FLA to AGM - charge profile?

[tiz]

Our FLA 8d batteries are dying. Mainship 390 with two 8-D batts that run everything except generator start.

I will go to 8-D AGM just to keep the wiring the same. Normally we have plenty of power. But do i need to install an external regulator? Or is the charge profile essentially the same? I can get my alternator (cummins/delco) changed to be external regulated but would avoid the cost if there is no value in that.

Please no comments on lithium etc. Not going there.

--Kevin

 

[tiltrider1]

An internally regulated alternator does not need to be modified for AGM.

By your description you use these batteries to start your engines as well as house loads. If this is correct then LiFePo4 would be inappropriate for you. If this is not the case then you are doing your self a disservice for not considering LiFePo4. I am not saying you should go with LiFePo4 just that you should be open minded.

 

[tiz]

Im open minded but not open walleted. Id be happy to add lifepo4 batteries but its a $5k project and i don't have need of that or the money for it.

 

[Flatswing]

Our FLA 8d batteries are dying. Mainship 390 with two 8-D batts that run everything except generator start.

I will go to 8-D AGM just to keep the wiring the same. Normally we have plenty of power. But do i need to install an external regulator? Or is the charge profile essentially the same? I can get my alternator (cummins/delco) changed to be external regulated but would avoid the cost if there is no value in that.

Please no comments on lithium etc. Not going there.

--Kevin

Kevin: A little more information on your usual usage would help support suggestions. For instance, if you never anchor out, or if you do, you run the generator lots for AC etc. that would be very different usage than if you don't usually plug in each night and anchor out routinely etc.

Unless you have large power/inverter needs, consider the tried-and-true switch to FLA GC2 batteries. Yeah, they are old school but durable, & usually fit nicely in the space for you 8D's, charging profile remains the same. Yes, you will need a few inexpensive cables to convert to the 2-series/2-parallel configuration since they are 6v batteries. You might even spring for a battery watering system for $1-200, if you're lazy like me. But the batteries will run about $5-600 at Sam's, NAPA etc. and last 7+ years if you have a decent 3 stage charger for shore power. Biggest advantage is once you get the 8d's out, GC2's are much easier to lift/move.

 

[tiz]

Ok. Boat lives on a mooring. Almost never use ac unless on shore power. There is no inverter. Gas stove. Led lights throughout. Vacuflush head system. As long as its sunny we can run the fridge 24/7. If its not we get some charge with generator/110v charging and otherwise from engine run (105a alternator).

Not going to any lifepo.

Just need to understtypical difference between 12v fla battery charging parameters, and a deep cycle agm same format. Not using golf cart batts or 6v. The yard will do the battery lifting.

--Kevin

 

[tiz]

Also have 400w solar on the boat.

 

[Flatswing]

Just need to understtypical difference between 12v fla battery charging parameters, and a deep cycle agm same format. Not using golf cart batts or 6v. The yard will do the battery lifting.

--Kevin,

Go to the web site of the battery manufacturer to find their recommended charger settings. Marinehowto.com feels quite strongly that you should be able to duplicate these on your mppt solar controller(s) (since these are your major source for recharging and will have the most effect on battery health long term) as well as your 3 stage AC charger. Be wary of the stock "FLA" or "AGM" settings as they may not be optimal for your particular battery brand & most new chargers/controllers have custom setting abilities. For the relatively brief periods of charging from your propulsion engines, it's probably not worth switching to external regulation of your alternators.

 

[tiz]

Ok i did that for the current fla batteries (interstate). Their tech support gave me numbers and i set the victron mppt. Can change that easily as well as the 110v charger. Point taken on not using generic agm settings.

 

[tiltrider1]

I understand, while you can buy LiFePo4 batteries for significantly less than AGM there is always some additional expense to convert to LiFePo4. This expense adds up fast if you pay others to do it.

 

[dhays]

Ok i did that for the current fla batteries (interstate). Their tech support gave me numbers and i set the victron mppt. Can change that easily as well as the 110v charger. Point taken on not using generic agm settings.

Should be a very simple swap. Just set your solar mppt and your shore charger to the specs for the AGM batteries you buy.

If the yard is going to do the heavy lifting, then the huge, ungainly, massively heavy 8d batteries may not be an issue.