If you are getting 15-20 years then something is working in your favor, but it's not likely to be EQ. If I did not know better I would guess you have GEL batteries or industrial batteries like a Rolls or similar. By industry standards a battery is considered dead when it can no longer deliver 80% of its original 20 hour Ah capacity rating. I routinely see this occur in less than 2 years with the typical automotive case size batteries typically used on a Hunter 30.. Even just calendar life kills most basic flooded batteries before 15-20 years and that is without any cycling at all.
So to clarify, I have only ever used flooded lead acid batteries. However, reading all that you have posted on what to do or not do, seems I'm being really quite a "good" battery operator. I never let my batteries go below 75% charge before recharging if I can avoid it. If I do, then I immediately re-charge to 100% and then perform an equalization (my flavor) on the battery. To date, I've not been without shore power for more than about a month, and more frequently only a week at a time. Work so gets in the way of the things I like to do....
Lifeline AGM batteries can be equalized but they are currently the only AGM's that can be.. For FLA batteries the biggest reasons we need EQing are due to improper charging by so called "smart chargers", most of which are are not smart at all & PSOC (partial state of charge cycling) use.
In a perfect world deep cycle flooded batteries should be charged at 14.7V to 15.3V yet very few battery charger makers are anywhere close to that with their rather stupid "dip switch" set points.
Very interesting!
I don't use commercial battery chargers, I only use laboratory power supplies. I've always used 14.8V as my set point for charging FLA's. I have no real experience with commercial battery chargers, and that is one of the motivating reasons for me getting into this discussion. I really need to understand the fundamentals of battery charging beyond my simple working knowledge that is what I've used to date. And I REALLY thank you for taking such an enormous amount of time to answer all the questions that are thrown at you.
It is my desire (time will tell if it is realized) to retire onto a sailboat and sail for some undetermined amount of time, but at this point I'm thinking until my bones no longer want/can do it. Once I am at the point of living on a boat, I then need to have fully developed a system of battery maintenance that does not include having access to shore power as I currently have.
A true EQ is not really done as the charger makers want us to believe, but is the only practical way of doing it in the field.. The way a manufacturer would do it, and some call it a reforming charge, is to charge from a very low SOC such as 0% SOC / 10.5V and use a very low charge current such as .005C to .01C (0.5A to 1A for a 100Ah battery) and to let the voltage wind up where it will. With healthy batteries it can go over 17V towards the end of charge but requires in excess of 100 hours to do so...
First you say the above...
EQ's in the field should ultimately not begin until the bank is already at 100% SOC with your existing charger. If you do that even a 1.3A power supply should be able to push individual batteries over 15.5V. EQ should always be temp compensated and done at manufacturers voltage guidance.
then you say this above. Can you please explain this a bit. It seems to be somewhat contradictory?
The effects of sulfation actually happens far faster than folks assume it does. In a 30 cycle PSOC (partial state of charge cycling) test done for Practical Sailor (May 2015 & August 2015) one popular AGM battery lost 1% in capacity for each PSOC cycle or 30% of it's Ah capacity lost due to sulfation in just 30 cycles..
Oh boy, is this the darned truth! Sulfation happens very fast, especially the lower you go in state of discharge! I have direct hands on knowledge of just how right MS is on this one!
So, you have published in other posts you've made what the end of charge is when charging to achieve 100% SOC (can't recall right now, will have to go look for it again).
When do you know you've reached the end of an equalization cycle?
Another question - I had been told (no idea from whom - not the electrical engineer from Hoover) that when a FLA had been discharged to below 50% charge, that you should use low current charging (what we used to call trickle charging) until it reaches at least 50% charged, then you can hit it with lots of current to bring up to full charge. Is that correct? And if not, what would be correct?
Thank you very much for your time and answers. I'm going to have more questions, I'm sure...
dj
