I recently purchased one of those cheap hygometers that measures the health of your battery fluid with a simple good/poor color reading card. When I check my voltage on my panel meter each of the two batteries reads 10 volts. The hygrometer reading just barely sits a needles worth or two on the "good" side. I know these batteries are at least three-four years old, and I run the switch on "both" for starting and cabin DC needs. I always heard that you need to read 12 volts or you have problems! So, at what point are they ready for the recycler? Its an issue too of trusting my panel and that lame hygrometer. Thanks Bob 30-Catalina
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Remove & recharge first.
I would remove the batteries from the boat, make sure the electrolyte level is up to the rim at the bottom of each cel. Do this by adding distilled water (not battery acid) and recharge them on a trickle charger until they read better than 12 V (Landsend says 12.6 and is correct)10 volts doesn't cut it. If you can get them up to 12.6 volts, the hydrometer should read @ about 1260. Then after charging have them load tested at any local automotive shop. If you can't get them to 12.6 volts then they are junk. Biggest mistake people make is overcharging and boiling the electrolyte out of the batteries. It is a good practice to check them regularly especially if you are plugged into shore power with an automatic charger. If they won't pass a load test after recharge, replace them. Fair winds. Ken
I would remove the batteries from the boat, make sure the electrolyte level is up to the rim at the bottom of each cel. Do this by adding distilled water (not battery acid) and recharge them on a trickle charger until they read better than 12 V (Landsend says 12.6 and is correct)10 volts doesn't cut it. If you can get them up to 12.6 volts, the hydrometer should read @ about 1260. Then after charging have them load tested at any local automotive shop. If you can't get them to 12.6 volts then they are junk. Biggest mistake people make is overcharging and boiling the electrolyte out of the batteries. It is a good practice to check them regularly especially if you are plugged into shore power with an automatic charger. If they won't pass a load test after recharge, replace them. Fair winds. Ken
Digital voltmeter
The difference between say, 100% and 50% charged is too small to see on an analog voltmeter... get a little digital one from Radio Shack or something. I found the following rule of thumb online: 12 Volt battery state: (percentage of charge, volts overall, volts per cell) 100% 12.70 2.12 90% 12.50 2.08 80% 12.42 2.07 70% 12.32 2.05 60% 12.20 2.03 50% 12.06 2.01 40% 11.90 1.98 30% 11.75 1.96 20% 11.58 1.93 10% 11.31 1.89 0% 10.50 1.75 I then tracked my voltage over the winter with the results below. I'm on a mooring so all I could do was run the engine to charge. State of Charge Date Bank #2 Bank#1 Runtime 2/4/06 12.14 12.40 +1.5 hour 2/20/06 11.40 12.40 +1.5 hour 2/26/06 11.43 12.42 +1 hour 3/11/06 10.48 12.37 +1.5 3/18/06 10.46 12.42 +1.5 3/24/06 11.86 12.44 +1.0 4/1/06 11.62 12.53 +1.5 4/9/06 11.66 12.40 +4.5 (Voltage is measured before the engine is run, when the battery is at rest). As you can see bank #2 went downhill fast, and basically was flat after a couple of months. I found and fixed a current leak on 3/18, but by then it was too late, I was only holdng 20% or so. #2 would not crank the engine. Even after I put them on shore power for a week, they would still not crank the engine, so out they went. This is (I believe) a text book case of what *not* to do with batteries. You don't get to cycle them down to 0% more than a few times without killing them. Its also a good example to see how running the engine for an hour or two will not really push a battery above 80%. You need a long period of time to do that. I've got a solar panel ready to install now. BTW - I attended a seminar at the boat show in January on "12 Volt Systems: Energy Management", presented Warren Miller of West Marine, which I would really recommend. I think he does the boat show circuit each year. (Note - I'm by no means an expert on this subject)
The difference between say, 100% and 50% charged is too small to see on an analog voltmeter... get a little digital one from Radio Shack or something. I found the following rule of thumb online: 12 Volt battery state: (percentage of charge, volts overall, volts per cell) 100% 12.70 2.12 90% 12.50 2.08 80% 12.42 2.07 70% 12.32 2.05 60% 12.20 2.03 50% 12.06 2.01 40% 11.90 1.98 30% 11.75 1.96 20% 11.58 1.93 10% 11.31 1.89 0% 10.50 1.75 I then tracked my voltage over the winter with the results below. I'm on a mooring so all I could do was run the engine to charge. State of Charge Date Bank #2 Bank#1 Runtime 2/4/06 12.14 12.40 +1.5 hour 2/20/06 11.40 12.40 +1.5 hour 2/26/06 11.43 12.42 +1 hour 3/11/06 10.48 12.37 +1.5 3/18/06 10.46 12.42 +1.5 3/24/06 11.86 12.44 +1.0 4/1/06 11.62 12.53 +1.5 4/9/06 11.66 12.40 +4.5 (Voltage is measured before the engine is run, when the battery is at rest). As you can see bank #2 went downhill fast, and basically was flat after a couple of months. I found and fixed a current leak on 3/18, but by then it was too late, I was only holdng 20% or so. #2 would not crank the engine. Even after I put them on shore power for a week, they would still not crank the engine, so out they went. This is (I believe) a text book case of what *not* to do with batteries. You don't get to cycle them down to 0% more than a few times without killing them. Its also a good example to see how running the engine for an hour or two will not really push a battery above 80%. You need a long period of time to do that. I've got a solar panel ready to install now. BTW - I attended a seminar at the boat show in January on "12 Volt Systems: Energy Management", presented Warren Miller of West Marine, which I would really recommend. I think he does the boat show circuit each year. (Note - I'm by no means an expert on this subject)
Try these references
www.amplepower.com -- download the Ample Power Primer -- great battery info West Marine -- read the catalog -- the Advisors are a great source of info, also available on the web Google or use this website, BoatUS, Sailnet, and read -- tons of great information We could copy it all here, or you could do some more research and homework Sorry to sound like your aunt or mom, but it really is all out there, and it's a great question as a starting point. All the best, Stu
www.amplepower.com -- download the Ample Power Primer -- great battery info West Marine -- read the catalog -- the Advisors are a great source of info, also available on the web Google or use this website, BoatUS, Sailnet, and read -- tons of great information We could copy it all here, or you could do some more research and homework Sorry to sound like your aunt or mom, but it really is all out there, and it's a great question as a starting point. All the best, Stu
Take them to a battery shop and have them tested.
Bob: The easiest thing to do is to take you batteries to a shop that can charge and test them. Charging a battery to a specific charge is fine, but if it does not hold that charge you are sunk. They need to be properly charged and load tested. Based on your description of these batteries I would not spend any money on having them tested. Now it's time to determine what type of replacements you are looking for!
Bob: The easiest thing to do is to take you batteries to a shop that can charge and test them. Charging a battery to a specific charge is fine, but if it does not hold that charge you are sunk. They need to be properly charged and load tested. Based on your description of these batteries I would not spend any money on having them tested. Now it's time to determine what type of replacements you are looking for!
The old fashion way
or how to do it at see. Lets see, 10 volts is 2 volts less than 12 volts. Each of the 6 cells in a 12 volt battery produce 2 ish volts so my first guess is that you have a bad cell in at least one battery. This will cause the other good battery to go bad too. To test it, take that old analog voltmeter and do the following. Take off the battery caps, put the neg probe on the neg terminal of the battery and the positive probe in the fluid in the cell next to the negative post. You should get something like 2.1 volts. Move the positive probe to the next cell and you should measure 4.2 volts. Continue until you get to the last one where you should get full battery voltage. If you find that a cell does not show an increase in voltage then that cell is shorted. That is the battery to replace. Digital voltmeter! You know we where using batteries for quite a while without digital voltmeters and we got along just fine.
or how to do it at see. Lets see, 10 volts is 2 volts less than 12 volts. Each of the 6 cells in a 12 volt battery produce 2 ish volts so my first guess is that you have a bad cell in at least one battery. This will cause the other good battery to go bad too. To test it, take that old analog voltmeter and do the following. Take off the battery caps, put the neg probe on the neg terminal of the battery and the positive probe in the fluid in the cell next to the negative post. You should get something like 2.1 volts. Move the positive probe to the next cell and you should measure 4.2 volts. Continue until you get to the last one where you should get full battery voltage. If you find that a cell does not show an increase in voltage then that cell is shorted. That is the battery to replace. Digital voltmeter! You know we where using batteries for quite a while without digital voltmeters and we got along just fine.
both?
Bob, why do you use both batteries to start and for house supply? The purpose of having two batteries is to dedicate one for starting and one for house, so that you will not get stranded somewhere with dead batteries. I use a deep cycle for the house and then a separate starting battery.
Bob, why do you use both batteries to start and for house supply? The purpose of having two batteries is to dedicate one for starting and one for house, so that you will not get stranded somewhere with dead batteries. I use a deep cycle for the house and then a separate starting battery.
time and money
Try what is said below and if it still won't hold a charge toss it. A new deep cycle from wal-mart is about $60.00 I wouldn't waste too much time on an old battery. But definately put then on a charger and see if they recover. But in the past I've messed around with an old battery then had t toss it anyway. A couple of new batteries is cheaper than a short tow by a commercial outfit. They once charged me $60.00 for a boost and I was just outside their marina. I had sailed in but couldn't get into the marina itself without a motor. They didn't come 50 yards.
Try what is said below and if it still won't hold a charge toss it. A new deep cycle from wal-mart is about $60.00 I wouldn't waste too much time on an old battery. But definately put then on a charger and see if they recover. But in the past I've messed around with an old battery then had t toss it anyway. A couple of new batteries is cheaper than a short tow by a commercial outfit. They once charged me $60.00 for a boost and I was just outside their marina. I had sailed in but couldn't get into the marina itself without a motor. They didn't come 50 yards.
switching battries
can you switch from #1 to #2 batrey after you start the engine?like from srart to house battery.will it hurt the alternator?
can you switch from #1 to #2 batrey after you start the engine?like from srart to house battery.will it hurt the alternator?
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