SternWake
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Mainesail has wonderful writeups on many things related to how we use batteries/electricity, and his 'what is a deep cycle battery?' shows just how superior a real flooded/wet deep cycle battery is compared to a 12v flooded/wet group 24/27/29/31 marine battery that is often the battery of choice due to the ease of availability, warranty, and cost and possible space restricitions in the intended location.
He had updated this article on this site in the fairly recent past:
http://www.pbase.com/mainecruising/deep_cycle_battery
But I just noticed he has set up a more modern site with more upto date and detailed information regarding deep cycle batteries, that is well written with more data, that can help many members here understand and extract more deep cycles from their lead acid battery banks, meaning more money in their pocket to further their accumulated life experiences, rather than handing it over to a battery retailer and/or stressing out when battery failure comes as a complete surprise.
https://marinehowto.com/what-is-a-deep-cycle-battery/
But the quick version for those with limited data will be condensed in the following quoted material:
Simply being aware of what kills Lead acid batteries( this includes AGM and GEL) should go a long way toward helping members extract more cycles from their batteries. But clicking every box to get the most possible life from batteries might have one thinking they are a battery servant rather than the other way around. It can be much easier to accept marinal battery longevity and simply replace them more often, but that should be an individual's choice.
Much of the things to extend lead acid battery life are simply not trusting that any automatic charging source with 3 stages, or 8 stages, or 22 stages followed by oral copulation, knows what is best for the battery. Most charging sources, including solar charge controllers, will allow a premature reversion to float voltage before the battery is actually full. This is NOT good. This can/will all too easily lead to partial state of charge cycling and will reduce battery capacity much faster than the battery that actually gets to a true 100% state of charge regularly.
Those who cycle their batteries deeply, and only have a 1 to 1 solar wattage to AH capacity ratio and do not employ, or rarely employ other charging sources, will likely rarely ever reach the true 100% state of charge on solar power alone, and as such their batteries might endure only half or less the total accumulated cycles before replacement cannot be put off any longer, compared to a higher wattage to AH ratio.
There are lots of variables affecting battery longevity, but I urge those who want to get good to excellent lifespans from their batteries to use a good temperature compensating hydrometer and check that the batteries are actually at 1.270 or higher specific gravity when their solar controller first reverts to float voltage, and then again after a few hours at float voltage to see if the duration of the float stage before late afternoon/early evening, increased specific gravity at all, which is not very likely.
The solar charge controller reverting to float voltage/stage, does NOT mean the batteries are full, and battery recharging slows down significantly at lower electrical pressure(voltage). Perhaps some deeply cycled batteries will actually achieve full by sundown when prematurely allowed to enter float stage, but this would be very rare, and when the solar wattage is there to hold absorption voltage longer, but is not allowed/programmed to hold absorption voltage as long as required, then a crime is being committed against the battery and to the budget of the battery renter.
Many users with light solar wattage to AH ratios would eek more life from their batteries by not allowing float voltage to be initiated at all, when their batteries are cycling below 80% each and every day.
It depends on the solar controller, but some will not allow extending absorption voltage duration, but will allow one to raise the float voltage to the same as absorption voltage, and thus be able to feed the battery bank more full, daily, which will extend battery longevity.
Those who raise float upto absorption voltage NEED to lower it again when their overnight electrical consumption stops or suddenly drops to significantly lower levels or they then risk overcharging.
Float Stage/voltage is there to keep a fully charged battery, fully charged with minimal water usage and minimal electrolytical plate erosion. But if float is continuously initiated prematurely on a less than fully charged battery, it will be much more detrimental to the battery than increased water usage and erosion.
How to know if float voltage is being prematurely initiated? A hydrometer on a flooded battery, or an Ammeter used on a AGM battery when holding it at absorption voltage. For an AGM battery to be considered fully charged, The amperage should taper to 0.5% or less, of the 20 hour Ah rated capacity At absorption voltage, not float voltage.
Anything less than a 100% true recharge is detrimental to the lead acid battery to some degree.
Sometimes/Often the 100% recharge cannot be accomplished before discharging begins. Oh well.
The forum member who knows they are not achieving true full charge time and again day after day for 5/7/ 10? days or more, should, when convenient, make an attempt to actually achieve the true 100% recharge, and this will have the effect of returning the battery to the maximum of its remaining potential capacity, as well as possibly making it easier( less time consuming) to fully recharge afterwards.
This will likely require using significantly less electricity the night before a forecasted sunny day, then achieving absorption voltage ASAP the next morning by all and any means available. Abused Flooded batteries might not ever get back upto 100% state of charge without an Equalization charge, which can require voltages upto 16.2v. Voltages this high are too high for many 12v devices, so they should be disconnected during EQ charges.
AGMS should not be subjected to voltages over 15.5v and this should only occur under close observation and after a prolonged absorption charge stage was first carried out. The prolonged absorption stage before an EQ charge applies to flooded batteries too. Hold them at absorption stage until amps taper to 2% or so of the 20HR capacity before allowing/programming the charging source to allow as high as 16.2v. Agms are 0.5% of capacity and no more than 15.5v allowed
Ignore converter/charger marketing material that says their product has an equalization charge stage. These will NOT achieve EQ voltages, they simply bump voltage back upto absorption voltage from float voltage every so often to mix up the electrolyte through bubbling/gassing that occurs at absorption voltage. An EQ charge is a forced controlled overcharge to revert the specific gravity back upto the maximum on all cells, not a simple destratification of the electrolyte in those cells.
Those who wrote the marketing material of converters claiming oto have an EQ stage, basically calling destratification an equalization, should be strung up by their short and curlies and whipped relentlessly and then squirted with battery acid, as they have blurred the acceptable definitions of battery charging, and have ripped off the consumer who believes their intentional deceit/ ignorance/ utter Bull shit.
Also members need to be aware that ALL manufacturer recommended charging voltages assume a battery temperature of 77F/25C. Higher battery temperatures require lower voltages, lower battery temperatures require higher voltages.
Never assume battery temperature is the same as ambient temperature, and those who can achieve high amperages by sources other than, but not disincluding solar, have to realize the batteries will warm up when charging and more so at high recharging amperages, and will keep heating nearly all the way through the absorption stage. Combine high ambient temperatures with high charging amperages and the depleted batteries can get dangerously hot. 120F is the absolute limit where recharging should be stopped, but once they get past 110F, 120 F will not take much more time at all.
So do not believe that a charging source reverting to float voltage means the battery is full. Especially on systems with 1 to 1 solar wattage to AH ratios and whose batteries are regularly drawn below 80%. The deeper the average depth of discharge, the higher the solar wattage to battery AH capacity ratio should be, or if not possible, other charging sources need to be occassionally employed, preferable early morning, so there is enough time to actually complete the absorption stage/ achieve 100% true full charge, before the next discharge cycle begins.
Also some members stress out that during Absorption stage, there will be more and more available solar wattage not being used and think it is wasteful. They might try to aim for just enough that no, or little solar wattage gets wasted. Target foot, shoot. When absorption stage is met, there will be more and more electricity available to power other things while the batteries are safely being recharged as fast as they can possibly be at that point.
After absorption voltage has been achieved, those not wanting to waste the solar wattage available can then plug in their laptops to recharge, turn up their compressor fridges( turn them back down before dark), crank up their ventilation fans, use whatever electrical device they want, as long as the system can maintain absorption voltage, and the longer the absorption voltage has been held, the more power there is available as the batteries need less and less amperage/wattage to be held at absorption voltage as they get more and more charged.
During absorption stage, there is not wasted energy, but absolutley free excess energy to be used while the batteries are charging as fast as they can be safely charged. Employ that extra electricity elsewhere, or don't.
Achieving absorption voltage earlier in the day by using less or little electricity in the morning is another strategy that can be employed so that the solar alone has enought TIME, to get the battery as full as possible before the sun is too low in the sky.
Another pretty well written article about getting more from lead acid batteries can be read here:
https://www.solarpaneltalk.com/foru...-storage/19316-are-you-killing-your-batteries
Forum members here should view their charging source's 'float' stage, with a high degree of suspicion, as it could be reducing the longevity of their batteries, and perhaps significantly so.
No one needs to tick every box to achieve ultimate lead acid battery longevity, but they should know what would be required if they chose to aim for that ridiculous goal, and knowing that might keep them from needlessly harming their batteries by chronically undercharging them.
He had updated this article on this site in the fairly recent past:
http://www.pbase.com/mainecruising/deep_cycle_battery
But I just noticed he has set up a more modern site with more upto date and detailed information regarding deep cycle batteries, that is well written with more data, that can help many members here understand and extract more deep cycles from their lead acid battery banks, meaning more money in their pocket to further their accumulated life experiences, rather than handing it over to a battery retailer and/or stressing out when battery failure comes as a complete surprise.
https://marinehowto.com/what-is-a-deep-cycle-battery/
But the quick version for those with limited data will be condensed in the following quoted material:
Simply being aware of what kills Lead acid batteries( this includes AGM and GEL) should go a long way toward helping members extract more cycles from their batteries. But clicking every box to get the most possible life from batteries might have one thinking they are a battery servant rather than the other way around. It can be much easier to accept marinal battery longevity and simply replace them more often, but that should be an individual's choice.
Much of the things to extend lead acid battery life are simply not trusting that any automatic charging source with 3 stages, or 8 stages, or 22 stages followed by oral copulation, knows what is best for the battery. Most charging sources, including solar charge controllers, will allow a premature reversion to float voltage before the battery is actually full. This is NOT good. This can/will all too easily lead to partial state of charge cycling and will reduce battery capacity much faster than the battery that actually gets to a true 100% state of charge regularly.
Those who cycle their batteries deeply, and only have a 1 to 1 solar wattage to AH capacity ratio and do not employ, or rarely employ other charging sources, will likely rarely ever reach the true 100% state of charge on solar power alone, and as such their batteries might endure only half or less the total accumulated cycles before replacement cannot be put off any longer, compared to a higher wattage to AH ratio.
There are lots of variables affecting battery longevity, but I urge those who want to get good to excellent lifespans from their batteries to use a good temperature compensating hydrometer and check that the batteries are actually at 1.270 or higher specific gravity when their solar controller first reverts to float voltage, and then again after a few hours at float voltage to see if the duration of the float stage before late afternoon/early evening, increased specific gravity at all, which is not very likely.
The solar charge controller reverting to float voltage/stage, does NOT mean the batteries are full, and battery recharging slows down significantly at lower electrical pressure(voltage). Perhaps some deeply cycled batteries will actually achieve full by sundown when prematurely allowed to enter float stage, but this would be very rare, and when the solar wattage is there to hold absorption voltage longer, but is not allowed/programmed to hold absorption voltage as long as required, then a crime is being committed against the battery and to the budget of the battery renter.
Many users with light solar wattage to AH ratios would eek more life from their batteries by not allowing float voltage to be initiated at all, when their batteries are cycling below 80% each and every day.
It depends on the solar controller, but some will not allow extending absorption voltage duration, but will allow one to raise the float voltage to the same as absorption voltage, and thus be able to feed the battery bank more full, daily, which will extend battery longevity.
Those who raise float upto absorption voltage NEED to lower it again when their overnight electrical consumption stops or suddenly drops to significantly lower levels or they then risk overcharging.
Float Stage/voltage is there to keep a fully charged battery, fully charged with minimal water usage and minimal electrolytical plate erosion. But if float is continuously initiated prematurely on a less than fully charged battery, it will be much more detrimental to the battery than increased water usage and erosion.
How to know if float voltage is being prematurely initiated? A hydrometer on a flooded battery, or an Ammeter used on a AGM battery when holding it at absorption voltage. For an AGM battery to be considered fully charged, The amperage should taper to 0.5% or less, of the 20 hour Ah rated capacity At absorption voltage, not float voltage.
Anything less than a 100% true recharge is detrimental to the lead acid battery to some degree.
Sometimes/Often the 100% recharge cannot be accomplished before discharging begins. Oh well.
The forum member who knows they are not achieving true full charge time and again day after day for 5/7/ 10? days or more, should, when convenient, make an attempt to actually achieve the true 100% recharge, and this will have the effect of returning the battery to the maximum of its remaining potential capacity, as well as possibly making it easier( less time consuming) to fully recharge afterwards.
This will likely require using significantly less electricity the night before a forecasted sunny day, then achieving absorption voltage ASAP the next morning by all and any means available. Abused Flooded batteries might not ever get back upto 100% state of charge without an Equalization charge, which can require voltages upto 16.2v. Voltages this high are too high for many 12v devices, so they should be disconnected during EQ charges.
AGMS should not be subjected to voltages over 15.5v and this should only occur under close observation and after a prolonged absorption charge stage was first carried out. The prolonged absorption stage before an EQ charge applies to flooded batteries too. Hold them at absorption stage until amps taper to 2% or so of the 20HR capacity before allowing/programming the charging source to allow as high as 16.2v. Agms are 0.5% of capacity and no more than 15.5v allowed
Ignore converter/charger marketing material that says their product has an equalization charge stage. These will NOT achieve EQ voltages, they simply bump voltage back upto absorption voltage from float voltage every so often to mix up the electrolyte through bubbling/gassing that occurs at absorption voltage. An EQ charge is a forced controlled overcharge to revert the specific gravity back upto the maximum on all cells, not a simple destratification of the electrolyte in those cells.
Those who wrote the marketing material of converters claiming oto have an EQ stage, basically calling destratification an equalization, should be strung up by their short and curlies and whipped relentlessly and then squirted with battery acid, as they have blurred the acceptable definitions of battery charging, and have ripped off the consumer who believes their intentional deceit/ ignorance/ utter Bull shit.
Also members need to be aware that ALL manufacturer recommended charging voltages assume a battery temperature of 77F/25C. Higher battery temperatures require lower voltages, lower battery temperatures require higher voltages.
Never assume battery temperature is the same as ambient temperature, and those who can achieve high amperages by sources other than, but not disincluding solar, have to realize the batteries will warm up when charging and more so at high recharging amperages, and will keep heating nearly all the way through the absorption stage. Combine high ambient temperatures with high charging amperages and the depleted batteries can get dangerously hot. 120F is the absolute limit where recharging should be stopped, but once they get past 110F, 120 F will not take much more time at all.
So do not believe that a charging source reverting to float voltage means the battery is full. Especially on systems with 1 to 1 solar wattage to AH ratios and whose batteries are regularly drawn below 80%. The deeper the average depth of discharge, the higher the solar wattage to battery AH capacity ratio should be, or if not possible, other charging sources need to be occassionally employed, preferable early morning, so there is enough time to actually complete the absorption stage/ achieve 100% true full charge, before the next discharge cycle begins.
Also some members stress out that during Absorption stage, there will be more and more available solar wattage not being used and think it is wasteful. They might try to aim for just enough that no, or little solar wattage gets wasted. Target foot, shoot. When absorption stage is met, there will be more and more electricity available to power other things while the batteries are safely being recharged as fast as they can possibly be at that point.
After absorption voltage has been achieved, those not wanting to waste the solar wattage available can then plug in their laptops to recharge, turn up their compressor fridges( turn them back down before dark), crank up their ventilation fans, use whatever electrical device they want, as long as the system can maintain absorption voltage, and the longer the absorption voltage has been held, the more power there is available as the batteries need less and less amperage/wattage to be held at absorption voltage as they get more and more charged.
During absorption stage, there is not wasted energy, but absolutley free excess energy to be used while the batteries are charging as fast as they can be safely charged. Employ that extra electricity elsewhere, or don't.
Achieving absorption voltage earlier in the day by using less or little electricity in the morning is another strategy that can be employed so that the solar alone has enought TIME, to get the battery as full as possible before the sun is too low in the sky.
Another pretty well written article about getting more from lead acid batteries can be read here:
https://www.solarpaneltalk.com/foru...-storage/19316-are-you-killing-your-batteries
Forum members here should view their charging source's 'float' stage, with a high degree of suspicion, as it could be reducing the longevity of their batteries, and perhaps significantly so.
No one needs to tick every box to achieve ultimate lead acid battery longevity, but they should know what would be required if they chose to aim for that ridiculous goal, and knowing that might keep them from needlessly harming their batteries by chronically undercharging them.
