V-Twin Forum banner
1 - 5 of 5 Posts

·
Registered
Joined
·
86 Posts
Discussion Starter · #1 · (Edited)
Faulty charging system...battery damaged. (Update)

Hi all,

This is the story with my FLSTS:

I replaced the original battery six months ago because began to discharge very often and since it was four years old...

...Surprisingly the new battery also was discharged when parked more than 2 weeks...

...So I thought there was a drain problem but lived with it, charging the battery when necessary (two or three times)...

(...last August the bike shutdown because faulty main circuit breaker, it didn't recover, when I put it off it was totally corroded. I put a new one...checked voltage at idle - around 14 volts - and run...)

...last week I was charging the battery one more time but the charger diagnostic - after a whole day charging - says 'bad battery'. Once checked the static voltage it reads 11.9 volts...

It seems that a faulty charging system (voltage regulator, alternator, loose ground...) has damaged the battery's capacity. Is this possible?

I've read in the forum archive how to check the charging system (more or less) but what to do with the battery? Warranty? Buy a new one?

Thanks in advance for your comments and Happy New Year! :)


Twin Cam
FLSTS '01
Spain
 

·
Have chrome will travel
Joined
·
506 Posts
I'd take it back under warranty but then again I'm a no good, low down, dirty...:whistle:
 

·
Registered
Joined
·
413 Posts
A bad voltage regulator could be both the source of your battery drain and the culprit to damaging the battery. Take care to make sure the voltage regulator isn’t a problem before subjecting another new battery to the ordeal. An Amp-meter in series with one of the battery leads will indicate how much current draw is present when the bikes ignition and lights are off. If you were to unplug the voltage regulator connection while taking such a measurement and find that the current draw drops significantly, then the voltage regulator is suspect.
 

·
Hellbound Train
Joined
·
5,595 Posts
Check all your connections again, if you are reading the 14v on the lead (as in led, not lead) of the battery post itself, all your connections are good. Make sure there is no corrosion on the bolts or washers. Also check resistance from the negative post to the frame, should be zero ohms.
 

·
Registered
Joined
·
86 Posts
Discussion Starter · #5 ·
Update:

- The battery was shortcut. I've bought a new one (from another stealer)

- Checked connections:

From battery - to ground. Less than 1V with engine running.
From battery + to starter. Idem

Circuit breaker connections Ok.

Voltage regulator ground Ok.

Connector between VRegulator & Alternator: soaked in oil. I've read that is quite common...

Passing lamps: I never use them. Put ON for checking...lights fuse blown. Checking wires I've found one cut making contact with the lamp body.

Alternator phases OK. 0.2-0.3 Ohms between them. Not grounded.
With engine running, voltage around 20VAC at idle increasing well with rpm.

Battery voltage 14.4V at idle up to 14.7 when revving.

I still have some doubts about Voltage Regulator (it's a chrome one) so I'll put back the original one and will see.

Thank you for the inputs.

Twin Cam
FLSTS '01
Spain
 
1 - 5 of 5 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top