Anything if that`s how it`ll be charged all the time Hook up should power even an old knacker fridge but once off mains depends on which fridge , how it`ll be used etc etc etc ... Get the biggest one you can fit in there - simple ...
I am no electrician, but here goes. Any leisure battery is strong enough. The difference is how long they last without being charged. The rating “amp hours” is how long a certain amount of amps can be drawn (used) at once, before it goes flat. For you, Fridge = 28W. So, when on 12v is about (28w divided by 12v) is 2.5 amps. LED lights = depends how many and what rating. Lets say 5 x 2w LEDS = 10W, then 12v is about (10w divided by 12v) 1 amps Stereo = depends on your stereo. If a run-on-the-mill stereo from Halfrauds, then peak power is likely 5-10 amps. Call it 10amps. TOTAL = 10amps + 2.5amp +1amp (+1.5amps for luck) = 15 amps, with lots of rounding up to be on the safe side. A 70Ah battery will therefore go dead in (70Ah divided by 15amps) 4.5 hours. A 100Ah battery will therefore go dead in (100Ah divided by 15amps) 6.5 hours. An so on. ON A RELATED NOTE, regarding your fridge there, what make is that please? And is it a compressor or absorption? I would guess compressor based on the wattage? This is interesting to me though as I have been doing bench tests running my fridge on 12v and doing lots of googling, seeing if I should bother with 12v (I only ever use it on hookup, on 240v). My Findings You will read loads about 12v only really meant to be used on a journey, to keep the fridge cold during that journey. People don't always follow this rule of course, and many are very happy. I reckon this might be an old fashioned rule, and modern fridges can run on 12v, whereas old fridges struggled. Mine is a 40 year old Electrolux RM123, and I found 12v did not get the fridge cold from a standing start. I need 240v to get it cold first. So, 12v only keeps it cold during a journey. After using 240v to get the fridge freezer compartment freezing ice cubes, I switched to 12v. After 48 hours, the freezer compartment unfroze , although the beer was still super cold. And tasted lovely. It was a lager, but I prefer real ale. I digress. The seals on my fridge were not great. When I sorted those, the fridge stayed cold without any power after 48hours. But, the beer was not AS COLD as when 12v was topping it up. This time it was a guinness. Not so fond of cold guinness, prefer it the old fashioned way. I don't think I am going to bother plugging 12v back in in case I forget to turn it off. Hope that helps. Jim
If your stereo actually uses more than 2 amps average it would be quite loud. But the rest of the estimate make sense. Dont forget a normal lead acid battery is only long lived if discharged less than 50-60%. In reality a 100AH will go for maybe a couple of days without hookup or solar.
