Battery Warning Light ON...

1982 Yamaha Seca... yep, it's me... Still trying to figure this thing
out!
The battery warning light stays on, but yet the battery is staying at
12 volts...
Anyone know why that would be??

 

A properly charged battery should read around 13 to 13.2 volts. Clean
every connection, everywhere, if that doesn't help, look at the charging
system.


"War is an ugly thing, but not the ugliest of things; the decayed and
degraded state of moral and patriotic feeling which thinks nothing is
worth a war, is worse." --- John Stuart Mill: 

 

So, where, pray tell, did you get that little piece of mis-information ??

A wet-cell, lead acid battery has 2.1 volts per cell. String 6 of them
together and you get.......12.6 Volts.

A properly operating charging system, however, might well read 13-13.2 V. at
the battery while it's charging but it won't stay at that voltage very long
after the charge is removed.

Of course, none of that helps the OP, since, so far, nobody knows what the
battery light is actually monitoring. Some bikes had a probe to alert when
the electrolyte was low.

 

Yamaha : XJ750J (1982 Motorcycle) had an electrolyte level sensor in
the original equipment battery. If the electrolyte is low (or the
sensor is disconnected) the battery light will stay on when the engine
is running.

 

So going back to the original posting, it'd be a good
idea to check the fluid levels, fill as needed with
distilled water, place the battery on a charger
overnight, then check the voltage with the engine
both stopped and running. Should be about 12.5
stopped and 13.5 or better while running fast.

If it won't charge and hold to about 12.5, it's
time for a new battery. If it'll charge to 12.5
volts but the charging system can't bring
it to 13.5, the charging system probably needs
some attention. If it goes much over 14 volts
while running fast, there could be a regulation
problem causing the battery to boil away water.

 

Didn't those old Yama's use brush type alternators?
Check to see they're not too short.

 

just replaced a brush in mine. do you have a sensor? the warning is
about the sensor or the level it's sensing , nothing else. kind of
pointless with the lines on the side of the battery and all.

 

Yabbot, my 1982 Suzuki GS1100 came with a sensor battery before
maintenance free batteries were available, and the battery is buried
underneath the airbox.

To add water to the battery, the seat, aftermarket horns, side covers,
gas tank, and air box must be removed.

The level lines cannot be seen because of the battery box design...