The Good, the Bad, and the Diode

[Gary]

Most of you know I've been fighting a non-charging scooter problem for some months now. A couple of weeks ago I replaced the heat sink diode and found it had a strange effect on the scooter, making the engine idle and run very poorly. So I bought a third diode to try. Low and behold the scooter runs fine with this new diode, and the charging system may actually be working now.

I did some tests on the old and new diode with a battery and a light bulb. Connecting the battery, bulb and diode in series, I found that the new diode (diode number 3) would conduct electricity one way but not the other - just what it is supposed to do. The old diode (diode number 1) would not conduct electricity either direction - definitely bad. Diode number two is still mounted to the scooter under the body panels so I don't have access to test it, but it will be interesting to see how it checks out. I suspect it is bad - maybe conducts both ways - who knows.

In any case, I'm keeping my fingers crossed that this solves the charging problem. I'd also advise anyone with charging problems to perhaps try a couple of diodes - they are cheap enough.
Gary

[aristide1]

This is an educated guess but,

Here's a great time to take care of that dim headlight at idle problem. A single diode should get tossed and 4 diodes should take it's place. They are usually sold as a bridge rectifier and are all on one small package. Of course high power ones will be a little larger.

One diode does half wave rectification. It disregards half of the sine wave of the AC. Full wave does just that, which means there are no time gaps between those charging pulses, so more amps should be available across the entire RPM range, but most noticeable at idle.

Go to google images and type in "full wave rectifier" and you'll see how the 4 diodes are layed out to perform the AC to DC change. Here's the most basic image:

[Gary]

Aristide -
Not entirely sure, but believe the function of the heat sink/resistor/diode is not rectifying AC to DC, but rather to prevent backflow of current from the battery through the lights when the ignition is off. People with the diode reversed have a lights always on problem.

But a full wave rectifier is better than half wave.

[monty57]

gary,

I hope this is the end you your electrical problems and you fully start to enjoy your scoot!

[Gary]

Monty,
Thanks. I'm enjoying the heck out of the scoot despite the frustration with the charging system. I've got 4,000 km on it now and it runs great.

Unfortunately, I don't think the diode solved the charging problem. I swear when I first installed the new diode I saw good voltage readings at the battery and thought the scoot was charging. But I rechecked the readings yesterday and nothing. So maybe there is a loose wire somewhere that is making intermittent contact, or a bad ground, or maybe the voltage regulator is bad. I'm still chasing...

In any case, I can still ride the scoot back and forth to work and around town, and I'm having a blast. We have absolutely perfect riding weather here in San Diego - hasn't rained since April and likely won't rain until October. So, I'm still having fun with my sub-$2K china-scoot, although I do occasionally lust after your Majesty or a Kymco.

Cheers,
Gary

[lubejob66]

Gary,

When I replaced my diode, the charging system works great now, when I replaced it I was telling the mechanic that has a shop down the street about how there was 2 diodes on my scooter, one attached to the frame like it was suppose to and NO wires going to it, then I found another diode tie wrapped to a hose with the wires going to that one. He said the manufacture probably tie wrapped it instead of mounting it to the frame because it was grounding out against the frame and shorting it out. When I got the new diode I hooked it up to the wires and tie wrapped it up and has been working for over a month now. When I have time the mechanic wants me to bring it in this winter and he will trouble shoot it and find out why it cant be grounded.
Try this it might help, because we have the same scooter.
Joe

[mike]

Gary,
Where can a person buy the Diode? My was bad from the go. A replacement part I'm told is on it's way but that has been 2 months. The lights stay on 100% of the time. I have to disconnect the diode to save the battery after every shot off, a real pain.

[Gary]

Lubejob,
Thanks. Your experience is encouraging. I'll bet though that the diode mounted to your frame is bad. I'll suspect the people at the factory tested the charging system, realized the diode was bad and just threw in a new one with tie wrap to save time. I actually have mine tie wrapped to the outside of the scoot while i try to debug things.

Mike - I got mine from Scooters Georgia www.scootersgeorgia.com/tascpa.html. They give great service and should get the diode to you in no time. Yuo might though try connecting the diode in reverse (with some temporary wires). At least one person with the lights always on issue fixed the problem by reversing the wires.

Gary

[Gary]

Well, I think the new diode may have solved my charging problem. I have a new battery, and have been running without overnight recharging for several days now without the battery going dead. The engine now keeps running if I disconnect the battery, which is a good sign (it didn't do this before). The voltage across the battery goes from about 12.9 volts with the engine at idle, up to about 13.4 volts with the engine revved up. So clearly the charging system is putting out something. Maybe in a few days I can declare victory over this problem. Its been a long time coming.

I do have a new problem with intermittent rough idle. I'll start a new post on this.
Gary

[aristide1]

The voltage across the battery goes from about 12.9 volts with the engine at idle, up to about 13.4 volts with the engine revved up.

Good, just like a car's charging system.

[Gary]

Yes, I think I can finally declare victory over the charging problem. The scoots been running for a week now (over 100 miles) without having been on the float charger.

I can't believe I went through all this agony over a $10 part. But hey, at least I got off cheap.

[aristide1]

gary505 said:

I can't believe I went through all this agony over a $10 part. But hey, at least I got off cheap.

That's the right attitude.

[buckeyescoot]

Hi Gary -

Let me chime in! I followed your lead and purchased a diode from Scooter Georgia and installed it before I got my stator replacement from AllNew. Got the stator last night, put the scooter back together. Hooking the battery back up and the lights came on!

Hmmm. That was the original problem I had back in May and I switch the wire around to resolve. I reversed the wires back to the original configuration and fired up the scooter. Wahoo! 13.5 VDC coming across the battery leads now!

I was so excited that I didn't even check the VAC on the three stator lines! I will check them later. Put the rest of the scooter back together and took it around the block (at midnight) which is late for me since I normally hit the hay at 9-10 PM and up at 4:00 AM.

You are right, a $10.00 solution to fix a 5 month troubleshooting problem. Three volt regulators, two stators, disassemble and re assemble the wiring harness twice.

In my case, All new indicates that the Roketa 250's do not have a Diode as part of it's make up. I.E. replace the above. Oh well, I sure learned a lot over the past 5 months!!

I did send the old diode to Michael at Allnew and explained the even through Roketa's parts list says it does not exist, it does in fact exist and resolved the lights on and charging problem. Hey, we all have new things to learn. I hope with this info he can help other customers, or at least send them to the Dawg Pound!

Joe

[Gary]

Joe -
Congratulations! Yuo went through a lot. Hope you can now ride your scoot some before winter sets in.
Gary