Breaktru Forum

eCigarette Forum => Battery => Topic started by: methos on February 11, 2014, 10:10:53 PM

Title: C rating on lipo cells
Post by: methos on February 11, 2014, 10:10:53 PM
I wanted to see how I can find the C rating on lipo cells from the smok groove. I have about 6 here and I wanted to build a DNA 30 mod with mah out the wazoo. LoL  I've seen one done before but I don't want to push a battery to far.
Title: Re: C rating on lipo cells
Post by: CraigHB on February 12, 2014, 12:44:22 PM
If I had to guess, I'd say those are 2C cells and they may or may not have a low enough DC resistance to power a DNA30 to the maximal 12 Amps it can demand.  The cells are at least 2C and with 3800mAh, that gives them a continuous drain limit of 7.6 Amps.  Burst limits are safe for 3C with a 2C cell so that gives you a burst limit of 11.4 Amps.

You can get an idea by measuring the cell's voltage drop under load.  You want to check using a fairly heavy load.  You can use something like a 25 Watt 1/2 Ohm wirewound resistor or a 1/2 Ohm atomizer. 

You need two meters.  First a 10A ammeter inline to measure current and a voltmeter on the battery terminals.  Measure voltage with no load then measure voltage with a fairly heavy load.  Divide the change in voltage by the current and you'll get the DC resistance of the cell. 

You probably need to see a DCR no higher than 25 mOhms when the cell has a good charge on it.  I have some small LiPos good for 14 Amps continuous and that's what the DCR is on those.
Title: Re: C rating on lipo cells
Post by: methos on February 12, 2014, 06:43:00 PM
Thanks Craig. I may have to bring he some stuff from work this weekend to test them.