Any reason not to jump-start a 2018 RT?

[Ken S]

The RT has been in storage over a year.  The trickle-charger will have been on for 24 hours when I get back to the bike today.  Is it OK to jump-start it, if needed?  The friend where I left the bike didn't keep the charger on it for quite a while.

 

When I left the bike in Albuquerque in Oct 2019 I couldn't imagine a situation that would keep me from getting back for a ride in a few months.  I was on my way back in March 2020, but then things happened.

[92Merc]

The thing that I go buy is to NOT have the donor vehicle running.  Just tap into the battery only.  The other vehicle running can sometimes send out a spike or too much voltage that could ruin systems on the bike.

 

I don't know if that's an old wives tale.  But to me it's sounds reasonable.  Plus the donor car/truck usually has way more reserve power in the bigger battery.  So the extra voltage really isn't needed on a bike.  Just my opinion...

[Skywagon]

Jump-starting with a donorbattery voltage higher than 12 V can damage the motorcycle electronics. The battery of the donor vehicle must have a voltage of 12 V. Make sure ground is level and firm and park motorcycle. Remove battery cover ( 131). When jump-starting the engine, do not disconnect the battery from the onboard electrical system. Begin by connecting one end of the red jump lead to the positive terminal 2 of the discharged battery and the other end to the positive terminal of the donor battery. Connect the black jump lead to the negative terminal of the donor battery and then to the negative terminal 1 of the discharged battery. Run engine of donor vehicle during jump-starting procedure. Start engine of the vehicle with discharged battery in usual way; if engine does not start, wait a few minutes before repeating attempt in order to protect starter motor and donor battery. Allow both engines to idle for a few minutes before disconnecting jumper cables. Disconnect jump lead from negative terminals first, then disconnect second lead from positive terminals

 

directly from the manual page 129

[dirtrider]

49 minutes ago, Skywagon said:

Jump-starting with a donorbattery voltage higher than 12 V can damage the motorcycle electronics. The battery of the donor vehicle must have a voltage of 12 V. Make sure ground is level and firm and park motorcycle. Remove battery cover ( 131). When jump-starting the engine, do not disconnect the battery from the onboard electrical system. Begin by connecting one end of the red jump lead to the positive terminal 2 of the discharged battery and the other end to the positive terminal of the donor battery. Connect the black jump lead to the negative terminal of the donor battery and then to the negative terminal 1 of the discharged battery. Run engine of donor vehicle during jump-starting procedure. Start engine of the vehicle with discharged battery in usual way; if engine does not start, wait a few minutes before repeating attempt in order to protect starter motor and donor battery. Allow both engines to idle for a few minutes before disconnecting jumper cables. Disconnect jump lead from negative terminals first, then disconnect second lead from positive terminals

 

directly from the manual page 129

Afternoon David

 

"Jump-starting with a donor battery voltage higher than 12 V can damage the motorcycle electronics"

 

I'm guessing that first sentence is a misprint in your manual as that should probably read 15 volts as 15v  is the usual BMW high voltage upper threshold. Almost every 12 volt battery that has a full charge is well over 12v.   

 

 

[Skywagon]

I agree with you.  It is what is says exactly as I did a cut and paste.  I think what they mean is don't use something like a 24-36V from a golf cart, boat, airplane, etc.  I think my old 1150 said don't start the donor car, but this one does say start it....  A slightly different question.  If you didn't have enough juice to run the starter, but still had some juice....can you actually push start these bikes and get them going in say 2nd or 3rd with a battery that might register 10V or so.  Will the alternator keep them going?  The reason I ask is I've been thinking about buying and packing one of those little jump chargers that say they are 20,000 mAh for $50-75...

[RPondaRoad]

On page 152, my '18 manual reads: 

* Run engine of donor MOTORCYCLE during jump-starting proceedure.  

My understanding of "best practice" is that when jumping from an automobile, the engine is not to be running.  

https://www.yuasabatteries.com/resources/motorcycle-battery-jump-start-guide/

 

https://www.rideapart.com/features/423957/jump-start-motorcycle-battery-with-car/

 

https://www.motorcycle.com/ask-mo-anything/ask-mo-anything-jumpstarting-a-motorcycle-from-a-car.html

 

https://www.motorcyclistonline.com/jump-start-dead-motorcycle-battery/

[szurszewski]

@Skywagon

 

Even if you can push start one, I think you’d be much happier with the lithium jump pack. I’ve used a number of brands - including multiple Antigravity - and finally settled on buying them at Costco. Initially that was so I could return them easily (two antigravity units failed early), but I haven’t actually had to return one yet (in over three years). I have one in (almost) each vehicle and don’t use them on our stuff much but often help someone I find on the road/in a parking lot. 

[Rougarou]

When I was running into battery drainage issues with the PC680 (dead after only three days) and before that with the slow death of the Deka battery, I'd jump start it with the wifes truck running.....I've got no electronic issues and have done plenty of jumps.

[Ken S]

Thanks all. I did jump-start the bike from my truck -- not running.  It has charged up fine, and I've put over 300 miles on it in a couple days.

 

The twisties going up to Sandia Crest (10,600' elevation) east of Albuquerque, were lots of fun.  But several ice patches and one declining-radius turn certainly got my attention.  Then down to see the sandhill cranes at the Bosque del Apache Wildlife Sanctuary.

[Cap]

On 11/4/2020 at 8:24 PM, Ken S said:

The twisties going up to Sandia Crest (10,600' elevation) east of Albuquerque, were lots of fun. ...

 

Did you go down the north side, on the dirt road, towards Placitas?  I looked at that dirt road, and some recent ride reports on ADVrider, and decided I would explore other parts of NM!

 

[Ken S]

Same here!  I started up the road through Placitas last time I was in NM, but turned around shortly after it turned to dirt.  I decided that the RT is not the bike for that road.

[Lowndes]

On 11/3/2020 at 11:57 AM, Skywagon said:

I agree with you.  It is what is says exactly as I did a cut and paste.  I think what they mean is don't use something like a 24-36V from a golf cart, boat, airplane, etc.  I think my old 1150 said don't start the donor car, but this one does say start it....  A slightly different question.  If you didn't have enough juice to run the starter, but still had some juice....can you actually push start these bikes and get them going in say 2nd or 3rd with a battery that might register 10V or so.  Will the alternator keep them going?  The reason I ask is I've been thinking about buying and packing one of those little jump chargers that say they are 20,000 mAh for $50-75...

 

Skywagon,

 

I'd guess it would be a very narrow voltage window that would not allow the starter but would allow the ECU to function, but my experience says the ECU cuts out first on my older bikes.  Later bikes may be different.  Dirtrider will know.

 

I've also learned that cracking the throttle a tiny bit while cranking on a low battery will decrease the load on the starter motor (it lowers the intake vacuum) and may be the difference between cranking and not cranking. 

 

I wore out three friends and a brother one morning trying to push-start my '99 R1100S with a very low battery.  Now I just carry a Li-on jumper pack.  It comes in handy for all kinds of things.  You might want to install an easily accessable + (positive) connection point if your battery is hard to get to:

 

 

I installed a nearby SS ground connection point (same terminal part as the positive under the black "+" cap above).  Good, accessable, bare, unpainted steel or aluminum ground connection points are surprisingly hard to find on some bikes:

 

[dirtrider]

58 minutes ago, Lowndes said:

 

Skywagon,

 

I'd guess it would be a very narrow voltage window that would not allow the starter but would allow the ECU to function, but my experience says the ECU cuts out first on my older bikes.  Later bikes may be different.  Dirtrider will know.

 

I've also learned that cracking the throttle a tiny bit while cranking on a low battery will decrease the load on the starter motor (it lowers the intake vacuum) and may be the difference between cranking and not cranking. 

 

I wore out three friends and a brother one morning trying to push-start my '99 R1100S with a very low battery.  Now I just carry a Li-on jumper pack.  It comes in handy for all kinds of things.  You might want to install an easily accessable + (positive) connection point if your battery is hard to get to:

 

 

 

I installed a nearby SS ground connection point (same terminal part as the positive under the black "+" cap above).  Good, accessable, bare, unpainted steel or aluminum ground connection points are surprisingly hard to find on some bikes:

 

 

Morning  Lowndes

 

I don't know the exact low voltage threshold on the newer water cooled BMW boxers to push start but even if I could put a number to it that number would wobble around a bit depending on (if) the engine was somewhat warm and had  already been running just prior.

 

The BIG problem is you can't go by BATTERY voltage, you need to go by SYSTEM voltage just before & throughout the pushing-off.

 

A good rule of thumb on the electronic  marvel bikes is 10 volts at or above in the system RIGHT AT FIRE OFF. With all the stars aligning you m-i-g-h-t get a push-off start at 9.5 system volts but it better stay at that voltage or above until it fires off.

 

10 volts at the battery with key off (basically a dead battery)  sure won't give you 10 volts in the system with the key on. 

 

Even 10 volts in the system with key-on will probably drop much lower when you start pushing & the fuel pump kicks in & the fuel injectors & coils come on line. 

 

Just keep in mind that with a lower than full battery voltage  at push off the fuel injectors will only be giving a lethargic spray, the coils will be sparking at partial output, the fuel pump will be low on supplied pressure so on  a dead cold  push off everything is stacked against you. 

 

Now on the water cooled BMW's with permeant magnet alternator rotors  IF you push (or more likely pull with another vehicle) fast enough to get the engine spinning fast enough to get the alternator to come on-line & produce charging current then there is a possibility that will boost the system voltage enough to get a fire-off. (take a pretty good, way above walking speed, pull for a distance for this to work though)   

[lkraus]

I tried push starting my '06 RT, once.  Even in sixth, on flat pavement, I could not get enough momentum to overcome compression. Now, if I'll be too far from home for "Honey, bring me the jumper cables", I carry my portable jump starter. 

 

I understand the wetheads have some sort of decompression mechanism, so maybe they could be push started if the battery is not completely dead. Try it before it is a necessity.

[Lowndes]

THANKS, again, Dirtrider!!  Excellent explanation.  

 

Somehow the notion of being towed at speed on a bike is not comforting.  Must be something in my dim distant past.  Whenever I hear the phrase "getting jerked around", it always conjured up memories of being towed on a bike.

 

 

[Skywagon]

Thanks guys....my question was out of curiosity not because I have a failing battery.  I change my battery every 3 years regardless.  I do the same on all my vehicles.  I for sure couldn't push it very far or very fast.  If I could find a steep downhill maybe spin the alternator up...Oh year I live in Houston...it's so flat you can see Oklahoma from my front porch.

 

Whats your favorite portable jump starter?  

[Lowndes]

"Whats your favorite portable jump starter? "

 

Skywagon,

 

Check szurszewski's Nov 3 post above.

[lkchris]

Jump starting is certainly a topic listed in the Owners Manual index for my Camhead ...