battery drain.. not sure what it is - BMW NineT Forum
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post #1 of 13 Old 04-13-2019, 06:14 PM Thread Starter
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battery drain.. not sure what it is

Hi Guys,

had a bike since they came out. wondering if anyone has heard of stories of a constant battery drain on the bike?

I took my bike in twice for battery issue. I told them I can tell something is wrong, the cranking doesn't sound right and feels like a lack of power.. they tested I guess the electrical charging system, nothing wrong, it's in my head.. second time a guy brought the bike to the shop for fluid change, was there a week and battery was dead when he went to pick it up, they thought it was a dud battery that we just replaced... I finally got my bike off the boat from shipping to Hawaii, and again battery was dead with a new BMW battery...

so something is wrong.. I'm just not sure where to begin or if anyone has had this issue, seems so odd.

any opinions, directions, help, advice appreciated!
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post #2 of 13 Old 04-14-2019, 04:04 AM
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I always keep mine on an Optimate 4 charger and always leave my bikes that way to help keep the battery in good shape.

Do you have an alarm? They have been know to drain the battery. The R9T is a pretty basic motorcycle without a lot of electrical goodies so that should not be happening.
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post #3 of 13 Old 04-14-2019, 10:29 PM
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There is always some parasitic drain on the battery, as is the case with all modern vehicles.

What kind of interval are you talking about, a week, or a month without charging or running?

Have you added anything to the electrical system or have anything plugged into the accessory socket on a regular basis?

You can check for yourself if there is an unusually high drain on the battery, but it requires getting to the battery with a multimeter.
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post #4 of 13 Old 04-15-2019, 05:52 AM
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A USB adaptor will do it

If you leave a USB plugged in it will drain the battery as it does draw current even with out something plugged into it. Also the '14 and early '15 got a lower cranking amp battery from the factory, you should get the higher cranking amp battery.
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post #5 of 13 Old 04-17-2019, 03:23 PM Thread Starter
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Thanks guys. I mean serious. We had a new battery installed. Got immediately shipped on a boat to Hawaii which was 2 weeks. Battery was dead on arrival.

I have nothing plugged into the bike. No USB. No nothing. Only some pigtails for a ctek charger and a SAE plug ( battery tender brand ) that’s the only thing I can think. I do know the blinkers were changed before I got them. I got a led back light on the bike. I can’t think what could possibly drain the battery.

This same thing happened to the first battery. It would maybe be dead In a Week if I didn’t put it on a charger everyday.
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post #6 of 13 Old 04-18-2019, 07:44 AM
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As others mentioned, be sure that you do not leave anything in 12V plug. CanBus is checking time to time what's in. I left there (by accident) Navi holder (without Navi!), so there should be almost 0 current taken, but it drained my battery to almost 0 capacity in couple of days. Lesson Learned...

RnineT, FJR1300AE, F3 800, R1200RS, G650GS, CMX500, XL125V
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post #7 of 13 Old 04-18-2019, 12:37 PM
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Originally Posted by kebo View Post
As others mentioned, be sure that you do not leave anything in 12V plug.
Not to say you're wrong, but I've had my USB adapter w voltmeter in that plug for about 6 months with no battery issues whatsoever. Voltage always where it's supposed to be. I ride almost every day on a 2018.

I share this info to learn more. Why am I not experiencing any issues? Or am I draining my battery in a way that I'm not able to measure by V alone? I rarely use that port so I'd have no problem unplugging if need be. Thanks!

2018 BMW R nineT Pure
Oakland, CA

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post #8 of 13 Old 04-18-2019, 01:50 PM
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I think it depends on the accessory connected to the socket. The bike's CANBUS system checks the accessory socket and is meant to shut power down after a minute or so, unless it's told to stay alive (My Optimate 4 charger apparently does this - don't know how though), however my Garmin 590 has power removed by it a minute after the ignition is turned off. Some accessories may somehow confuse the bike into leaving the socket active and this is when flat batteries happen.

Unplugging any accessory from the socket would be the first thing I'd try if I was having battery issues.

Just my thoughts, I'm by no means an expert.

Best practice would be to remove any accessory from the socket unless you know for sure how the accessory socket will behave.

Today I'll be mostly riding.....

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1979 Moto Guzzi MK1 Le Mans (950 conversion, proddy race engine)

Last edited by BaldyDave; 04-18-2019 at 01:54 PM.
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post #9 of 13 Old 04-19-2019, 02:51 PM
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Since you are replacing the battery, it would be a good idea to check for an unusually high parasitic drain.

When you have a known good battery, put a multimeter in line between the bikes main ground and the battery ground, with the bike OFF.

IMPORTANT: Do not key on the bike, honk the horn or try to start it with the multimeter inline. (unless you hate your meter and want to buy a new one after you fry it)

With the multimeter set to DC Amps, start at 20 or 10A range, measure and go to a smaller range from there if needed.

If you get a reading higher than a 50mA draw, you have an electrical problem on the bike and you need check individual components.

Anything added aftermarket would be a good start. Unplug one by one and see if the mA reading drops.

When it does, you've found your culprit.

If not, then maybe you are just having incredibly bad luck with batteries (try a different brand?).

This can be a very time consuming, and costly process, so your garage may not have wanted to spend the time on it.
Much cheaper and fast for them to swap the battery and tell you everything is fine.

Happy hunting!
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post #10 of 13 Old 04-19-2019, 08:52 PM
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+1 for a multimeter check of the parasitic current drain.
Sometime last century I worked on vehicle security systems, and a dark current of even 10mA is sufficient to flatten your battery if left for a couple of weeks.

/// Motorrad
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