I bought one of these to do load test to see if battery is good, also shows the battery voltage, and if alternator is working proper. Just follow the directions. They work well and worth the money.
When my vehicle got to higher milage over 200k, I had to put on a new positive terminal connector. I got one at Napa for a few dollars.
www.harborfreight.com
When my vehicle got to higher milage over 200k, I had to put on a new positive terminal connector. I got one at Napa for a few dollars.

100 Amp, 6/12V Battery Load Tester
Amazing deals on this 100 Amp 6/12V Battery Load Tester at Harbor Freight. Quality tools & low prices.