It reads what the voltage is so maybe the voltage source is 75 volts. Without stating what the voltage is suppose to be it is hard to give an answer to this question.
That depends on the battery, and the charger. my charger has different settings for higher amps to give a faster charge or jump. A fully charged battery will show 12.6 volts. The charger will read it's maximum amperage if the battery is totally discharged. A fully charged battery will read 12.6 volts with a digital DC volt meter. If it reads 12 volts it has less than 25% charge.
With a digital volt meter a 100% fully charged battery will read 12.6 volts. At 75% charge it will read 12.4 volts, at 50% it will read 12.2 volts and at 25% it will read 12.0 volts. It can more than likely start the engine at a 50% charge an possibly at 25% charge, depending on the outside temperature and the condition of the engine.
A centimeter is less than a meter.
What voltage battery are you referring to? An automobile battery is 12 volts and a fully charged auto battery should read 12.6 volts.
Maybe because your alternator is not working. While the engine is running, test the battery with a volt meter, anything less than 13 volts is a problem Should have min of 14 volts. If its at 12 volts, then replace the alternator.
Greater than 1 meter, as there are 100 cm in 1 meter.
Less. There are 100 centimeters in a meter, so 90 cm would be 10 cm less than a meter.
Check the voltage at the battery with a DC volt meter. It is reads 12.6 volts is it 100% charged. 12.4 volts 75%, 12.2 volts 50%, and 12.0 volts 25% charged. Less than 12.0 volts is a dead battery. If the battery will not hold a charge with the negative cable disconnected it has a dead cell and must be replaced.
Drive to your local auto parts store and have the electrical system checked. You can also check the output of the alternator at the battery with the engine running. You should read 13.5 to 15.5 volts with a digital DC volt meter. If it is less or more than these figures it is defective.
1 yard is a little less than a meter. 1 decimeter = 1/10 meter. 1 centimeter = 1/100 meter, etc.
You can test it with a simple digital DC voltmeter. Set the voltage of the meter to the 20 Volt DC scale. Start the engine and let it idle. You should read 13.5 to 15.5 Volts at the battery posts. Any less than 13 or more than 16 volts and the alternator is suspect. Best to drive it to your local auto parts store where they will inspect the charging system for free.
Most likely the alternator, run a volt meter on the battery while the engine is running. Should have 14.5 volts. Less than 13, replace the alt.