Help - dead battery?

[Scott A]

I just returned from two weeks out of town, tried to start my bike (k1200s), and the bike acts like it has a dead battery - at first the dash lit up, but it wouldn't turn over. Then, the dash stopped lighting, but the front parking light and the headlight are both on, but dim.

 

So, I tried my battery tender (an older model, purchased for an 11RT). When connected to the aux. socket, it blicks red, indicating nothing at all is hooked up. So I tried an automotive charger, directly on the battery (which I disconnected from the bike). According to the auto charger, the battery is fine (green light indicates charged). Fearing damage to the sealed battery, I quickly disconnected.

 

Shouldn't the battery tender work through the aux socket? Okay, maybe it's not one of the BMW-specific tenders, desigend for gel batteries, but still, just to juice the battery enough for starting?

 

First - are the any other reasons besides dead battery for the wymptoms I'm seeing?

 

Second - assuming the battery is dead - any ideas about why the battery (less than 1 year old) would die after jsut two weeks?

 

Third - what's my best method of charging, without purchasing another charger (unavailable over the weekend)

 

Thanks for any advice...

[Scott A]

PS - voltage across the battery terminals reads 5.75!! What the heck happened?

[kuyaed33]

I just returned from two weeks out of town, tried to start my bike (k1200s), and the bike acts like it has a dead battery - at first the dash lit up, but it wouldn't turn over. Then, the dash stopped lighting, but the front parking light and the headlight are both on, but dim.

 

So, I tried my battery tender (an older model, purchased for an 11RT). When connected to the aux. socket, it blicks red, indicating nothing at all is hooked up. So I tried an automotive charger, directly on the battery (which I disconnected from the bike). According to the auto charger, the battery is fine (green light indicates charged). Fearing damage to the sealed battery, I quickly disconnected.

 

Shouldn't the battery tender work through the aux socket? Okay, maybe it's not one of the BMW-specific tenders, desigend for gel batteries, but still, just to juice the battery enough for starting?

 

First - are the any other reasons besides dead battery for the wymptoms I'm seeing?

 

Second - assuming the battery is dead - any ideas about why the battery (less than 1 year old) would die after jsut two weeks?

 

Third - what's my best method of charging, without purchasing another charger (unavailable over the weekend)

 

Thanks for any advice...

 

scott,

The aux socket on the CAN bus bikes only turn on when the key is turned on or with the BMW special charger for the CAN BUS bikes. If you have a flat battery check with your dealer to make sure there is no problem with your charging system. I know with some of the early CAN BUS bikes there was an issue with draw on the battery from the ZFE when the key is off. Also when you're not going to ride the bike for a long period of time it is a good idea to keep the battery on a tender. If you're going to use the older BMW charger that's for gel batteries, you have to go directly to the battery because it will not activate the aux socket. The new BMW battery charger for CAN BUS bikes have the ability to "wake up" the onboard computer (ZFE) and activate the aux socket so u can charge the battery through the aux socket. good luck with that and let me know what you find.

 

Eddie

[Scott A]

I got the bike running - don't know why the battery was dead in the first place, but I was able to jump start the bike with my car, and after a short cruise around the block, I hooked the the battery tender up with the ignition on, and it's currently charging the bike.

 

According to the manual, the aux socket shuts down if the voltage drops too far, which explains why the battery tender was not seeing the battery when hooked up before.

 

I'm not sure why the car charger saw the battery as okay, but then, it probably wasn't a great idea to hook it up to that little battery to begin with.

 

I'm still curious about why the battery died after sitting for only two weeks, with only the clock to pull from it (no alarm or other accessories installed). Maybe I should ask my dealer, while the battery is still under warranty.

[Scott A]

Thanks, Eddie.

 

It seems that the behavior of the aux socket is not so simple as turning off when the bike is off, since it stayed activated when I shut off the ignition while the charger was plugged in (only after I jumped the bike, presumably because the ZFE was at that point alive and able to see the connection at the aux socket).

 

I wonder how the CAN-bus-compatible charger is able to signal the ZFE through an aux socket that's been disabled. Good trick. It also implies that the ZFE does draw current all the time the bike is off?

[haddoncoach]

Sorry for my naive question here but - CAN? BUS? I have a 2000RS that I hook up to a battery tender every night through the aux plug on the side - ignition off. Is there something I should know here?

[kuyaed33]

Sorry for my naive question here but - CAN? BUS? I have a 2000RS that I hook up to a battery tender every night through the aux plug on the side - ignition off. Is there something I should know here?

 

on the CAN (Controller Area Network) bus bikes there is a special charger available from BMW. The way the CAN BUS aux sockets work is that when the key is turned off the aux socket will eventually stop supplying power. Your RS's aux socket is hooked directly to your battery and is always "hot," which allows you to charge your battery even with the key off. With the CAN BUS bikes there is a special charger and a special procedure in hooking up that charger. On a CAN BUS bike, with the key in the "ON" position, plug the charger into the aux socket, then plug the charger into the wall, then turn the key "OFF." This will allow the aux socket to stay "hot," while the charger works. Hope that helps answer your question. For more info on CAN Bus check out this site

[RFW]

Sorry for my naive question here but - CAN? BUS? I have a 2000RS that I hook up to a battery tender every night through the aux plug on the side - ignition off. Is there something I should know here?

Why on earth would you put the battery on charge EVERY NIGHT? This is useless at best, and potentially damaging to the battery in the long term at worst. You wouldn't do it to your car, so why are you doing it to your bike??

 

CAN BUS is a system that eliminates a lot of wiring compexity, and substitutes it with electronic compexity. There is basically a single power wire running through the bike (or car or whatever), and each user of power has an electronic black box that receives communication via a separate "bus", and switches on when commanded, drawing power from the power "bus". The idea is that a huge amount of separate wires in a wiring loom can be dispensed with.

 

CAN BUS is a Bosch inovation, that they came out with about 15 years ago.

 

Bob.

[cjack]

Thanks, Eddie.

 

It seems that the behavior of the aux socket is not so simple as turning off when the bike is off, since it stayed activated when I shut off the ignition while the charger was plugged in (only after I jumped the bike, presumably because the ZFE was at that point alive and able to see the connection at the aux socket).

 

I wonder how the CAN-bus-compatible charger is able to signal the ZFE through an aux socket that's been disabled. Good trick. It also implies that the ZFE does draw current all the time the bike is off?

 

The accessory socket stays on for about 1 minute after the key is turned off. The BMW gray charger can charge the bike thru it by keeping the accessory socket on (I measured some 120 cycle 15 volt peaks on an average charging voltage of about 14.x volts, which I assume is what keeps the socket live). There is some confusion about whether you have to turn on the ign first then plug in the charger, etc. or just plug in the charger. I have seen both work on my S.

There is another issue which has been fixed with the upgraded software from BMW where the bike electrics draw a significant current while the bike is off if you turn the key on and off in one second. Also there was an issue where the parking light could be turned on by depressing the turn signal switch for a short time instead of the later software program which required a 5 second period...leading some to unknowingly turning on their parking light, draining the battery.

Since the acc socket only supplies 5 amps and it is not sufficient to run my Gerbing heated liner (note that some of the BMW heated vests in the xxlarge sizes take more than 5 amps), I have installed an acc socket directly on the battery, fused, and use if for all charging and heated clothing. Just make sure that your charger is smart and doesn't go over 14.x volts (like a Battery Tender) when charging so it won't damage any bike electrics.

 

[haddoncoach]

My bad - I meant that I leave it hooked up over the winter when I don't ride it.

[tallman]

Actually, some of us do hook it up to a tender all the time.

I run Motolights, sometimes w/PIAA's, can have my wife's Gerbings jacket liner/gloves, my jacket liner, GPS, etc,

on at the same time.

I've done the put it on the Tender if I haven't ridden routine, the put it on on a regular cycle routine, and the put it on after every ride/leave it hooked up routine.

Anecdotally the last method has worked best for me. This has been on airheads, oilheads, and the KGT.

With the first two methods my battery life was shorter than it has been w/last method.

It can't hurt.

[USAF1]

I have a 20 mile ride to work and home every day.....I put the (BMW) charger on when I get to work....and it takes 7 hours to show a solid green light.

 

Pat

[bmwmick]

Pat,

I predict there is a new battery in your future.

After a 20 mile ride with heated grips on High and my Widder vest plugged in (460 Watt Alternator), my Battery Tenders only take about an hour to go green.

 

Mick