AGM vs Lead Acid Battery Charging

[Mac G]

Removed a lead-acid 4D battery and replaced with two (2) Group 24 AGM batteries.
Both of the Group 24s fit nicely into the old 4D battery case.
Still have other lead-acid batteries in system (2 @ 8D) and also other AGMs (golf-cart batteries for house bank).

My Question is regarding charging:

Someone said the new AGM batteries don't need the same charging level as the old lead acid and could risk overcharging them and harming the AGMs if on same system as the lead-acid 8Ds.
Is that correct?
Are golf-cart batteries therefore also at risk?
Please advise
I apologize for the ignorant question.

Thank you

 

[ranger58sb]

It's not necessarily as simple as AGM versus flooded. Nor is it always as simple as gold-cart (presumably deep cycle) versus dual-purpose or starting.

Best to look at the maker's specific voltage recommendations for your various batteries -- for bulk, absorption, and especially float -- then compare that with voltages you charger can supply. Some mix-n-match is sometimes possible.

-Chris

 

[rslifkin]

Every battery maker has different specs, so I'd check the recommended voltages for the new batteries and match your charging to that.

 

[DavidM]

When AGMs first came out and the only chargers were for FLA batteries, the AGM manufacturers said it is ok to charge one, the other or both types with the FLA charger- the voltage requirements are close enough.

I assume that is still true.

David

 

[tiltrider1]

Every battery maker has different specs, so I'd check the recommended voltages for the new batteries and match your charging to that.

This is the correct answer.

AGM’s use a different charging profile from FLA. Using a FLA profile on AGM will shorten the life of an AGM battery.

What is a golf cart battery? 20 years ago it was a 6v deep cycle Lead Acid battery. Today it is more likely to be a LiFePo4 battery. Lead Acid is FLA regardless of deep cycle or CCA version.

LiFePo4 is a whole different subject and should never be used as a direct replacement for FLA.

 

[ranger58sb]

When AGMs first came out and the only chargers were for FLA batteries, the AGM manufacturers said it is ok to charge one, the other or both types with the FLA charger- the voltage requirements are close enough.

I assume that is still true.

In general, probably often true.

OTOH, Lifeline (for example) wants a lower float voltage than many of the FLA profiles provide... and matching specific voltages to specific batteries is easier with at least some of the newer chargers. ProMariner ProNautic (and Sterling clone) and Victron come to mind; probably others.

-Chris

 

[luna]

Every battery maker has different specs, so I'd check the recommended voltages for the new batteries and match your charging to that.

Although the above may be the correct answer, one would need more information to draw that conclusion.

The op has these 2 new Group 24 AGM batteries, 2 8D flooded monsters plus a house bank of AGM Golf Cart batteries. All brands are unknown.

To me the best approach would be to optimize the charging of the most expensive bank to replace, in an effort to extend its lifespan.

I doubt that the new AGMs are that bank.
It is likely the AGM house bank.

 

[RickyD]

My setup has my main house bank of Trojan L16 6v batteries charged from my Victron main 120amp charger of course set for FLA. Then my auxiliary 30amp Victron 3 bank charger is set for AGM and charges my 2 8D AGM start batts, group 31 AGM generator start batt, and then the 3rd leg goes to the FLA house bank. The AGM profile offers float below max for the FLAs so it is safe.

 

[dhays]

Every battery maker has different specs, so I'd check the recommended voltages for the new batteries and match your charging to that.

...or as close as you can get. I have two different types of AGM batteries that have different ideal charge profiles. So I used a custom charge profile that gave the "best fit possible" of the two battery types.