Hard start-how do I tell if it's batteries?

[Badfish740]

My truck has been getting harder and harder to start over the past month or so. Obviously the weather isn't a problem because it's only gotten below 70 degrees just recently. It never fails to fire, it just cranks a LOOOONG time and somewhat slowly. It usually cranks a little easier if I start it after its been running a while, like if I run into a store and back out again. I have no other problems, no lights, no electrical issues, etc...but the last thing I want to do is blow money on two batteries just to find out its my alternator, etc... Is there a simple test I can do with my multimeter that will tell me for sure that its the batteries?

[vitalidle]

Yep fully charge your batteries and put the meter on the batteries and crank the engine if it drops below 10.5 volts you might have a bad battery. Could be resistence in the starting circuit also, so the best way to test is with a battery tester that will put a load on the battery or check each cell for the specific gravity and that is a cheap tool at any car parts place.

[MrJohnWayne]

You can do like vital said to check the batteries. To check the altenator use a voltmeter and test at the single wire connection on the back altenator. should produce 14+ volts. Anything lower and altenator is going bad.

Easy and cheap (if not free) fix to try is clean you battery cables at the battery. If they are corroded and or loose it will cause those sypmtoms.