LED Replacements

GeForce

GeForce

GeForce

Soldato
Joined
14 Feb 2006
Posts
4,644
Location
Surrey, UK
Hi all,

So my car is going be in a situation from now on where it rarely gets good long journeys, so I was thinking about replacing the more power hungry bulbs (H7 55W headlights and 21W stop/tails) with LEDs, which will be a substantial power saving.

Is this sensible? Is this legal? Is there anything of which I should be aware?

Thanks :)
 
GeForce said:
which will be a substantial power saving
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What are you hoping to achieve via this 'substantial' power saving?

Consider your car probably has an engine that produces power in the order of tens of kilowatts at the least, what difference is a 50W bulb really likely to make?
 
Fair point Kenai. You'll have to excuse the ignorance I'm afraid.

So what kind of power do you get out of an alternator when the engine's idling?

My concern was lots of short journeys at low engine speed and at night, meaning the battery never really gets charged.

So I guess I can reword my question as: does the alternator provide enough power to run the entire car electrical system inc. lights, even at idle?
 
How short is short? Unless you're talking literally a mile down the road and that's it, I really don't think you're going to have any problems.
 
GeForce said:
does the alternator provide enough power to run the entire car electrical system inc. lights, even at idle?
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Easily.

Certainly how I was recharging my battery at the campsite I was at last month, and that was whilst running the car, the audio, the 12v coolbox and the 200W inverter for recharging the laptop.
 
Kenai said:
How short is short? Unless you're talking literally a mile down the road and that's it, I really don't think you're going to have any problems.
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So it's probably a 2-3 mile trip a couple of times a week (in the dark), and then a good 200 mile journey every 3-4 weeks.

Thanks for the input guys, appreciate it :)
 
GeForce said:
Fair point Kenai. You'll have to excuse the ignorance I'm afraid.

So what kind of power do you get out of an alternator when the engine's idling?

My concern was lots of short journeys at low engine speed and at night, meaning the battery never really gets charged.

So I guess I can reword my question as: does the alternator provide enough power to run the entire car electrical system inc. lights, even at idle?
Click to expand...

The biggest drain on the battery is the amount of juice it takes to start the engine.

The reason that lots of very short trips can flatten your battery is due to the drawn on startup and then never getting chance to recharge it.

Changing your bulbs for ones that use a few less watts is not going to make naff all difference to this. Remember, your car produces more electricity than it needs whilst its runing at idle. Thats why it charges the battery up, and why your battery will never go flat if you drive your car enough (unless its old and fails of course)


If your car was using too much electricity due to its non LED bulbs, then the battery would never recharge, no matter how long the journey.
 
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MrLOL said:
If your car was using too much electricity due to its non LED bulbs, then the battery would never recharge, no matter how long the journey.
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I was wondering if the engine needed to be spinning above, say 2krpm, for the electrical power out of the alternator to be sufficient to charge the battery. But as you (and others) have said, that's clearly not the case.

So a related question: if indicators or side/stop/tail lights fail, could I replace them with LEDs? The aim being longevity rather than power usage.
 
You can do

but they are usually more hassle than they are worth. I've had all sorts of problems with them throwing blown bulb warnings (due to using less power and fooling the system into thinking your bulb has gone), failing prematurely due to poor build quality ,low light output etc..

Just stick to normal ones IMO.
 
Fair enough, I'll take your advice and stick to filament bulbs.

I've heard about the blown bulb warnings, but my car is 1998 and pre-OBD so has no such feature. But the poor build quality and low light output issues do concern me.

Thank you again :)
 
If you find some good ones, let me know :p

But i'm sick and tired of buying ones that promise to be decent, but end up just being crap.

I'd like some properly decent LED sidelights, but just can't seem to find any that are as bright as filament bulbs that arent a faff.
 
I've read some good things about the CREE ones, like this:
http://www.lightec-autostyle.co.uk/high-power-cree-xenon-white-sidelight-bulbs-p-243.html

Next time one fails I might be tempted to give a couple of flavours a try. The sidelights on my car are particularly dim and I would like slightly brighter ones, so these might be a solution.

Edit: from the review: "the diffuser on them also means that the light fills the reflector instead of giving just a single point of light.". This was something that I was concerned about (the single point of light issue).
 
Yeah I know what you mean. I still might just go ahead and try them. If they're no good then no great loss.

I'm sure someone else here must have tried this; some more opinions & suggestions would be very welcome!
 
GeForce said:
My concern was lots of short journeys at low engine speed and at night, meaning the battery never really gets charged.

So I guess I can reword my question as: does the alternator provide enough power to run the entire car electrical system inc. lights, even at idle?
Click to expand...
With me Living on a 7 mile long island all my journeys are short and my car and bike charge the battery fine....;)
 
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