Yes, the adaptors mA name plate capacity is the maximum amperage that can be drawn from the device. The load of what is plugged into the adaptor is what governs the draw from the adaptor.
If the adaptor with the 350 mA maximum load worked, then the 450 ma adaptor has more than enough capacity for the connected device.
Just make sure that the adaptor is the same output voltage type. Some are rated at 12 VAC at 450 mA, while others are 12 VDC at 450 mA. The output voltages must match to be interchangeable.
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.
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. The formula for watts is amps X volts. 1000ma is one amp. So, 12V X 2.2A = 26.4 watts Your adaptor can only supply 26.4 watts. This is not enough for the invertor, which needs a little more than 300 watts. Also, chances are your mower needs more than 300 watts to run anyway. A mower that uses 300 watts would draw only 2.5 Amps. Check the nameplate on your mower, I would guess it draws anywhere from 6 to 10 amps. Sorry. Nice try though.