IRISHROVER Headlight power

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dogsbody

dogsbody

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IRISHROVER

With MIKEV8SE getting all sorts of 'help' with whether or not to fit spot lights to his Rangie I sort of remember you saying a while back that you'd run for years with over-power headlight bulbs.

As the BECM wizard (even though you've sold your wand) what power lights do you reckon that the BECM can handle without causing expensive problems?

I tried the HID route but didn't like some of the weird dashboard warnings that I got but would still like a bit more light without fitting spots.

I know that I could have made this a PM but I thought that it's the sort of info that quite a few others might like.
 
I found that the Becm and wiring will run 100/65W and 100W auxillary main beam without any problems.
On my old Disco. which admittedly did not have a Becm, just an ordinary circuit and the wiring was the same size as that on the P38 loom, I had 130/80W headlamp bulbs (No auxillary lamps apart from a pair of "A" bar mounted spots) and again the wiring and relays stood up to it no problem.
The Mosfet controlling the headlamps on the P38 is rated at 15A max. continuous current so with a combined load of both headlamps at 200W this equates at approx. 15.3 amps at a battery voltage of 13V. I guess that uprating to lamps above this may probably be the straw that breaks the camels back and that is the reason why I didn't push my luck.
It could be overcome by fitting a relay and suitable resistor to fool the Becm into thinking that the correct bulb was fitted and not give a bulb failure message but I didn't go to the trouble of progressing along that line.
 
Thank you very much.
Now I can start experimenting with which actually gives me the best light for driving.
 
Ive got hid,s fitted and with the use of a few diodes i get no messages at all
I get a wireing diagram from on heer as to were the diodes go but i cant find it now
im sure somone will have it though
 
Irishrover said:
I found that the Becm and wiring will run 100/65W and 100W auxillary main beam without any problems.
On my old Disco. which admittedly did not have a Becm, just an ordinary circuit and the wiring was the same size as that on the P38 loom, I had 130/80W headlamp bulbs (No auxillary lamps apart from a pair of "A" bar mounted spots) and again the wiring and relays stood up to it no problem.
The Mosfet controlling the headlamps on the P38 is rated at 15A max. continuous current so with a combined load of both headlamps at 200W this equates at approx. 15.3 amps at a battery voltage of 13V. I guess that uprating to lamps above this may probably be the straw that breaks the camels back and that is the reason why I didn't push my luck.
It could be overcome by fitting a relay and suitable resistor to fool the Becm into thinking that the correct bulb was fitted and not give a bulb failure message but I didn't go to the trouble of progressing along that line.
Click to expand...

John, you been on the booze when you wrote that? Two 130 watt bulbs = 260 watts not 200W. That comes to around 20 amps at 13 volts by my reckoning. You didn't use your car much, maybe that's why the MOSFET's survived. Personally I think running MOSFET's at more than 80% of rated maximum is asking for trouble.
As the vehicle voltage is about 14.5 volts with the engine running, I would say that gives a safe working load of 175 watts.
 
Datatek said:
John, you been on the booze when you wrote that? Two 130 watt bulbs = 260 watts not 200W. That comes to around 20 amps at 13 volts by my reckoning. You didn't use your car much, maybe that's why the MOSFET's survived. Personally I think running MOSFET's at more than 80% of rated maximum is asking for trouble.
As the vehicle voltage is about 14.5 volts with the engine running, I would say that gives a safe working load of 175 watts.
Click to expand...

:behindsofa:

Keith I think you have been on the vino !!!
If you read my post correctly you will see that I had two 130W bulbs fitted in my old Disco and currently have two 100W fitted to my P38. To build in a safety factor that is why I based the Voltage as 13 instead of the usual 14+V. You will also read that I have not considered fitting 130W bulbs for fear of Mosfet failure.
Admittedly the car has been used less frequently for the past few years but the 100W bulbs were fitted almost 8 years ago and the car was used regularly, doing around 10-12K miles for most of the time I have owned it without any problems.
I have powered the same type Mosfets on the bench and loaded them on test over a 4 hour period at 20Amps and they have not blown..Got hot, Yes !!
Main Beam is not used 100% of the time anyway.
Best bet is to fit separate driving lamps with 130W bulbs driven via a relay with the main beam circuit energising the coil if you are prepared to have an "A" bar on the car.

:5bcheers2:
 
Last edited:
Running 90w/100w for dip / main and standard 65w driving lamps. Done it for years. No problems and not a MOT issue here. Could be one for you though.
 
Irishrover said:
:behindsofa:

Keith I think you have been on the vino !!!
If you read my post correctly you will see that I had two 130W bulbs fitted in my old Disco and currently have two 100W fitted to my P38. To build in a safety factor that is why I based the Voltage as 13 instead of the usual 14+V. You will also read that I have not considered fitting 130W bulbs for fear of Mosfet failure.
Admittedly the car has been used less frequently for the past few years but the 100W bulbs were fitted almost 8 years ago and the car was used regularly, doing around 10-12K miles for most of the time I have owned it without any problems.
I have powered the same type Mosfets on the bench and loaded them on test over a 4 hour period at 20Amps and they have not blown..Got hot, Yes !!
Main Beam is not used 100% of the time anyway.
Best bet is to fit separate driving lamps with 130W bulbs driven via a relay with the main beam circuit energising the coil if you are prepared to have an "A" bar on the car.

:5bcheers2:
Click to expand...

Sorry John I totaly miss read that:eek:

Academic over here as uprating the wattage is illegal and if spotted will fail the MOT as I think it will in the UK from next year, again if spotted.
 
Apology accepted Keith :5bcheers2:

Never had a problem MOT wise, yes I do take it over the water every year 'cos it's still on UK plates. The first year I swapped the bulbs back to the original, and swapped them back over after I got the ticket. The next year I forgot and she passed no problem and they have been left in ever since. Additionally I have never been "Flashed" on dip beam despite the MOT guy a few years ago adjusting them as high as possible that the MOT would allow. I do get "Flashed" on main beam if I am a bit late dipping, obviously you have to allow for the extra distance and dip earlier, you do of course still get cussed if you dip too late with standard bulbs.
 
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