'18 EC300 (battery not charging)
 

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.

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

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.

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

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.

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

The battery is not required for the bike to run.

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.

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

Look on page 68. Shows the wiring schematic.

https://www.dropbox.com/s/i93vw77r9k...anual.pdf?dl=0

You may have a bad voltage regulator/rectifier.

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.