36V light bulbs

Measure voltage. If it's well over 36V, this may be the casue.

"Charles A. Sherwood" wrote: (clip) I am looking for a source for quality bulbs that will last.(clip) ^^^^^^^^^^^^ The problem may not the the quality of the light bulb. I once had a motorcycle that burned out lots of bulbs until I figured out what was wrong. It had a loose connection in the charging circuit. When the contact broke, the inductance of the starter/generator forced the current to surge through the light bulb, making it flash very bright for just a moment. But this happened over and over until the bulb failed.

If you do find that the voltage is too high it shouldn't take much effort to wire the appropriate sized wirewound resistor in series with it to drop the voltage a bit. You'll need about four ohms of resistance for each volt you want to drop. The resistor should have a power rating of at least a third of a watt for each volt it's dropping.

Or, you might get lucky and find that a 6 volt bulb, two watts or greater, in series with the present bulb would drop the voltage close enough for government work.

Good Luck,

Jeff

It's more probable that you'd need to fix the charger, as it may be rapidly damaging the batteries too.

I'll give you that Ian.....But read on..

"Once de voltage goes up, who cares ven it comes down. Dot's not my department, says Wernher Von Braun."

(With apologies to Tom Lehrer.)

Didn't the OP say this was a ELECTRIC scooter? Doesn't that imply that the headlight would be OFF while the scooter's sitting there connected to it's charger? And if that's it, then all he'd have to do is make sure it's switched off before each charging, huh?

I've got a feeling the OP's original though is correct ("It's the bulb, dummy.")and the ones the manufacturer uses are not designed for "automotive" use, and can't take road vibration or a fully charged battery's voltage as well as they need to. Running them a little cooler could help that.

But, what he really ought to do is ask Don Foreman to help him design a white LED replacement assembly for that bulb. He could get more light for less current and probably ride a few hundred feet further on each charge too.

What say?

Jeff

Sounds like fun. Say 24 LEDs at 18mA each at 36V. Say 3.25V Vf, would be 3 strings of 8 or, or 560 ohms.

So 24 white LEDs and 3 450 ohm 1/4W resistors. Cost about $14.

Total power consumption 2W.

Best regards,

Best regards, Spehro Pefhany

^^^^ 560 that should be

Best regards, Spehro Pefhany

And here's what the layout might look like using narrow-angle 10,000+ MCD 5mm diameter LEDs, in a 2" circle (could obviously be made smaller).

Best regards, Spehro Pefhany

Bah. HID is the way to go.

Spehro has offered a good low-cost solution using multiple LED's at 18 mA, though I strongly doubt that this solution would be comparable to the light output of a 10-watt incandescant bulb.

A single 5-watt Luxeon white LED in a suitable reflector would probably eclipse the 10-watt bulb you're using. A 3-watt Luxeon would probably at least match it. The advantage to the white Luxeons is that they can provide a beam at least as good as an incandescant bulb using the same reflector, if you can do a bit of machining to mount a Luxeon emitter on an aluminum stud (heatsink) that projects into the reflector. Jerry Martes and I have each made 3-watt lights using 3" reflectors from $4.68 Eveready lanterns (with battery from Home Depot, all we used was the reflectors) that easily beat the beamwidth, uniformity and brightness of these 6-volt lanterns. Projected "bulb" life is 50K hours or so. Illumination of targets/objects 100 meters distant is no problem.

The 3-watt emitters go for about 20 bux. You'd need either a dropping resistor or suitable electronics to operate from a 36-volt supply. If efficiency isn't an issue, a resistor would work just fine. Current should be set to between 0.75 amp and 1 amp, LED voltage at that current will be about 3.9 volts.

That would unbalance the discharge of the batteries, which might cause problems.

One high-tech alternative would be to use a switching regulator chip and a few other parts to reduce the 36V to an accurately regulated voltage for the bulb (probably something like 13.5V).

Best regards, Spehro Pefhany

some follow up info. The scooter is electric. It is plugged into 120VAC to charge the batteries. Therefore the head light is not on when the batteries are charging so its not an overvoltage issue caused by the charger. I have not measure the no load battery voltage, but I suspect it will be a bit above 36 volts when the batteries are freshly charged.

One reason I suspect the light bulb is that the bulb is very bright and a very white light for a 10 watt bulb. The bulb resembles an automotive backup light but the glass is a smaller.

I have not opened up the battery compartment but I think it has three

12V lead acid gel cells. The drive motor is rated 350W which is a healthy current draw of about 10amps. BTW, this scooter really moves with a kid on it and does pretty well with an adult. It will cruise at 15+MPH on flat ground and will top at 18MPH with a kid. I also have a 24V scooter which is move appropiate (and plenty fast enough) for small kids.

I would prefer a simple light bulb replacement. But LEDs are not out of the question.

thanks chuck

That's why I suspect the charger. The light from an 'ordinary' bulb will get a lot brighter if it's ran at a voltage adequate to burn it out in an hour. Anyway, voltage will answer this one way or anohter.

If you want to reduce the voltage a bit, just put a couple of forward biased silicon diodes in series with the lamp.

However if they are burning out that fast there may be some other issue, like they put in the wrong lamp or wired it incorrectly.

First off what is the number on the base of the lamp that you removed?

Jim

================================================== please reply to: JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com ==================================================

That's probably the simplest solution. a 12-volt bulb and a LM2576T-12 switching regulator. $2.80 from Digi-Key. See:

for datasheet and sample design. You'd also need an inductor and a diode, neither of which costs more than a buck or two. Some minor soldering required. You select a 12-volt automotive bulb that fits your socket and provides the light output you want.

Feel free to email me if you'd like help with this.

Don:

I'm currently designing the LM5007 into a product- check this out:

I'm using the 4mm x 4mm package. ;-)

Best regards, Spehro Pefhany

But the charger in not hooked up when you are riding the scooter. Do I don't understand why you say its the charger.

Don't hold your breath waiting for an answer, I asked Ian the same thing yesterday and he hasn't debated me about it yet.

AFAIK overcharging batteries wont't result in their developing higher than normal voltages once the charger is disconnected.

But if I'm wrong about that, I'm more than willing to learn something new.

I still say, "It's the bulb, stupid." (For not being "automotive rugged".)

Jeff