I JUST RECEIVED A "AGM" BATTERY WHICH HAD BEEN IN STORAGE. PLEASE ADVISE HOW THE BATTERY CAN BE CHARGED, CHECKED FOR FLUID LEVEL, AND WHAT THE VOLTAGE SHOULD BE WHEN FULLY CHARGED. BARNEY
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I think this link should help
Not a battery expert but I think the guy that wrote this site is. http://www.phrannie.org/battery.html
Not a battery expert but I think the guy that wrote this site is. http://www.phrannie.org/battery.html
that is an interesting article but from experience
I find that I don't entirely agree with his statements. I check my battery voltage on my 3 AGM batteries whenever I am on the boat and they rarely exceed 12.25 volts the day after I have run the engine for three hours. one month later they may show 12.0-12.2 volts but will start the engine with no voltage drop while cranking. After the 3 months of winter storage the battery voltage is 11.92 volts as it is every spring and I start the engine with no difficultly.
I find that I don't entirely agree with his statements. I check my battery voltage on my 3 AGM batteries whenever I am on the boat and they rarely exceed 12.25 volts the day after I have run the engine for three hours. one month later they may show 12.0-12.2 volts but will start the engine with no voltage drop while cranking. After the 3 months of winter storage the battery voltage is 11.92 volts as it is every spring and I start the engine with no difficultly.
Sealed and no way to replenish
Generally you can charge a AGM with a regular car battery charger if you need to. They will charge faster than a flooded battery and can use the same specs as the flood battery without harm. To get the most out of a AGM or GEL you really need a smart charger that can be set to monitor your battery tyep/chemistry. There is no way that I have ever heard of to fill or check the levels in a AGM or Gel battery. The one big advantage of a AGM is the fact that they can be store for prolonged periods without going dead from lack of charging. PS: turn off the caps. ARE YOU STILL YELLING?
Generally you can charge a AGM with a regular car battery charger if you need to. They will charge faster than a flooded battery and can use the same specs as the flood battery without harm. To get the most out of a AGM or GEL you really need a smart charger that can be set to monitor your battery tyep/chemistry. There is no way that I have ever heard of to fill or check the levels in a AGM or Gel battery. The one big advantage of a AGM is the fact that they can be store for prolonged periods without going dead from lack of charging. PS: turn off the caps. ARE YOU STILL YELLING?
Try this one instead, Barney.....
I confess I didn't read all of the other link, but I think this site explains batteries and charging better. You shouldn't need to check electrolyte level in an AGM battery - it is 'sealed'. Before you charge it, you can determine the state of charge by measuring it and looking on the table in the link. Ross's bateries at 11.92v are approximately 40% charged, which is pretty good after 3 months of storage, but AGM's hold their charge better than wet-cells. Fully-charged voltage can vary - it depends on the TRUE state of charge and the specific gravity (which you can't check in your AGM) and the temperature of the battery at the time it is tested. Anything over 90% is generally considered fully charged, whch means 12.5V is a good number. As the battery ages, especially if it has been subjected to numerous deep discharges or periods of being left un- or under- charged, its ability to fully charge and/or hold that charge diminishes. Since your battery is used, and you presumably have no reliable way of knowing how it has been used or mis-used, I'd say you should charge it up and use it, but not as your ONLY battery. For charging, you're best off with a 'smart' charger, like the Xantrex models. You're a lot better off not using anything of the 'automotive' variety, since those are only designed to charge wet-cell batteries (which are a LOT more forgiving of less-than-perfect charging). Cheers, Bob s/v X SAIL R 8
I confess I didn't read all of the other link, but I think this site explains batteries and charging better. You shouldn't need to check electrolyte level in an AGM battery - it is 'sealed'. Before you charge it, you can determine the state of charge by measuring it and looking on the table in the link. Ross's bateries at 11.92v are approximately 40% charged, which is pretty good after 3 months of storage, but AGM's hold their charge better than wet-cells. Fully-charged voltage can vary - it depends on the TRUE state of charge and the specific gravity (which you can't check in your AGM) and the temperature of the battery at the time it is tested. Anything over 90% is generally considered fully charged, whch means 12.5V is a good number. As the battery ages, especially if it has been subjected to numerous deep discharges or periods of being left un- or under- charged, its ability to fully charge and/or hold that charge diminishes. Since your battery is used, and you presumably have no reliable way of knowing how it has been used or mis-used, I'd say you should charge it up and use it, but not as your ONLY battery. For charging, you're best off with a 'smart' charger, like the Xantrex models. You're a lot better off not using anything of the 'automotive' variety, since those are only designed to charge wet-cell batteries (which are a LOT more forgiving of less-than-perfect charging). Cheers, Bob s/v X SAIL R 8
nothing negative except for the cost.
Ross: That is correct. The only thing that is negative about AGM & Gel's may be the cost. All batteries need a good charger regardless of the chemistry. I would assume that even cheap-o Walmart batteries would last longer with a proper charger. The lack of maintenance make them a big winner in my book. You don't need to worry about them exploding or spilling acid either.
Ross: That is correct. The only thing that is negative about AGM & Gel's may be the cost. All batteries need a good charger regardless of the chemistry. I would assume that even cheap-o Walmart batteries would last longer with a proper charger. The lack of maintenance make them a big winner in my book. You don't need to worry about them exploding or spilling acid either.
i have used AGM bateries since 1999. I put them in
place, connect them, monitor the voltage and when they no longer hold a charge for a week I change them. I installed a new set of two group 31 batteries in 2005. That was the first change. They get charged by the 50 amp alternator on my volvo diesel. Beyond that they get no attention at all.
place, connect them, monitor the voltage and when they no longer hold a charge for a week I change them. I installed a new set of two group 31 batteries in 2005. That was the first change. They get charged by the 50 amp alternator on my volvo diesel. Beyond that they get no attention at all.
AGM FACTS
An AGM battery, fully charged at rest and with no loads for several hours will read approx. 12.8V if it is in good condition. Readings of lower voltage after complete chargin and again wil no loads of less than 12.7V mean that there is sulfation or damage in one or more cells. The charging regime for an AGM is similar but not identical to a flooded battery and VERY different from a gel. Set your 3 stage charge as follows: Use 14.4 volts and as many amps as you can put out (at least up to amp hour capacity of the battery) during bulk charging stage. Use 13.8 volts during absorbtion phase (approximately 80% full) Use 13.3 volts and just a couple of amps or less for float stage to bring the battery up to 100%. NEVER discharge the battery below 50% capacity (12.24V AT REST/NO LOAD for at least an hour)...doing so will greatly reduce the lifespan of the battery.
An AGM battery, fully charged at rest and with no loads for several hours will read approx. 12.8V if it is in good condition. Readings of lower voltage after complete chargin and again wil no loads of less than 12.7V mean that there is sulfation or damage in one or more cells. The charging regime for an AGM is similar but not identical to a flooded battery and VERY different from a gel. Set your 3 stage charge as follows: Use 14.4 volts and as many amps as you can put out (at least up to amp hour capacity of the battery) during bulk charging stage. Use 13.8 volts during absorbtion phase (approximately 80% full) Use 13.3 volts and just a couple of amps or less for float stage to bring the battery up to 100%. NEVER discharge the battery below 50% capacity (12.24V AT REST/NO LOAD for at least an hour)...doing so will greatly reduce the lifespan of the battery.
You can discharge an agm all the way
AGM batteries were made with the idea to discharge all the way. They are made mostly for trolling motors (originally) that could work at the low voltage levels. I charge mine with the factory recommendation of a 3 amp trickle charger on all the time( i only use my sail boat once a week or so though). Good luck.
AGM batteries were made with the idea to discharge all the way. They are made mostly for trolling motors (originally) that could work at the low voltage levels. I charge mine with the factory recommendation of a 3 amp trickle charger on all the time( i only use my sail boat once a week or so though). Good luck.
Sorry, but sweet is wrong
DO NOT discharge your AGM beyond 50% unless you like buying batteries alot. They are popular for trolling motors because they are sealed, and will accept a charge faster than other types, and they can be charged with just about any charger without damage. AGM's were originally designed by Concorde batteries for military aircraft. The design criteria was to withstand severe vibrations and shock loads, operate in any position (inverted), and withstand severe overcharging without catastrophic failure. There is some interesting reading about thermal runaway in batteries at the Concorde battery website under the technical info link. AGM's are designed to contain all acid and flames or arcs without case failure.
DO NOT discharge your AGM beyond 50% unless you like buying batteries alot. They are popular for trolling motors because they are sealed, and will accept a charge faster than other types, and they can be charged with just about any charger without damage. AGM's were originally designed by Concorde batteries for military aircraft. The design criteria was to withstand severe vibrations and shock loads, operate in any position (inverted), and withstand severe overcharging without catastrophic failure. There is some interesting reading about thermal runaway in batteries at the Concorde battery website under the technical info link. AGM's are designed to contain all acid and flames or arcs without case failure.
Never say "Never" and "all the way down"
They are two extremes and when it comes to discharge levels and battery longevity. The reality lies somewhere in the middle. I have some decent AGM batteries, not the absolute best but better than most and what levels you can deplete the batteries will reduce the the total cycles the battery will have (see chart from manufacturer in link). http://www.mkbattery.com/images/lagm.pdf I let my batteries go below 50% when I need to and they are doing fine. There are times I am on the hook for the weekend and I don't want to start my engine just to bring the batteries up above 50%, especially when I know I am going to be firing up the "Iron Genny" later that day when I leave. There are also people that are full time cruising and they would have to run the engine everyday to keep the batteries above 50%, so instead they let the batteries go a little longer and save engine wear. Looking at the specs it says that discharging to 50% gets 500 discharge Cycles and discharging 75% leaves you with 250 discharge cycles. On a 200 A/H batteries and discharging to 50% gets you 50,000 A/H over the life of a battery. That same battery but discharging to 75% gets you 37,500 A/H over the life of a battery. Not as good as the 50% discharge but still not that bad and to many people it might be worth it if that means starting the engine less. Two other interesting data points. 1) 25% discharged battery will get 1200 cycles which relates to 60,000 A/H which only relates to a little increase in total A/H than a 50% discharged. 2) A 100% discharged battery will get you 200 cycles (!) which relates to 40,000 A/H over the life of the battery. Thats more total A/H than discharging to 75% !! *pop. Putting this into perpective , if I was living on the hook & had 2 4D AGM batteries (400 A/H) and had a daily A/H usage of 100 A/H then I could go 400 days while letting them deplete to 100% (and saving engine run time) or go 500 days depleting them to 50% but running the engine more often The thing is that batteries (especially AGM's) will take a lot more charging current a lot longer when the batteries are down further. For instance 3 hours of engine run time with a fully depleted battery and a high output alternator would/could yield well over 225 A/H (more or less). But if your batteries have already hit approx 85-87% of capacity it starts to accept much less current. It takes a LOT of alternator engine run time for the batteries to go from 90% charged to 100% charge. Obviously in this case augmenting the batteries via wind and/or solar is how cruisers get much more life out of a battery
They are two extremes and when it comes to discharge levels and battery longevity. The reality lies somewhere in the middle. I have some decent AGM batteries, not the absolute best but better than most and what levels you can deplete the batteries will reduce the the total cycles the battery will have (see chart from manufacturer in link). http://www.mkbattery.com/images/lagm.pdf I let my batteries go below 50% when I need to and they are doing fine. There are times I am on the hook for the weekend and I don't want to start my engine just to bring the batteries up above 50%, especially when I know I am going to be firing up the "Iron Genny" later that day when I leave. There are also people that are full time cruising and they would have to run the engine everyday to keep the batteries above 50%, so instead they let the batteries go a little longer and save engine wear. Looking at the specs it says that discharging to 50% gets 500 discharge Cycles and discharging 75% leaves you with 250 discharge cycles. On a 200 A/H batteries and discharging to 50% gets you 50,000 A/H over the life of a battery. That same battery but discharging to 75% gets you 37,500 A/H over the life of a battery. Not as good as the 50% discharge but still not that bad and to many people it might be worth it if that means starting the engine less. Two other interesting data points. 1) 25% discharged battery will get 1200 cycles which relates to 60,000 A/H which only relates to a little increase in total A/H than a 50% discharged. 2) A 100% discharged battery will get you 200 cycles (!) which relates to 40,000 A/H over the life of the battery. Thats more total A/H than discharging to 75% !! *pop. Putting this into perpective , if I was living on the hook & had 2 4D AGM batteries (400 A/H) and had a daily A/H usage of 100 A/H then I could go 400 days while letting them deplete to 100% (and saving engine run time) or go 500 days depleting them to 50% but running the engine more often The thing is that batteries (especially AGM's) will take a lot more charging current a lot longer when the batteries are down further. For instance 3 hours of engine run time with a fully depleted battery and a high output alternator would/could yield well over 225 A/H (more or less). But if your batteries have already hit approx 85-87% of capacity it starts to accept much less current. It takes a LOT of alternator engine run time for the batteries to go from 90% charged to 100% charge. Obviously in this case augmenting the batteries via wind and/or solar is how cruisers get much more life out of a battery
Tom...You are right...
I was simplifying to give some basic guidance. 50% discharge level is really just a sweet spot to aim for that gives you optimum power/recycling ability and keeps the rather high battery replacement costs at reasonable intervals. My own bank of AGM's is 1100A/H's and believe me...I don't want to replace them any time soon. On the other hand...at 50% discharge I can but a bulk charge into them of 110amps...for nearly 4 hours before moving to acceptance or float levels so I can often simply cycle between 50% and 80% (350 A/H) with an occassional topping up at the dock to keep things shipshape internally. For a real cruising situation I agree that the AGM's are superior if you can handle the initial price tag.
I was simplifying to give some basic guidance. 50% discharge level is really just a sweet spot to aim for that gives you optimum power/recycling ability and keeps the rather high battery replacement costs at reasonable intervals. My own bank of AGM's is 1100A/H's and believe me...I don't want to replace them any time soon. On the other hand...at 50% discharge I can but a bulk charge into them of 110amps...for nearly 4 hours before moving to acceptance or float levels so I can often simply cycle between 50% and 80% (350 A/H) with an occassional topping up at the dock to keep things shipshape internally. For a real cruising situation I agree that the AGM's are superior if you can handle the initial price tag.
Tom I agree with you,,,sort of
It is not a problem to go below 50% occasionally provided you bring them back up soon. Discharge them below that and let them sit for extended periods of time and they will suffer. Your thinking as far as total AH out of a battery for different discharge cycles assumes 100% capacity for all the cycles. In a perfect world this may be true, but we don't live there. If you did a controlled test of this you would find that the deeper you discharge, the sooner the battery capacity will suffer per cycle and the less effeciently they will recharge. I service a remote solar installation that cycles between 20 and 50% and occasionally they will go lower depending on weather and seasonal input. The AGM's in that installation are 10 years old and have over 2000 cycles. They are still above 80% of their rated capacity. All things considered, I think AGM's are worth the price and the way to go in a boat.
It is not a problem to go below 50% occasionally provided you bring them back up soon. Discharge them below that and let them sit for extended periods of time and they will suffer. Your thinking as far as total AH out of a battery for different discharge cycles assumes 100% capacity for all the cycles. In a perfect world this may be true, but we don't live there. If you did a controlled test of this you would find that the deeper you discharge, the sooner the battery capacity will suffer per cycle and the less effeciently they will recharge. I service a remote solar installation that cycles between 20 and 50% and occasionally they will go lower depending on weather and seasonal input. The AGM's in that installation are 10 years old and have over 2000 cycles. They are still above 80% of their rated capacity. All things considered, I think AGM's are worth the price and the way to go in a boat.
I just came back from a trip to the boat.
I record battery voltage in the log and this is what we have. On November 30 the boat was hauled and placed on the hard for the winter. Battery voltage 12.12. The boat was next visited on December29 Air temp: 43 degrees F Battery voltage :11.98 Next visit March 10 this spring battery voltage 11.93 air temp. 44 F. . Today Battery voltage 11.99 air temp. 56. I started the engine, normal fast cranking engine fired on the 4th compression stroke. I ran the engine for about thirty seconds and shut her down. Battery voltage 12.08.
I record battery voltage in the log and this is what we have. On November 30 the boat was hauled and placed on the hard for the winter. Battery voltage 12.12. The boat was next visited on December29 Air temp: 43 degrees F Battery voltage :11.98 Next visit March 10 this spring battery voltage 11.93 air temp. 44 F. . Today Battery voltage 11.99 air temp. 56. I started the engine, normal fast cranking engine fired on the 4th compression stroke. I ran the engine for about thirty seconds and shut her down. Battery voltage 12.08.
Let's keep it simple
Again, Tom's right. Please to to www.amplepower.com and download & read the Primer. Then read it again. Please.
Again, Tom's right. Please to to www.amplepower.com and download & read the Primer. Then read it again. Please.
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