308 Instrument panel lighting upgrade tests

Yesterday did mine.

I cannot find the Led's here in Malta, but changed the bulbs in the tachometer with 5W ones.

The rheostat bypas I did not do, as when I removed wires, mine were Black, White and Yellow. I do not play around with electrical wires.

Re bulbs, the old one are also white, so the red colours comes from within the instrument itself.

Now need to buy those LED. Any ideas.?

Regards,
Stephen

 

I might add that any LED substitution for the little red indicator spots in the gauges must be bipolar LEDs. These llamps are wired in reverse i.e. the switches go to ground to light the lamps instead of to +12. This would include the OIL Pressure gauge, Fuel Gauge.

Also, do not substitute the battery indicator lamp with an LED as the bulb is part of the charging circuitry.

 

How does that work?

 

The bulb provides power to the field coil(stator) until the alternator is turning fast enough to self excite the field coil & the regulator has taken over:
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Do you guys really drive your car at night?

 

Mike, Night driving is great during certain seasons. Being able to read your instruments is a plus. The real advantage however is being able to see the blinker indicator and not having to open the panel to change bulbs any more.

 

I agree Robert, I actually drive mine at night occasionally. Now that I have my HID headlight, the driving is even more pleasant.

 

So if the bulb is LED or just burned out, the alternator will still charge the system, it just has to spin up faster before activating.?.

 

The field coil has to have a minimum amount of currentflow generating a magnetic field before the alternator will begin charging. The bulb supplies that minimum current. IIRC, the alternator will not even begin chargeing at ANY speed with the bulb burned out.

I agree with Crowndog, LEDs draw a lot less current than incandescent bulbs. I suspect the LED will not supply sufficient current to excite the alternator. It won't hurt anything to try it tho. If you try it, please post the results.

 

I tried it. It takes higher revs to extinguish the LED. At that point I realized that it ain't right. Paul_308 straightened me out on this point.

 

Would a relay solve this problem? Seems to be a weak link.

I tried a different LED last night and it shows promising results. Will take it for a test drive later to see if the light goes out.

 

One of those endearing design quirks that keeps it all interesting. I'll add an ALT bulb to my tool kit

 

So the LEDs I have found seem to work great. After a warm up the yellow LED went out, and after the revs got up the red LED turned off. Will post images and information later.

 

"Warning Will Robinson". I would recommend keeping the bulb in this application. Remember a LED is like a diode, it only passes current in one direction for practical purposes. Below is excerpt from one of Steve's posts:

...so how do I relate that to voltage....
You don't . The only thing that the "gen" light reliably detects (if the alternator is working) is if the alternator output goes below the battery voltage (because the belt breaks). The gen light will often come "on" if something goes wrong inside the altenator, but not always.

One side of the gen bulb filament is connected to the alternator output diode array and the +12V post on the battery (call this terminal X). The other side of the gen bulb filament is connected to another (identical) output diode array inside the alternator (call this terminal Y).

At low current load from the alternator, terminal X = terminal Y = 13~14V = no light from bulb, and your battery gets charged.

At high current load from the alternator (as your in your example), the voltage might droop down to ~12V, but terminal X still = terminal Y = no light from bulb, but you may not be charging the battery.

If the alternator belt breaks (or with key "on" but the engine not running), terminal X drops to the battery voltage ~12V, but terminal Y goes to 0V = the bulb lights brightly.

If something goes wrong inside the alternator gizmology where terminal Y is just always the same voltage as terminal X = the gen light never comes "on", but your battery still goes flat . This is the case where an ammeter gives you better information than an idiot light (but ammeters are troublesome because the current is so high so manufacturers have good reason to not use them -- ask the 246 guys ).

 

You can relate the alternator schematic in post #79 to the preceding description as follows:
Terminal Y corresponds to schematic point D+,
and terminal X corresponds to schematic point B+.

A possible way of supplying the correct field current while substituting a LED would be to determine the current drawn by the bulb when it's ON. A resistor that delivers that current less the LED's current could be connected in parallel with the LED.

YOUR MILEAGE MAY VARY:
The resistor is a hypothetical solution, but the design may depend on other incandescent bulb characteristics. For example, I don't know if the alternator design depends on the fact that an incandescent bulb's resistance decreases rapidly as the voltage to the bulb decreases. (A cold incandescent filament has about 1/10 the resistance of a hot filament). This would tend to increase the field current as the alternator output inears self sustainging voltage!!! A LED/parallel resistor would not have this characteristic.

A 2nd possible problem is that an LED bulb requires about 3V x #light emitting diodes before it is fully on. So would conduct significantly current at lower than 12V - 13V differences between B+ and D+, leaving only the current thru the resistor.

IMHO, stick with the incandescent bulb here. The bulb is on such a brief time that it's unlikely to ever burn out. A spare in the tool roll is adequate & cheap insurance against that unlikely event.

 

Agree. One could build a circuit to emulate the bulb but is it worth it? IMHO no.

 

My 2 cents:

We need to upgrade to LED only the bulbs that we need to work properly, like the ones that lightens the speedo, the tacho or the other gauges. And if we're driving at night, these bulbs must be lighting the dash all the time, so the consumption and heat is reduced a lot with LED; upgrade to LED is a must do in this case.

Also we need to upgrade to LED the ones that we need to see on daylight like the direction indicators or the high beam.

I haven't upgraded to LED the warning lights like the alternator, warm engine, interior fan or emergency brake. We can see theese ones very well with the incandescent bulb. Think that these bulbs are on only a few seconds, not all the time, so the consumption and heat are very low, not a real problem.

It doesn't worth spending time upgrading to LED the alternator light, IMHO.

P.S.: I've found a new LED for the tacho with 8 SMD 5050 chip that has a very good light spread. I will post it later...

 

Agree and thank you for the great LED post that started me on the road to conversion. I am very interested in the new LED for the Tach. I was even thinking of mounting one in front of the face to illuminate the needle better but still inside the front crystal.

 

Thanks Robert!

I will post soon the new results.

 

Well, Fchatters.

After spending some time testing new led bulbs for the tacho, I've found the definitive bulb for our dash. It's a new T10 type with eight 5050 chip, that has a brilliant beam.

Check out the result at this address, where I've uploaded the shots -sorry, no more space on my account to upload anything-:

https://plus.google.com/photos/105653416865818415483/albums/5646746259545645441

Yo can see a shot of the dash, with the tacho very well lighted, finally, with the new eight 5050 chip led bulb. Also you can see two photos with the different types of led lamp I've found, with the 5050 chip, very powerful. Of course, I've done some modding changing the T10 socket for the BA9s socket. Easy to do, with a little bit soldering and an empty Ba9s shell. You must check the polarity, because some bulbs are polarized.

I've bought the bulbs on Ebay and also on dx.com -no affiliation, of course.

If you've any question, I will try to help.

 

Unfortunately, your G+ link returns Error 400; URL not found.

 

If you get the right LED,s the dimmer works just fine ,i did my 328 2years ago no proble at all and very bright but i can dimm them,

 

Agree. I also found no need to remove dimmer and it does in fact work with the LED conversion quite well.

 

I ended up just removing the dimmer altogether and jumping them. Hasn't been a problem.

 

Sorry Don.
Try with this link:

https://picasaweb.google.com/antonio.regidor/FerrariDetails?authuser=0&feat=directlink

I hope it works.

Thanks