Question on these Mecer 2400va UPS inverters.
HOw long would i get on 2x 105ah Battery's ? (if the load is approximately 300watt)
Then... how often does one need to replace the battery's (think the one's i'm getting are Energizer 105ah Deep cycle battery's)
Then.... on the mecer 2400va (does it show you the wattage or battery percentages) ?
You definitely want to limit the discharge of your battery to 50% at most... So from a 100 Ah battery, you only want to draw 50 Ah MAX. The battery is 12V, so it will give you 50 x 12 = 600 Wh.
That means, with a load of 300 W, it will run for 2 hours. If you have two batteries, you have 2 x 600 Wh = 1200 Wh. So your 300W load will run for 4 hours.
Whether two 12 V batteries are connected in series or parallel is only a requirement of the inverter... it does not change your battery capacity. So does the inverter need 24V or 12V? I think the inverter that you are talking about is this one: Mecer 2400VA, 1400W, 24V DC-AC Inverter. (Modified Sine Wave). So you connect the batteries in series... so you'll effectively have one big 24 V battery (12 V + 12 V) with a 100 Ah capacity... which if you discharge to 50%, it will give you 24 x 50 = 1200 Wh (same as calculated above).
Those energizers some like standard deep cycle batteries... They should last 2 or 3 years for typical load shedding. The less you discharge them, the longer they will last.