70hp 1988 battery issue

[dngharvey]

After three or four days my battery is so low it won't start the motor. Is there something on the motor that can draw it down?

[rodbolt17]

the regulator could be failing.
a quick test,dissconnect the battery next time your going to let it sit.
or take it by most any parts store and have the battery tested.

[dngharvey]

battery issue

Starting to really watch this issue and am puzzled. Battery is a good marine name brand ( Interstate ) one year old. 800 CCA. I now leave the battery switch off when not in use, only thing hot is bilge pump. Battery tests okay but says it should be replaced soon. This happened before a year ago. Watching a voltmeter in my depth sounder it shows only 11.9 volts till up and running when it will reach 12.8 and quickly drop back to 12 as soon as it is shut down.
After two or three days it will be down to 11.7, any longer it will be too low to crank over and have to be charged.
I,ve owned the motor two years, third battery, replaced the rectifier, it does charge, just eats batteries up?
Hoping Rodbolt, the Yamaha genius has some thoughts. Thanks.

[Moonman62]

If you haven't figured out the problem try charging the battery with terminals off. Get a volt meter and check the battery voltage after charging .connect the motor cables back to battery and then check voltage at the starter.Voltage should be the same or very close to the voltage at the time you reconnected the motor cables back to the battery.
Battery cables can get oxidized under the right conditions. If the wire in the cables is blck and not copper colored you got bad cables and the won't conduct power to the motor or back to battery from the alternator. Easy test and easy repair.

[dngharvey]

Thank you!

Thanks, checking everything! Nothing like jumping in the boat and finding we have to wait for a charge!