Battery not charging

[Bazza]

Hi all, any chance of a little help?

I have a 2014 1200gsa 26000 miles, hasn't been used much over last year and had replaced the battery 5 months ago. tried using it this month and after 4 miles the warning light and battery light came on, anyhow I charged the battery that night and tried next day, few minutes later the light came on again, volt meter on dash showing charging at 12.3v.

So checked the forums and the dreaded 'dead alternator' came up..... so I got worried £££££££.

So after testing various parts I have this.

Battery disconnected = 12.8v
Battery volts when connected and bike running = 12.3v
Grey cable disconnected from rectifier 1-2/1-3 & 2-3 = ~24Vac between each with engine running
Black cable disconnected from rectifier with engine running = 15Vdc
Voltage check at 50A fuse point = 12.3Vdc with one side disconnected = one side 15Vdc other 12.3Vdc

So from here im stuck?

Could it still be the alternator??? even though correct voltage but can't push a load???

Any help greatly appreciated. Thanks

 

[pbbanks]

Not quite sure i follow but are you saying one side of fuse 15v & other side 12.3v ??. Probably misunderstanding but if not isnt it the fuse that's blown.

 

[Bazza]

Not quite sure i follow but are you saying one side of fuse 15v & other side 12.3v ??. Probably misunderstanding but if not isnt it the fuse that's blown.

No badly explained, I checked voltage at this fuse point and was getting 12.3V, I had checked the fuse and was good. I disconnected the fuse at this point to see if was same upstream and downstream and got 15V up and 12V down with ref to neg terminal on battery, from this point I don't know where cable goes.

 

[BillWright]

Hi

The easiest way to check the alternator is put a voltmeter across the terminals.

When you start the engine and increase the revs, the reading should increase from 12V to 14.3V.

Bill

 

[Winjar]

Maybe just bad luck new battery not use for 5 months, maybe new battery not good

 

[BobT]

Think of voltage as electrical pressure. If the engine is running and the system voltage is lower than the static battery voltage then it will not push volts into the battery to charge it.

 

[pbbanks]

If you are only getting 12.3v with multimeter on battery terminals & engine running its certainly not charging. You have 24vac across alternator phases so its putting something out. And you picked up a 15v reading from somewhere??.
Maybe check all wiring\connectors for any signs if problems then check rectifier.
There is a link here (sorry if you've seen it) it does gives lots of details of similar problems , although his was a faulty alternator, i would hope yours is ok with getting 24vac out of it.
https://www.advrider.com/f/threads/...ator-and-vintage-regulator-rectifier.1119480/

 

[squibb34]

It does sound horribly like a stator failing - let's hope not, given cost/PITA job. Have you had the fault/error codes read, GS911/dealer?

What if any after-market electrical consumers have been fitted? - often best to disconnect anything, like ezCAN/lights/nav/sockets for heated gear etc, just to ensure you don't have a significant parasite at work.

Then, we need to know the AC outputs from each alternator wire, say at 1k rpm intervals, until they peak; you mention 24v AC engine running - was this at tick-over?

Can we assume the condition of the main 50A fuse is still good - double check with a meter. Have you checked all the earth/neg connections are tight & free of corrosion?

Obviously it's worth getting the battery tested by a battery specialist in case there is a cell going down - most will do this for a small fee.

 

[Bazza]

It does sound horribly like a stator failing - let's hope not, given cost/PITA job. Have you had the fault/error codes read, GS911/dealer?

What if any after-market electrical consumers have been fitted? - often best to disconnect anything, like ezCAN/lights/nav/sockets for heated gear etc, just to ensure you don't have a significant parasite at work. no aftermarket equipment all from BMW

Then, we need to know the AC outputs from each alternator wire, say at 1k rpm intervals, until they peak; you mention 24v AC engine running - was this at tick-over? yes tick-over

Can we assume the condition of the main 50A fuse is still good - double check with a meter. Have you checked all the earth/neg connections are tight & free of corrosion? 50A fuse is good and what I can see seems tight.

Obviously it's worth getting the battery tested by a battery specialist in case there is a cell going down - most will do this for a small fee.

- will try and get the battery tested this weekend.

Thanks for the responses boys.

 

[fizzer]

when i was in the motortrade it did often happen that a battery would have a fault, and on a multimeter it looked like it was the alternator ,when realy it was a battery at fault.

 

[Hann]

All the answers to your charging woes are here - careful and methodical testing will soon give you an accurate diagnosis without any guessing........:


https://www.ukgser.com/technical/ni...f charging system (R-series, '13 on) V1.0.pdf

 

[Bazza]

Thanks for that, I had something similar. But the voltage from the stator windings is indicated as 70Vac on this fault finding write up. Where others I’ve seen specifying 20Vac + also getting 15Vdc from the r/r. So still clutching at straws

 

[Hann]

I`ve never done any testing on a GS LC motor but have done plenty of times on Jap bikes, with the stator isolated (multi plug disconnected) you usually get around 20 - 30VAC at idle speeds on all 3 phases (wires 1&2, 1&3 and 2&3) and it rises rapidly to 60 - 70VAC when engine speed is increased so your 24V looks low - if measured correctly.
Have you tested for any continuity from all of the 3 stator phase wires to earth/ground?
Should be very high resistance, open circuit, no continuity.

 

[Bazza]

I`ve never done any testing on a GS LC motor but have done plenty of times on Jap bikes, with the stator isolated (multi plug disconnected) you usually get around 20 - 30VAC at idle speeds on all 3 phases (wires 1&2, 1&3 and 2&3) and it rises rapidly to 60 - 70VAC when engine speed is increased so your 24V looks low - if measured correctly.
Have you tested for any continuity from all of the 3 stator phase wires to earth/ground?
Should be very high resistance, open circuit, no continuity.

Have rechecked the stator voltage with a willing volunteer to increase the revs, and you are correct, 24vac on idle and sharp increase to 65-70Vac when increased revs

But am getting almost a short between each phase and earth? Which I measured a while ago after going through the fault finding tips in post above. But took it as must be wrong as I’m getting voltage at all point……… and I didn’t wanna believe stat is dead

 

[Hann]

I agree, that is very odd.
Usually, if your stator has shorted to ground the VAC output readings would be very low or one phase would be noticeably lower/different than the other two, but your results suggest that the stator is in a healthy condition and behaving normally (24V at idle and 65/70 at higher engine speeds) despite having continuity to earth...

Don`t do anything rash at this point until you are 100% sure wher the fault lies, it might not be so sinister as a stator fault when you consider the bike has not been used much lately which could be ample time for corrosion or high resistances to develop in wiring connecetions/plugs etc.

.........but saying that if you deffo have a short to earth your stator is FUBAR....

 

[pbbanks]

Not adding up is it. Have you checked the readings with a volt meter at the battery terminals rather than relying on the reading on the clocks. And checked \remade all the ternminal connections to\from battery, both live and earths. And screw connections on main fuse . Also look for any corrosion in the earth connection cable crimps (maybe nip them up a bit ).
Doesnt make sense as you are getting 15v at one side of main fuse. But then its not getting to the battery??.
With fuse in and engine running is it then not giving 15v at the fuse?.

 

[squibb34]

This just doesn't add up - 70v AC at 4k revs, but no stator resistance.

Are you sure that multi-meter is good, with a new battery, & you aren't touching the probes with your fingers when testing. Old batteries can lead to some strange/inaccurate readings, particularly when testing resistance values.

Is there any outcome with testing the battery?

What resistance values is the reg/rec showing when you probe between the terminals?

You say the 50A main fuse is good - has it been checked for continuity, with a meter, in situ? The eye can deceive.

 

[Bazza]

Battery disconnected is showing 12+v and showing 12+ v when connected and running on the dashboard.

The 50A fuse I've removed/disconnected and checked for continuity and all good. I did the tests for the Rectifier, diode mode etc and looked good. only thing which doesn't add up is the continuity from stator wires and earth!!!! 15v from rectifier, is this too high? could it be rectifier bad?, when the cable comes out of rectifier and charging circuit (50A fuse) where does it go from here? does it go in the ecu first or straight to battery???

things aren't adding up and unfortunately to swap and check will be expensive. But surely if I had a short on the windings, I wouldn't be getting voltage ant the plug?

Ill get the battery tested this week, at least its something I can discount

 

[pbbanks]

Think 12v measurement for an agm or wet battery means its basically flat. At standstill with no load think it should be at least 12.4 v or above?. Simple basic way to check if battery has any life left is to charge it up for a night on your smart charger. Then measure voltage with your meter and it should be 12.6v or so. Then start bike and stop it , then put some drain on it by switching headlight on for a minute. Next start and stop bike a few times. If battery still turns it over ok every time Id say theres a fair chance the battery isnt your problem. Again if you put your meter on the battery while you are doing all the things it should show 13v to 14+v when the engine is running, if not, its not putting charge to battery. And about 12.4v to 12.6v with ignition off.
The voltage on the bikes instruments at standstill will show a slightly lower voltage than just a meter straight onto terminals (with ignition off) because there is already some load when you have turned the ignition on to read the instrument display.

 

[pbbanks]

Ps 15v from rectifier is probably ok because for whatever reason it isnt getting to the battery to be able to know what to regulate it down to.
Doesnt your smart charger have a display?. If so, that should give you an indication of charge voltage your battery takes. Think mine shows a charged ramping up to about 14.4v when first connected , then back down to a float charge of about 13v . Think bike clocks should show about 14.4v when running and charging correctly.