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I need help with my 04 K1200rs .I need to leave the battery on trickle charge each evening or so. If not the battery looses it full charge and there is not enough to start my machine. This is a brand new battery which i thought would solve my problem. The bikes charging rate is fine. Once i,m riding the machine it charges up the battery and alls good for a day or so. Can anyone out there help me....before i loose all my hair.
 

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I would say you either have a bad battery, or a short someplace drawing current when the bike is off. Easy way to find out charge the battery, and disconnect the leads to the bike. Give it a day or two then connect the battery. If it starts your battery is good, and you have a short. If not battery is shot. If it does start get an amp meter, and disconnect the positive cable with the bike off place the meter in series with the cable, and battery post see how many milliamps it draws.
 

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2008-K1200GT said:
I would say you either have a bad battery, or a short someplace drawing current when the bike is off. Easy way to find out charge the battery, and disconnect the leads to the bike. Give it a day or two then connect the battery. If it starts your battery is good, and you have a short. If not battery is shot. If it does start get an amp meter, and disconnect the positive cable with the bike off place the meter in series with the cable, and battery post see how many milliamps it draws.
Cheers i'll give this a try and get back yo you...Ger
 

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I would guess that if it was happening with your old battery than its probly not the new battery that is at fault but instead its a short in one of your circuts ...to test turn your ignition switch off and make sure that if you have any add ons that they are all off and that you can get to those fuses also by just removing the seat.... remove your neg battery cables with a test light clip the end of the test light to the neg battery terminal and with the prob end of the test light touch your neg cables...if the light is one then you have a draw in one of your circuits...to find out witch one it is get to your fuses and start pulling out your fuses till the light goes out...that will be the circuit that is at fault...now you need to figure out where in that circuit the problem lies...another possibility is that your alt may have an internal shot....after the bike has sat over night and before you start it reach in and feel your alt....should be cold...if its warm than there is your drain even thou no battery light comes on when your ridding and battery still charges.
 

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I think you and I have the same principal in mind, but unless I'm mistaken th light will definitely come on wether or not you have a short. Don't forget the clock is running, and whatever else the ECU has in memory. This is why I suggest an amp meter it should read milli amps only anything higher is a short.
 

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2008-K1200GT said:
I think you and I have the same principal in mind, but unless I'm mistaken th light will definitely come on wether or not you have a short. Don't forget the clock is running, and whatever else the ECU has in memory. This is why I suggest an amp meter it should read milli amps only anything higher is a short.
Was thinking that the computer had its own battery back up..but even if it didn't I would think the draw would be so minute that it wouldn't light a test light..or if it did it would be very dim...dunno...never did it to my bike...good point!
 

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Discussion Starter #7
BAK04GT said:
I would guess that if it was happening with your old battery than its probly not the new battery that is at fault but instead its a short in one of your circuts ...to test turn your ignition switch off and make sure that if you have any add ons that they are all off and that you can get to those fuses also by just removing the seat.... remove your neg battery cables with a test light clip the end of the test light to the neg battery terminal and with the prob end of the test light touch your neg cables...if the light is one then you have a draw in one of your circuits...to find out witch one it is get to your fuses and start pulling out your fuses till the light goes out...that will be the circuit that is at fault...now you need to figure out where in that circuit the problem lies...another possibility is that your alt may have an internal shot....after the bike has sat over night and before you start it reach in and feel your alt....should be cold...if its warm than there is your drain even thou no battery light comes on when your ridding and battery still charges.
Cheers for all the information, I've stripped all panels off the bike and i will carry out further tests tomorrow. I feel there is a short some where, heather its the Alt or in the wiring system i'm not sure but i will use your information and hopefully sort out my problems ,will let you know if all works ....Ger :)
 

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Discussion Starter #8
battery problems

Well guys i carried out my tests today. Battery is fine. positive test no draw on the battery, negative test with 12v light no problems there either. Bike charging rate 1390 approx so i feel this is fine, so i now feel that i have a bad earth or a poor power connection to the starter or something in this area. Now the fun and games start.......getting to the starter to check all out. May be in the work shop for some time. Anyway cheers for all the advice. :clap: :clap: :clap:
 

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Battery problem solved

At last its fixed, the thoughts of having to take of wheels ,drive shafts etc was really not an option but alas during my search...the cause was a damaged wire coming from the alternator,which lights the red light on the dash to show the the battery is charging, so wiring repaired and its on the road again....well as soon as i put the wheel back on. Thanks for all the help lads. In case your thinking that it took a long time to fix....well some times one just sits and thinks and other times one's just sit... :eek:ldster:
 

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Swaggerman said:
,<snip>

In case your thinking that it took a long time to fix....well some times one just sits and thinks and other times one's just sit... :eek:ldster:
I just did an alternator replacement ... took me three weeks, learning as I went and building special tools.

The wire which was your problem source also broke on mine as I was troubleshooting the problem. The connector is not designed to alleviate stress on the wire.

Turns out the regulator was bad on mine. One of the brushes was completely used up, the other fine. I replaced with a low-mileage unit purchased online.

I did a lot of sitting and thinking, and sometimes just sitting also!



 

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Had lost the alternator on my 86 k75 and put new brushes in I think it coast about $6-$8 bucks and not that bad a job what kind of spec. tools did you have to make to get it out of the k12 the k75 took about 1/2 hr. with the bikes tool kit have had it out 3 or 4 times for other things not that bad.
 

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K12rsK75c said:
Had lost the alternator on my 86 k75 and put new brushes in I think it coast about $6-$8 bucks and not that bad a job what kind of spec. tools did you have to make to get it out of the k12 the k75 took about 1/2 hr. with the bikes tool kit have had it out 3 or 4 times for other things not that bad.
To get to the alternator, you have to lift the frame off the engine, which requires removing the swing arm. That's why you see the engine hoist in the pictures above. It's used to lift the frame off the engine/tranny.

You need a deep socket with a window cut into it to properly torque the swing arm pivot and final drive pivot bearings.


Even though I could have just replaced the brushes, I replaced the entire alternator. The the bike as 98,000 miles on it, and I don't want to do this again. Who knows how many more miles were left in the alternator bearings, or if the stator insulation was breaking down. With this much effort, it just made more sense to replace the whole thing. A new unit from BMW is $800, I bought a used one with less than 9,000 miles on it for about $150. I'm sure I can get the old one rebuilt, but not sure if its worth it.
 

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Thanks for the info it seems to be a little more work on the k12 vs the k75 this should help if I have take it out on my k12

Thanks
Dave
 

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I had my K12 alternator out when I lifted the frame. I can't see it coming out easily unless you make some room behind it. At 36K the brushes and bearings were good. But they have a very wimpy very short wire which attaches to a terminal to run the charge light.

Judging by my minimal brush wear, I would guess at 100K before having to do something and at this mileage both brushes and bearings could be up for it. I checked the starter brushes too and they were good. In my opinion both units are pretty well made and the K12 alternator is big enough to run a city!



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