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BigBadBass

Battery Dead or Alive?

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Ok, took my boat out today and realized when I got to the marina that I left the key in the on position last week. Well I guess you can figure out I was completely dead. So I took the boat home and hooked up a battery charger/tester to it and it is showing that it has 11.7v at less than 20% battery life.

I'm not too good with what a battery is supposed to be but shouldn't it read out on the tester 12v or more? Is this something that will rise when the battery charges?

Another thing,, I got a jumpstart at the marina while I was there and it started no problem off a good battery. I sat in the marina revving up the engine steady for half an hour. I turned it off to see if it would start again before I head out in the bay and it was completely stone dead. Could that be the battery being that dead? Or is it not holding a charge for some reason?

When I got home I took the battery out of my other boat and it started right up. Any help would be great,, I'm not too up on the battery/electronics of my boat.

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sounds like the battery is dead or almost dead and not holding the charge. Once the boat is started and running it does not use the battery it runs off the alternator. I would think it should have charged in the half hour that you had it running at the dock if it was not dead. Ide try a slow charge overnight and see if that works if not have it load tested at an auto supply shop like pep boys or auto zone they all have load testers.

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Age of battery could be a factor, not knowing age I woiuld say you have a dead cell or a weak one, that is why it will not hold a charge. I would replace it. Once you discharge a battery, it may never be reliable again. If you have only one battery in the boat, no way I would trust it. How are you terminals and wires?

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Souunds like you do have a dead cell and i is pulling the charge from the other cells. Put it on a charger and open the top. See if one of the cells bubbles excessively. If so then that is the bad cell. Also get a hydometer. Which test the specific gravity of the battery fuild which will tell for sure.

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View PostAge of battery could be a factor, not knowing age I woiuld say you have a dead cell or a weak one, that is why it will not hold a charge. I would replace it. Once you discharge a battery, it may never be reliable again. If you have only one battery in the boat, no way I would trust it. How are you terminals and wires?

 

 

The battery is not that old but I did fully discharge it. I've been treating the boat like a car and just starting and going,, I should have put a trickle charge on at the end of each trip. The terminals and wires are just fine.

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If you fully discharge a regular starting battery thats several yrs old it may kill it. Batteries aren't that expensive I'd go the replacement route. Its expensive and a pita to have to be towed in . I change batteries every 3yrs regardless. JP

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Voltage alone won't tell you the condition of the battery. You need to do a load test. Auto Zone or pep Boys will do one for you but I suspect that your battery needs replacement

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If your battery is 3yrs old or older I think it's time to get another battery.The adverage Marine battery will give you 3yrs! You don't want to get stick in the middle of the ocean with out any power!

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batteries are fairly new,, 1 year. I have them each on a battery charger and I just borrowed a load tester from my buddy. Should I wait till they are fully charged or can I test them while they are at about 75% right now?

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Your batteries may not be dead. A fully charged battery reads 12.8-13.2 volts(depending on which theory you use based on different DC experts) a 11.7 is dead without any load. The problem is that you only ran it for a half hour. Especially if you have 2 batteries on one motor. The way a Battery accpts charge is like this. at less than 50% charge, it takes a LOT of amps, of which very few boat alternators can produce. They are set up to do mid-level charge. A heavy charge, that initial charge, could be accepting somewhere near 50 Amps per battery. Most outboard alts, or speedos, can produce something like 20. The reason for this is that GENERALLY, you get on, mnotor starts, taking almost no amperage out of the batter, and then is charging, often never needing that charge rate. So if the battery doesn't get that full charge initially, it can take a LONG time to charge back to life. Hook them up to the charger for 24 hours, let it cycle it's different phases of charging, and then load test. Unless you have AT LEAST 12.6V, DO NOT LOAD TEST. It will almost never be accurate below 12.6 volts.

 

GL

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headscratch.gif Charge 'em,

Wait a day,

Check 'em again.

Question answered.confused.gif (I assumed.)

 

If they hold a charge they're good.

If they don't I figure they're toast.

Is there more to it than that? headscratch.gif

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View PostYour batteries may not be dead. A fully charged battery reads 12.8-13.2 volts(depending on which theory you use based on different DC experts) a 11.7 is dead without any load. The problem is that you only ran it for a half hour. Especially if you have 2 batteries on one motor. The way a Battery accpts charge is like this. at less than 50% charge, it takes a LOT of amps, of which very few boat alternators can produce. They are set up to do mid-level charge. A heavy charge, that initial charge, could be accepting somewhere near 50 Amps per battery. Most outboard alts, or speedos, can produce something like 20. The reason for this is that GENERALLY, you get on, mnotor starts, taking almost no amperage out of the batter, and then is charging, often never needing that charge rate. So if the battery doesn't get that full charge initially, it can take a LONG time to charge back to life. Hook them up to the charger for 24 hours, let it cycle it's different phases of charging, and then load test. Unless you have AT LEAST 12.6V, DO NOT LOAD TEST. It will almost never be accurate below 12.6 volts.

 

GL

 

 

Chief I always get good info from you, thanx. I'm getting 12.8- 12.9 reading from both batteries now that they are fully charged,, load tested them and they both stay in the green. I'm gonna take it out this weekend and see how it does but I'm definetely taking a spare battery in case. Plus I have a jump starter thats coming too but I think you were right that the batteries were just completely depleted.

I bought the boat with those batteries the beginning of this season and the guy I bought it from said the batteries were new last season. I'm hoping I can get this season out of them and get some new ones for next season.

Thanx again!

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ummm, usually the batteries have "punched holes" that signify the month and year they are sold. If it has this, but NOT punched, there's no way to tell. When you do get new ones, try and mark them some way that you will know exactly. Always a good idea to let yourself know how old they are. And you're welcome. Glad it could help.

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Batteries also have a headstamp date of manufacture on the side top rim of the case. If your battery fails and you do not have a receipt, the headstamp date is used to pro rate the Battery.

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