Battery Mooch Information Mentioned In The Video

Thank you Mr. Mooch!!

Watt-hours are the best way to examine the differences between any multi-battery setups for a regulated mod.

On paper, those two battery setups in your video will run for the same amount of time in a regulated device. The series setup runs at roughly 1/2 the total discharge current level that the parallel setup does. But, the parallel setup splits the current. This means that both setups draw the same amount of current from each battery.

The total Wh for any setup can be calculated using the nominal voltage where Wh = Nominal Voltage x Capacity (in Ah) x Number of Batteries.

Your parallel setup = 3.6V x 3Ah x 2 = 22.2Wh
Your series setup = 3.6V x 3Ah x 2 = 22.2Wh

Both setups can deliver the same nominal 22.2W for one hour.
But this is only at the same current level used to set the nominal voltage, about 0.3A-0.5A. Higher current levels lower the nominal voltage so this is not an accurate way to calculate actual run time. But, this is still a good way to compare setups.

I have a way I really like for calculating battery current for any regulated mod battery setup….

Wattage Per Battery = Total Wattage / Number of Batteries
Max Battery Amp = Wattage Per Battery / Cutoff Voltage / Regulator Efficiency

Cutoff voltage is typically about 3.2V and regulator efficiency can be conservatively set at 0.9 (90%). Adjust as necessary but those two numbers make it easy to get close to the worst case current (when the battery is at its lowest voltage).

This works for a series or parallel mod, it doesn’t matter once you know the wattage per battery.

Regulator types and efficiencies…

Now it gets ugly. Regulators for parallel mods often have to step up, or “boost”, the battery voltage up to a higher level to achieve the requested wattage level at the coil.

Series mods usually only have to step down, or “buck”, the battery voltage to the coils.

Buck regulators in series mods are typically more efficient than the buck-boost regulators in parallel mods for various reasons. In the example above this means that the series setup would, in real life, probably last a bit longer than the parallel setup due to the less efficient regulator in the parallel mod wasting more power as heat.

But this difference doesn’t always have to exist and it might not even be noticeable in real world use of the mods. But a well designed buck regulator will always be several percent more efficient than an average buck-boost regulator.
FRI 9:03PM

In an unregulated device your explanation holds true in theory on its own but when going from a parallel mech to a series mech the coil resistance would usually increase, lowering the current drawn from the batteries (versus what was used in a parallel mech). This would increase the series setup’s running time. For example…..

3.7V parallel mod into 0.2 ohms = 18.5A and 58.5W.
3.7V parallel into 0.2 ohms = 18.5A at 68.5W
7.4V series into 0.8 ohms = 9.25A at 68.5W

Same wattage at the coil for both setups. The run time would be about the same because the parallel is supplying 9.25A per battery, the same as the series setup.

There would be small differences between them because higher curren levels, through the same size wiring, causes greater power losses (voltage drops) in the wiring. But the run times between the two setups would be about the same if the coil resistance is adjusted to deliver the same power to the coils for both setups. Very much like a regulated setup in that regard.

Bottom line…the parallel setup has a capacity rating of 6000mAh, versus the 3000mAh rating of the series setup, but the effective capacity (run time) of the two setups is the same. Capacity only works well when describing single battery setups or when not taking coil resistance changes into account, i.e.., you’re just talking about the theory of parallel vs. series. Watt-hours are just so much better to use when comparing multi-battery setups. No need to account for series or parallel, it just doesn’t matter.