A BATTERY MOOCH POST: Can the 2500mAh VTC5A run for longer than the 3000mAh 18650’s?

The Sony VTC5A is more efficient, i.e., it has a lower internal resistance, than the 3000mAh Sony VTC6, Samsung 30Q, and LG HG2. This means it has less voltage sag when being used and takes longer to drop to a low voltage cutoff point. But does it hold its voltage up well enough to run for longer than batteries with 500mAh more capacity?

If you just compare the mAh delivered by both down to 3.2V (https://imgur.com/a/QvYU2) then it looks like the 30Q is equal to or better than the VTC5A. But for a regulated device the voltage the battery runs at is important too, not just the capacity. You want the battery to stay above the mod’s low voltage cutoff for as long as possible. The watt-hour (Wh) specification for the battery take both the voltage and capacity into account.

I compared the watt-hours delivered by the VTC5A and 30Q at 10A/30W and 20A/60W down to 3.2V (about 3.5V-3.6V when put on a charger). At 10A/30W the 30Q was the winner, lasting about 10% longer.

But at 20A/60W they both ran the same amount of time.

Why? The larger voltage sag of the 30Q shortened its running time enough that the VTC5’s greater efficiency, and smaller voltage sag, let it run for just as long.

Bottom Line: At up to about 17A/50W or so the 30Q, VTC6, and HG2 will run for longer in a regulated mod. At above 20A/60W the VTC5A is the better choice. It will run for the same amount of time or longer and will run cooler at any power level.

For an unregulated/mech mod the VTC5A is the better choice since it hits harder, i.e. runs at a higher voltage, at the discharge current levels typical for those mods.

The Sony VTC6 and LG HG2 perform about the same as the 30Q and these results will be about the same for them.

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Author: John Muchow