Puzzling battery advice

[Frank Langer]

I monitor my batteries carefully and have a smart charger that bulk charges them to 80%, then trickle charges to fully charged, and kicks in again if the level drops. I have been trying to keep them fully charged, and definitely never discharged below about 70%, though I know I can discharge them to about 50% if necessary without much damage. (They are 7 year old AGM batteries).
But I recently read an article that advised that batteries should be maintained between 50% and 80% charged, that both higher and lower levels adds stress to the batteries. It talked about the speed at which ions move from one plate to the other, etc.
Does anyone know if there is truth to the suggestion that charging higher than 80% adds stress to the battery and will wear it out faster? I had never heard that before.
Frank

 

[gareth harris]

Lithium batteries are best kept in the 50% to 80% range according to every source I have read, but I have never seen that said about lead acid which it has always been standard procedure to keep fully charged.

Gareth
Freyja E35 #241 1972

 

[Christian Williams]

My AGMs are kept at 100 percent by the shore power charger, at least according to the battery monitor.

 

[Frank Langer]

My AGMs are kept at 100 percent by the shore power charger, at least according to the battery monitor.

My charger and most that I'm familiar with do work to keep the batteries charged to 100% or close to that. That's why I was puzzled by the 50% - 80% advice. Gareth's comment about applicability to lithium batteries is interesting, but why them and not all batteries, and the article I read didn't specify lithium.
I'm guessing that chargers are efficient because we all want maximum charge when leaving on a cruise, even though that may not be optimal for our non-lithium batteries. I wish I knew more about this stuff.
Frank

 

[G Kiba]

With all due respect Frank. You may not want to know more!
Seems like there are so many different opinions about batteries that have been around forever (Lead-acid) and even more about the ones that have somewhat been around forever (AGM, gell, etc) , and even more about the new ones coming out. Although it seems that the lithium crowd pretty much agree that they are better than everything else! And maybe they are? I'm staying with my AGMs a while longer.

 

[Nick J]

With all due respect Frank. You may not want to know more!

This is probably the best advice on here. The more you learn about the different battery chemistries, the more questions you're going to end up with. The difficult part is separating critical advice from nice to have advice. Keeping batteries between 50-80% is probably best for the battery, but very difficult to do in practice especially when there isn't a charger on the market that's capable of doing it (at least not one that I'm aware of). Maybe you loose a few cycles off the stated expected cycles, but if you don't have any other options I wouldn't worry about it.