Mid-Winter Battery Charge

[Stephen_Chase]

I confess to not having charged my gel battery yet this winter. Frankly, not having done it before I am reluctant to try it for fear of damaging the electrical system.

 

Can anyone tell me the proper procedure? I have a plug adapter & have made a 12V plug-in with 2 leads (alligator clips, isolated from one another).

 

BTW, the bike was put away correctly according to this site: Stabil & fresh oil/filter. It will be approx. 2 mos. before a ride is likely.

Thanks!

Stephen

[Alien_Hitchhiker]

Stephen, what kind of charger do you have? As long as it is a trickle charger it's doubtful that you'll hurt the battery or the electrics, even if the charger is not marketed as specific for your brand of battery. It just may not give it an optimum full charge.

 

If you're paranoid about using it pull the battery and charge it on the floor.

 

I routinely use a Battery Tender Jr with my BMW/Marek gel battery, although it's rare for my bike to go for more than a week without a ride (ahh, North Carolina!)

 

If the thing blows up, ignites your bike and burns your house down, I'll deny everything

[Stephen_Chase]

I forgot to add that I have a "smart" battery charger that allows a trickle charge.

Stephen

[ShovelStrokeEd]

Just charge it up and don't worry over much about it.

 

If you are really paranoid, you could follow the advise above and just disconnect the leads from the battery and charge it that way. Having done so, when you do go to start the battery, don't forget to teach the Motronic the TPS settings. What it does varies with the year of the bike but either way, key on (don't start) wind throttle from full closed to full open twice, and you are good to go.

 

When you disconnect the battery, the EFI computer (Motronic) forgets some settings, one of which is the range of the TPS, the other is a set of "learned" riding habits. Until it relearns these things, it will not run exactly the same as it did before. Nothing serious mind you, but the first couple of tanks of gas may not yield the same fuel milage you were getting before.

[Pictou]

If you have a smart charger then just hook it up to the battery and your good to go. I plug one into the power outlet on my 1150RT all the time with no problems. Mine is a BMW branded charger (which is just an overpriced Deltran Battery tender plus) and it came with the adapter to plug into the power outlet. So BMW seems to think it is fine to charge the battery while its still connected to the electrical system of the bike. I don't think you will have a problem just charging the battery without bothering to disconnect it.

[Spat]

the EFI computer (Motronic) forgets some settings, one of which is the range of the TPS, the other is a set of "learned" riding habits. Until it relearns these things, it will not run exactly the same as it did before.

 

Ed, when diconnecting the power, explain please what riding habits is "learned"?

 

 

I have always charged batteries connected and use a trickle charger. I have ruined a battery once over the year by over charging it and cooking it to death. Without burning the house down by the way, it isn't a turkey frier but could happen I guess.

[ShovelStrokeEd]

The Motronic monitors the TPS signal all the time and actually learns your habits in regards how often and how much you turn the throttle. It then works to modify its response to these throttle turns such that you will see a marked difference in fuel economy if you spend a couple of weeks of round town riding and then go on a long trip. The first tank will be the same but as the Motronic learns the new riding pattern which would be long periods of steady throttle operation, it adjusts itself to provide better economy such that the third tank would probably show a 2-3 mpg decrease in fuel consumption. Don't ask me the details of this as I don't know exactly how it is done. Years of observation have proven it so as have some discussions with folks far more familiar with the Motronic system than I.

 

The TPS learning thing is simple. The bike needs to know both the idle position and the wide open throttle position to decide which portion of the internal maps to use. The map, at its most basic, is engine RPM on the X axis, throttle position on the Y and a set of values for fuel injector pulse width for each step in both. When you teach the Motronic the idle and wide open positions you are scaling that y-axis. It is actually a good deal more complex than this as ignition timing adds a third dimension to the graph. AFAIK, the learned portion of the thing acts as a kind of overlay on the base map. For example, if you are in the habit of making large throttle transitions such as might be encountered in around town riding with its stop and go or slow and accelerate traffic patterns the Motronic may provide you with a bit more fuel in the lower RPM regions to sharpen throttle response. Similarly, long periods of steady throttle may find the motor leaning out a bit to improve economy. Kinda like the piston driven airplane engine specification of best power mixture as opposed to best cruise mixture.

[No_Twilight]

Stephen, you're a double victim of the evil marketing executives.

 

1. They want to scare you into buying their battery chargers by saying that normal ones can cause damage.

 

2. You bought their expensive charger like they wanted you to but were still afraid to use it because of the scary messages they've sent.

 

Sure, if you leave a normal battery charger installed it will cook your battery. Thus the smart chargers were developed that automaticly switch to trickle for those forgetful people. But if you put a trickle charger on your battery when it is already charged, you'll never need a high current charger.

 

Harbor freight has their trickle charger on sale for $7.99.

 

--Jerry

[Spat]

Thanks for the explaination Ed.I had never heard that, sounds like PFM.

 

Back to Stephens question. The dealer has always told me you can charge your battery through your accessory plug, sounds simple, keep it simple.

[jellero]

i would worry more about the harbor freight tenders bursting into flames than my battery. j

[Spat]

Well I have been reading other threads here and adv. on battery charging issues. I now plead ignorance on sensitivity of charging issues for BMW's. I will read on and learn.

Thank you for your post and all responses.