Originally Posted by eman.cardona
2C - 10% voltage sag
3C - 15% voltage sag
3.5C - 20% voltage sag
Thanks for the info.
There's little data that others post about voltage sag. But based on a few posts (tomofreno
, etc.), 10%-15% at 3C seems to be the range for the Chinese prismatics. With 10% being good and 15% acceptable. Low temperatures make it worse.
Originally Posted by Yabert
About battery, the calculated impedance from your data is pretty bad. That give 2.7 mohm for those 60Ah cells and the Calb 70Ah claim to be under 1 mohm.
Comparing internal resistance (mohms) is problematic. First, the ESR is non-linear and the datasheets don't say at what currents those were taken. If the CALB data was true then those 70Ah cells would only have 6% sag at 3C. Second, most people get confused comparing the resistance of low capacity cells with higher capacity ones. Quoting voltage sag at several Cs would give a better picture.
So based on first glance I would rate these cells as an improvement on energy density (100 Wh/kg and 189 Wh/liter), but with minimal improvements on power density (because of the lighter weight and volume) and no improvements on performance. I define 'performance' as voltage sag under a given current, closely related to power density. Of course, the lower the sag, the better the performance, the higher C discharge possible.