Obtaining Accurate Test Results

Eliminate any surface charge BEFORE performing the ED-18 test.
If the battery is in the vehicle and the vehicle was shut off in the last 15 minutes, the battery will likely have a surface charge. To remove the surface charge of a battery, you may:

allow the battery to sit for two to three hours (if there's time),
turn the headlights on for 30 seconds to a minute or
use a load tester place a 150-amp load on the battery for 10-15 seconds.

Visually check the battery BEFORE performing the test.
Yes. First inspect the battery to determine that it is not damaged and that the cables are not cracked or damaged. Then make sure that the terminals are clean and free of corrosion, dirt or acid.

Ensure proper connections BEFORE performing the test.
Make sure you have excellent connections. Corrosion or an improper connection may hamper a valid result. The serrated end of the clamp is the only good connection point.

Always tighten side-post terminals before testing. Use a wrench instead of hand-tightening the terminals. If the result is MARGINAL or REPLACE, it is best to disconnect the cables and connect the side-post adaptors, then retest. Never connect the ED-18 to the steel side-terminal bolts.

If you are unable to connect to the battery posts, connect to the jumper posts, which are located in the engine compartment and are connected to a battery located in the fender well, under the back seat or in the trunk. If the jumper-posts test result is MARGINAL or REPLACE, you must retest at the battery posts.

Enter an accurate battery age and CCA rating.
NOTE: The age of the battery doesn't affect the battery test results, but it is important information for the consumer regarding anticipated longevity.

If the date code is visible, use this chart to determine the age of the battery. (Insert date code chart that's on clipboard - Bibi)

Note:
If you don't know the battery age, here are the best methods for determining it: 1) date of vehicle manufacture if OE battery, 2) punch-out dater, 3) date code sticker, 4) heat-stamped date code, 5) asking the customer (often ineffective).

For the battery's CCA, 1) identify either by a CCA or load test amps tag or 2) look up vehicle-specific information in the Interstate Replacement Guide and test at recommended OEM specs.

Attain an accurate temperature reading of the battery to be tested.
Aim the infrared temperature sensor at the side of the battery from a distance of about one and two inches for most accurate results. The side of the battery is normally the closest to actual internal temperature due to the direct contact of battery acid and plates to the cover. If the battery is completely covered with a heat shield on the sides, aim the ED-18 at the top. Any direct battery temperature is closer to being accurate than under-hood temperatures or the temperature of the plastic covering around the battery.

Always print test results while connected to the vehicle battery.
This is an excellent power-management technique. Because of the amount of power the printer requires, you should expect only 50 to 70 tests when using only alkaline batteries. If the alkaline batteries have less than 5.5 volts, the ED-18 may not power up or print properly even when connected to a live vehicle battery. For instructions on replacing the internal batteries, see Replacing the Batteries.