I finally had to replace the battery on my Capri 22. It had a fairly standard combination deep cycle/starting marine battery (not a gel type), and that is what I replaced it with. I did a search here for any advice on getting a long life out of it; the main points seem to be: 1. Avoid discharging it completely. 2. Don't let it overheat when charging. 3. Keep the water topped off. #2 is where I'm a little hazy. There are no mechanisms aboard for charging; that is done with an auto-type charger ashore. It's a relatively low-power device - I think 6 amp, if I remember off the top of my head. There's an ammeter that tells me how much charge the battery is taking. My basic questions are, do I have anything to worry about wrt overcharging, and how long should I expect to have the battery on a charger like that if the voltage has dropped below 12?
Basic battery care
- Thread starter Ben16737
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It's hard to give specific answers to your
questions as I don't know specifically the kind or type of battery or battery charger you have. But on a previous boat that didn't have a charger, I also charged that battery with a 6 amp 12v automotive battery charger. It had an ammeter that showed the rate of charge. When you first plug it in and connect to the charger, the rate of charge will be high and then gradually fall off as the batter charges. When it gets down to 1 or 2 amps, it's charged about as much as it's gonna be. That might take 3-4 hrs or longer depending on how significantly the batter was discharged, a key factor in the life of your battery. At the chart below shows, letting a battery get below 12v means it only had 25 % of it's charge left (or it's 75% discharged). DON'T let this happen. I suggest not letting your wet cell battery ever get below 50% in order to get as much life out of it as you can. You may want to buy a 5 amp solar panel and use that when you are away from your boat. State of Charge Specific Gravity Voltage 100% 1.265 12.7 *75% 1.225 12.4 50% 1.190 12.2 25% 1.155 12.0 Discharged 1.120 11.9
questions as I don't know specifically the kind or type of battery or battery charger you have. But on a previous boat that didn't have a charger, I also charged that battery with a 6 amp 12v automotive battery charger. It had an ammeter that showed the rate of charge. When you first plug it in and connect to the charger, the rate of charge will be high and then gradually fall off as the batter charges. When it gets down to 1 or 2 amps, it's charged about as much as it's gonna be. That might take 3-4 hrs or longer depending on how significantly the batter was discharged, a key factor in the life of your battery. At the chart below shows, letting a battery get below 12v means it only had 25 % of it's charge left (or it's 75% discharged). DON'T let this happen. I suggest not letting your wet cell battery ever get below 50% in order to get as much life out of it as you can. You may want to buy a 5 amp solar panel and use that when you are away from your boat. State of Charge Specific Gravity Voltage 100% 1.265 12.7 *75% 1.225 12.4 50% 1.190 12.2 25% 1.155 12.0 Discharged 1.120 11.9
How to understand Warren's numbers
Ben, Warren posted some numbers for you and they are good numbers but, you need to know that those numbers are with no load connected at all - i.e. open circuit voltage measurements. The measurements you make will be up to 10 percent accurate with his numbers. If the battery is allowed to sit for 72 hours in an open circuit(not practical really) the accuracy goes up to 2.5 percent. Warren's numbers do not have a space between the specific gravity and the voltage so for example - 100%(state of charge) 1.265(specific gravity) 12.7(volts) Good post Warren.
Ben, Warren posted some numbers for you and they are good numbers but, you need to know that those numbers are with no load connected at all - i.e. open circuit voltage measurements. The measurements you make will be up to 10 percent accurate with his numbers. If the battery is allowed to sit for 72 hours in an open circuit(not practical really) the accuracy goes up to 2.5 percent. Warren's numbers do not have a space between the specific gravity and the voltage so for example - 100%(state of charge) 1.265(specific gravity) 12.7(volts) Good post Warren.
That's reassuring
Thanks to both of you for the responses. What you described is basically the way that I treated the old battery - during the last couple seasons. Which was too little, too late. I pretty much ignored/abused the battery the first few seasons I owned it, which likely shortened it's life. I think that if I get a digital volt meter and pay more attention to this new battery, it should last quite a while.
Thanks to both of you for the responses. What you described is basically the way that I treated the old battery - during the last couple seasons. Which was too little, too late. I pretty much ignored/abused the battery the first few seasons I owned it, which likely shortened it's life. I think that if I get a digital volt meter and pay more attention to this new battery, it should last quite a while.
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