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'05 R1200RT Battery Charging


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<sorry for the repeat, I posted to "oilheads" by mistake>


I'm still confused about battery charging over the winter months for my '05 1200RT. I searched the posts but they seem to be more about charging through the power outlet.


1. Can I use a regular Battery Tender or Battery Tender Jr. (i.e. not the BMW version)? connected directly to the battery? I don't have the BMW outlet plugs.

2. Can I leave the battery cables connected while charging? i.e. will charging with the B/T cause damage to the CANBUS system? Or should I disconnect the cables and remove the battery?

3. I have but the B/T and B/T Jr. Does it matter which one I use (other than charging time)?


Battery is BMW OEM and from what I can tell from previous posts, it's a GEL type (I haven't verified it on the bike).





'05 R1200RT

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Rich -


I think you have two concerns here: 1) damage tothe CanBus system; and 2) damage to the Gel battery.


Below, I've attached a copy of the "official" word from BMW which has been posted on this board several times. Contrary to what it says, a lot of folks here say they are attaching their Battery Tenders directly to the battery without disconecting it from the bike, apparently with no problem. I guess the bottom line here is to proceed at your own risk.


Regarding the Gel battery. Appartently, a "regular" Battery Tender can damage a gel battery because it's output voltage can be too high. Deltran makes Tenders, including two for BMW shown below, that address this problem. I've also heard but can't confirm that the Junior model is ok to use on a gel battery. Perhaps someone else can comment on that or you can send an e-mail to Detran for an answer.


Good luck - Brian


Here's BMW's take on these issues:


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Hi Brain,


Thanks for the reply. That is the info I saw on this board previously. I was concerned about the CANBUS if I connected the Battery Tender directly to the battery. However I see that Deltran makes one specifically for Gel batteries and cheaper than the BMW one:



Also, the Deltran FAQ, http://batterytender.com/faqs.php,

states the Jr. is safe for GEL batteries (FAQ #5):

"The Battery Tender Jr. is capable of charge maintenance on all lead acid battery types, including both AGM and GEL cells."


Deltran hasn't responded to my specific concern yet, so I guess to be safe I will remove the battery from the bike and use the Jr.



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Here is the link for the Battery Tender selection guide.

I chose the Battery Tender Plus as it says its good for the lead acid, Gel and the AGM. I used the supplied connector with the loops right to the battery connections and wire tied the cable to the frame to keep it from flopping around. I left the end just under the rear seat area. I just pop off the rear seat and plug in. http://batterytender.com/selection_guide.php

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The fused lead connected directly to the battery is perfect for your electric clothes as well. My R1200ST has the AGM battery and I plug in my Battery Tender Jr anytime I am not riding. thumbsup.gif

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I'm new to BMW m/c's and not familiar with the technicals of the 1200GS. Does it have the CAN-Bus too?

Yes. All of the 1200 series boxers and the new K bikes are canbus.
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