# What does Ah mean on a battery?

What does Ah mean in the world?Is a 2Ah battery more powerful than a 5Ah one?Does it last longer?The video above and the article give an explanation of Amp hour and how it affects your tools.

Amp hour is a unit of measurement that has nothing to do with power and it’s a completely different unit than Ampere.Amps are used to describe an hour, but they are different units of measurement.

If a battery has at least a 4Ah capacity, it will be prominently displayed on the battery like the 5Ah in FIG 1.

The capable charge of a battery is described.We can draw 5 Amps for 60 minutes before our battery runs out.It’s under ideal conditions, perfect temperature, and consistent power.In the real world, you never meet those ideal conditions.One battery holds more of a charge than the other.Before the battery runs out, you can use your drills, circular saws, and jigsaws longer.

Peukert’s law applies to lead-acid batteries like the ones shown in this article and video, but it does not apply to Li-ion batteries.Peukert says that a battery’s hour rating is reduced disproportionately as more current is drawn from it.Li-ion batteries have a self- heating characteristic that counteracts internal resistance.

Taking our 5Ah battery above it’s easy to say that we can draw 5 Amps for 1 hour – 10A for 30 minutes – or 20 A for 15 minutes, in a linear calculation.

Peukert’s law explains why it is not true for lead-acid batteries, as the more you draw from that type of battery the less charge time is available.You can draw 5 Amp for 1 hour, but only be able to draw 10 for 13 minutes.

If Peukert’s applied to your tool batteries, the companies that make them would all have the same charge/discharge rates.

You can make a straight comparison between the 18V (or 20V max) 5Ah battery of any brand and the 2Ah batteries of other brands.

An 18V (or 20V Max), 2Ah battery has 5 cells in it and each one of those cells is a 3.6V,2Ah cell.All 5 are connected in series, but not their hour rating.There are five 3.6V, 2Ah batteries connected in a series.

There are two packs of 5 cells in the bigger battery.The cells have more capacity than the 3.6V cells.The two packs are connected to each other in parallel.The difference between connecting in series and in parallel is the Amp hour rating.

The battery has two 18V, 2.5Ah packs connected in parallel which results in a 5Ah battery.

The larger battery will usually give you a little more power than the Amp hour rating.It is possible to more consistently meet the demand of the tool by having 10 cells doing the work that only 5 cells are doing in the smaller battery.

There is a video showing a test done by the guys at Pro Tool Reviews.They use a single drill and a 2Ah and 5Ah battery to see if there is a difference in power.The results are interesting.