A good battery should be between 12.4 to 12.6v at rest, it will drop some if any accesories are on (lights, radio, phone or gps chargers, flashers, etc) if you have an automotive voltage/amperage tester available, you can do a load test on the battery (hook it up and load it by 1/2 the cca rating of the battery for 15 seconds) if it drops below 10v, it's time for a new battery. Most autoparts stores can do this test for you, but beware, if they don't know what they are doing, they could test it as needing replacement when it does not. Also, the test must be done fully charged. Also, after testing it will be mostly dead and unable to start your car, requiring a recharge. After starting the engine battery voltage goes very high. Thats normal.

Case Study 1: if your car doesn't start also no power at all (no dashboard lights/no other lights working) but after you check it then recognize the battery is also OK. Then this may be a car ground problem.You will need to check your car grounds.:

When I was buying my Lancer i didn knew about ECUs aka. Engine control units - a small computing unit resides on modern cars (cars after 1996 in JDM) its also known as vehicle computer which amazed me. I got more excited after hearing this word 'vehicle computer' which seems related to computing because of my passion towards computing related stuff and also being an IT guy in profession. So I was thoroughly researched more about this subject. Had a great curiously to find out whether my car has such computer on its! (since its 1997 mitsu lancer). I directly went to my neighborhood mechanic uncle and asked to do a OBD scan for my car....And whoohoo! i was so lucky, it had a OBD2 port which is the latest version of OBD update to date (but later i got to know it was using a sucking protocol called MUT)

Then i wanted to buy a scanner like the uncle had but he said "its a professional one So this costs like 1lack putha!` :-( disappointing! then i was looking for a simple tool which i could use to read the ecu of my lancer. and found out there;s a elm327 bluetooth device which comes handy with a nice android application called `torque`. I ordered it from ebay. After lots of tries it appeared that particular tool isn't has the support for Mitusubishi MUT protocol which was the same one used in my car ecu. Again disappointing !

Well! after lots of reading on Evoforums, i was able to find a tool called "EVOScan" which seem fit to read the lancer ecu. And the tool was quite expensive (7000 in LKR) and i had to wait till i have some money in the pocket!
Finally it received it in last week after long waiting and glad i could read the car ecu with it, yey! :-)

Its so fun to read the car ECU, which shows us the readings of car sensors and lots of other useful information. In the other hand we can use EvoScan software to write into the ECU as well; which is very dangerous (for example using that evoscan write Cable (1.3U) we can change the fuel + air ratio used in internal combustion engine, so it could blow up even LOL! nothing so funny thats why i ordered the Evo scan cable which only lets me to read the ECU! :)

FYI: This is the cable i used: EvoScan 1.3D cable this is suitable if you have a Lancer CK2A MX Touring; 1997 YOM car

Here are some screenshots of EvoScan which shows the power of this tool.