Help me confirm I need a new battery?

1498 Views 34 Replies 13 Participants Last post by Mark Jackson, 17 d ago

daniel.poirier

Discussion Starter · 1 mo ago

I bought my 2017 R1200R a little over a year ago, and it had been meticulously maintained by the original owner. However, I don't know if (a) it still has the original battery, making it 6 years old, and (b) if the owner regularly used a battery tender (though he had installed a quick-connect battery charger cable connected directly to the battery, which seems to indicate that he used a charger).

Anyhow, I had it on a trickle charger all winter, the bike started beautifully earlier this spring, but now if I let it sit for a week or so, it won't start. After a two-hour recharge, it starts fine. Over the phone, my bike mechanic said the battery probably doesn't hold its charge anymore and most likely needs to be replaced.

But the reason I'm checking in with all you wonderful people is that the R has a lot of bells and whistles and blinking lights and alarms and keyless misbehavior, so I wonder if even a brand new battery might end up also being continuously discharged slowly.

Other than all the standard doodads that are using up power on the bike, I have two passive cables connected straight to the battery (the aforementioned recharge quick connect cable, and a usb charger cable I routed to the handlebar area to plug in my phone if ever). Both of these are just cables, no switches, no led lights, nothing... but could they trick the ecu into flicking on and off all the time to check something or other, and therefore discharging the battery?

The other thing I just remembered is there is a red blinking light on the display panel (alarm system enabled?)... Is that supposed to be blinking all the time, and does it explain a discharging battery?

If I can rule out these two remote possibilities, then I can just go ahead and get a new battery.

Huge thanks in advance for any guidance!

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Lee F

· #2 · 1 mo ago

I've seen posts where some of the USB charging cable have caused a battery drain problem.
I don't know anything about the OEM alarm.
Maybe others can chime in about the USB charger.
You could always disconnect the USB charger and see if the bike battery holds it's charge longer.

r0ckrat

· #3 · 1 mo ago

Yes - many USB converters don't know how to turn off when not in use and can create a drain on the battery. Accessories of any sort are best connected to a circuit controlled by a relay triggered from a switched power source (tail light, for instance).

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daniel.poirier

Discussion Starter · #4 · 1 mo ago

r0ckrat said:
Yes - many USB converters don't know how to turn off when not in use and can create a drain on the battery. Accessories of any sort are best connected to a circuit controlled by a relay triggered from a switched power source (tail light, for instance).

Hell and damnation! Even a silly passive female usb receptacle connected to the two battery terminals? What power could it possibly draw?

r0ckrat

· #5 · 1 mo ago

A "passive female usb receptacle" isn't as passive as you think. It must reduce 12v to 5v (or less). Most of them don't include the switching circuitry to disable the conversion when the current is not being drawn, so it just keeps chugging away reducing 12v to 5v and bleeding off a little current... You can actually test this yourself with a decent multimeter by putting it between the positive battery line and the positive terminal on the usb charger.

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daniel.poirier

Discussion Starter · #6 · 1 mo ago

r0ckrat said:
A "passive female usb receptacle" isn't as passive as you think. It must reduce 12v to 5v (or less). Most of them don't include the switching circuitry to disable the conversion when the current is not being drawn, so it just keeps chugging away reducing 12v to 5v and bleeding off a little current... You can actually test this yourself with a decent multimeter by putting it between the positive battery line and the positive terminal on the usb charger.

Thanks for that, I learned something today. Just to clarify, what would I expect to see between the battery positive and the USB socket positive? Some range of, what, milivolts?

mikeS

· #7 · 1 mo ago

Six years is a good run for a battery, and just for peace of mind, I’d replace the battery next service. I've had my ‘17 since new always on a battery tender, at home but I replaced the battery at 90k. Batteries tend to fail at the most inconvenient time/place.

Sent from my iPhone using Tapatalk

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r0ckrat

· #8 · 1 mo ago

daniel.poirier said:
Thanks for that, I learned something today. Just to clarify, what would I expect to see between the battery positive and the USB socket positive? Some range of, what, milivolts?

I'm afraid I don't know the answer to that - I just know that the circuitry doesn't "sleep" properly on most USB chargers, so they bleed energy.

Long Ranger

· #9 · 1 mo ago

I’d just replace the battery to end the anxiety.

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daniel.poirier

Discussion Starter · #10 · 1 mo ago

Thanks to you all. I replaced the battery. Now the remaining question / mystery is: do I remove that usb socket to avoid any suspected battery drain in the future... I'll ponder that for a bit.

Lee F

· #11 · 1 mo ago

mikeS said:
Six years is a good run for a battery, and just for peace of mind, I’d replace the battery next service.

Sent from my iPhone using Tapatalk

The OP doesn't know how old the battery is.

Panzermann

· #12 · 1 mo ago

daniel.poirier said:
Both of these are just cables, no switches, no led lights, nothing... but could they trick the ecu into flicking on and off all the time to check something or other, and therefore discharging the battery?

If connected directly to the battery, the chassis computer won’t know they’re there. It’s a different story if they’re plumbed into the accessory socket wiring - such accessories as a USB charger can keep the chassis computer live, draining the battery even more than a supposedly dormant USB adapter will when attached directly to the battery.

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Panzermann

· #13 · 1 mo ago

daniel.poirier said:
Thanks to you all. I replaced the battery. Now the remaining question / mystery is: do I remove that usb socket to avoid any suspected battery drain in the future... I'll ponder that for a bit.

Did you look at the date on the old battery, just to see how old it is?
As per earlier comments, an unswitched USB adapter connected directly to the battery will drain it somewhat.

zer0netgain

· #14 · 1 mo ago

I’ll say I’ve had lackluster performance from the RS battery. I replaced mine with one from Big Crank, which I know is good (should be better than OEM), but even then is need to plug in the battery tender is I’ve not used the bike in a couple of weeks. Granted, I have a DVR system installed that draws power until the battery level drops to a given voltage, but even before the install, it seemed the OEM battery needed topping off regularly. I think the CANbus stuff and keyless tech imposes a minuscule drain that adds up over time. Also, that everything is digital, low voltage is more noticeable than it would be on an analog system where starting doesn’t need a pre-flight check from the ECU.

arfingdog

· #15 · 30 d ago

Sure sounds like a battery at the end of its life. They'll charge up and show decent voltage, but have little capacity. As others have said, I'd replace it just to avoid the inconvenience and worry. And let's face it, in BMW world, a battery is a relative inexpensive part! You might want to put a switch on that USB charger or check its draw with the bike off.

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daniel.poirier

Discussion Starter · #16 · 30 d ago

arfingdog said:
... You might want to put a switch on that USB charger or check its draw with the bike off.

I'm still trying to figure out how to measure any current draw. Putting an ammeter in line is not really feasible.

r0ckrat

· #17 · 30 d ago

voltmeter set for 12v. If it shows anything between the battery and the charger, it's drawing (open). It should be like a switch. Off should show 0v (closed), anything but 0v is open/on.

You could even put a simple switch inline for testing to double check. Switch off should disconnect, switch on and nothing plugged into the charger should also also be "closed"/0v on the line. If it's not 0v then it's slowly draining the battery.

A phone plugged into the charger should also show some number greater than 0v, but (hopefully) less than 12v.

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r0ckrat

· #18 · 30 d ago

Oh - if you want to connect it to a switched source of power, on the right below the pillion seat there might be a "Powerlet" outlet that many/most bikes in the US came with (like a mini-cig-lighter plug). I'm pretty sure those are ignition-switched power sources (for heated gear, etc.) If you remove panels you can get to the back side connector for that and wire the charger to it.

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daniel.poirier

Discussion Starter · #19 · 30 d ago

You guys rock! Thanks a bunch, I now have a few options

Panzermann

· #20 · 29 d ago

If the USB adapter is connected directly to the battery, then simply disconnect its positive lead and put your ammeter in series with that line (i.e. one lead to the battery and one to the disconnected lead). It doesn't really matter which lead is which - for any current draw one way around you'll get a positive number, the other a negative. You will likely need to put the ammeter's red lead into an Ammeter rather than Voltage/Resistance socket on your ammeter (and be sure its fuse isn't blown). A milliamp setting on your meter should be appropriate.

Take care using the Powerlet/Hella socket wiring to connect such a device - they've been known to trick the chassis computer to switch back in after it's post key-off shutdown time, and continue this cycle continuously. It happened to my LC in the early days and flattened the battery over my workday.

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