Power from Car Battery

[Oznog]

Look into a class "D" amp. It will do the job efficiently. Speakers don't do very well without speaker boxes, you may find managing size-efficient speakers will be even more of an issue than the battery.

Non-sealed (flooded) lead acid batteries only generate hydrogen when charging rapidly or overcharging. Realistically, it is a small amount and mainly presents a risk if a small enclosed box is used.

Charging is difficult. As noted, this may blow the cigarette lighter's 10 amp fuse. Also, an alternator usually regulates at a voltage good for floating a battery, but is lower than desired for bulk charging. It will take a lot of engine time, in the hours.

You can get a charger specifically designed for it. If you can only find a 120V charger, get a power inverter.

Some older alternators burn up under surprisingly little added load. Something to consider.

A solar panel would need to be large. The rated current is for the best of direct sunlight, which doesn't happen many hrs out of the day.

Given your description, I would recommend sealed lead acid gel batteries, there's a size of around 17 amp hrs used for UPS & other bulk storage and accounts for 80% of SLAs sold. You may need a couple of them, which has the benefit of being able to charge one while using another. 3 hrs of music is not an unreasonable expectation, but it depends on amp & speaker efficiency and just how much sound we're talking about. It may last 1 hr or 12 hrs.

This is apparently an obscure definition of "camping" which I am not familiar with. Scouting has changed... starting to sound more like a rave.

 

[grrr_arrghh]

This is apparently an obscure definition of "camping" which I am not familiar with. Scouting has changed... starting to sound more like a rave.

lol, camping in the loosest possible sense of the word... Seriously though, it is a major cocern the scouts still have the same image as they did in the 1960's, despite the fact that we have changed a lot. Its an ongoing problem. (just in case your interested, **broken link removed** site may give you some idea of what we do now)

Speakers don't do very well without speaker boxes

I had considered that, and intended to try and build some sort of box into the final design. I don't know how well it will work, but I'm going to try it.

Thanks for ALL the advice, I shall now go away and do some serious research, and try to perusade the rest of my unit that they want to spend the money on this.

Thanks for everything, I couldn't do these things without you lot.

Tim.