Battery draining...why? UPDATE

[KeyWestBoater]

Hello all,

I have a 2008 Key West 1520CC with a 2 stroke Yamaha. I use the boat primarily for fishing. Ever since the boat has been about 6 mos old I have has a problem out on the water with the battery running down to the point where the engine almost didn't start and one time it woudn't. The boat has only one battery (original) and when we're fishing anchored with the engine off the only things turned on are the fishfinder and aerator. I have talked to several others who said that they can run like this all day without running down the battery. A few months ago after 1 1/2 - 2 hours the battery went down to 9 volts. This past weekend after 1 hour it went down to 11 volts. I have been to the dealer 2 times and they checked the charging system and the battery. Also I brought the battery to West Marine this past weekend and they said it was good. I checked to see if there was anything else drawing current using a test light but found nothing. I've checked the voltage at just over idle with a voltmeter several times and it is over 13 v. Whenever I go out the battery is always charged as I leave it on a trickle charger while the boat is stored. Can someone help? This is frustrating!


Thanks,
KWB

 

[bruceb58]

Re: Battery draining...why?

Re: Battery draining...why?

Get a meter and pull off the battery post. Put the meter between the battery post and the cable so you can measure current and turn on all the things that you use when you go out and see what the current draw is. Using a test light for something like this is pretty much worthless.

Could very well be that your trickle charger doesn't put out enough current to ever get your battery fully charged. Your outboard doesn't put out much current either so when you come in, the battery is probably quite low.

If you have let your battery get down to 9V many times, it is probably on its last legs. What kind of battery is it?

A fully charged battery is around 12.6V when it is fully charged at rest which means you pull the charger off of it and let it sit for 20 minutes. If you get to 12V you only have 40% capacity left. I never let a deep discharge battery get below 12V.

If you are doing all of this with a start battery, your battery is already toast. When they test your battery, they really can't test to see how much capacity it has. They can test the amount of current it can deliver in a fully charged state but your battery may be at the point that it has been discharged too many times and too deeply that it is time to replace.

 

[stylesabu]

Re: Battery draining...why?

Re: Battery draining...why?

you will need to measure amp draw. I have a flke 88 which can read up to 10 amps draw without blowing fuse. something is kicking on at times. this may not work for you as my meter is about 400.00. you could use a low amp clamp hooked to multi-meter and monitor it while running. and with some luck you will see what is causing the draw

 

[bruceb58]

Re: Battery draining...why?

Re: Battery draining...why?

You don't need a $400 meter to do this. An $8 one will suffice.

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=92020

 

[stylesabu]

Re: Battery draining...why?

Re: Battery draining...why?

most meters can't handle over 4-5 amps, but you can use a cheap meter with an amp clamp and measure higher draw.and i agree if this has happened too many times his battery is done.

 

[bruceb58]

Re: Battery draining...why?

Re: Battery draining...why?

The one in the link has a 10A scale.

 

[KeyWestBoater]

Re: Battery draining...why?

Re: Battery draining...why?

Could very well be that your trickle charger doesn't put out enough current to ever get your battery fully charged. Your outboard doesn't put out much current either so when you come in, the battery is probably quite low.

I have checked my battery before going out several times and it reads 12.5 v. So it looks at least like it's fully charged before I go out.

How many amps should the FF and aerator pull?

About how long should I be able to run the fishfinder and aerator before the battery is to low?

And how many volts is "too low"?

Thanks again,

KWB

 

[robert graham]

Re: Battery draining...why?

Re: Battery draining...why?

Your 70HP Yamaha has a 6 amp charge rate, but your aerator and fishfinder are just pulling it down after a couple of hours. Maybe a seperate battery for aerator or a dual-purpose, starting/deep cell battery would hold up better. Dead batteries on the water not good!

 

[mAlton]

Re: Battery draining...why?

Re: Battery draining...why?

Som fishfinders can have the sensitivity turned up to the point that they are sucking current quickly. Being out with no juice to start is bad. I would get a second battery for all but starting the engine. You put it on a charger anyways when home. At least then, you will always be able to start up when ready. Good luck.

 

[Silvertip]

Re: Battery draining...why?

Re: Battery draining...why?

My $30 meter also has a 10 amp capability. But I would suggest that the battery is simply no longer able to deliver its rated capacity. Sort of like a new bucket holding water with no leaks. Over time the bucket can rust and water leaks out although it was full when you left the well. Now how is that for an analogy. My approach would be to use the meter as suggested but rather than turning everything on, turn everything off. Then see if something is drawing current that you are not aware of -- such as the memory in your radio. Small current draw to be sure and it will not run down the battery in a short time, but if the battery is weak in the first place, it simply adds to the problem. As for current draw, the livewell aerator will draw somewhere between 2 and 5 amps depending on size so if it is running continuously, that is a fairly high current draw on a weak battery. The locator draws less than that. Measuring battery voltage is not a test of its condition. It does show it is fully charged, but if the battery cannot hold that charge it is meaningless. The real test is to charge it, let it rest for 1 hour, then attach the VOLTMETER across the battery terminals. Now turn the key to START and watch the voltage drop like a rock. That is the indication of a bad battery. If the voltage stays up while cranking, the battery is good. As was also mentioned, a 6 amp output from the alternator would take many hours of wide open throttle running to fully charge a deeply discharged battery.

 

[bruceb58]

Re: Battery draining...why?

Re: Battery draining...why?

I have checked my battery before going out several times and it reads 12.5 v. So it looks at least like it's fully charged before I go out.

How many amps should the FF and aerator pull?

About how long should I be able to run the fishfinder and aerator before the battery is to low?

And how many volts is "too low"?

Thanks again,

KWB

If you actually have a deep discharge battery and your current draw is 5 amps, a 60 amp hour battery could be drawn on for 6 hours and your battery voltage would still be at or near 12.1V. That is of course if the battery still has all of its capacity which i don't think yours does. I would never let it get down below 12.0V.

As mentioned, I would consider installing a second battery. I would also install an onboard charger to make sure you are completely charging your battery. Not sure what charger you are using but if its a trickle charger it may be either not charging the battery fully and/or once the battery gets fully charged, doesn't go into a float mode so the battery doesn't overcharge. Allowing a battery to sit lower than its fully charged state will also reduce its capacity as it will start to sulfate up.

 

[Yepblaze]

Re: Battery draining...why?

Re: Battery draining...why?

Have you tried a new battery?

 

[KeyWestBoater]

Re: Battery draining...why?

Re: Battery draining...why?

Have you tried a new battery?

I was convinced that I had a bad battery and was prepared to buy one last week but when they said it was ok I didn't. I thought when they test they do a load test or something...

I will try the tests mentioned. If there is a correct draw then I will replace the battery, maybe with something with more amp hours.

Thanks again,

KWB

 

[bruceb58]

Re: Battery draining...why?

Re: Battery draining...why?

When you say that you have 12.5V, is that with a digital multimeter or with your dash gauge? If its the dash, those are very inaccurate and you may not be really starting off with 12.5V and therefore not a fully charged battery.

 

[JustJason]

Re: Battery draining...why?

Re: Battery draining...why?

2 things... are you using a maring starting battery, a deep cycle, or 1 of those combo batterys?

Are you running anything else with the engine off. A radio? Depthfinder, Radar???

Running a battery down to 9 volts in 2 hours is more than what a bilge pump/aerator is pulling for current.

As far as using a meter goes. With everything off use an amp clamp first, before you put the meters leads inline with anything. Me tinks you have more than a 10amp draw for the battery to drain that fast. If your showing less than 10 amps draw to the accesory wires then you can safely disconnect leads without worry of frying your meter.

1 more thing, with the engine off, put an amp clamp on your main starting wire, the big battery cable. It should show absolute 0. If your getting any current draw on the main wire you may have a bad diode in the rectifier. The engine will still charge the battery (you'll get a little more AC then it's supposed to), but when the motor is off it will drain the battery.

 

[bruceb58]

Re: Battery draining...why?

Re: Battery draining...why?

No need for a clamp meter. First test everything off like Jason said and then turn on the aerator and measure. It will definitely be less than 10 Amps. If it is fairly high, you can turn it off and then turn everything else on and just add the number you got for the aerator.

 

[JustJason]

Re: Battery draining...why?

Re: Battery draining...why?

No need for a clamp meter

I say use a clamp meter first only because if his meter is only fused for 10A but he's pulling 12 its going to pop the fuse.
That and if you have 16 wires comming off the battery it's easier to which ones are drawing

 

[Home Cookin']

Re: Battery draining...why?

Re: Battery draining...why?

just buy a new battery, and keep the old one they said was "perfect" for your auxillaries or a spare.
It sounds like you test it before you start--have you tested it just after you started, to see how much it dropped?

 

[KeyWestBoater]

Re: Battery draining...why?

Re: Battery draining...why?

OK. First to clarify a few things then some questions.
1. When I checked the voltage on the battery before going out, I used a multimeter and it was 12.5 volts so at least it's fully charged but it could be as you said that the battery doesn't have the capacity anymore.
2. The low voltage occurs after sitting 1-2 hours with the engine off, and the key off. The only things turned on are the FF and the aerator. In order to run the FF the "accessories" switch must be turned on.
3. The battery has 3 wires on each post; 2 small and the third being the large main cable.

Now questions.

1 more thing, with the engine off, put an amp clamp on your main starting wire, the big battery cable. It should show absolute 0. If your getting any current draw on the main wire you may have a bad diode in the rectifier. The engine will still charge the battery (you'll get a little more AC then it's supposed to), but when the motor is off it will drain the battery.

1. In using the amp alamp to test the rectifier, do I have to remove any cables?
2. Exactly where do I hook the amp clamp? On the battery or one of it's cables?
3. If I get a multimeter with a ampmeter then it should be at least 10 A in order not to need an Amp clamp?
4. When they test the battery don't they do some sort of load test to check the capacity?

Thanks again for all your help,

KWB

 

[JustJason]

Re: Battery draining...why?

Re: Battery draining...why?

1. No removing of the cables, if you did, you wouldn't have a complete circuit and would have no current flow in any direction.
2. On the positive cable with the arrow on the clamp facing the motor (amp clamps are directional)
3. Depends, if you put a DMM with a 10 amp rating inline in a circuit thats pulling 15 amps, your going to pop the fuse in the meter. Then you'll be cussing up and down because your meter is popped and you have to drive all over town looking for a correct 2 dollar fuse. The problem is, you don't know if your pulling more than 10 amps until you measure it.
4. Yes and no. Carbon pile load testers are the way batteries have been tested for 100 years. In the last 10 or so years, they have these fancy digital testers, I prefer my toaster, cheaper and I know it works.

Here is what I use to check charging and starting systems.
1. Fluke 88V
2. Old Fluke model 8 (which is my favorite meter in the whole wide world, shame they don't make it anymore)
3. Fluke amp clamp model i410
4. Matco branded battery load toaster (pretty much the same as this http://www.tooldiscounter.com/ItemDisplay.cfm?lookup=ASC6026 )

Now that's alot of money/tools for all that. The easiest way to test a charging system for a diode fault (which will cause a current draw back to the engine) is to put any old DMM on Millivolts AC and put the red to + and the black lead to - on the battery. With the engine running, if you get any more than .250 AC, then you have a charging system problem, and a current draw problem with the engine off.