Re: Built in battery tester. Yep, that's how the $20 battery load tester works. Excellent point!

There's a 100amp heating element inside the dedicated tester which may (or may not!) be a larger load than the starter. The weak range is 9 to somewhere over 10 volts depending on battery capacity (cold cranking amps). Below 9 volts is definitely bad.

I like the inexpensive tester 'cuz it will test batteries on the bench as well as the car.

If the battery has caps (do any these days?) I'd check the electrolyte level periodically in the desert. Topping of with distilled (and preferably deionized) water may expend battery life.

-- Chuck

 

I have seen low 12v unable to start the car.
And other cars batteries tested fine at the store on the computerized machine (whatever it does) but was no good for service.
how did you find your initial reading of 200v?

 

Our starter motor is rated at 100A but the initial current is going to be at least 3-4 times higher than that.

 

My batteries of late are sealed. Yes, they have an evaporation hole, yet these are designed so that you don’t add water to them. Our summer heat in Phoenix will be above 110F and even as high as 118 or 120F. That heat stress is murderous for auto batteries. Two summers is the rule of thumb in this town.

 

A battery can have a good voltage reading and still be bad. Chemical bridges can form between plates creating issues. Deep discharges, changes to electrolyte solution (lack of water) heat and age take its toll.

I have found over time that replacing the battery solves almost every electrical gremlin I may have from autos to auto start home generators. In my climate, (hot summers and mild winters) car batteries last about 5 years. My Onan Cummins auto start generator battery lasts 3 years. My RV/Deep cycle (tent trailer and electric fish motor) go out around 8 years. However, just last week I replaced a 14 month old Interstate/Costco battery on my daughter's TL. She admitted to several complete discharges (interior lights) including one period of a week without a start. Full Costco refund.