Roof Lights

[R1cho]

I'm thinking of converting these to roof lights but how would i go about changing them to 12v?
http://www.ebay.co.uk/itm/BLACK-500...K_SportGoods_CyclAcces_RL&hash=item3cd534b061

 

[TONUP]

Could you keep the battery supplied with them, and use an inverter?

This might be a clumsy solution though.

Regards

Alan

 

[R1cho]

Could you keep the battery supplied with them, and use an inverter?

This might be a clumsy solution though.

Regards

Alan

i did think that myself as i do have an inverter but would rather them be wired in direct :nenau

 

[solarman216]

looks like the battery is 8.4 volts, so a 9v cig lighter dropper would do the job, make sure it is regulated, I think I should have one or two kicking around, will let you know if I find them, Rick

 

[Fez_uk]

Why don't you just buy 12v led lights?

 

[davenclaire]

they will work connected direct to 12v there leds.

 

[solarman216]

Led's are usually 3 to 5 volt and as is is running on an 8.4 volt battery I would not want to run it on 12v specially as when charging it will rise to 14.8, Rick

 

[davenclaire]

i thought the intention was to connect them direct with out the battery pack. and fez is right just buy 12v lights. rick they will still work no problem i have a rechargable torch have to use a 12v charger for it as original one went pop it was 8ish volts

 

[Ogri]

Something like this seems cheap enough and small enough to be hidden away anywhere:

http://dx.com/p/mini-3a-4-5-28v-inp...n-voltage-regulator-green-238815#.UvFd6ncYbVU

Ian

 

[R1cho]

Why don't you just buy 12v led lights?

because i like those ones :lol

 

[Fez_uk]

i thought the intention was to connect them direct with out the battery pack. and fez is right just buy 12v lights. rick they will still work no problem i have a rechargable torch have to use a 12v charger for it as original one went pop it was 8ish volts

No I mean proper 12v led lighting.

 

[solarman216]

be careful here led's are volt specific ie most are as said 3 to 5 volt, the fact you can buy a 12 volt one does not mean it runs on 12 volt but that it has dropper resistors to drop 12 volt to its required voltage, Rick

 

[Sweety]

As a mountain biker I know these do put out a lot of light which when on the trail etc is fantastic & they have a wider beam than most bike lights but TBH I wouldn't use them as roof lights as the beam isn't as big as a spotlight & it won't go as far. I've seen spotlights which look very much like these on LR forums (I know but I had a LR:doh) can't think of there name tho might be X-lite or something like that

 

[rustic]

Right, some confusion here as to what you are buying.

I have not seen one of these before, but as far as I can see, you are buying a twin set of LED lights, with control electronics, which can vary the power to the LEDs.
The power comes from a rechargeable battery, that can be charged over a long period of time. I will assume that this charger will not have enough power to drive the LED's directly. So using an inverter or DC power supply from 12 Volts will just not work the way you want it to.

Estimating the current required from the data given.
6400 mAh battery, yet the run time says <= 30 min.
So the units would consume 12.8 amps ( 6400 mA = 6.8 Amps so it will be double this if it only runs for half an hour) This MUST be wrong.:doh:doh


What you would need to do is remove the switch on the unit, as I guess you won't want to get out to press it every time you want to use it.
Remove the control electronics, and make up a regulated supply, with maybe a dropper resistor, maybe have both LED's in series, depending on the Vf ie forward voltage of the LED or voltage drop, which could be several volts, then choose a resistor to limit the current and a voltage stabiliser to cope with the range of voltage on the vehicle.

So not an easy task, unless you know what you are doing.
The data you have is incorrect, and I could have a better idea how to do this if more information was available on the LED.

I cannot believe that the current to the LED's will be this high, if it was tested in situe, ie when lit with the 8.4 volt battery, measure the current, and the voltage across the LED when lit, then I could advise you on how to build a circuit capable of delivering the required current, at the right voltage.

I certainly like the lights, and I can imagine a set on the front of my boat, but if they used 12 amps... forget it.

Hope this helps,

best regards,
Rustic

 

[rustic]

Following on, looking at other units from other suppliers, they quote run times of between 3-6 hours, so meaning that the LED current is in the order of 2 or 3 amps.

I then looked at specs for similar types of LEDs, and they can take 3 amps, with a voltage drop of 3.1 volts across the LED.

So two LED's could be wired in series but would need regulation.

So there would be a lot of wasted heat.

 

[Lazy-Ferret]

Right, some confusion here as to what you are buying.

I have not seen one of these before, but as far as I can see, you are buying a twin set of LED lights, with control electronics, which can vary the power to the LEDs.
The power comes from a rechargeable battery, that can be charged over a long period of time. I will assume that this charger will not have enough power to drive the LED's directly. So using an inverter or DC power supply from 12 Volts will just not work the way you want it to.

Estimating the current required from the data given.
6400 mAh battery, yet the run time says <= 30 min.
So the units would consume 12.8 amps ( 6400 mA = 6.8 Amps so it will be double this if it only runs for half an hour) This MUST be wrong.:doh:doh


What you would need to do is remove the switch on the unit, as I guess you won't want to get out to press it every time you want to use it.
Remove the control electronics, and make up a regulated supply, with maybe a dropper resistor, maybe have both LED's in series, depending on the Vf ie forward voltage of the LED or voltage drop, which could be several volts, then choose a resistor to limit the current and a voltage stabiliser to cope with the range of voltage on the vehicle.

So not an easy task, unless you know what you are doing.
The data you have is incorrect, and I could have a better idea how to do this if more information was available on the LED.

I cannot believe that the current to the LED's will be this high, if it was tested in situe, ie when lit with the 8.4 volt battery, measure the current, and the voltage across the LED when lit, then I could advise you on how to build a circuit capable of delivering the required current, at the right voltage.

I certainly like the lights, and I can imagine a set on the front of my boat, but if they used 12 amps... forget it.

Hope this helps,

best regards,
Rustic

I am glad you wrote this, as I was looking at those figures, and came to the same conclusion...

The biggest problem would be the switch though, as you would loose the water proofing, and not only that, but by default, when power is supplied, the light will be off, so you would need to put a circuit in place to give a pulse to turn them on, every time you switch to main beam.

 

[R1cho]

ah well i wont bother then :lol just liked the way they looked that was all

 

[exosteve]

you don't want them. you want these

 

[exosteve]

oops! these

 

[exosteve]

last time:doh