I charged my 80 amp house battery (group 24?) over a couple of days with a car 1amp battery charger. Long story short, the battery was charged to over 12.7 volts. I've been told that after charging, let the battery rest for 24 hours before checking the voltage. Well, after 24 hours, the voltage is varies between 12.3 and 12.4 (e.g. 70-80%). This after I added water to the battery. Is this an example of a dead battery or is there another way to keep the battery charged at capacity? Thanx
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I doubt that it was over charged!
Tony: I doubt that you will overcharge anything with a 1 amp charger. I would put it on there for another 24 hours and test it again. Most charger have some sort of voltage regulator. Depending on the age of the battery it may not make any difference. Some of these cheapo batteries have a life of 2-3 years. You may want to think about a good quality Xantrex 10 amp charger in the future.
Tony: I doubt that you will overcharge anything with a 1 amp charger. I would put it on there for another 24 hours and test it again. Most charger have some sort of voltage regulator. Depending on the age of the battery it may not make any difference. Some of these cheapo batteries have a life of 2-3 years. You may want to think about a good quality Xantrex 10 amp charger in the future.
Battery Capacity
Tony, At best you will have put 48 Ampere hours into the battery (48 hrs x 1 Amp). More likely only about half that because the charger will most likely only be a "taper charger". If the battery was flat then you will need to charge for many hours with this charger. As Steve said you need to get a higher output charger, if possible a three or more stage one. Also it is normally only necessary to let the battery sit for an hour or so before testing the voltage. An even quicker way is to to apply a light load for a few minutes such as to run the cabin lights for 5 mins, switch everything off and test.
Tony, At best you will have put 48 Ampere hours into the battery (48 hrs x 1 Amp). More likely only about half that because the charger will most likely only be a "taper charger". If the battery was flat then you will need to charge for many hours with this charger. As Steve said you need to get a higher output charger, if possible a three or more stage one. Also it is normally only necessary to let the battery sit for an hour or so before testing the voltage. An even quicker way is to to apply a light load for a few minutes such as to run the cabin lights for 5 mins, switch everything off and test.
Battery Charging
A charger with a 12.7V output will never fully charge a battery . Battery Charging: Battery Charging takes place in three basic stages: Bulk, Absorption and Float Bulk Charge - The first stage of 3-stage battery charging. Current is sent to batteries at the maximum safe rate they will accept until voltage rises to near (80-90%) full charge level. Voltages at this stage typically range from 10.5 volts to 15 volts. There is no "correct" voltage for bulk charging, but there may be limits on the maximum current that the battery and/or wiring can take. Absorption Charge: The 2nd stage of 3-stage battery charging. Voltage remains constant and current gradually tapers off as internal resistance increases during charging. It is during this stage that the charger puts out maximum voltage. Voltages at this stage are typically around 14.2 to 15.5 volts. Float Charge: The 3rd stage of 3-stage battery charging. After batteries reach full charge, charging voltage is reduced to a lower level (typically 12.8 to 13.2) to reduce gassing and prolong battery life. This is often referred to as a maintenance or trickle charge, since it's main purpose is to keep an already charged battery from discharging. PWM, or "pulse width modulation" accomplishes the same thing. In PWM, the controller or charger senses tiny voltage drops in the battery and sends very short charging cycles (pulses) to the battery. This may occur several hundred times per minute. It is called "pulse width" because the width of the pulses may vary from a few microseconds to several seconds. Note that for long term float service, such as backup power systems that are seldom discharged, the float voltage should be around 13.02 to 13.20 volts. Charging at 15.5 volts will give you a 100% charge on Lead-Acid batteries. Once the charging voltage reaches 2.583 volts per cell, charging should stop or be reduced to a trickle charge. Note that flooded batteries MUST bubble (gas) somewhat to insure a full charge, and to mix the electrolyte. Float voltage for Lead-Acid batteries should be about 2.15 to 2.23 volts per cell, or about 12.9 - 13.4 volts for a 12 volt battery. At higher temperatures (over 85 degrees F) this should be reduced to about 2.10 volts per cell. Flooded battery life can be extended if an equalizing charge is applied every 10 to 40 days. This is a charge that is about 10% higher than normal full charge voltage (about 15.5V), and is applied for about 2 to 16 hours. This makes sure that all the cells are equally charged, and the gas bubbles mix the electrolyte. If the liquid in standard wet cells is not mixed, the electrolyte becomes "stratified". You can have very strong solution at the top, and very weak at the bottom of the cell. With stratification, you can test a battery with a hydrometer and get readings that are quite a ways off. If you cannot equalize for some reason, you should let the battery sit for at least 24 hours and then use the hydrometer. Never add acid to a battery except to replace spilled liquid. Distilled or deionized water should be used to top off non-sealed batteries. For more info’ - goto: Understanding a model for battery charge acceptance: http://cruisersforum.com/showthread.php?s=&threadid=1442&highlight=Battery+charging How "fast" you can reliably charge your battery: http://cruisersforum.com/showthread.php?s=&threadid=1432&highlight=Battery+charging HTH, Gord May
A charger with a 12.7V output will never fully charge a battery . Battery Charging: Battery Charging takes place in three basic stages: Bulk, Absorption and Float Bulk Charge - The first stage of 3-stage battery charging. Current is sent to batteries at the maximum safe rate they will accept until voltage rises to near (80-90%) full charge level. Voltages at this stage typically range from 10.5 volts to 15 volts. There is no "correct" voltage for bulk charging, but there may be limits on the maximum current that the battery and/or wiring can take. Absorption Charge: The 2nd stage of 3-stage battery charging. Voltage remains constant and current gradually tapers off as internal resistance increases during charging. It is during this stage that the charger puts out maximum voltage. Voltages at this stage are typically around 14.2 to 15.5 volts. Float Charge: The 3rd stage of 3-stage battery charging. After batteries reach full charge, charging voltage is reduced to a lower level (typically 12.8 to 13.2) to reduce gassing and prolong battery life. This is often referred to as a maintenance or trickle charge, since it's main purpose is to keep an already charged battery from discharging. PWM, or "pulse width modulation" accomplishes the same thing. In PWM, the controller or charger senses tiny voltage drops in the battery and sends very short charging cycles (pulses) to the battery. This may occur several hundred times per minute. It is called "pulse width" because the width of the pulses may vary from a few microseconds to several seconds. Note that for long term float service, such as backup power systems that are seldom discharged, the float voltage should be around 13.02 to 13.20 volts. Charging at 15.5 volts will give you a 100% charge on Lead-Acid batteries. Once the charging voltage reaches 2.583 volts per cell, charging should stop or be reduced to a trickle charge. Note that flooded batteries MUST bubble (gas) somewhat to insure a full charge, and to mix the electrolyte. Float voltage for Lead-Acid batteries should be about 2.15 to 2.23 volts per cell, or about 12.9 - 13.4 volts for a 12 volt battery. At higher temperatures (over 85 degrees F) this should be reduced to about 2.10 volts per cell. Flooded battery life can be extended if an equalizing charge is applied every 10 to 40 days. This is a charge that is about 10% higher than normal full charge voltage (about 15.5V), and is applied for about 2 to 16 hours. This makes sure that all the cells are equally charged, and the gas bubbles mix the electrolyte. If the liquid in standard wet cells is not mixed, the electrolyte becomes "stratified". You can have very strong solution at the top, and very weak at the bottom of the cell. With stratification, you can test a battery with a hydrometer and get readings that are quite a ways off. If you cannot equalize for some reason, you should let the battery sit for at least 24 hours and then use the hydrometer. Never add acid to a battery except to replace spilled liquid. Distilled or deionized water should be used to top off non-sealed batteries. For more info’ - goto: Understanding a model for battery charge acceptance: http://cruisersforum.com/showthread.php?s=&threadid=1442&highlight=Battery+charging How "fast" you can reliably charge your battery: http://cruisersforum.com/showthread.php?s=&threadid=1432&highlight=Battery+charging HTH, Gord May
Battery voltage nearly meaningless
Measuring the voltage on an unloaded battery is just about meaningless. It doesn't tell you anything about charge state, battery health, etc. Certain kinds of cell damage (a short, for example) will alter the voltage, but the only way to really assess a battery's health is under load, over time. You can buy a zillion dollars worth of gadgets to give you that information, but you can tell a lot just by using common sense. I presume that you weren't happy with what you had after you charged it with the car charger. My guess is you have a nearly dead battery, probably allowed to dry out. Buy another one. It's a common story in the Spring. Paul McGhee sv Escape Artist h336
Measuring the voltage on an unloaded battery is just about meaningless. It doesn't tell you anything about charge state, battery health, etc. Certain kinds of cell damage (a short, for example) will alter the voltage, but the only way to really assess a battery's health is under load, over time. You can buy a zillion dollars worth of gadgets to give you that information, but you can tell a lot just by using common sense. I presume that you weren't happy with what you had after you charged it with the car charger. My guess is you have a nearly dead battery, probably allowed to dry out. Buy another one. It's a common story in the Spring. Paul McGhee sv Escape Artist h336
1amp charger
so, is it futal to try to charge a dead 24 group battery with an 1amp charger? Regardless of how many hours its going to charge. Do I really need to buy the 3 stage chargers.
so, is it futal to try to charge a dead 24 group battery with an 1amp charger? Regardless of how many hours its going to charge. Do I really need to buy the 3 stage chargers.
Thanks Gord!
Just this morning I was thinking that the electrical system is one of my weaker (in a long list) of weak knowledge areas. You explained this very cleanly and I, for one, appreciate the thoroughness of your response. Thanks!
Just this morning I was thinking that the electrical system is one of my weaker (in a long list) of weak knowledge areas. You explained this very cleanly and I, for one, appreciate the thoroughness of your response. Thanks!
No need to buy a 3-stage charger....
... to charge a single flooded cell battery. Sophisticated charging systems are designed to get every last amp-hour into the batteries, and also to help the batteries last for as many charge-discharge cycles as possible. This is important when you have a large and expensive house bank that supports the boat for long periods of cruising. All of the fancy multi-stage chargers work off of shore power, and there are boats out there with properly functioning battery banks that haven't been connected to shore power since the Clinton administration. Fancy chargers are wonderful in appropriate situations. Yours isn't one of them. If the battery is not damaged, you'd be able to put a "good enough" charge on it with your trickle charger. People keep their batteries topped off just fine with single-panel solar chargers, which produce small currents. Thing is, you said you "added water." That means you probably let the battery dry out. If so, it's damaged beyond repair.
... to charge a single flooded cell battery. Sophisticated charging systems are designed to get every last amp-hour into the batteries, and also to help the batteries last for as many charge-discharge cycles as possible. This is important when you have a large and expensive house bank that supports the boat for long periods of cruising. All of the fancy multi-stage chargers work off of shore power, and there are boats out there with properly functioning battery banks that haven't been connected to shore power since the Clinton administration. Fancy chargers are wonderful in appropriate situations. Yours isn't one of them. If the battery is not damaged, you'd be able to put a "good enough" charge on it with your trickle charger. People keep their batteries topped off just fine with single-panel solar chargers, which produce small currents. Thing is, you said you "added water." That means you probably let the battery dry out. If so, it's damaged beyond repair.
Ah, Paul,,,,
I have a 3-stage regulator that controls my ALTERNATOR. It's a Balmar. Xantrex makes them too. It's seen in the upper-center of the photo. Also note the box next to it. A rectifier is in the box and cooled by a 12 volt blower. (par) That's because stock automotive rectifiers in my model alternator blow up (the solder melts) with a three stage regulator and heavy usage. (trust me) This is photo #53 on my web site. There is also more verbiage on this modification. As far as water getting low on your cells, it depends. If its just below the plates then you probably caught it in time. If it's down a couple of inches, that's a problem.
I have a 3-stage regulator that controls my ALTERNATOR. It's a Balmar. Xantrex makes them too. It's seen in the upper-center of the photo. Also note the box next to it. A rectifier is in the box and cooled by a 12 volt blower. (par) That's because stock automotive rectifiers in my model alternator blow up (the solder melts) with a three stage regulator and heavy usage. (trust me) This is photo #53 on my web site. There is also more verbiage on this modification. As far as water getting low on your cells, it depends. If its just below the plates then you probably caught it in time. If it's down a couple of inches, that's a problem.
Not at all. It depends,,,
how big is your bank? What do you draw? Do you have a large inverter powering AC appliances? How about lots of DC stuff? Do you hang on the hook or use marinas? How often do you start the engine and for how long? It depends. The box seen in the photo was built to solve a rectifier problem caused by a 3 stage regulator, not the internal regulator.
how big is your bank? What do you draw? Do you have a large inverter powering AC appliances? How about lots of DC stuff? Do you hang on the hook or use marinas? How often do you start the engine and for how long? It depends. The box seen in the photo was built to solve a rectifier problem caused by a 3 stage regulator, not the internal regulator.
Charging
Gord and Tony: It may be worth re-reading the original post. The fact that the tested battery showed a charge of 12.7 v is different than whatever the output of the charger was. Presumably it was in the 14.5v range needed. The fact that the battery was only showing 12.7v is probably an indication that it's life on earth is nearing an end. I also agree that voltage reading tells you little about how many cranking amps the battery could put out. Yet I owned a C&C 24 yrs ago (a great little boat) and don't think they came with an inboard like the C&C 25 did (a miserable Vire engine....). So the real question is: what are you using the battery for? If you are starting a small outboard, you don't need much power and could probably start it with its pull cord. If you are using the battery as a house bank, I think you know it's probably time to trade in for a newer one. Finally, most alternators on small outboards (if that is what you have) really don't put out out enough amps (typically 4) to really charge a battery fully. When you get the new battery, give some thought to charging it/or maintaining it by a more robust and capable system like those described here by others.
Gord and Tony: It may be worth re-reading the original post. The fact that the tested battery showed a charge of 12.7 v is different than whatever the output of the charger was. Presumably it was in the 14.5v range needed. The fact that the battery was only showing 12.7v is probably an indication that it's life on earth is nearing an end. I also agree that voltage reading tells you little about how many cranking amps the battery could put out. Yet I owned a C&C 24 yrs ago (a great little boat) and don't think they came with an inboard like the C&C 25 did (a miserable Vire engine....). So the real question is: what are you using the battery for? If you are starting a small outboard, you don't need much power and could probably start it with its pull cord. If you are using the battery as a house bank, I think you know it's probably time to trade in for a newer one. Finally, most alternators on small outboards (if that is what you have) really don't put out out enough amps (typically 4) to really charge a battery fully. When you get the new battery, give some thought to charging it/or maintaining it by a more robust and capable system like those described here by others.
The Missing Link
...was what the output of the original poster's charging source was. If you read Gord's reply, which is the right way to charge batteries, regardless of their use, then it becomes critical. Just because the batteries read 12.7 V after charging could mean a lot of things. Like, the charger could hav been only putting out 13.8 V overnight, like a really bad charger usually does. Or a lot of other things. C'mon, this is basic stuff, like Gord says. Unless the batteries are charged properly, they WILL have problems. A "CAR 1 AMP CHARGER!!!" Who ya kidding? In addition to Gord's post, try, as mentioned many times before, www.amplepwer.com, and download and read the Ample Power Primer, plus the West Marine charging advisor. Stu
...was what the output of the original poster's charging source was. If you read Gord's reply, which is the right way to charge batteries, regardless of their use, then it becomes critical. Just because the batteries read 12.7 V after charging could mean a lot of things. Like, the charger could hav been only putting out 13.8 V overnight, like a really bad charger usually does. Or a lot of other things. C'mon, this is basic stuff, like Gord says. Unless the batteries are charged properly, they WILL have problems. A "CAR 1 AMP CHARGER!!!" Who ya kidding? In addition to Gord's post, try, as mentioned many times before, www.amplepwer.com, and download and read the Ample Power Primer, plus the West Marine charging advisor. Stu
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