Switching from lead to AGM, anything to keep in mind?

[GrahamHO]

Just one last note from me on the subject. The Optima AGM site has lots of information that no doubt closely applies to other makes of AGM. "Blue Top Starting Batteries. Charge voltage with alternator from 13.3 V to 15 V no amperage limit." Interesting! G.O.

[Wotname]

Originally Posted by GrahamHO

Just one last note from me on the subject. The Optima AGM site has lots of information that no doubt closely applies to other makes of AGM. "Blue Top Starting Batteries. Charge voltage with alternator from 13.3 V to 15 V no amperage limit." Interesting! G.O.

GrahamHO, I not wishing to be dificult but ....
My experience with several types of AGM suggest the opposite. Different manufacturers suggest differnt charging regimes. The only constant is that they accept high charging currents but even that varies from one manufacturer to another. Another example, some accept low current high voltage conditioning charge and others expressly forbid it.

YMMV

[GrahamHO]

Originally Posted by Wotname

GrahamHO, I not wishing to be dificult but ....
My experience with several types of AGM suggest the opposite. Different manufacturers suggest differnt charging regimes. The only constant is that they accept high charging currents but even that varies from one manufacturer to another. Another example, some accept low current high voltage conditioning charge and others expressly forbid it.

YMMV

Thanks for that. I only have experience with the 3 types of AGM that I own. Optima, Exide,and a good Chinese one; I forget its brand. They have all proven reliable. The Optimas with solar and a Next Step regulator going up to 14.4 v. with a battery temperature sensor, with starting and house types. The Exide is in a car with standard car charging of 13.8 v. The Chinese one is only on solar. But I still go back to what I have repeated. The key to long life of any type of battery is keeping it correctly charged; and correctly should be with reference to the manufacturers figures. Also it should be the correct type for either starting or house use.

People who condem AGM I think are mistaken. The Optimas and Exide at least are very resistant to vibration and motion, they can be installed at any angle, don't spill, the terminals stay clean, though should be checked from time to time, they don't fume; unless they are overcharged. And that is the main caution as you can't add water. That problem hasn't occurred with my batteries during 13 years use.

[Scrimshaw4]

Depending on the battery charging system you have you may have to reset the Phuket (?) value. Your owners manual should be referenced or contact the mfg. if unsure. The battery mfg. can tell you the value for your specifict batteries. This can affect the charging cycle.

[exMaggieDrum]

Peukert. And it should be set correctly.

[tenchiki]

The Firefly AGMs look like they could be game-changers, at least for longevity and robustness. I was measuring to see if a pair of golf-cart batteries would fit in my battery box when I won one...

[ranger58sb]

Originally Posted by tenchiki

The Firefly AGMs look like they could be game-changers, at least for longevity and robustness. I was measuring to see if a pair of golf-cart batteries would fit in my battery box when I won one...

They don't do GCs yet. There's another thread around here where several folks recommended that as a next product... and adding your support to that would maybe help.

-Chris

[Cabo Jim]

I recently replaced my Deka 105 amp-hr AGM batteries with lead acid. The reason is because I experienced an thermal runaway (Google it)with the AGMs. If you go with the AGMs I would highly recommend a battery temperature sensor wired to your charger to prevent a thermal runaway.

[Pete7]

I ditched our Tescup battery charger when I bought the boat. Hugely over engineered and only charged at one voltage. I was also astonished how much it weighed, nearly as much as the outboard.

Replaced with a modern multistage charger. You have a 600 amp hour bank so could go up quite a bit in charger size.

Pete

[exMaggieDrum]

Originally Posted by Cabo Jim

I recently replaced my Deka 105 amp-hr AGM batteries with lead acid. The reason is because I experienced an thermal runaway (Google it)with the AGMs. If you go with the AGMs I would highly recommend a battery temperature sensor wired to your charger to prevent a thermal runaway.

In my work as a tech, I encountered two thermal runaway situations. Both were with wet flooded batteries, not AGMs. It is a potential problem for any type of battery. Battery temperature sensors might help to avoid this but they are not a failsafe. I do intend to put them on my AGM batteries in the future though on my new/old boat.

[AfterHoursNLCT]

Took this long, but I finally ran across the link:

Deep Cycle Battery Information and FAQ

LL

[GrahamHO]

I have Optima AGMs with Ample Power Next Step smart alternator regulator with temp sensor.
My regulator is over 13 years old now as are the AGM house batteries. My Blue Top starting battery only lasted about 11 years and I replaced it with the same model Optima Blue top.

The batteries are all on solar all the time (except night!) with separate panels and solar controllers for house and start, and instruments.

No problems ever. My Yanmar 2GM 20 starts in a millisecond. A small Engle electric fridge runs all the time when we are cruising.

My battery system keeps on going and going like the Energiser Man.

A similar set up with flooded batteries and correct charge settings would no doubt keep going just the same except, I'd need to check the battery water, and they would need to be well ventilated as hydrogen is produced. (my AGMs in lockers are not ventilated and I haven't had an explosion yet).

Flooded tend to get more deposits on the terminals and can spill acid. There are "sealed" flooded batteries too. They just have a larger capacity of liquid electrolyte which extends well above the plates. With that type I've had in cars it was possible to prise off a long cap and check the electrolyte.

But flooded might have a cost advantage over time?? though I'm very happy with my Optimas cost life ratio. I have one other Chinese AGM powering the instruments only, isolated including separate negative. That is only on solar charge to avoid voltage spikes from the alternator and from various items on the house circuit such as Autohelm. That battery just keeps going too.

One early problem I did have relating to the use of a smart regulator was a single alternator drive belt with an 80 amp alternator tended to slip and wear quickly. I then installed custom made double belt pulleys with the alternator pulley made 10mm larger than original for better belt wrap and less load. So one thing leads to another and there can be cost involved.

Leave any batteries uncharged over winter or whenever and they won't last. One percent loss every day and they are virtually flat in a couple of months. Then the plates sulphate and then they are stuffed.

As usual others will agree or disagree in the AGM debate but that is my experience.