Bmw battery and charging issue

[reofix]

R1200GS has flat battery .... seems stuffed so i buy a new one... a week later the new one is dead flat .. diagnosis please... ps i didnt leave the key on... dodgy diode?

[puddytat]

That , or you didnt use the special BMW tool for the job

[pete376403]

Was the bike used between battery changes or did it just remain in the garage?

[thepom]

I,d say reg rec is not working so no charge to the battery.....




Follow this simple guide and you can work out what is needed.



1) Remove the seat cowl

2) Unplug the reg/rec ( See note *i )

3) Set your multi-meter to 200v AC range ( that is the one with the wavy line not the one with a straight line and or dotted line )

4) You are going to check the generator output voltage so you need to start the bike

5) Looking at the reg/rec plug(s) you will see three yellow wires. It matters not what order, but for simplicity sake I will call them wires one two and three.

6) Start the bike and get someone to hold the revs to ‘about’ 2000 rpm. Now use the meter to check the voltage across wire one to two, then two to three, and finally wire one to three. All three voltages should be quite close and all around the 26v AC mark. The exact voltage is not critical, this is a ‘ball park’ figure. What is critical is that all three voltages are within 1 or 2 volts max.

7) If one of the voltages is significantly different, or indeed you are not getting anywhere near the correct voltages on any of the tests, then the generator coils have gone a.w.o.l.

8) If the voltages are all ok, then the reg/rec is the problem.


Addendum:

If the generator coils have gone phut there is every chance that is all that is wrong. However !

It has been found that the original problem has been the reg/rec, which in turn cooked the gen coils.

If you find the gen coils are faulty then the first step must always be to replace them.

After you have fitted them set up the multi-meter on 20v DC and get someone to hold the probes on the battery terminals for you.

Start the bike and make sure the indicated voltage starts to go up immediately.

If it does not move, or indeed drops, turn the bike off immediately as it would mean the reg/rec has indeed gone duff.

Providing you do this quite quickly ( say, within about 45 seconds which is actually quite a long time ) no harm will come to the gen coils.. Of course the down side is that you will have to replace the reg/rec as well

As an aside, the tests suggested in certain manuals are pretty useless unless you have access to a VERY expensive meter, or a stabilised power supply and a scope, as a ‘normal’ multi-meter is no where near accurate enough to make the very fine measurements required to establish if a gen coil has a partial short ! ( But of course, they do not actually mention that little fact !! )

Note *i ….

On the carb bikes there is one single plug but on all EFI models there are two. It is the one with the three yellow wires you need to unplug.

[That looks like fun]

Could be a lot of things Reo, your bike would not have carbs so I would charge the battery then check the draw off by the bike before reconnecting it. An ampmeter between the terminal and the conncter will show the amount of current draw).
Not sure what it should be for your scooter but that information shouldnt be hard to find.
It could just be something as simple as a dud battery

[tri boy]

Got heated grips?
If so, run them via a relay off an accessory powered fuse.
Direct draw from the battery is an absolute mistake, no matter what Oxford etc say.

[Padmei]

Great diagnostic procedure Umopom.

Got heated grips?
If so, run them via a relay off an accessory powered fuse.
Direct draw from the battery is an absolute mistake, no matter what Oxford etc say.

I can't see what difference that would make Triboy? What's the reasoning behind your advice?

[reofix]

bike is in the hands of an auto electrician ... will let you know the problem and the cost

[gammaguy]

R1200GS has flat battery .... seems stuffed so i buy a new one... a week later the new one is dead flat .. diagnosis please... ps i didnt leave the key on... dodgy diode?

get it on a diagnostic,saves hours of pissing about

probably not shutting off the accessory socket...common issue

[tri boy]

Great diagnostic procedure Umopom.





I can't see what difference that would make Triboy? What's the reasoning behind your advice?

Buggered if I know either, but the scrambler would regularly get a flat batt with it direct wired, and also went through two controllers, but havn't had a problem since I used a relay.
Possibly the controller electrics have a leak/fault.

[Aslan]

Reo & all I have zero electrical skills - I leave that to the experts like Padmei.

However - a genuine BMW battery lasted less that 12 months and was replaced in August last in my 1150 under warranty. This winter when I didn't use the bike for a week the battery went flat. Spoke with others in the BMWOR who had similar experience and suggested I buy a battery tender - which I have and have mine plugged in via the accessory plug all the time.

good luck with yours (oh and yes TriBoy - my Oxford hot grips are wired directly ) Cheers S