Okidoke, i shall struggle to answer it to the best of my ability, but dont do anything drastic till sumone else here has either backed me up, or shot me down
... here goes;
100 amp hours means you can run something that draws one amp/hr for 100 hrs, easy enough, BUT you dont generally want to drain a battery past 1/2 full cause it shortens its life span. So this should give you 50Ah to play with. So what you need to find out is what all these little gadgets draw in amp hours.
For eg, my fridge draws4.5 Ah. So I should be able to run this fridge for 11.1 hrs before battery is half charged ( 50 divided by 4.5)
Fluro lights should draw bugger all, and I imagine the DVD player would be similar
. Is it rechargeable or does it run straight off a car battery?? You should be able to find out how much juice they require on the back off the box or maybe on the bottom of the actuall DVD player, but it might be in 'watts'.. in which case wait for another reply cause I only just had Ah's explained to me
You shouldn't have any trouble running multiple gadgets at one time, just means the battery will drain quicker.
Gadget you can get to keep track of how much juice is left and/or being used is called a 'multi-meter'. Less than $30 i think for a not too shabby one.
And I can't see over-charging a deep-cylce being a problem, but stay tuned for a more definate answer
. BTW, deep cycle battery's take longer to charge than a normal car battery, so 1-2 hrs might not be enough
You can tell when it's charged with the multi meter doohickey, also, most battery chargers have alittle light on em that tell you when its charged