Motor draining battery

[scottham]

I have a 1974 Johnson. I put a new battery on it and it started fine. I came back a day later and no juice. I took the battey back to Wal-Mart thinking I got a bad battery. I put another new battery on it and it started great. Next morning no juice again. I haven't left the lights on or anything like that. Could there be something wrong with my motor that it is draining the battery while it is sitting in my driveway with nothing running? Please help!

 

[12Footer]

Re: Motor draining battery

You bet, there is. Everything with a positive lead on it. Anything from the bilge pump float switch to the Depth finder.<br />At the fuse box, start pulling fuses one at a time,with an ohm meter between the battery terminals (battery disconnected). When you pull the fuse with the drain problem, the meter will zero-out. NOW, we have to know what the fuse protects, and what is wrong with it.<br />This process of elimination is the best I can do for you, but I know you'll find it this way.

 

[JB]

Re: Motor draining battery

Good instructions from 12Footer, but a bit confusing. Never measure a "live" circuit with the meter in the ohms position. One of your normal 12v circuits is draining the battery by being "on" when it should be "off", or an accidental circuit (short) is doing the same thing. To do the test that 12Footer describes, disconnect the battery and use the meter as though it were the battery. It will give a reading of some low number of ohms at first. As you disconnect each normal circuit you may or may not get a big change in the reading (ohms to ground). If the reading makes a major change toward infinite ohms, you will have just disconnected a circuit that was draining the battery. If disconnecting all of the normal circuits brings the ohms reading to infinity everything is okay as far as a short goes, but you may still have a "normal" circuit that is ON when it shouldn't be. Go back to the one that caused the big jump in the reading when you disconnected it. Leave it disconnected and see if the battery goes down. If your problem isn't clear by this time, come back and tell us what you found.... in detail.<br /><br />Red sky.... JB

 

[Walter]

Re: Motor draining battery

Say fellas...<br /><br />I'd consider connecting a ammeter inline with one of the battery cables. From what he's describing, I think we all agree there's a substantial parasitic draw on the battery...whatever the cause. With an ammeter, it would be quite easy to see what the current draw is. Then by doing what you guys describe, that is disconnecting one fuse at a time for each load device, it should be very obvious when the current draw drops.<br /><br />I think we're all on the same page here...<br /><br />Walt

 

[12Footer]

Re: Motor draining battery

So true, Walter. But not everyone has one. Even so, it is worth mentioning, in case Scottham does. I'm wondering about the Ham in his handle,if he might be a fellow ham radio opp...N4ZAW,here.