The problem with folks who don't know how to equalize batteries is that they do it before they have fully recharged their batteries.
FIFY
There seems to be a lot of mystery around equalization. When to do it, how long to do it for, when to start it, when it's actually complete.
When to do it seems more clear, if you've deeply discharged your batteries - do an equalization. Periodically (lots of different time frames there) it should be done, but really? When do we know we need to equalize?
Now I say that because there are two aspects of equalization, where the name comes from which is the stratification of the cells, but there is also the very real added benefit of converting lead sulfates back into lead and sulfur.
The how long to do it for? Now that one is a real crap shoot! Do we really know how long to do it? I look into all the programs that come embedded in the chargers that claim they do it and I'm not convinced. You can do density readings on the cells and look at it that way. How do you do that on Lifeline AGMs????? I'm not getting a real warm fuzzy here...
When to start it? Here there are as many opinions as there are those talking about equalization, seems anyway. Do it once a month, do it every quarter, do it a couple times a year, do it before commissioning in the spring... I'm sure there are more. Yeah, you an go take density measurements, you an look at voltage, but are these really telling you what's needed? I've no idea and I've never heard anyone give good solid scientific answers...
Then real question I've never seen an answer to - once you start an equalization cycle when is it done? All the routines I've seen in the chargers that claim to have an equalization cycle appear to depend on time. I don't think time is the answer. If depends upon how much work needs to be done in getting the sulfation removed as much as you can on that particular battery. That's not time dependent. That's amount of sulfation dependent. But how do you measure that? I've still not seen a good answer to this one.
@Stu Jackson says above that folks run their equalization cycle before their batteries are fully recharged. I imagine for anyone using an off the shelf charger that has a timed cycle that is absolutely correct.
But it's not how I do my equalizations. Unless I'm doing a routine equalization, which I do a couple times a years normally, I'm often doing an equalization because I screwed up and dropped the charge level in my batteries below 65% (that's just my own internal number - how far to draw down your batteries is a whole other subject). When I drop my batteries below that "magic number", I consider that sulfation is now going to be a concern and I'll hook up my power supply and run what I consider my full equalization cycle. It's actually a full recharge and equalization cycle in one.
How that works for me is I hook up my favorite power supply which is a programable voltage/current power supply that I can program in the voltage to the nearest hundredth of a volt and I set my current to a specified amount depending upon battery size.
Typically for the size batteries we have on sailboats that's 3 amps. It also happens to be the maximum power output for my particular power supply. The key here is you don't run enough amps into the battery to cause heating. Heat kills batteries real fast. I do have smaller and larger programmable power supplies, but the larger one is just too dang big to be schlepping around onto the boat, that 3 amp supply is heavy enough... The smaller one I use on smaller batteries, like my car batteries. I then set that supply to 16.00 volts, 3 amps and let her run. I'm doing a battery right now in fact, for a friend of mine. I don't even worry about the charging state, set up this way the battery just naturally goes through those phases as the charging progresses. Once the battery reaches full charge (I don't monitor this at all) it then enters into the equalization phase as the state of charge dictates within the state of charge of the battery itself. I now monitor for the end of cycle meaning the end of the full recharge and equalization.
Now you can tell me I'm doing things all wrong, go for it. But I'll tell you I've been doing this for about 4 decades across a lot of batteries, both my own and several close friends batteries. Batteries properly treated this way tend to last 12 to 15 years. The only batteries I've lost in a shorter time period than this are those I didn't do this cycle on when I knew I had to... Oh yeah, I've also had batteries have catastrophic failure sooner than that, but that's just the nature of batteries. If they have a mechanical internal failure, that's nothing to do with what this is about.
My big dilemma is learning the real cut-off points for each of the steps. As I move to going off-grid and not have access to consistent shore power and have to rely on solar and wind generated power, I'm trying to understand the more specific parts of this process and how to implement it in a less controllable environment. The battery I'm working on right now has been sitting on this recharge/equalization cycle for pretty close to 24 hours at this point. But that battery was at 5.8 volts when my buddy gave it to me. So it was way beyond fully discharged. I was checking a bit ago and it's running up close to the full end of cycle, but I'd guess it's going to take another 6 to 8 hours to reach end of cycle according to how I see that. Just for kicks, I went out to see what the battery was taking right now as far as current and it's taking just over 300 mA.
I can't run a 24 to 36 hour cycle like this off-grid... that's what I' struggling with...
FWIW
dj
