mah isnt different from 18650s to lipos right? the way I vape I go through 3 fully charged VTC4 (2100mah) a day, 40watt vaping. This is about 10ml a day.
mAh is dependent on the C-rate, which is based on how long a battery runs at a continuous discharge. For example, if a battery runs for 1 hour at 2000mA, it has a 2000 mAh capacity. The C-Rate is calculated as by dividing one hour by the time the battery lasted. Thus, for the example above, the C-rate is 1 C. If that same battery lasted for 30 minutes at 3500 mA, we would say that it has 1750 mAh at a C-rate of 2 C.
The reason I bring up C-rate is because that's how battery specs are read. They will give you a nominal capacity (mAh) at a nominal discharge rate (which is a particular C-rate). For example, quite a few high-current 18650s give their advertised (nominal capacity in mAh) at around 0.2 C (usually somewhere around 500 mA).
This should not be confused with the C-rating. That is a different measurement, which is what is the max draw one can do given the advertised capacity. For example, a C-rating of 10 C on a battery with a nominal capacity of 2500 mAh can support up to 25 A. However, the battery will not support a C-rating of 10 C at 2500 mAh. Rather, because a battery's capacity declines as current draw increases, it would probably be about 85% of the nominal capacity on a high-drain battery. It's confusing terminology, but the key thing to understand is that C-Rate and C-rating have nothing to do with each other.
So, when comparing batteries, mAh doesn't always mean the same thing. For example, two batteries may have the same mAh, but they are defined at different C-rates. Thus, the battery with the lower C-rate would actually perform worse (in terms of mAh) at the higher C-rate of the other battery. Sometimes specs give capacities for more than one C-rate, but often they do not. So if you're trying to compare two different batteries, sometimes you actually need to do some testing to see how they actually perform (or find someone who has published it).
