battery keeps going dead!

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ratking20

Petty Officer 2nd Class
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Jul 20, 2010
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recently hooked up a new radio so im assuming thats why.
i ran new power and ground wires, ground straight to the battery(neg) and power to the battery but before the perko switch. anything wrong with this that would cause battery to die???????
 

NYBo

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Oct 23, 2008
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7,107
Re: battery keeps going dead!

The memory circuit for a stereo draws very little current; a good battery will run it for weeks on end and still be able to start the motor. However, if you have a power amp that is staying on all the time, that's a different matter.
 

ratking20

Petty Officer 2nd Class
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Jul 20, 2010
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Re: battery keeps going dead!

no amp, brand new battery
last used the boat 6 days ago but not for that long
had problems once before that and bought new battery
thinking problem might be the alternator ?

with the perko switch off, what could be drawing power from the batt? i know the bilge could but how would i check that. i have a multitester??????
 

TerryMSU

Senior Chief Petty Officer
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Jul 31, 2007
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743
Re: battery keeps going dead!

Mine will go dead in less than a week. Thinking it thru, I bet I am leaving the radio on, rather than just the memory circuit.

TerryMSU
 

NHGuy

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Re: battery keeps going dead!

So is the positive radio connection always hot? And is there a switched wire to wake up the radio when you want the radio on or when you start the boat? That's how most work.
If you have a volt ohm meter you can get some of the values, you just can't check the battery cranking power and that stuff.
Set the meter on a DC range that includes up to about 20 volts. Now read across the battery terminals. You hope for 12.73 volts but can expect 12.5 or so, below that is weak.
Now run your cooling water, fire the motor and check the same spot, running above idle you want 13.7 to 14.3 volts.
If those are good shut down the motor, & run the blower for a couple of minutes. If there is any fuel smell quit right there.
If the air is clear you can test for a draw on the battery by disconnecting the positive terminal. Plug your probes into the COM and AMPS DC contacts of the multimeter. Now set you meter to maximum amps and probe briefly between the positive terminal of the battery and the positive battery cable. Your reading should be approximately the rated amp value of the standby circuit which remembers the radio stations etc. It will be a small value like .5 or some amp value below that even. If it's higher there's something else pulling power, check your switches and wires. Make sure the powered stuff is off and the connections are clean/tight.
 

NYBo

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Oct 23, 2008
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7,107
Re: battery keeps going dead!

no amp, brand new battery
last used the boat 6 days ago but not for that long
had problems once before that and bought new battery
thinking problem might be the alternator ?

with the perko switch off, what could be drawing power from the batt? i know the bilge could but how would i check that. i have a multitester??????
Your pattern of usage may be the problem, especially if you have an older outboard that puts out very little charging juice. You may not be replenishing what you are using because you aren't running the motor long enough. Of course, if the charging system is bad, it wouldn't matter how long you ran the motor. Any idea of the charging voltage? Do you put the battery on a charger after outings?
 

ratking20

Petty Officer 2nd Class
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Jul 20, 2010
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Re: battery keeps going dead!

i have a i/o ... a 260hp 5.7 mercruiser, not an outboard
i tested the battery with a multitester, seems thats not the problem, read above 13
i do not charge the battery between outings, never had a problem b4
when i turn the key i get nothing. i get a single click and nothing, seemed like the battery but now i dont know,
 

Lakemeadan

Petty Officer 2nd Class
Joined
May 25, 2010
Messages
123
Re: battery keeps going dead!

Make sure shifter is in neutral and lantern kill switch is on.
 

Pierutrus

Senior Chief Petty Officer
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Mar 25, 2007
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721
Re: battery keeps going dead!

recently hooked up a new radio so im assuming thats why.
i ran new power and ground wires, ground straight to the battery(neg) and power to the battery but before the perko switch. anything wrong with this that would cause battery to die???????
NO, sounds like a coincidence, don't think it's the new radio.

no amp, brand new battery
last used the boat 6 days ago but not for that long
had problems once before that and bought new battery
thinking problem might be the alternator ?

with the perko switch off, what could be drawing power from the batt? i know the bilge could but how would i check that. i have a multitester??????

I would first check to see that the alternator is putting out and keeping the battery charged while running. By what you are stating, it sounds like your alternator is dead.
Charge the battery back up. Once that's done, put the muffs on and start the engine.
Let it warm up a bit and then take a reading directly off the battery terminals.
You should be getting between 13.5 - 14.5 VDC.
If you are still only reading the 12 Volts like the boats not running than your alternator is dead and needs to be replaced.

i have a i/o ... a 260hp 5.7 mercruiser, not an outboard
i tested the battery with a multitester, seems thats not the problem, read above 13
i do not charge the battery between outings, never had a problem b4
when i turn the key i get nothing. i get a single click and nothing, seemed like the battery but now i dont know,

If the battery is fully charged up and all you get is a click when you try to start it..........
Then it's time to check/change the starter/selinoid. It's getting weak and it's taking more to turn over the engine. Check the wires going to it to see if any are loose also.


If you've done all the above and both the alternator and starter are good then...........
You've stated that the only thing that's hooked directly to the battery is the bilge pump correct?
And everything else is going thru the perko switch?
Then turn the perko switch off, disconnect the bilge pump positive wire from the battery and do a current draw test with your multimeter. It shouldn't be drawing anything when it's not running.
If it is, you've found the culprit.

On a side note........
On my boat.......the only thing connected directly to the battery is the tilt/trim pump.
That's so I can raise/lower the drive while trailering/launching.
Everything else is thru the perco switch. Bilge pump included.

All bets are off on the side note if you store your boat in a slip.
 

Pierutrus

Senior Chief Petty Officer
Joined
Mar 25, 2007
Messages
721
Re: battery keeps going dead!

no amp, brand new battery
last used the boat 6 days ago but not for that long
had problems once before that and bought new battery
thinking problem might be the alternator ?

I'll betcha a beer that if you would have ran the boat a wee bit longer on the last outing...........It would have died on ya!
Change the alternator.;)
 

groovy_moon

Seaman Apprentice
Joined
Aug 6, 2018
Messages
31
What was the final verdict? Just curious... I am having the same issue... I have purchased a clamp on ammeter and will start working my way thru the electrical system starting at the (+) battery terminal. I have already checked my alternator and it is putting out appropriate voltage
 
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