Just read through the description of this unit and it is just a small load tester, used in the automotive industry for years. One correction, it cannot measure resistance, as resistance is measured through a solid object. Any sort of voltage flowing through an object while testing for resistance will ruin a meter. In a battery there is no solid connection, if there where the battery would have what is called a dead short. Mechanics normally call it a bad cell.
Batteries over time can and do short cells to one another. They have a sediment tray in the bottom of the case. When a car or mower hits a bump, over time, small bits of lead fall off the plates and land in the tray. Again over time, this tray fills up with lead. And now thanks to salesmen and corporate giant companies squeeking every penny, the trays are SMALLER and offer the ultimate sales gimmick, more CCA's. So now, they offer thinner plates to stack more plates in the case = more cca's. So we think wow, this battery has 1000 cca's and it's wonderful. Now, with construction paper thick plates LOL, no wonder these new batteries don't last for 4 sneezes.
Moral of this novel is get your proper case size. Get the LOWEST rated CCA you can possibly find. That's right the LOWEST. Why, the plates inside are thicker and last longer. Back to tractor/farm batteries. They have a deeper sediment tray and thicker plates. How many tractors sit outside in the weather and will crank over a year after it was ran? Try that with your new 1000cca walmart job LOL.
P.S.
Do we need 1000 cca's? Most of today's cars and trucks offer gear reduction starters. They are smaller and lighter blah blah. Most draw like 100 amps. Do the second grade math on that one. Finally the starter is the highest drain in the vehicle. I need a nap...... LOL
slomo