Originally Posted by wrcsixeight
The marine guys who can perform actual capacity tests, meaning they load the battery with a precise amperage load for 20 hours keeping the battery at 77f in a water bath, have tried all sorts of 'pulse' Desulfating chargers and none of the results have ever come back any higher than what a normal extended time held at higher voltage would achieve.
A true capacity test of a 100Amp hour flooded battery would require the battery be held at precisely 77F, and the load held at a constant 5 amps for 20 hours, which is not easy to achieve as as battery voltage drops the loads amperage will likely also change.
I believe in some narrow cases the pulses might be beneficial, but by and large, the general view that a pulse desulfation is effective, merely shows how effective marketing is, rather than actual verifiable results using actual measuring tools and collecting data, performing before and after experiments controlling the variables in order to make any relevant conclusion..
If you want to try and revive a battery, after it is 'fully' charged, load it with 10 to 15 amps of load per 100Ah of capacity until the voltage falls below 10.5v under that load. Take note of how long this took, for later comparison using the same discharging loads. Immediately apply no less than 20 amps of charging current per 100Ah of capacity (Odyssey AGM says no less than 40 amps per 100Ah of capacity) and hopefully this charging source will hold that amperage until mid to high 14 volts is achieved at the battery terminals. One there, it should be held until amperage tapers to very low numbers for AGM and less than 1.5 amps per 100Ah of capacity for flooded. This time span after achieving 14.4+ at the battery terminals, is no less than 3.5 hours and might take 10 times that depending on the condition of the battery.
While this method is way outside the 'trickle charge it is always best', grandpa's advice which was wrong both then and now, the higher amperage causes heating of the hardened sulfate, and stands the best chance of driving it bck into the electrolyte solution, in my opinion.
Keep voltage at 77f battery temperature from exceeding 15, until amperage tapers to very low levels. hotter batteries, lesser voltage, colder batteries higher voltage.
Dot not allow battery to exceed 120f but it will rise very quickly from 105f to 120f, so be on the look out for quick increases of battery temperature, and do not try these hail mary recharges in hot ambient temperatures. unless very closely monitored.
Flooded batteries will offgass a lot, ventilate the area properly, and use eye protection when getting near the battery and wear clothes you do not care about. Baking soda dissolved in water is good to have on hand to neutralize battery acid.
AGMs can have the valves release some pressure. Many people think this is instant death of the AGM. They are wrong. They are not one time vents and a single release it not going to cause them to 'dry out' as you will read about on forums such as these. The vents also do not open easier on subsequent monitored overcharges.
True equalization charges of flooded batteries requires upto 16.2 volts (At 77*F/25*C)and a battery will require 5 to 6.5 amps of current per 100Ah of capacity to get voltage up that high initially. These should only be initiated after the battery has spent many hours held at 14.5 to 14.9v. One should not attempt without a hydrometer, compensating for rising electrolyte temperature, no longer shows any gains in electrolyte density. One specific gravity stops rising there is no point in continuing. AGMS require an accurate ammeter since one cannot take electrolyte readings. Amperage will bottom out at some point at a constant 14.x volts, and will likely stay there on healthy batteries, and start rising again at some point on less healthy batteries. This might be the beginnings of thermal runaway, which is to be avoided.
Concorde AGM, who make Mil-Spec AGM batteries have a conditioning procedure as well as a deep discharge recovery procedure one can read about here:
http://lifelinebatteries.com/wp-content/uploads/2015/12/6-0101-Rev-E-Lifeline-Technical-Manual.pdf
Odyssey's reconditioning procedure is here:
https://www.odysseybattery.com/documents/ODYSSEY_Battery_Reconditioning_Charge_Procedure.pdf
Note that the procedures are not able to be achieved with just any off the shelf charger, they require higher amperage capability and the ability to both seek and hold higher voltages for longer durations than any 'smart' charger will allow, as they are basically intentional overcharges. Smart chargers are all about NOT overcharging, and as such they are basically automatic smart 'underchargers' which will compromise longevity compared to a charger capable of reaching a true 100% state of charge each time.
Somebody with a garage charger has no chance of performing true recovery procedures. Even stopped and restarted multiple times a 'smart' charger has little chance of recovering lost capacity. The desulfating charger holding the battery at 13.6v for weeks on end, will likely have no different results than a NON 'pulse 'desulfating charger holding the battery at the same voltage for the same amount of time.
Rolls Surrette is pretty much the top dog in the deep cycle flooded battery department, their literature is also well written
http://rollsbattery.com/public/docs/user_manual/Rolls_Battery_Manual.pdf
The person who reads and comprehends the Concorde and Rolls user manuals will have a better understanding of lead acid batteries than 99.99% of the people who respond about batteries on the internet. The rest just want to believe marketing and the wiseness of the purchase whose product marketing they fell for.
Trojan also has well written documentation on the proper care and feeding of lead acid batteries:
https://www.trojanbattery.com/pdf/TrojanBattery_UsersGuide.pdf
https://www.trojanbattery.com/tech-support/battery-maintenance/
Batteries are just rented, their contract length is determined by how they are treated. They always want to be kept cool, and fully charged and todays starting batteries are made as cheaply as possible. Where deep cycle manufacturers cant get away with such shenanigans.
Hail mary attempts at returning capacity to sulfated batteries is by and large futile for most of the battery using population, as it requires special equipment and knowledge more costly than a new battery.
Seeing this, the marketers have fastened onto 'pulse desulfation' as their latest goto for max profit.
Unless the charger is taking the battery up into the 15.5v+ range after a normal 'full' charge, any restoration of capacity or performance is extremely doubtful, and it is my opinion a quick 100% depletion of the battery, followed by a higher amp recharge until amperage tapers to very low numbers at voltages in the 14.4 to 14.9v range, stands the best chance at being effective. After this high amp recharge to low amperages in the high 14's, then higher voltages can be initiated, but the battery must be monitored for heat build up and possible thermal runaway.
Overcharging does degrade the battery if done excessively. The perfect recharging regiument would stop once the battery is inded fully charged, but this is a moving target. No product can achieve this every charge cycle on each and every battery, and the ones which can come the closest, automatically, are in teh 350$+ dollar range and still require being programmed for the specific batteries in a specific usage by a human capable of determining and testing the efficacy of those settings.
Starting batteries are at the mercy of the vehicle's voltage regulation and underhood temperatures. Wiser battery 'owners' will seek to return the battery to as close to 100% charged as their equipment will allow, on a regular basis.
Those cycling lead acid batteries better be able to afford to simply replace them when they have lost too much capacity for the intended usage, or they figure out how to properly and promptly recharge them to full as often as possible to get the most total KWH delivery from them, over their lifespans. the equipment which allows one to approach ideal chrging, can cost as much as many sets of new batteries, so accepting lesser longevity using less than ideal charging sources, is a valid strategy, for some.
And this, dear reader, explains why battery electric cars will NEVER replace internal combustion cars...