Ошибка ews bmw f800gs

Ok so i have been off the bike a bit too long. 2012 F800GS Trophy edition. Sat in the garage and the battery went dead.
— bought new Yuasa battery
— charged battery using Yuasa branded charger/maintainer
— installed battery and a pigtail for the battery maintainer.
— fired up the bike — started right up.
— brief test ride (brake function, etc.) around the neighborhood — 2 miles or so.
— bike ran fine (surprisingly, no issues with fuel system being gunked up, etc.)
— for a second or two only bike seemed to accelerate roughly, then resumed running smoothly. Idle was smooth.
— I shut the engine off using the key (fortunately at home)
— Bike will not restart
— bike displays yellow triangle warning light and «EWS».
— upon inspection, I notice I had failed to fully torque the screw that holds the positive lead on the battery before my test ride. This happened because I had to try a couple different options to make the (faux) «gas tank» cover fit correctly with the pigtail in there. Once it I found a good routing, I tightened down the cover but inadvertently left the battery lead a bit loose.
— I properly torqued the screw securing the positive lead.
— Battery appears undamaged/has been on the battery maintainer.
— «EWS» still appears and bike will not start.

Question:
Any idea why the EWS would come on AFTER my test ride?
Is there any way to clear that «EWS»?
Would adding the pigtail cause the EWS fault?
What should i check before i drag the bike to my local dealer and get my wallet cleaned out?

IRRC EWS is the key FOB/Ring antenna issue If the battery in your key FOB is low it will trigger this code.

Search this forum for «EWS».

Have you removed the key from the ignition and kept it that way while you fully recharge the battery? A lot of EWS errors are related to low state of charge…

long story short, (had the exact same thing happen to me this summer and I had exhaustively searched the internet for an answer, changed my E.C.U in the end)

good senario: the ring antenna is faulty and needs replacement ~ 50 euro part
bad senario: the E.C.U needs replacement. ~1.000 euro part

note: If the Low beam comes on and “EWS” is displayed, when the ignition is switched on the first time after the battery has been removed, the Ring antenna is NOT faulty!

I have come to the conclusion that only the BMW-charger should be used for charging the battery, hardwiring the battery to an external socket and charging it while its connected to the E.C.U is not a good idea I think. The motronic E.C.U is very sensitive unfortunately.

I think this is true IF the «smart» charger in question has a desulphation mode. If the charger decides that the battery is sulphated and goes into desulphation mode it hammers the battery (and the bike’s electronics) with high voltage pulses. This could explain why an ECU would go bad after a battery replacement. The weak old battery was charged with such a smart charger and the damage ensued. The old battery did not recover and was replaced. Upon power up the damaged ECU is manifested as an EWS error. It’s a theory.

The manual for my 2013 F700GS says not to connect a charger directly to the battery unless the battery is disconnected from the bike, i.e. removed.

According to the manual, the only safe way to trickle charge the battery while it is still connected/installed in the bike, is via a special BMW brand charger connected via the 12V Hella port. It states that sensitive electronics are at risk if you connect and charge directly at the battery without first removing the battery.

That said, my bike came to me with an SAE 12V pigtail hard-wired to the battery. The previous owners also conveyed a 1.3A Battery Tender trickle charger that they used to keep the battery topped up during periods of non-use.

I trickle charge my 2016 F700gs and my 2017 R1200GSA with pig tails directly to the battery and never have had an issue. In fact I have done this on every bike I have owned. I use a Battery Tender Jr. and only hook it up for a couple of days at a time then disconnect it for a couple of weeks. Repeat if the bikes have not been ridden.

My precaution of always using the bmw charger for the bikes battery is simply to eliminate a possible cause of a possible ECU failure.
I dont claim to know the exact cause of ECU failures.
With my limited experience of electronics and from discussions with Electrical Engineers, a bikes ECU is basically a circuit board which can fail
either by overheating, by unsteady input voltage, or by very intense vibrations. Most probably my ECU would come to life again if it was reballed like a laptop, I chose not to try and repair it to a shop although perhaps I could have.
My ECU failed on a day of quite some off roading and another 2 hours of road use. I hadnt used a hard-wired charger in the past 3 years.
I am in my 3rd battery so far, the OEM one lasted from 2009-2011, my 2nd one 2011-2018 (the one I was charging now and then),
and the last one from 2018 until today. I have now ordered a bmw charger just to treat this ECU a little better.
A new ECU from BMW would only have a 2 year warranty. A bit funny for an adventure motorcycle.
The company claims this is not a frequent failure, yet they take no responsibility for it.