Quote Originally Posted by Archerfish View Post
From the other thread about battery, I asked if is possible to just use a multimeter to check the battery health instead of a hygrometer.

Upon searching about this battery tester, I saw a video explaining​ how to use a voltmeter to check how healthy your battery is. It said that normally, voltmeter reading will be 12 and once you crank your engine it will read below 12. You should not have a reading below 10 volts while starting the car. Below 10 means your battery is about to "give up". Once the engine is running, you should have a reading of about 13-14 volts.

My question now is, how can you check the battery without cranking the engine and by using only a multimeter? Is this even possible?
A battery is made up of 6 cells, each cell is about 2.1V

6x2.1V = 12.6V, thats the peak voltage of a healthy battery

When an engine is started the starter draws current from the battery. Thats known as loading (starter) the source (batt). When current is drawn from the source the voltage of the battery source will sink (go down). Thats the nature of the battery with and without a load.

Now if a cell of a battety deteriorates, the peak voltage of 12.6V will go down to 10.5V. Each cell that dies on a battery reduces the voltage by 2.1V.

If cranking the starter reduces the voltage by 2V. A healthy batt with 12.6V will sink to 10.6V for an engine to start. A batt with dead cell will have a 10.5V to begin with will sink to 8.5V once the engine is started. As more cells die the battery becomes weak and no longer useful to start an engine and replaced

So a voltmeter is an uncommon tool found on cars. Refitting one is a good move for any car owners. Its the best companion in any travel to monitor the health of your car battery

Complement it with a portable jumpstarter and always keep it charged could be a charm when your battery begins to show signs of failing.





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