'18 EC300 (battery not charging)

[TerraMoto]

Hello, recently got my starter working after following the official guide and rebuilding my bendix etc. A few rides later I now find the battery isn't charging.

* Voltage across battery doesn't change from when ignition is off / idling / revving.
* All lights / dash / horn etc work perfectly and front light gets brighter when revved (so I'm guessing the stator & regulator are okay?).

Battery voltage is now worryingly low and any suggestions would be very welcome as this is the first time diagnosing such a problem.

Thank you.

 

[gasgasman]

What is the actual voltage at the battery while the bike is running?

 

[TerraMoto]

It's all the way down to 4 volts today, is it done for? No change from off to when it's running.

When I first fixed the e-start, it would start the bike from cold immediately without any hesitation whatsoever.

 

[gasgasman]

You voltmeter may be bad.
The bike won't crank with 4v.

 

[TerraMoto]

Voltmeter is good, battery is just low due to not charging.

I should note that the bike runs perfectly fine without the battery.

Hoping to get some ideas on what could cause this and how to go about troubleshooting it.

 

[gasgasman]

When the battery shows 4v, does the bike turn over normally?

The battery is not required for the bike to run.

 

[Gez]

I had a charging issue with mine albeit minor. The bike would rarely climb over 12.5v while I was testing with the volt meter (this is verified with the gauge on the dash whilst riding). My fix was to disconnect the low beam of the headlight which of course is always on. It now will idle with 13.1v and the gauge is showing nice and high on the dash. This may not assist you but it's worth a mention.

 

[TerraMoto]

Glad you got your issue fixed, but my voltage wont go up at all. At this point I'd be happy with 12.5v. Bike runs perfectly with or without battery, literally the only issue is that it wont charge up whatsoever. I've checked fuses and all connections are secure.

Does anyone have any ideas which circuits I should be testing or which points to measure voltage or continuity to ensure current is being supplied back to the battery?

Is there a troubleshooting guide to test the reg/rec just to be sure, or any other tests I can perform? Any ideas and info would be great

 

[gasgasman]

Look on page 68. Shows the wiring schematic.

https://www.dropbox.com/s/i93vw77r9kuszxs/gasgas%20workshop%20manual.pdf?dl=0

You may have a bad voltage regulator/rectifier.

 

[(F5)]

You should be able to test the ac voltage going into the rectifier with engine running but rectifier unplugged. Revved you should get ac voltage well in excess of what you need. If so try a new rectifier.

 

[Gasser Nate]

Make sure you do a voltage drop test as well. Very common for dirt bike harnesses to have shitty crimp joins internally and it drops voltage by the time it goes back to the battery. If you check the charge rate straight out of the regulator and it is significantly higher than at the battery you have an issue.

 

[TerraMoto]

Thanks very much guys, you gave me something solid to go on.

The wiring schematic (my regular manual didn't have this section!) proved useful in testing the AC stator output with the reg unplugged. Got up to ~100 volts with a brief rev or two.
Looks like its definitely the reg/rec as I tested again after cleaning all contacts (regulator pins were full of mud) and absolutely no DC is being supplied upon revving.

Will post a follow up after the replacement is installed. Cheers

 

[Gasser Nate]

The regulator has to be left plugged in when testing dc output. You should at least have battery voltage there. If not you may have a broken wire in the harness.

There is also a diode module that switches power to the main harness when the bike is running. This may have an issue as well if it controls power to the regulator. But I don’t have the harness diagram near me at the moment to confirm.