I could still get at least 50 amps...

Clear as mud?

 

[Merv]

Some other battery tips
Always give your battery a cool down period, at least 15 minutes, longer is better. Battery’s need to cool after a change before you use them. AND need to cool after you use them before you change them.

Some battery manufacturers inflate the C rating, they will say 25-35 C. Always use the lower number, that is the continuous use C, the higher number is a burst rate. What you can pull for a short burst, say 15 seconds.

There is little to no correlation between price and quality. I buy Turnergy, Gray Hobby, and Gene Ace, all have given my 3-4 years of service. My buddies buy expensive batteries, that will only last one season. I’m not saying these are the only good batteries. Just these has worked for me.

Time is the enmity, no Lipo will last forever, they will degrade just sitting unused on the shelf.