Think of the charger as a tap
the battery a bath tub which will be damaged if you let it get below half full....
and the load / inverter as one of those pop up drain plugs....
Imagine the bath holds 100l
The tap can put 5l an hour back in
And your inverter running your phone charger is draining 20l an hour out...
In 2.5 hours your bath is half empty you must top it back up. It will take 10 hours to refill the bath
But a 12v car phone charger is only taking 2l an hour out for example... Gives you a 25 hour run time
Now replace litres with amps and that's the basic principle of power supplies from a battery banks....
A 100ah battery has double the capacity of a 10ah battery
Its a lot more complex than that if you read up further but that's the basics in a nut shell
Discharge a battery quickly it isn't as efficient as one been slowly discharged most leisure batteries have a ratings plate showing this
Lead acid batteries like car / caravan batteries or SLA (sealed lead acid) should never be taken below 50 % charge and recharged as soon as possible...
See here
http://batteryuniversity.com/learn/
http://www.leisurebatteries.net
https://www.google.co.uk/url?sa=t&sourc ... HhviLhsOjw
After doing some research I think I will go for a pure sine wave inverter rather than the modified sine wave inverter. Although it costs more, it will work with a wider range of appliances.
