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BMW Battery Tender gone bad?
Posted: Tue Apr 13, 2010 7:21 pm
by Talon Six
Anyone ever heard of a BMW battery tender going bad? I had it hooked into my R12R three days ago and it worked just fine. Now when I plug the battery tender in, it keeps blinking red for "improperly connected".
I checked the tender voltage and, lo and behold, there's nothing coming out of the tender on the 'plug into motorcycle' end. This thing is only three years old and has hardly been used...what the heck?
Re: BMW Battery Tender gone bad?
Posted: Tue Apr 27, 2010 9:30 pm
by tptran
I had the same problem two days ago. I also used a DMV to measure the voltage output of the battery tender and it read 0V. Further study of the manual, it stated that the battery must be at least 3V in order for the unit to work. I went back and cleansed the brass connector which plugs into the side left side of the bike. Low and behold, the red light stopped blinking and remained solid. After one hour, the green light started to blink, signaling that the battery is 80% charged. Another, 1/2 hour, the green light remained solid. Fully charged! Good luck. Use 600 grid sand paper to clean up the brass part of the connector.
Re: BMW Battery Tender gone bad?
Posted: Thu Apr 29, 2010 10:59 am
by jb44
tptran is correct. You cannot check the voltage output with a meter. The charger has to sense at least 3 volts before putting out any voltage.
Clean the contacts and hope for the best. Try connecting the charger to a known good battery... your car battery... and see if it works.
I have not had good experiences with the BMW/Deltran battery tenders. Out of the 5 Battery Tenders I have only 2 work. It wasn't worth the cost to me to send them back for repair.
I have had good luck (no failures) with the Optimate chargers, and oddly enough the 800 ma Deltran waterproof charger.
jb