1978 650 yamaha voltage loss

 I'm searching for why the battery gets low so fast when sitting.
I spliced a voltmeter between the battery positive post and the large wire
to the starter solenoid and I'm losing .2 volts with nothing else connected.
Will that low of drain kill the battery in a few weeks? More importantly
should there be ANY drain with nothing else connected? There doesn't seem to
be any continuity between the two large posts on the solenoid, so how can
voltage be going through?

 Thanks for any help.

 
Kim Neubert wrote:

When you charge a battery and take a voltage reading immediately after
disconnecting it from the charger, you might read anywhere from 13.2 to
14.5 volts across the terminals.

But, if you let the battery sit for half an hour or so, the voltage
drops off to 12.8 volts in a fully charged battery "at rest".

If you don't charge the battery again and you measure the voltage again
after a month or so and the battery voltage is now down to less than 12
volts, you can be sure that it is discharging itself.

The usual suspect is the voltage regulator. The diodes are supposed to
block reverse current from flowing through them to ground, but if the
diodes leak, the battery will discharge slowly.


Voltage drop across the starter cable doesn't really tell you much
about why your battery goes dead while sitting.


The voltage regulator will always be connected.


Make sure the ignition switch is turned off. Select the highest
milliohmeter range on your volt-ohmmeter.

Briefly touch the positive probe to the positive post of the battery,
and the negative lead to
the chassis.

If you get a reading, you have a current leak. If you disconnect the
voltage regulator and repeat the test and you don't see any reading,
you've found the culprit.

 Thanks for the reply.

I only have the main wire going to the positive battery terminal and the
battery ground connected. That wire goes straight to the solenoid and from
the solenoid to the starter. I disconnected ALL other wires. I even removed
the two small wires on the solenoid that go to the starter button. When I
did your test it showed no reading. It sure looks like it's bleeding through
the solenoid some how. The battery is only a few months old and is fully
charged now. I'm going to see how long before it goes below 12 volts.

Thanks , Kim

 Kim Neubert wrote:

You may have an internal short in the battery. Gunk falls off the plates
and fills up the bottom of the battery to the point where it shorts the
plates. Can't really be fixed although there are some schemes of
dropping high current pulses to fry the short. Better to return the
battery if it is under warranty or just buy a new one.

 Just wanted to say thanks for all the ideas. If I find what it was I'll post
it.

Have a great Christmas.


Noob