Series 3 Installing a camplight in the LR

Good day
I tried installing and powering up (from car's electrical system) an old camplight which works with 4 AA batteries in back of my landy and to my surprise it did not work. My know-it-all neighbour who was passing by gave me a wiseman to village idiot look and mumbled something about AC and DC currents.
I did a small online search and apparently car is DC. My camplight is obviously DC and 6V. So it should have worked, maybe at most extra juice would burn the lamps, (that did not happen it still works with batteries) but they should be compatible. Yet it did not work.
Any idea why?
tx in advance

When you say ‘installing’ what did you connect to what? And is your Landy -ve earth?

Is the vehicle 12v and too high a voltage, high voltage cutout protection?, 12v led lights dirt cheap now

Search e-bay for 12v led interior light or camper light, budget under £10. Get warm white, the cold white is very harsh. Don't worry about pos or neg earth as they are usually double insulated with pos and neg wires. LED numberplate lights work quite well too.

When you say ‘installing’ what did you connect to what? And is your Landy -ve earth?
Yes -ve. I put 4 empty AA batteries in and passed two wires from the power supply on the dash to + and - end of one of the batteries. A bit unusual but theoretically it is a proper circuit. Did not work!

Is the vehicle 12v and too high a voltage, high voltage cutout protection?
That's a possibility but I doubt a simple inexpensive lantern having such sophistication. Since it has room for only 4 AA batteries I doubt if they made provisions aganst somebody giving it 12 volts.

Thank you all for suggestions but question still remains "can we power up little battery operated accessories which are not made for cars from car's electrical system?"
tx

85Santana3 said:

Thank you all for suggestions but question still remains "can we power up little battery operated accessories which are not made for cars from car's electrical system?"

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Not the way your doing it. And I would suggest you stop trying to do electrical work

J

Agreed. your question is the wrong one, it should be:
Can I connect 12v across some old 6v cells and thereby set fire to my vehicle?
YES!

If you know the wattage of the lamp you can connecti12V via a resistor to your lamp without the batteries fitted.
Or you could supply it via a voltage regulator so that it only gets 6V.
Are batteries you had in rechargeable cells?

marjon I think you may have something there. I once tried to repaire a tape-player and it became a radio instead! And rob1miles you must have psychic powers. I did it once unfortunately. I had to get all the dashboard and dials rewired after that fire
Blackburn the batteries were not recyclable (does it make any difference?)

85Santana3 said:

put 4 empty AA batteries in and passed two wires from the power supply on the dash to + and - end of one of the batteries. A bit unusual but theoretically it is a proper circuit. Did not work!

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Have I got this right....you connected 4 depleted (non-rechargeable) AA batteries together, and stuck 12V across them, with no current limiting? Oh dear...

Worth sticking a meter into the dash power supply points to see if there’s any current. Could be a PO disconnected the supply. Mine was only meant to power an inspection lamp and had the wires removed behind the dash.
Whatever though I don’t think wiring something up through dead batteries will ever work...

TheMegaMan said:

Have I got this right....you connected 4 depleted (non-rechargeable) AA batteries together, and stuck 12V across them, with no current limiting? Oh dear...

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That's the way i read it. Very lucky not to have had an explosion. There been a few fires in recycling yards where old aa batteries have been piled up and formed a circuit. Once they burn they are really hard to put out.

I put the dead batteries inside their place and soldered two wires to + an - of the last one, passed it to power. I had no idea this could cause problem! My methods may seem wired but I am sure that's how one of my weirdo caveman ancestors discovered fire

Anyone else smell a windup?

85Santana3 said:

A bit unusual but theoretically it is a proper circuit.

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Not according to my definition of 'proper'.

Si Click said:

Anyone else smell a windup?

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I sure hope so!

You don't need the batteries to test the lamp. Just connect + to where the + post of the outermost battery goes and at the opposite end of the group connect the - wire. You will likely burn out the bulb or LED though.

85Santana3 said:

Yes -ve. I put 4 empty AA batteries in and passed two wires from the power supply on the dash to + and - end of one of the batteries. A bit unusual but theoretically it is a proper circuit. Did not work

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you would have a better chance removing dead batteries and connecting a power supply to one side and an earth to other side rather than 2No power supplies as this would not be a circuit

Thanks everybody for your input. I learnt a few surprising things. Since somebody expressed doubt as to my sincerety I attach a couple of photos. The arrow shows the hole I drilled to pass the wires. Since it did not work wires soldered to battery were discarded.
Oddly enough by proving that I am not pulling anybody's leg I am also proving that I am an idiot

One of the best ways of learning is by doing.

I apologise for doubting your sincerity, and my respect for your honesty. But please learn some electrical basics before any more wiring. 12V DC systems are relatively safe from an electrocution perspective, but because the Amps flowing in DC circuits can be high, the risk of fire is serious if the wrong wire is used or it is not properly protected.
Your best bet may be to buy a battery powered LED portable lamp. The power consumption of LEDs is tiny so batteries last far, far longer than the old bulb types. They can also be bought for only a few pounds. Alternatively, if you want it wired in, go for a strip of LEDs. They are very light, very flexible and can be mounted almost anywhere. The come with DC adapters so that you can connect to a domestic supply or you can run them off a 12V battery. One wire to earth, the other to a permanent live. Add a switch and an in line fuse and job done.