It’s human nature to forget just how long ago was the last time you replaced the battery in your car. With the price of 12-volt car batteries running anywhere from $90 to $200, it is no wonder it always seems like you just replaced that guaranteed 4–6-year life battery only a couple of years ago, when in fact you are more likely to be near its expected lifespan limits.
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So, it is not unusual to think that when a service tech or mechanic comes to you with the recommendation of replacing your battery that they are just trying to upsell you with additional charges when you really do not need it. I mean, after all your car starts up just fine so the battery must still be good. Right? Not necessarily.
Weak Batteries with Just Enough Cranking Power
As it turns out, the way cars and batteries are built today, a relatively weak battery with a cell or two on its way out can hold just enough charge to crank your engine enough to get it started right away at the turn of a key or press of the start button. However, if you were to have your interior lights and headlights, AC system, and other accessories on before turning the key, then you might notice that dreaded low battery cranking response that is an indication your car battery is not as healthy as you might think.
That was the message in a recent Toyota Maintenance YouTube channel episode where the host discusses a customer who refused a car battery replacement because he felt that since it had not given him any problems thus far, that a battery replacement is not warranted.
Putting a Customer’s Battery to the Test
One of the first things a mechanic will do when it comes to your battery is check the battery label that should have its installation date clearly visible. If a battery is within one year of the expected (and guaranteed) expiration date of the battery, in most cases it makes good sense to replace that battery now.
However, you can just as easily put a car battery to the test with something as cheap and simple as a battery load tester to confirm that the car battery is beginning to feel its age…and that the mechanic or service tech is not trying to scam you. Bear in mind that those 4 or 6-year batteries often die or weaken significantly before their warranty period is reached, especially when maintenance and driving conditions are sub-optimal for battery life.
In the video posted below, the host showcases a $20 Cen-Tec Battery Load Tester to show that the customer’s car battery is nearing the end of its life. These load testers are essentially DC voltmeters with built-in resistance to place a physical load on the battery to give a more accurate sense of how strong or weak a battery is.
Test This at Home on a 9-Volt Battery
To better understand why a load on any battery makes a difference, you can build a simple 9-volt transistor battery tester at home by connecting a few low-ohm resistors in parallel to each other as a load cluster with one lead at each end to connect between the battery terminals of a questionable battery. Once the load is connected to the 9-volt battery, a DC voltmeter’s positive and negative leads are then placed parallel to the resistor cluster to show the tested battery’s true health.
A good 9-volt battery will show a voltage of anywhere from 6.7 to 9.8 volts on the voltmeter when set at a 10-violt range. A so-so battery will show anywhere between 5.8 volts to 6.6 bolts. And a bad battery will show 0.0 to 5.7 volts indicating it is unusable for its application.
Please note: Do not touch the resistors while attached to the battery as they can become warm enough to burn your fingertips.
You can further verify this by using a small transistor radio with the volume set at a standard volume setting and then placing one tested battery after another to compare your battery health values to the volume you hear from the radio’s speakers.
Why Buy an Inexpensive $20 Cen-Tec Battery Load Tester
Buying one of these car battery load tester devices is a good money-saving idea because:
That all said and done, watch the video below to learn how to use an inexpensive car battery load tester as well as a more expensive one that will provide you with even more useful information about your car battery’s health.
How To Test Car Battery Cheap Way
For more car battery related articles, here are two useful ones for your consideration:
Timothy Boyer is a Torque News automotive reporter based in Cincinnati. Experienced with early car restorations, he regularly restores older vehicles with engine modifications for improved performance. Follow Tim on Twitter at @TimBoyerWrites for daily new and used vehicle news.
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