using 20w led floodlights off a leisure battery

11 Jan 2004
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United Kingdom
I want to set up lighting that can be used at craft shows etc where there is no power available. My idea is to run several 20w led floodlights (not many) off a leisure battery.
Can anyone let me know ,in layman terms, how to achieve this. Are all the lights connected together to each terminal or is there some sort of equipment needed to act as a go between.
Also if four led floodlights(20 w) were running of a higher powered leisure battery how long before power runs out and is it OK to run a leisure battery out completely or does that damage the unit.
Hope that all makes sense.
Help and advice appreciated.
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ok assuming your talking 5 thats 100w 12.5w= l amp
so 5 lamps will use 8 amps in 1 hour
remember you need a compatable driver for your setup so order them from the same place or via recommendation

oo and 100w worth off leds will be around 9 100w normal bulbs
20W LED can be a single unit requiring heat sinks and some sort of driver or can be a unit designed to run off 12v or other voltage with the drivers built in. So two completely different answers one considers the drivers voltage range the other the LED's voltage range or to be more to the point current range.

There are two ways an LED is powered when using a higher than designed voltage one is a simple resistor the other is an integrated circuit the latter often switch mode and as a result will use less power than a simple resistor. At 12 volt and LED is around 2volt mark one would likely power 4 LED's with a single resistor and to reduce heat often using a resistor twice the size required would be way forward LED will be dimmer but no over heat problem, but I will for the moment assume they are in a package which will work directly off 12 volt in which case all in parallel.

Batteries come in three basic versions traction, leisure and automotive. Traction can be deep cycled i.e. run flat and automotive should be keep near fully charged with leisure being between the two. So normally you aim at no more than 50% discharge going over that one or twice OK but not on a regular basis.

110AH is about the largest anyone can carry on their own so working on a 6 hour day as most venues where it is temporary will not run for 8 then you will need three batteries to run 2 lights at 20W.

My living room is lit by 2 x 1.6W and 8 x 3W so 27.2W for a whole living room I would suggest 20W is rather over kill for a stand at a craft show. Also with say 2W spot lights lets say 8 of them you can switch off some during times where not all are required.
I ran an experiment at a recent camp. I took my 110Ah 12V leisure battery, along with a 300W inverter and a 230V 8W LED lamp.

I used it to illuminate the area while pitching tents and for washing up in the dark (!!)

It was deliberately left running longer than required and it lasted in excess of 12 hours, but the load was less than you require: the inverter including fan, plus 8W LED lamp. Not huge, but 12 hours impressed. Oh, and it charged a couple of smartphones twice for 30 - 45 minutes each, using a 230V charger, again via the inverter.
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I was considering an inverter. The inverter means some switch mode regulation where with simple 12 volt it could be simple resistors so in spite of first thoughts of being wasteful lifting to 230v only to be dropped again it may in real terms waste less power than 12v units which use resistors to control current.

With 230 volt LED units often there is a voltage range of 170 - 250 volt clearly switch mode regulation but with 12 volt LED units they seem to just state 12 volt with not declared tolerance. Some will have a switch mode control others will be simple resistors.

The inverter will normally have a under voltage cut out so will prevent over discharging the battery.

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