Any way to work out the actual C rating of a lipo?

[shazzy]

I bought one of these off ebay 18months ago as a newbie http://kooko.en.alibaba.com/product/595071881-212468186/NEW_5000mAh_3S_11_1v_50c_Lipo_Battery_high_capacity_lipo_battery.html

It says they are rated at 50C but im highly sceptical of that. I wanted to know if there was any way to work out the true C rating, as I now have a cell that runs down quicker than the other two cells in a pack. In hindsight, probably wasn';t a good idea buying chinese lipos as their quality is atrocious.

On hobbyking, I';ve found they sell single cells rated at either 20C & 40C and I was going to buy a cell to replace the dodgy one in the pack. My fairly competent at soldering but am not sure that the lipo is really rated at 50C, I have a hunch the cells in my lipo are actually rated at 20C.

So any way to really gauge the C rating of a lipo?
Thanks in advance!

[flybywire]

Found this, if any use?:
http://www.rcgroups.com/forums/showthread.php?t=1608752
Maybe somebody on here may know?
I couldn';t think of an ';obvious'; way to tell myself, but have often wondered about the accuracy of the sticker.

[shazzy]

Thanks flybywire.  I saw that thread, but unfortunately I don';t have a smart charger as they say where it measures internal resistance   

[flybywire]

I bought one of these off ebay 18months ago as a newbie http://kooko.en.alibaba.com/product/595071881-212468186/NEW_5000mAh_3S_11_1v_50c_Lipo_Battery_high_capacity_lipo_battery.html

I think I would be sceptical about that claim myself.

[guest325]

Looking at the thickness (or lack of it) of the power cables I would be very wary of using it if it were that high a C rating - they would get seriously hot with 250A going through them!
The pic enclosed shows the size of wire on my 40C 3S2200';s

[dirtyharry]

what are you using it for ?

For most quads a 20c 5000mah is more than adequate as long as the battery aint a crap one

I use turnigy blue 5000 25c batteries , the most I draw current wise is 60 amps on a 450 clone quad ( thats a mere 12c). There £20 from hobbyking uk and I can';t fault them.

[shazzy]

what are you using it for ?

For most quads a 20c 5000mah is more than adequate as long as the battery aint a crap one

Im using it for my quad. x2212 Motors so roughly a burst max of 70amp draw. I think the battery is dodgy but wanted to solder out crappy cell and put a new one in from hobbyking
http://www.hobbyking.com/hobbyking/store/__18562__turnigy_5000mah_1s_40c_lipoly_single_cell_.html

or

https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC8QFjAA&url=https%3A%2F%2Fwww.hobbyking.com%2Fhobbyking%2Fstore%2F__18560__Turnigy_5000mAh_1S_20C_Lipoly_Single_Cell_.html&ei=xNeLUprlCYbLhAfsu4Ao&usg=AFQjCNHGVgXuxKkRvKhOoLnrOypCPGXDcw&sig2=cyUouvQL3uPdj-MubzZWdQ&bvm=bv.56643336,d.ZGU&cad=rjt

Cant choose which one until I know what the C rating is in my pack!

[dirtyharry]

Good motors...ive got the same ones.
I doubt it will mater what c rating u use. The cells are in series and your only pulling 14c  ish  absolute max.Id prob get 20c one and then rate the hole pack as a 20c one, would be the safest route.

[dirtyharry]

Ps dont think u can work out the c rating without a bit of distructive testing. Kind of like trying to measure the rating of a fuse with no label on it.

[guest325]

A practical way of having an idea of what your C rating might be is by running your model full throttle for a couple of minutes, if the battery gets warmer than you expect it to then the C rating is lower than expected.
My homebrew V Tail found out a deteriorating battery that way, new 40C';s ran cool, the old one got quite warm; 25C';s got hot!
Your batteries should be fairly cool after the flight, anything more than lukewarm and you may be overstressing the battery i.e. approaching or exceeding its C rating.