A really good buy on-sale, with a coupon. I think I paid $15 for it. It is simple to use for three common tasks.

1) Test the voltage on a battery. It does this fine. Charge the battery first, connect the leads, you see the voltage.

2) Load test a fully charged battery to determine if it is holding power after a simulated 'start' with a 100 Amp, 10 second draw on the battery. I had a friend with a Subaru with a battery that kept losing charge. We charged it up, then load tested it. After the test, the battery showed in the green zone so we knew the problem wasn't the battery.

3) This device also tests alternators. With the Subaru running, the device showed only battery voltage, 12.4V. With a functioning alternator, it should show 13.5-14V. Thus, we knew the alternator was the problem. To be thorough, I checked continuity between the B+ terminal on the alternator and the positive post on the battery (disconnect the negative post first or your meter is toast). Since I had continuity, I knew the alternator was bad. A quick trip to the salvage yard, and $20 later, my friend had a working alternator and was back on the road. She was happy.

This thing works fine. Pick it up on-sale.

ITC for $9.99 and used on a half dead battery then put a Fluke on same battery and it actually works! Reg 29.95 you can't beat it with a stick!