Measuring 14 volts at your vehicle’s battery terminals doesn’t tell you squat about how your battery will perform when you actually try to start your vehicle — that’s where a variable load tester like Electronic Specialties’ #710 comes in handy. With this tester you can test batteries rated as high as 1,000 cold-cranking amps or 160 amp hours.
The tester simulates cranking loads with a 500A adjustable carbon pile — a carbon pile is just one big-ass variable resistor. You can also test alternator charging voltage and relative starter current draw. During its 15-second test cycle, the #710 displays voltage and current simultaneously on its large dual meters.
The #710 comes with 500A side terminal clamps with heavy-duty stranded cables, and Electronic Specialties also includes a a temperature compensation chart. It retails for $140, but you can find it for as low as $90.