Voltage drop. Is there a Charging Problem?

[sops]

Due to known stator issues on my ride (I'm riding a DRZ), I have a speedo with a voltmeter reading. Normally the voltage reading is at 13.5V when idle and voltage increases as I rev up (up to 14v).

 

A couple of weeks back, I went for an offroad ride and went really slow as it was muddy and a friend was on SM setup with road wheels. Our bikes overheated many times. Ever since, my bike had weird readings. On idle, it is still at 13.5v but as rpm increases, the voltage drops to as low as 12.8v when riding on the expressway.

 

Using a multimeter, the battery is healthy at 12.8v unloaded and at 12.1v when I switch on the ignition. Engine on and idling, it is at 13.5v.

 

I have diagnosed the regulator/rectifier (r/r) using diode check on a multimeter and the readings were fine. I've checked the output of the stator and it is within spec (more than 75V at half throttle on all 3 pairings of phases - I don't have a tacho to check the output against 5000rpm).

 

I tried tracing the wires and there were no burnt parts. I've wrapped parts that are torn in electrical tape.

 

Do anyone here have the same problem? The bike works fine but I'd rather do preventive maintenance if there's any problem than have the bike die on me halfway, especially in the trails.

[qystan]

Is the voltmeter working ok?

 

Try cross checking that against the multimeter.

[Tachnicolour]

There was a fellow rider once how experienced such a problem. Exact same symptoms. Normal voltage when cold, but it would fail to charge once bike was warmed up n moving. Hard to diagnose at a workshop cuz it would read normal.

 

In the end, they found that the rectifier was cracked. When cold, it would be a closed circuit, allowing charging. However, once the bike heated up, the slight expansion in the rectifier would cause the cracks to widen, breaking the circuit and failing to send charge to the main electrical system.

 

Now, not saying it would definitely be your rectifier, but you may wish to check all items upstream of your charging system. If there are any cracks/splits to connectors etc.

 

Run your bike till hot, when the voltmeter shows 12v, e.g. No longer charging. At that point, check that the rectifier is putting out voltage and if possible, the leads from the stator, if an appropriate a/c charge is being provided. Could be the rectifier or even the wiring from stator. Crack in stator or whatever.

 

Just my 2 cents based on past information.

 

P.S. : if you're saying that the voltage varies directly with rpm, then it's likely load based. Meaning that even at idle, when you rev it up, the voltage drops. Or when the bike is running hot and the voltage has dropped, when you clutch in n let the engine idle, it goes back to 14v healthy charging.

Edited April 28, 2014 by Tachnicolour

[FrostyTheAngrySnowMan]

experienced the same and it was the coil issue.

High chance it is rectifier or charging coil.