Boat battery dying, finding short

Pydpiper

Flashlight Enthusiast
Joined
Jan 4, 2005
Messages
1,778
Location
Brantford/Woodstock
My fishing boat is having issues with keeping the battery charged, I bought a new one yesterday and don't want to cook it too..
It is used to start the boat, run a trolling motor and a few lights. It is connected to a small distributor block I made and I fear I may have a short somewhere or something is stealing current when it's not supposed to. I have a decent multimeter but I don't know how to tell if current is being hijacked.
Anyone want to guide me a bit here? I don't know where the leads go on the meter to find the draw. /ubbthreads/images/graemlins/help.gif
Thanks!
Pyd
 

DarkLight

Enlightened
Joined
Jan 13, 2005
Messages
538
Location
Elkhart,IN
the meter goes INLINE to measure current.
disconnect everything but one item and test each thing separate, you should have no current draw when things are off...do not run the motor esp while meter is inline..

mine can take 6amps but thats not much..enough for lights though..
 

Pydpiper

Flashlight Enthusiast
Joined
Jan 4, 2005
Messages
1,778
Location
Brantford/Woodstock
My shortcoming is the meter itself, and the reading it will give me.
There are several options on the meter, dial settings as well as where the leads plug in.
What amount of current should I be looking for? It is not a dead short (if there is one at all) but more of a very slow constant drain.
 

Stingray

Flashlight Enthusiast
Joined
Nov 21, 2002
Messages
1,202
Location
Chicago
If you want to keep an eye on current draw, one idea might be to get an auto or marine ammeter and install it permanently. They're made to take the current, and cheap enough. Then you can keep an eye on things whenever you're in the boat.
 

gnubee

Newly Enlightened
Joined
Jul 28, 2005
Messages
21
turn the dial to 10a and plug the red lead into the 10a hole.then use the meter between the battery and the circuit you are suspicious of. the meter must be the only path from the battery to the positive connection of the suspect circuit. connect one lead with an alligator clip to the battery and poke the other lead momentarily with the pin end to the circuit tested. watch the display and it will show current draw when you find the circuit that is shorting. if it is a dead short the leads will get hot in your hand and you might cook your voltmeter. still cheaper than any marine shop. oh, and before you try this check what your voltage is across the battery leads while the motor is running. might be a problem with the charging circuit. too low and it wont charge, too high and it cooks the water right out of your battery.

////////make sure the voltmeter is set to 10a when checking for current only. when checking voltage move the red lead from the 10a position and move the dial also- and store this way also. testing for voltage with the dial or lead in the 10a position is a great way to start a fire, or if using on a 220 v circuit, a great way to start ON fire.////
 

turbodog

Flashaholic
Joined
Jun 23, 2003
Messages
6,425
Location
central time
Set the meter up for current measurement. You need the scale that reads from .25A to maybe 3A (this is a guess).

Disconnect positive or negative battery lead and put the meter inline.

See what current it reads, it should be zero. Turn on a SMALL light to verifiy that it is working. A small clearance-type light will pull an amp or so.

If it reads something other than zero when ALL stuff if off, start disconnecting circuits by pulling fuses or some similar method.

Check the meter after each circuit is killed. Eventually you will find the drain.
 

Pydpiper

Flashlight Enthusiast
Joined
Jan 4, 2005
Messages
1,778
Location
Brantford/Woodstock
Thanks guys, that was what I needed to know..
It is hard to tell how fast the battery depletes, the motor charges while it is driving.
I am uspecting it may also be intermittant, perhaps moisture is playing a part.
I am going to apply some of your recomendations this morning and see what happens, now that I understand how to use my meter. /ubbthreads/images/graemlins/smile.gif
 

mattheww50

Flashlight Enthusiast
Joined
Jun 24, 2003
Messages
1,048
Location
SW Pennsylvania
I wouldn't rule out the possiblity that the charging system on the motor is the problem. One very simple test.
Watch the brighness of the incandescent ligts that are on as you go from Idle to high speed. If they don't get noticeable brighter, the charging system is suspect. This can be easily verified. With the engine off, the battery voltage should be something around 13.2-13.5 volts. With the motor running at high speed, it should be higher, at least 14.2 volts, 14.5 is quite possible. If the voltages don't get that high, you aren't charging the battery.
 

yuandrew

Flashlight Enthusiast
Joined
Apr 12, 2003
Messages
1,323
Location
Chino Hills, CA
If there's a short, I think you could disconnect the battery and use a continunity tester to "probe" each circuit.
 
Top