Came out to a dead battery..

[Paper]

I rode my 81 R65 to work yesterday.. It was 45 degrees out, and it started just fine and played the typical "it's cold out, do you really want to ride?" game for a couple minutes.. I think I had to restart it once..

Rode to work and everything was fine..

Walked out of work (70 degrees out) and inserted and turned the key, pulled the clutch, hit the starter button and was given the rer, rer, rer, clickckckckckckck.. Hit it again.. rer, clickckckckc..

So, I got a jump start from a co-worker (straight off the battery, not running) and rode the 10 miles back home..

When I got home I shut the bike off, and tried to restart... Nothing.. Not even the dreaded ckckckckkckc..  :-/

The battery is a year old, and has never had any issue starting the bike. I tossed the charger on it at 2 amps for 4 hours and the battery functions like new..

So, I'm guessing I've got a bad Alt or diode board... This is purely a guess, but I'd like to do the proper job of eliminating them, one at a time, but I don't know what to look for as far as connections and voltage that should be there..

So, I'm open to all suggestions..

And Yes, I'm a Simple Stuff First kind of guy, and I've already checked battery connections.  

[Barry]

First step put a digital voltmeter across the battery with the engine running. It should read around 12 volts at idle and rise to 14 volts at 3-4000 RPM.

But before that make sure the battery is fully charged. If the battery was really flat, 4 hours at 2 amps won't come near to a full charge. You need to put in more like 9 hours at 2 amps for a 16Ah battery and correspondingly more for a 19Ah. If you measure the battery voltage after an overnight rest it should be 12.6 volts or a little more depending on the battery type. Any less and the battery isn't fully charged. Don't measure the voltage immediately after charging or running the bike as it will give a false high reading due too the surface charge effect which takes many hours to dissipate.

Let us know what you find.

[Bob_Roller]

If it's serviceable type battery, remove the caps on the cells and check the fluid level .

Motorcycle batteries need a bit more attention than  car batteries in keeping the fluid level to where it should be .

[montmil]

Hold off for a bit before buying possible unneeded and pricey parts...

The battery provides electrical power for everything on your R65. The charging system does not kick in fully until you have 3-4K revs on the engine. Don't know how far your commute is and how much stop n' go traffic you encounter, but such trips can quickly drain a battery.

Here's a scenario:  Several short trips and commutes to work. Not many miles with the engine cruising at 4K+ and putting enough charge into the battery to keep engine running, lights on and put in some additional charge to maintain full battery voltage.

Your jump at work provided power to operate the starter -a big battery drain- and crank up. The charging system did only a little bit to get you home. The two hour charge was only a little bit of good.

So. Get the bike running and use a VOM to read what charge is going into the battery at 3-4K revs. Report back your findings.

Also, consider investing in a Battery Tender maintainer that you can keep plugged in overnight. I believe the majority of Airhead owners have a Tender or similar in use.

Also, batteries can be fair weather friends; good for awhile and then they don't want to know you. After getting your current battery fully charged, take another voltage read with key off. Report back.

[Paper]

Thanks guys.. I'm leaving for work for a couple days, but will give it a full charge and do the checks this weekend..

My 85' R80 has done this ride to and from work for a couple years and never once has had a charging issue, but I'll give this a fair shake before ordering anything.. I've got a trickle charger/tender set up with a Powerlet plug, so charging takes nothing more than plugging it into the bike. I actually have this set up on all my bikes to keep them topped off during the winter..

What's got me concerned is going for an extended ride and draining the battery while doing so.. But the 14v test at 3-4K will tell me if that's an issue.

And I'll check out the fluid level while I'm at it.. The only thing I run on the bike when riding is a old school Garmin GPS, but my R80 and KLR (also terrible charging system) run the GPS just fine.. The R65 GPS is tapped into the running light wire, so it's switched off when the bike's not running..

[tvrla]

All these replys, and even your description of the problem, make no mention of the best trouble shooting tool on the bike - the charge light. They're called 'idiot lights', but you know, even though an idiot can tell whether it's charging or not, it takes some understanding to use it to figure out what's up with the system.

Does the charge light behave normally? Does it come on with the key, stay on until about 1200 RPM, then go totally dark?

From what you've described I'd guess the rotor died and the absence of the charge light wasn't noticed.

[Cano]

Had similar symptoms last year about this time.  Turned out to be a bad voltage regulator that caused the battery to just run down and not charge.  Easy to check by bypassing the regulator with a jumper while checking voltage at battery posts -- snowbum has the procedure detailed in an article on charging issues on his site.  Good luck.  

[R65LS]

 here is Part 1 of the same problem I very recently experienced ..... much wisdom here:
http://www.bmwr65.org/cgi-bin/yabb2/YaBB.pl?num=1330669123

In my case, it was the rotor, so the charging system didn't work.  I replaced the rotor, problem solved.

Cheers,

Carl