15NOV06 - Battery Tender

Probably much worrying about nothing, but something the salesguy where I bought Maria the RT had said had stuck in my brain and surfaced occasionally to nag at me. He'd mentioned to me that riding with the riding lights on, and the highbeam on (which is how I ride for max light visibility) might cause the battery to not get fully charged up on short rides. Since during the workweek I do short rides mostly, 11 miles each way, to and from work, this was something that worried me a bit.

I went so far as to add a voltmeter and did notice it being below 12 volts when idling, it'd be in the 13 volt range when at speed so I assumed that during those times the battery was charging but when it read below 12 volts that it was discharging.

I called the local beemer dealer and he had the Deltran Battery Tender Jr for $32 and the bmw power connector cord for $12. He told me several other motorcycle owners (whose motorcycles use the GEL battery) were using it instead of the fancier version, the Deltran Battery Tender Plus and had all had good luck and no issues with the Jr so I went that route.

It charges up to 14.4 volt then goes into "float mode" where it monitors the battery's discharge. Soon as the battery hits 13.5 volts it goes back into charging mode back to 14.4 volt. These are the specs I've gleaned from the beemer forums that one must meet for the GEL battery that my RT has. One apparently cannot exceed 14.4 volts with GEL batteries!

By buying the bmw power outlet cable to go with it, I can simply plug the tender into the wall and plug the other end to one of the two power outlets on the motorcycle. Easy.

I'll monitor it for now, checking with a voltmeter when the charges is in "float" mode and see if it's really doing what's its supposed to do.

UPDATE: 24NOV06 - Well, when the light on the charger turns green, my battery reads 13.17 volts with a multimeter connected to the battery terminals. So I guess that's max charge that the tender will maintain. Well below the 14.4 volt maximum so I think this unit will serve me well.