12V Battery health check

Dear friends,

Is there any circuit or IC or any other solution to find out the battery remaining charge, same as that we see in laptops (Ex:- 44% charge remaining). I want to test this for 12V 120Ah car battery.

Thanks

It should involve mocrocontroller and precise monitoring the energy that was delivered to the battery during FULL charging process and energy that was drained from the battery. Pay attention ENERGY (Ah) not only voltage (V). It is not impossible but far from easy.

With lead acid battery's this would be very hard.
You can roughly estimate the state of charge by the cellvoltage (after a cooldown c.q. recovery period after loading it), but then You miss a couple of points.
The Peukert factor means that the true amount of Ah's of your battery variates depending on your discharge current.
This means that with 40A discharge your battery might be empty after 2,5 hours but when the discharge current is 5 A it would be empty after 30 hours.
These figures are made up but it shows the Peukert effect in simple words.
Bad cell's after just a few minutes or hours of charging your cellvoltage seems good, but with a little load your battery is down again (there goes the voltage measuring method).
You would have to measure what amount of power goes in during charge and You would have to keep an eye on how much power comes out and with what current it comes out and then calculate your Peukert factor accordingly.
Also If You want a healthcheck it would be good to keep an eye on internal resistance of the battery.
Sulfation of your battery will increase the internal resistance and this can be used as a rough measurement of the aging proces within the battery.
(keeping an eye on the internal resitance after each charge discharge cycle will show a certain aging process, the internal resistance will increase slowly and eventualy will make your battery useless)
The more advanced measurement systems use a method of internal resistance and impedance measurements.
But You should look this up with google.

This aint a easy topic, but i hope this helped You a little.

enemra said:

Dear friends,

Is there any circuit or IC or any other solution to find out the battery remaining charge, same as that we see in laptops (Ex:- 44% charge remaining). I want to test this for 12V 120Ah car battery.

Thanks

Click to expand...

Remaining charge showing with voltage level, but health check is different thing. Internal resistance one of relevant things. Use this circuit to measure internal resistance with AC current. Very good.

Already tried with measuring energy consumed and -total capacity of battery under full charge-. But not effective. Thinking of some other factors. Will work it out. Thanks

enemra said:

Already tried with measuring energy consumed and -total capacity of battery under full charge-. But not effective. Thinking of some other factors. Will work it out. Thanks

Click to expand...

Internal resistance is relevant.

If there is no hardware fracture of grids and plate.

Set your car into Accessory Mode, which you can do by pressing the power button without touching the brake pedal. Then, switch to Maintenance Mode and make sure to press the "info" button. Press Display Check and Signal Check. This will display a few information items and one of them is the 12v battery voltage. If the battery is below 12 volts, you might want to reconsider replacement or something's wrong with your battery charging system.

Hope that helps!

**broken link removed**