Can anyone tell me as a rough guide how long could I use a 12v light (hours)
powered by a fully charged 12v car battery.

Thanks Keith

Depends on the wattage of the bulb and the power of the battery i.e 21 
watt bulb on a 75ah battery shoud last about 40hrs

Keith Hampson wrote:

> Can anyone tell me as a rough guide how long could I use a 12v light (hours)
> powered by a fully charged 12v car battery.
> 
> Thanks Keith
> 
> 

"Chris Rowan"  wrote in message 
news:431B6ADB.4020105@blueyonder.co.uk...

> Depends on the wattage of the bulb and the power of the battery i.e 21 
> watt bulb on a 75ah battery shoud last about 40hrs
>
> Keith Hampson wrote:
>> Can anyone tell me as a rough guide how long could I use a 12v light 
>> (hours)
>> powered by a fully charged 12v car battery.
>>
>> Thanks Keith
>>



Apart from the top posting I agree with Chris.

Adam

Not 'anyone' , It would probably have to be someone with enough technical
knowledge as to be able to work out a rough guide !!!   :-)



"Keith Hampson"  wrote in message
news:dffpeb$f4m$1@newsg4.svr.pol.co.uk...

> Can anyone tell me as a rough guide how long could I use a 12v light
(hours)
> powered by a fully charged 12v car battery.
>
> Thanks Keith
>
>

Keith Hampson wrote:

> Can anyone tell me as a rough guide how long could I use a 12v light (hours)
> powered by a fully charged 12v car battery.
> 
> Thanks Keith
> 
> 

Its not the voltage that dictates this, its the Current the lamp draws..

So its impossible to say

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Rod said! Its not the voltage that dictates this, its the Current the lamp
draws..
So its impossible to say

WRONG

The sums go something like this
Watts = Amps x Volts, so amps = watts/volts
Say it is a 100amp hr battery, that is 1 amp for 100 hours
So a 25W bulb uses around 2 amps, 25/12, so around 50 hours.

Chris said, Depends on the wattage of the bulb and the power of the battery
i.e 21
watt bulb on a 75ah battery should last about 40hrs

The sums go like this & prove him correct
75/(21/12)=42.8 or
75[AH battery]/(21[Watts]/12[Volts])=42.8 hours

-- 
regards
dave batter
www.kitchenman.co.uk
www.sxmitres.info
www.essex-sandivers.info
Skype me on kitchenmanuk
http://oneandone.co.uk/xml/init?k_id5568652

"Rod"  wrote in message
news:c7LSe.102556$G8.45912@text.news.blueyonder.co.uk...
Keith Hampson wrote:

> Can anyone tell me as a rough guide how long could I use a 12v light
(hours)
> powered by a fully charged 12v car battery.
>
> Thanks Keith
>
>

Its not the voltage that dictates this, its the Current the lamp draws..

So its impossible to say

-- 

Remove spamtrap to reply.

"kitchenman"  wrote in message 
news:UJMSe.7333$pm2.6002@fe3.news.blueyonder.co.uk...

> Rod said! Its not the voltage that dictates this, its the Current the lamp
> draws..
> So its impossible to say
>
> WRONG
>


No, RIGHT! The OP did not quote any watts for the bulb and without that 
knowledge you can't work it out.

However, like you, one can make some assumptions, although they may not be 
correct.

Rob Graham

kitchenman wrote:

> Rod said! Its not the voltage that dictates this, its the Current the lamp
> draws..
> So its impossible to say
> 
> WRONG


With only the Voltage figure it is impossible to work out. you are 
guessing the other fiqures
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"Rod"  wrote in message 
news:Av1Te.103022$G8.16184@text.news.blueyonder.co.uk...
kitchenman wrote:

> Rod said! Its not the voltage that dictates this, its the Current the lamp
> draws..
> So its impossible to say
>
> WRONG


With only the Voltage figure it is impossible to work out. you are
guessing the other fiqures

Kitchenman was not guessing. He gave a plausible answer and did not guess 
the figures (variables). He gave a worked out example that the OP could use 
to answer his own vague question. If the OP cannot work out the answer from 
Kitchenmans example then he should say so and give more info on his battery 
and lamp.

Adam