battery keeps going dead

[rcaspari]

Im having a problem with my electrical system.It is a Yamaha F 25 electric start.While I use the trolling motor, I have to start the motor every 15 minutes to keep the battery charged any more than 15 minutes it is pull cord time.I took the battery to walmart and it load checked good and accepted a charge. went fishing today and same thing draining battery. Pull started and ran motor back to boat ramp. I checked voltage at the battery and it showed 12.3 volt static and 12.6 running and up to 13.0 volts running above idle in gear. With motor running, I then disconnected battery and checked voltage 5.3 volts. If anyone can help me with this I would appreciate it.

 

[rcaspari]

Re: battery keeps going dead

I disconnected the neg while running and got a arc.

 

[glenn property of pam]

Re: battery keeps going dead

first thing is never remove the cables on a running motor as this can cause all sorts of problems but i guess you have figured that out now.

reading what you have wrote seems to make no sense. the battery was load tested and fully charged so that means you started with a battery at 12.6v then after 15 mins of trolling the battery was to low to start the outboard (thats odd for a good battery unless its a lawn mower battery). I would be surprissed if the outboard charged at 10amps so in one hour the battery would be 10amps better off (thats a tiny ammount) but a trolling motor proberly uses 20-30 amps a hour so in 15 mins it would use what the engine takes a hour to make (can you see where it doesnt make sense). Either the battery is realy small, the battery can not hold a charge or the starter on your motor has a weak or dirty connection.

What is the voltage at the battery when you can not get the motor to crank if its less than 12.1 then i surgest you have the battery retested at a diffrent store if its higher then i surgest you clean and tighten all the connections especially the ground on the motor block

12.6 is full - 12.1 is 50% - 10.5 is flat

 

[rcaspari]

Re: battery keeps going dead

i went out this morning after charging battery allnight. Started fine at ramp and headed to my first stop. trolling motor worked great of and on running for about 45 minutes then started motor fine and headed 15 minutes to second spot off and on trolling for 30-45 minutes. restarted motor no problems ran for 10 minutes at full throttle started trolling of and on for about an hour , then motor had to be started manually. Made run back to boatramp ,15 minutes, motor restarted on battery no problem. I will have the battery rechecked somewhere else.

 

[rcaspari]

Re: battery keeps going dead

I had the starter rebuilt Sept 2012 and installed new cables.

 

[kaldeh]

Re: battery keeps going dead

Does the trolling motor run of the starting battery? If so this may be your problem.

 

[rcaspari]

Re: battery keeps going dead

yes I only have 1 battery in the boat. I have been running it this way for over a year without any problems until now.
I went and had the battery charged and load checked at Oreilly auto. It checked good. Now what should I cvheck next.Thanks.RICK.

 

[Bosunsmate]

Re: battery keeps going dead

How many cca is that battery?
It may load test ok but being through a winter it wont be as good as last year.
Leave battery connected to motor overnight. Compare voltage before and in morning, may have a leak to ground somewhere

 

[99yam40]

Re: battery keeps going dead

With motor running, I then disconnected battery and checked voltage 5.3 volts. .

Can you explain this a little better?

What motor was running when you disconnected the battery and where did you take the voltage reading?

 

[rcaspari]

Re: battery keeps going dead

Can you explain this a little better?

What motor was running when you disconnected the battery and where did you take the voltage reading?

I checked the voltage on the leads coming from motor.

 

[rcaspari]

Re: battery keeps going dead

The outboard motor.

I checked the voltage on the leads coming from motor.

 

[99yam40]

Re: battery keeps going dead

I checked the voltage on the leads coming from motor.

Which leads and where did you put the meter leads?

Disconnecting battery leads on some motors while running will take out the rectifier/regulator.
High RPM I would expect voltage to battery around 14.5 volts

If the battery is good then you have a problem with charging system or something drawing way too much current .
Maybe your trolling motor has a problem or there is a short in wiring

 

[Capt Ken]

Re: battery keeps going dead

That engine's charging system was not designed to charge the battery, only to maintain the charge. I tried to look up the amps on the charging system and my book did not give it. The smallest motor that they give the charging rate of is the F50 and its only 16 amps. So the F25 is probably 10 amps or less. Your battery is getting tired and not holding a charge like it use to.

 

[glenn property of pam]

Re: battery keeps going dead

i have to agree that the battery needs to be replaced especially as its been discharged enoght times that its proberly given its best.

 

[rcaspari]

Re: battery keeps going dead

i have to agree that the battery needs to be replaced especially as its been discharged enoght times that its proberly given its best.

I think you guys are right,I went and bought a new battery and I'll see how that goes.

 

[Silvertip]

Re: battery keeps going dead

If you are running the trolling motor from a marine "starting" battery that's what is killing it. Starting batteries are not designed to be deeply discharged. You still haven;'t answered the question about the "type" or "capacity" rating of the battery. Your engine has a 15 amp alternator output but that output is at WOT. So lets run some numbers. You use the trolling motor (unknown size) but lets use 25 amps/hour at intermittent use and half power. So in one hours time you would have used 1/2 of 25 amps or 12.5 amps of juice from the battery. Now you say you run the motor for 15 minutes. Unless you are running the motor at WOT you are adding only 1/4 of 15 or about 4 amps. So you are using 2/3 more power than you are putting back into the battery. It is no wonder it is going dead. I'm going to guess that you will get by this season thinking this new battery solved the problem. I'm also going to guess that next year you will be faced with the same situation you have now. the simple fact here is that you are USING more power from the battery than you are PUTTING BACK INTO IT. The real solution here is to use the battery you have to run the 25 HP engine and accessories. You need a separate DEEP CYCLE battery for the trolling motor. And NO -- you cannot charge both from the engine. You need an on-board charger or a portable charger to immediately charge the troller battery when you get back to the dock.