Christmas tree lights - Power!

[stinkysteve]

Someone must have tried this, just wondered if anyone could give me some advice before i try this myself!

I have 12v outdoor lights that will go on a large tree out the front of my house in a week or so. Previously I've always used the transformers that come with, and powered from mains from the garage.

I want to try ditching the transformers, and hooking the lights up to a 12v car battery located by the tree. I just want to avoid having wires running across the driveway.

Has anyone tried this before? I guess I'll need to recharge the battery every few days which isn't a problem and i'd use a battery that i wouldn't mind damaging. (i'll only connect the lights at night for 4-6 hours.)

Any thoughts people? should i expect a flash and a bang followed by a trip to B&Q for replacement lights?

I believe it'll work well, 12v supply, 12v demand. Current pulled would only be appropriate to power demand. I may be very wrong, that's why i've asked.

cheers for any help.

[ol]

Get an outdoor socket from Tesco for about a fiver. Bury the lead that runs it into the house, job done with no explosions or electrocutions.

[stinkysteve]

Cheers, but burying the power cable would involve digging my drive up.

[davido140]

stinkysteve said:

Cheers, but burying the power cable would involve digging my drive up.

good excuse to hire a mechanical digger for the weekend!

[stinkysteve]

davido140 said:

stinkysteve said:

Cheers, but burying the power cable would involve digging my drive up.

good excuse to hire a mechanical digger for the weekend!

Cracking thought process, but i'm NOT digging up the drive for some poxy lights my wife insists upon!

I'd rather have my fun getting ingenious (or not as the case may be) and making sparks.

[DIW35]

Lights should run OK off a car battery. If you have an ammeter and can measure the current draw when the lights are switched on, you should be able to work out how long the battery will last before it needs recharging.

An LED will typically draw 20 milliamps, so if you have a string of 100 they will be drawing 2 amps. A 17Ah battery should last 8 hours at that rate - though you will need to check what rating the battery you intend to use is rated at, as it may not be 17Ah.

[mechsympathy]

Won't the lights be AC?

[stinkysteve]

DIW35 - thanks. That's exactly what i thought, i'll use the multimeter and calc the life, good thinking.

Lights are DC after the transformer.

[ninja-lewis]

stinkysteve said:

davido140 said:

stinkysteve said:

Cheers, but burying the power cable would involve digging my drive up.

good excuse to hire a mechanical digger for the weekend!

Cracking thought process, but i'm NOT digging up the drive for some poxy lights my wife insists upon!

I'd rather have my fun getting ingenious (or not as the case may be) and making sparks.

[stinkysteve]

Nice idea Ninja!

I was thinking about borrowing JCB's dieselmax to assist but you've trumped me there.

[esselte]

stinkysteve said:

DIW35 - thanks. That's exactly what i thought, i'll use the multimeter and calc the life, good thinking.

Lights are DC after the transformer.

To be pedantic a transformer only steps up/down a voltage (I think), a rectifier is what converts AC to DC (possibly)..

[stinkysteve]

esselte said:

stinkysteve said:

DIW35 - thanks. That's exactly what i thought, i'll use the multimeter and calc the life, good thinking.

Lights are DC after the transformer.

To be pedantic a transformer only steps up/down a voltage (I think), a rectifier is what converts AC to DC (possibly)..

I'm sure you are right there, I think people call them 'adaptors' (that's what it says on my laptop power pack), AC-DC and a step down in voltage all in one magic little box.

[GKP]

If you pop into Maplins on the way home and buy up all of their solar chargers, you'd never have to plug the battery onto the mqains charger again!

(How big is your front garden? Would eleventy million solar panels be a problem to set up?)

[Plotloss]

Car batteries arent good at providing a constant amount of power for a long time, they're geared for big ampage in short bursts.

Another large 12v battery would be better suited.

[mrmr96]

Don't forget to make sure all the connectors are waterproof and I'd wrap the battery in something to keep it dry too.

[Davi]

Plotloss said:

Car batteries arent good at providing a constant amount of power for a long time, they're geared for big ampage in short bursts.

Another large 12v battery would be better suited.

get a "leisure battery" instead (the kind they sell for caravan use). A red top from somewhere like Towsure would do the job. Get as high a Ah rating as you want to spend. Or get a couple and put in parallel.

[GreenDog]

Can't you just string the power cable from an upstairs window over the drive and into the tree - it'd be a fair bit easier I'd have thought.

[anonymous-user]

esselte said:

stinkysteve said:

DIW35 - thanks. That's exactly what i thought, i'll use the multimeter and calc the life, good thinking.

Lights are DC after the transformer.

To be pedantic a transformer only steps up/down a voltage (I think), a rectifier is what converts AC to DC (possibly)..

It does, & a light bulb is not sensitive to AC/DC just the input voltage. If they have a transformer just read what the output is-doesn't matter if it's 12v AC a 12V (DC) battery will work fine, for howe long i don't know...........