No, you need at least 12v to charge 12v. Most alternators charge at 13-14 volts.
For power supplies, if the voltage is the same, the rated amperage is equal to or greater than the requirements of the device, and the plug fits, the supply is safe to use.
can a 12v lawn mower sealed battery be charged with 12v battery charger use on cars
No.
No
Depends on the amperage of the charger. A 10 amp charger will charge it in about 1 hour.
Yes it will work quite well.
No
Yes, a 12V 10Ah battery can be used in a UPS designed for a 12V 9Ah battery, as it has the same voltage and a higher capacity. This means it can provide power for a longer duration without overloading the UPS. However, ensure that the physical dimensions and connectors of the 10Ah battery fit the UPS properly. Always check the manufacturer's specifications to confirm compatibility.
No you can't.
No, you can't.
It will take longer to charge the device