Battery drain issue

Reopeadres

Cadet
Joined
May 11, 2013
Messages
9
Having a issue with my battery, i can charge it before a trip and by the time it gets to the rap its dead. i think i have figured out what is causing it to die like that. its the big positive cable that connects to the starter when i connect the cable it sparks so im guessing its what is causing the battery drain. What do i need to do to trouble shoot and fix it.

its a 3.0l merc

thanks
John
 
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Grub54891

Vice Admiral
Joined
Jun 17, 2012
Messages
5,908
Re: Battery drain issue

You need to remove the cable,clean the connections,and posts. Load test the battery, and grease the battery terminals to prevent corrosion.
You may have to replace the terminals if they are in bad shape. What ya have is not a battery drain issue,just bad connections.
Oh yeah,make shure you don't have it hooked up backwards.
Good luck!
 

Bondo

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Staff member
Joined
Apr 17, 2002
Messages
70,470
Re: Battery drain issue

Having a issue with my battery, i can charge it before a trip and by the time it gets to the rap its dead. i think i have figured out what is causing it to die like that. its the big positive cable that connects to the starter when i connect the cable it sparks so im guessing its what is causing the battery drain. What do i need to do to trouble shoot and fix it.

its a 3.0l merc

thanks
John

Ayuh,.... Welcome Aboard,.... Where are ya doin' the hookin' up, at the battery's positive(+) post,..??

Basically, yer Whole boat is powered through that connection,...
Soooo,... Anything on the boat left "On", will draw power, killin' the battery,...

Make sure everything is turned Off,...
Jumper a Test Light 'tween the battery post, 'n cable,...
A draw will light the light,...
Start disconnectin' circuits outa the electrical system, til the light goes Out,...
That's the circuit that's drawin' when it shouldn't,...

If yer seein' Strong Sparks,...
I'm guessin' yer hookin' the cables up backwards, as it sounds more like a Dead Short,...
 

UncleWillie

Captain
Joined
Oct 18, 2011
Messages
3,995
Re: Battery drain issue

Turn OFF everything and remove ALL the fuses.
Place a Test light across where the fuses used to be.
The one that lights up is the problem.

If you still get a spark when reconnecting the battery with all the fuses out, you have a problem elsewhere.
The alternator would be one of my first choices.
Remove the battery cable from the Alternator/Starter.
Sparks gone?

Another test. Does the alternator charge the battery when the engine is running?
Start up the engine and measure the battery voltage.
If it is less than 13.5 you are not charging. Alternator Problem.
 

Reopeadres

Cadet
Joined
May 11, 2013
Messages
9
Re: Battery drain issue

Ok will try that this evening. The cable that sparks when connecting to the battery big cable that connects to the back of the starter. The alternator charges fine. Will pull the fuses and see what gives on it. Thanks.
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
Re: Battery drain issue

The alt can still charge fine even with blown diodes .you could remove the orange wire at the back of the dist.
Any chance somebody accidently hooked the cables backwards for a split second. That blows the diodes in the alt.
 
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Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
Re: Battery drain issue

NEVER pull the battery cable to check the alternator. This very crude test method was marginally OK when we had vacuum tube car radios and point-type ignitions, but it is a very bad idea now. The battery stabilizes the electrical system and loads the alternator, preventing high peak voltages or voltage surges as the alternator adjusts magnetic flux to produce the same average voltage at different current demands. If you rev the engine up and pull a battery cable, the alternator voltage can spike up to 100 volts or higher before the alternator flux dies off enough to bring voltage back down to 14 volts or so. This can kill the car's computer and other expensive electrical components. I've seen headlights blow out when a guy opened a battery switch while an engine was revved up. If you hear anyone telling someone this is a way to check an alternator in a modern vehicle, stop them
 

UncleWillie

Captain
Joined
Oct 18, 2011
Messages
3,995
Re: Battery drain issue

NEVER pull the battery cable to check the alternator. ... If you hear anyone telling someone this is a way to check an alternator in a modern vehicle, stop them

Agree!!

The earlier recommendation was to remove the Battery cable FROM the Alternator not from the Battery. It was assumed the engine was OFF also. If the Battery cable Stops sparking with the Alternator out of the circuit, the Alternator become the prime suspect.

Sometimes the details get lost in translation.:joyous:
 

Reopeadres

Cadet
Joined
May 11, 2013
Messages
9
Re: Battery drain issue

The radio was pulling most of the power. For some reason it's not turning off with they key. Gonna put it on a switch. Still got a little power drain. Boat was not running and I was not connecting the battery wrong. When the boat is running alternator is charging great.
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,585
Re: Battery drain issue

The radio was pulling most of the power. For some reason it's not turning off with they key. Gonna put it on a switch. Still got a little power drain. Boat was not running and I was not connecting the battery wrong. When the boat is running alternator is charging great.

Not knowing your radio configuration, some of those radios have to have power 24/7 to keep stations and clock and presets working. If that is your problem, you will have to keep a trickle charger attached when not running or sitting in your yard waiting for the next outing.
 

UncleWillie

Captain
Joined
Oct 18, 2011
Messages
3,995
Re: Battery drain issue

... some of those radios have to have power 24/7 to keep stations and clock and presets working. ...

The drain to power a radio memory is minuscule compared to the capacity of a battery.
The same situation happens in every auto manufactured in the last 30+ Years.
The radio memory will take well over 3 months to even begin to put a dent in the battery.

The radios do not necessarily turn OFF with the ignition on a boat.
You need to turn then off manually.
Same as lights, Pumps, GPS, Blowers, and many others.
Ignition switch controls the engine and related components like gauges and that's about all.

If your radio has a couple of power Amplifiers attached to it, The idle drain may be significant.
Be sure the radio is wired to shut down the Amplifiers also.
 

bruceb58

Supreme Mariner
Joined
Mar 5, 2006
Messages
30,454
Re: Battery drain issue

These radios have 2 power wires typically. One wire will power the presets and draw a small amount of power, enough to drain the battery in a months time possibly. The other wire if left powered will drain the battery much quicker, even with the radio off.

Easy way to tell is to find the fuse that the radio runs off of and measure the current across the fuse with a meter.

I have a switch on the radio in each of my boats because of this.
 

pyrotek

Petty Officer 2nd Class
Joined
Nov 19, 2011
Messages
183
Re: Battery drain issue

These radios have 2 power wires typically. One wire will power the presets and draw a small amount of power, enough to drain the battery in a months time possibly..

I just hooked up a new radio but did not have a continuous power wire for the presets. Interestingly the presets get saved in memory even without power. However the time resets.
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,585
Re: Battery drain issue

I just hooked up a new radio but did not have a continuous power wire for the presets. Interestingly the presets get saved in memory even without power. However the time resets.

The reason your presets are saved is because some newer radios use a system similar to the old EEPROMs. The EEPROMs are Electrical Erasable Programmable Read Only Memory, meaning that once they are programmed, power can be cut off without loosing the memory. But radio clocks have to have some type power to keep the oscillator running to count time... Have you located your battery draw problem yet?
 

Reopeadres

Cadet
Joined
May 11, 2013
Messages
9
Re: Battery drain issue

Yep. It was the radio the main power fuse for it. So as I pull it. No drain on the battery. So it will be switched. Also found a old switch that the previous owner had put in was wired wrong. But think it had burnt out. Could not get any power to go threw it. Just removed it.
 

gm280

Supreme Mariner
Joined
Jun 26, 2011
Messages
14,585
Re: Battery drain issue

Glad you finally located your source of battery drain. Some time people over look the obvious things installed on their boats. Simple fix and happen boating now... :thumb:
 
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