starting battery voltage

[Rick.]

Hello to all. I have a 1995 40 HP Johnson. I have only one battery which runs my fish finder and starts my motor. What is the minimum voltage required to start the engine. I am concerned about running the voltage too low and then not being able to start the engine. My fish finder has a voltage alarm but I don't know what is a reasonably safe voltage to set it to. Thanks for your help. Rick.

 

[tashasdaddy]

Re: starting battery voltage

it is the amperage you need to worry about. you can have 12 volts, but not the amperage to start the motor. unless very old the ff draws very little. clean battery connections, battery and motor ends are essential, for easy starting. if necessary, that motor is easy to rope start.

 

[jtexas]

Re: starting battery voltage

it would take a week of 24/7 operation for the fishfinder to drain the battery enough to measure the difference.

I run bilge, livewell fill & drain, horn, nav lights off my cranking battery, never once had a problem with it.

Luckily, this is something you can experiment with in the driveway. Turn the FF on and check the voltage every now & then. See how low it can get before it won't crank the battery.

 

[JimS123]

Re: starting battery voltage

You didn't say what kind of fishfinder you have. I used to use a CRT unit (as opposed to an LCD) and it used juice like crazy.

In my experience, I was able to go to 12 V and still start the engine. Below 12 and I was in trouble. I switched to a type 27 battery and solved the problem. After typically 4 hours of fishing with VHF radio and depthfinder running, I rarely go below 12.4 volts now, starting at about 12.7.

 

[Rick.]

Re: starting battery voltage

Thanks guys. I was a bit paranoid I guess. My finder is a Humminbird 595 and you are right. I was out all day today and it hardly used any power at all. According to the finder, voltage never went below 12.4 . I guess I won't have any problems because of the Humminbird. Thanks again. Rick.

 

[jtexas]

Re: starting battery voltage

I'm surprised it dropped that low...you sure your outboard charging system is working?

 

[Rick.]

Re: starting battery voltage

Yes it's working fine according to my volt meter. I was starting my motor quite a lot cause we kept drifting out of the walleye zone. Lots of starts and then just moving 20 or 30 yards at a time. Rick.