I understand the text-book definition of amp-hour rating of cordless tool batteries.

How long will a 1.5 amp-hour, fully charged, 18 volt battery run on a single charge when being used to drill pilot holes and drive 2.5 inch deck screws into treated lumber with an impact driver?

I understand this is not an exact science. What is your estimate?

 

The Big Blue store has cordless kits on sale, and I am trying to figure out if a 1.5 amp hour battery would be sufficient for home use. Would one battery run long enough to allow me to keep working until the second battery is fully charged?

 

I don't know the answer but you could look at it this way - if the battery dies before the last one is recharged it's probably time for a break anyway. .... and if it's a lithium battery you don't have to wait until it's fully charged to put back in service.

 

So many variables! Is it a fast/smart charger? The battery has to be in a certain temp range to charge...too hot, it will wait for it to cool. Otherwise most chargers are 15-30 min to full charge. I guarantee I could slam enough screws in 15-30 min to kill a second battery.

Is the wood wet or extremely dense? Also variables.

In the end...who cares? You can always buy 1 or 2 higher capacity batteries if you find out you need them, same charger should work. I currently have 5-4Ah and 4-1.3 Ah batteries. I'll use the small ones in some tools cause they're lighter and easier to sling around. I use the big ones in the saws or hammer drill for tougher jobs or when I don't want to be up and down a ladder (or tree) and want longer run time.

 

I think the 1.5 amp hour batteries are the small ones. That's all that's used in my factory as it keeps the drills light and handy. An extra battery is kept on the charger so they can be swapped out when needed.

When doing heavy work with them I can kill a 1.5 amp battery before the previous one is done charging. One thing that hurts is if you kill the battery quickly it heats up which slows it's charging time. Still, I find the 1.5 amp size pretty handy. My home cordless set came with two 1.5 amp batteries and I bought a pair of 3 amp at the same time and I've never been lacking for battery power. It's one of the non-premium brands so the cordless set and extra batteries were relatively affordable.

 

Thanks to all for your help.