6 minutes ago, Kirtley Howe said:

Didn't say they died quickly. 4-7 years can be expected life for them with proper care. What I said was they die SUDDENLY. They work great until they don't work at all.

Not true, they die like any other lead acid battery unless over charged.

Tom

Tom's got the right of it. Remember that AGM's ARE lead-acid...they just have glass mats to hold the electrolyte...like Gel-Cells use a special Silica to do the same thing. Electrically, Wet-Cells, AGMs and Gel-Cells are pretty close to identical...the electrolyte suspending mechanisms in Gel and AGMs are the only real difference.

Bottom line is...AGM batteries are being taken over by Lifepo4 ...which means fewer agm are being produced, so the agm prices are going up!!!  The fact that Lipo's are gaining in popularity means their price is comming down!!  So....if you need batteries right now, kind of a tossup....but in another year, like next boating season....I can see the lipos being a better deal...as they will come down in cost and the agm will continue to go up in price.  That is my plan, my current group 31 agm's  (3 of them) are on there fourth year, still doing great, but....after this year, it becomes questionable how long there gonna go....yes I will probably wait until they start falling off, but as time goes on, the lipos will become the better deal !!

I can only speak from my own experience, and will definitely bow to more knowledgeable persons. I suppose it is possible that I overcharged mine, but I have a smart charger with an AGM setting that has always worked well for me. Maybe I just got a bad one.....but it lasted me 5 years and then just died. It showed full charge, and started the motor fine several times. Then it was just dead, and would not take a charge period. For what it is worth, it was a DEKA brand.

Not sure I follow the economics on that.  It is a weird supply and demand paradigm. Typically, the price would go down as demand wanes. It isn't good business sense to increase price and lower supply to increase price. I'm thinking the price increases are simple inflation. Maybe I'm wrong. 

Sorry Kirt, my reply wasn't directed to you, but the earlier post. 

@airshot - funny, I just checked and the Mighty Max 100ah AGM I bought June of last year is actually less expensive now.

All lead-acid batteries can die a sudden death from a shorted cell.  More than one person has parked a vehicle that was starting fine, go into a store just to come back out and it's dead as a hammer.   Usually the first hot day of the year. 

Good observation. I had not thought about it that way....but I have never had a wet cell battery die like that. Guess I am just lucky.

On 8/3/2023 at 9:21 PM, MN Fisher said:

@airshot - funny, I just checked and the Mighty Max 100ah AGM I bought June of last year is actually less expensive now.

Like everything prices constantly fluctuate, however if you look at the last three years agm batteries have gone up in comparison to lipo batteries.  We are seeing even bigger drops in lipo prices as the market becomes more competative and they become more popular.  Not knocking anything, just the facts that agm are slowly going to fade away as lipo battery technology improves.  Lead acid batteries have really dropped in price in the marine groups in my area.  Not in automotive use, as people are always looking for the cheapest battery for there old car..

The difference between a NorthStar or Oddessy AGM and a Duracell is the case quality, corrosion proof hardware and internal construction. Fire trucks use the high end batteries for a good reason, the truck must start.

Most quick deaths with batteries is a result of a broken post connection.

Tom

I ran Deka wet cells for years without issue. Never had to add water or electrolytes.  

Folks that take really good care of their batteries rarely have issues, no matter what type they are.  But in many cases, batteries suffer from improper or lack of care.  A friend works part time in an auto battery store, he often talks about how people attach the battery cables....no wonder the studs break inside and the threads strip out.  They expect a warranty claim after a gorilla ripped out the posts !!