Bongo Fury

I've been thinking Is it possible to fit those little dichromic? spotlights that use a transformer to step down to 12v and wire them to use power direct from the battery when not hooked up but then work on 240v through the transformer when on hookup? Suddenly I feel tired......
lochan2

Just wire them direct to the 12V battery supply.

On hook-up you simply keep the batteries charged up via the charger.

Incidentally those 12V halogens are just that - 12V.
Not the max of 15V you can get when a car battery is being charged from the alternator.

Better still, buy LED versions of the MR11 or MR16 halogens but ensure that you get the ones with built-in voltage tolerance.

Have I used any words that are too technical?!!!

Yes pip...whats a Battery?

Those diagrams are brill... Even i can understand em...(which is saying something!)

Cheers pippin.....I think I've got it now

Typically these dichroic spots are 50W. Thats about 4A each from the battery. The typical battery capacity of 80Ah is usually based on a 1A discharge - it goes down as the current goes up, and also as the battery gets older. And its often very optimistic in the first place!
One dichroic spot left on overnight would probably flatten you battery.
There was a discussion here a month or so ago about electric blankets which are about the same power. Batteries did not last the night!

No problem at all if you have a hook up and a good battery charger though.

Dave

OOPS!

I should not have advised:

Just wire them direct to the 12V battery supply.

Of course there should be some sort of fusing involved.

I like your diagram (how do you do that?!)

As mentioned, the 50W lamps take 4A each so you need a hefty relay.

Actually 20W lamps would be more than powerful enough in a Bongo.

Even those will still singe your head if you get too near.

LED is the way to go and warm-white ones are now available.

They kick out a lot of heat too, mainly downward, so be wary of mounting them near anything meltable (including yourself!) They are also very bright, so have a look at one in action at B&Q before commiting to them. As mentioned, you can get an LED 'bulb' to replace halogen bulbs. The do tend to be a bluey/white colour which I dont think is very cosy. You can now get some more natural versions that have a more 'warm' look that has a slight yellow hint to them.

I use halogen mr16 and mr11 lamps for mountain bike lights and although they're specced at 12v you don't need to worry about running them off a car battery that may kick out ~ 15v on full charge. In fact they become significantly more efficient at higher voltages. I deliberately run mine off a 18.5v li-ion battery and haven't had any problems to date.

If you go with mr11 you can get 5w bulbs which should be more than adequate.

As has already been pointed out, the problem you will have is heat.

I also have an led mr16 http://www.ultraleds.co.uk/leds-seoul-c ... -1630.html but they aren't cheap and not as bright as halogens despite what the seller usually likes to tell you. That said they aren't too bad. If you choose to go for the cheaper mr16/mr11 leds be warned they don't really live up to expectations.

If you're handy with a soldering iron you could try modding you centre cabin light with some cree xr-e's or soeul P4s like this http://www.taskled.com/install.html but that's geeky and will lead you down the path to the candlepower forums so beware!

I got a set of 3 downlighters in Ikea - transformered 12v, 10 watt ones - just the business and run fine from the leisure battery

http://www.ikea.com/gb/en/catalog/products/90128382