What to do with that extra battery for your drill

[buz23]

OK, so most of us got two lithium batteries when we got our drills.  I find myself only going half to two thirds of the way through one during a typical session.  If I'm out with a couple other guys, I take a backup, but have only used it once.

What do you think the best strategy is to maximize usage and overall life of the two batteries?

1)  Rotate them - i.e., alternate which one you take on the ice.

2)  Use one as the primary and save the other for the day the primary finally dies.

I don't know how these batteries fail.  If age has any impact then rotating might be the way to go.

What do you think?

[willisdotcom]

I think they have a number of charges life expectancy.  After that number they are less reliable and don't last as long per charge.

[Idahogator]

They are the best value available, (so far). 

Several ways to keep them ready while on the ice or out in the cold.

A hand warmer with a little ventilation as it requires air to operate.

An inside pocket of your ice coat, so it can dig into your body in an irritating fashion.