by Justin Godber
I contribute on a website www.morganscloud.com
I wrote this a few months back, maybe this will help.
I am Justin Godber with Lifeline Batteries. I have been working with John and following this blog. (I thought I would start by responding to some of the topics above and clarifying a few things and answer some of the questions that will follow.
AGM batteries ARE a lead acid battery. So are GEL batteries. They all just contain the electrolyte in different ways. There are three types of lead acid batteries: Wet Cell batteries, GEL Cell batteries and AGM batteries.
Wet cell batteries as we all know are the type that you have to refill with water. They are messy and can be more dangerous because of the volume of hydrogen that is emitted during recharge.
GEL batteries have taken wet electrolyte mixed with silica sand to make a GEL. We used to make these until about 1989. As most people think this is a "newer technology", really it is quite old and as I stated we actually stopped making these in 1989. GEL batteries are sealed and work well with very strict charging regimes. The biggest problem with GEL batteries is the charging and the vibration. With vibration the GEL forms all these small air bubbles. Similar to what you would see in a bottle of hair gel. These air bubbles virtually cannot go anywhere so they stay in the GEL. All is fine until all these bubbles sit against the battery plate. Any and all bubbles that are against the plate will not be able to produce any capacity because there is air there, not electrolyte. This may not sound like a big deal but there could be thousands of bubbles in there covering more than 50% of the plates. Secondly, the charging. Charging GEL batteries can be very temperamental. GEL batteries require very strict charging voltages and cannot really deviate 1/10 of a volt either way to avoid premature death.
AGM Batteries. This is important. NOT ALL AGM BATTERIES ARE CREATED EQUAL.
AGM batteries have all the electrolyte absorbed into a fiberglass matting.
They are then charged and formed and then all the excess acid is dumped out.
We then seal the caps on the battery permanently. This results in a completely sealed battery. You can charge these batteries with 100% of their amp hour rating. This is a big advantage. You can charge a 100 amp battery with 100 amps. In fact they actually respond better in lab conditions when they are charged up faster. A Wet cell and GEL cell can only take 35% of their rated capacity on recharge. Making an AGM battery is like making a cake. The recipe has to be just right. We take pride in our batteries, we make everything (proudly) in the USA, and I mean everything. We also manufacture everything by hand. We have 17 quality checks as we are going down the line. We make batteries for Marine, RV, Aircraft, and Solar industries. We make a true deep cycle battery for the marine industry. Besides being very expensive to manufacture we really have no cons over any of the aforementioned battery types.
Now that all battery types have been explained, here is the part you have been waiting for. ALL batteries need to be fully recharged to avoid sulfation build up on the plates. I am not sure if I can post links on here so before I do I am asking. I can send links for Trojan Battery, Deka Battery, Odyssey Batteries, etc.They all state the same thing. Batteries must be fully recharged to avoid damage and premature failure. This is why: As I mentioned before these are all lead acid batteries. They all perform the same chemically when charging and discharging. These batteries are all made from lead and lead dioxide and electrolyte. When the battery is discharged the plates go under a chemical reaction called lead sulfate. When the batteries are recharged this reaction is reversed. This reversal changes the plates from lead sulfate back to lead and lead dioxide. When the batteries are left to sit in a discharged state the lead sulfate does not get reversed and starts to harden, or crystallize. When you look at it under a microscope it looks like crystals. The longer it sits like that the harder it gets and slowly starts to grow farther around the plates. This is the part where I will tell you how sailors eventually ruin batteries.
Trust me, if I was in most of your positions I would probably do the same thing even knowing what I know. Batteries are not like a fuel tank. You cannot refill them to 85% and expect to always have 85%. As I stated the hardened sulfate will start growing. So when you use the 50-85 rule it works great for the first six months and then as the resistance starts to build and the sulfate starts to grow it goes 50-84 and then 50-83 and then 50-82 etc.Even though your charger says you are back to 85% it doesn't really know because the resistance starts confusing the charger. It thinks it is back to 85% when it is slowly deteriorating. Eventually you will not be able to get the batteries above 12.2 volts and then we get a phone call.
There are a few solutions to avoiding this scenario. The easiest one for us, but not for you, is fully recharging every time. This will keep the batteries healthy all their life.
The other scenario when cruising is to use the 50-85 rule but you must equalize your battery bank once or twice a month. This will stop the sulfate from hardening as much as it would normally. John is currently using a similar scenario as field and we have had success in the past with some Trans-Atlantic crossings and they end up on the other side of the pond with fully charged batteries.
That last paragraph will bring up the next question. "I thought you couldn't equalize AGM batteries". Well, as I stated earlier ALL AGM BATTERIES ARE NOT CREATED EQUAL. I can only speak for our batteries but you can equalize them.
It is a great tool to use on the aforementioned scenario. Also a great tool just in general to help clean off the plates and gain some capacity back. Sailors have always struggled with all this battery/battery charging and we know why. We also know why you will only charge to 85%. As I stated I probably would do the same thing but we have been working and simulating your scenarios in the lab for years and we think the program that John is on is going to be successful.
I want to write so much more but I will wait for questions, concerns and comments so I can be more specific.