[Hot Rod]

I am thinking about replacing my two 8 D flooded (wet) batteries with AGM batteries. I have a 2007 Luhrs Open Sportfish with twin Yanmar 480 HP engines and Hitachi 80 amp internally regulated alternators (all original equipment).

Are these batteries a simple swap, or do I need to modify the alternators? Thanks

[Henning]

Originally Posted by Hot Rod

I am thinking about replacing my two 8 D flooded (wet) batteries with AGM batteries. I have a 2007 Luhrs Open Sportfish with twin Yanmar 480 HP engines and Hitachi 80 amp internally regulated alternators (all original equipment).

Are these batteries a simple swap, or do I need to modify the alternators? Thanks

No mods required, simple swap.

[Capt J]

Originally Posted by Hot Rod

I am thinking about replacing my two 8 D flooded (wet) batteries with AGM batteries. I have a 2007 Luhrs Open Sportfish with twin Yanmar 480 HP engines and Hitachi 80 amp internally regulated alternators (all original equipment).

Are these batteries a simple swap, or do I need to modify the alternators? Thanks

Simple swap, but there may be a different setting for your battery charger for AGM. (Usually a dip switch or something similar). ALSO, most AGM's don't have anywhere's near the cold cranking amps of flooded, so check that before making the switch or they might have a hard time cranking over your Yanmar 480's

[Pascal]

simple swap, just set the switch on the charger as Capt J mentioned.

not sure i see the point though, the only benefit is that you wont' have to add water to them, not really worth the extra $. they should last a little longer but not longer enough to offset the cost.

[Henning]

You'd only flip the switch if you are changing from Gell Cell batteries. Flooded Cell and AGM operate at the same voltage, it's the Gell Cells that require lower.

[Hot Rod]

Many thanks for the advise on the AGMs.

I plan on using 2 8D flooded (wet) for cranking the Yanmar 480s and 2 8D AGM batteries for the House/Electronics. I plan to have the House/Electronics bank batteries wired together in parallel with one of the Yanmar alternators providing charge while underway and its own dedicated battery charger set to "AGM".

I plan to keep the 2 8D cranking batteries separate from each other except for charging, when I plan to use a voltage sensitive relay battery combiner. I plan to have the other Yanmar alternator provide charge while underway and supply the cranking bank with its own dedicated battery charger set to "Flooded".

What are your thoughts and ideas about this preliminary plan? I currently have a stand alone battery to crank a 3 cylinder Yanmar powered Kohler 8-32EOZD generator. How do you think I should incorporate it into the system? I need to provide a charge to the battery when it is not in use? The current battery used by the generator is a standard marine sealed cranking battery.

[Henning]

Originally Posted by Hot Rod

Many thanks for the advise on the AGMs.

I plan on using 2 8D flooded (wet) for cranking the Yanmar 480s and 2 8D AGM batteries for the House/Electronics. I plan to have the House/Electronics bank batteries wired together in parallel with one of the Yanmar alternators providing charge while underway and its own dedicated battery charger set to "AGM".

I plan to keep the 2 8D cranking batteries separate from each other except for charging, when I plan to use a voltage sensitive relay battery combiner. I plan to have the other Yanmar alternator provide charge while underway and supply the cranking bank with its own dedicated battery charger set to "Flooded".

What are your thoughts and ideas about this preliminary plan? I currently have a stand alone battery to crank a 3 cylinder Yanmar powered Kohler 8-32EOZD generator. How do you think I should incorporate it into the system? I need to provide a charge to the battery when it is not in use? The current battery used by the generator is a standard marine sealed cranking battery.

Unless you are staying with the flooded cell battery for cost reasons, there is no good reason not to use an AGM for cranking. I would suggest that you get a multi point charger with a desulfinator cycle built in. Provides a great extension to battery life.

[Hot Rod]

I reviewed the details of my ProMariner ProTech-4 battery charger to insure that it properly addressed the desulfate process. Here is what it says, "Stage 2 Absorption Charge/Conditioning Mode = Precision 14.7 V DC to Fully Charge & Desulfate Battery(s)." The dip switches are set to 4 hours for 8D batteries for this stage. The charger also has three 3 DC output connections.

I discovered that this battery charger, which came installed on my 2007 Luhrs, has been discontinued. It has one setting for Flooded/AGM batteries (14.7 V Absorption, 13.5 V Float) and a second for GEL (14.1 Absorption, 13.5 V Float). That charger has been replaced by ones (ProTechi and ProNautic) that have three different battery type settings; Flooded (14.7V Absorption, 13.5V Float), AGM (14.4 V Absorption, 13.3 V Float) and Gel (14.1 V Absorption, 13.8 V Float). The AGM now has a different charging rate (.3 V lower for Absorption and .2 V lower for Float) and the GEL has a .3 V higher Float rate.

The question is, what is the affect of this change in charging rates on the AGM battery? Is it worth the investment in the newer model (ProNautic or similar brand) battery charger?

[Henning]

Originally Posted by Hot Rod

The question is, what is the affect of this change in charging rates on the AGM battery? Is it worth the investment in the newer model (ProNautic or similar brand) battery charger?

They will charge at a slightly slower rate, not get quite as warm and offgas at a slightly lower rate. I have never had an issue using old style battery chargers on AGMs, so I don't know if it would be worthwhile to get the new charger, but dropping the float to .1 volt above lead/acid batteries full charge sure won't hurt anything, and with the desulfation cycle you might get some impressive life span out of them. I had a desulfator circuit that I'd use on my airplanes battery and got over 7 years out of it (typical is 2-3) and it was still going strong when I sold the plane.

[Hot Rod]

Thanks to everyone that has participated in this post to date. I now feel that I am headed in the right direction with the selection of AGM batteries for the House/Electronics battery bank. I just purchased a ProMariner Pronautic model 1260 marine onboard battery charger. It has all of the features that have been pointed out to be necessary to prolong AGM battery life. I needed a second battery charger anyway, as I am going to dedicate my current ProTech 4 charger to the 2 8 D Wet (Flooded) cranking batteries.

The Pronautic 1260 has 60 amps of charge, 7 user selectable charging algorithms, employs battery balance which allows smaller group size batteries to be charged along with larger battery types, allows 100% of the available charging amps to be used by any one or combination of three banks, provides an individual charge/conditioning time based on the status of each of the three charge outputs resulting in a 100% charge while desulfating batteries, includes an automatic reconditioning mode every 10 days and last, has remote true temperature compensation from a remote battery temp. probe.

I still have some concern about using standard marine alternators with the AGMs, but in reality, the amount of time running the engines on the water being charged by alternators Vs the amount of time attached to the onboard battery charger is minor. So now that I have a charger that is ideal for AGMs, it's on to battery selection!

I would like to hear comments as to the best AGM for the investment and the best deal that can be had. Thanks

[Henning]

Originally Posted by Hot Rod

I would like to hear comments as to the best AGM for the investment and the best deal that can be had. Thanks

Deka Batteries

[Capt J]

I would recommend two things with your setup.

1. A Battery switch so that you can connect (parallel) the house batteries with the starting batteries in a dead battery situation, if one is not already installed.

2. I would use a battery isolator on the port engine, that way you can use the alternator to charge both house batteries and engine batteries and one battery bank would not backfeed the other. That way, you could run on only the port engine in an emergency situation or whichever.

[wingless]

Originally Posted by Henning

Unless you are staying with the flooded cell battery for cost reasons, there is no good reason not to use an AGM for cranking.

When I recently replaced my six group 31 batteries I used the published specifications for rated ampere-hours, cycle life and cost to caclulate the lifetime cost per ampere-hour delivered.

That caclulated lifetime cost was a wash between the flooded cell and the AGM battery.

The flooded cell has the benefit of a lower initial cost, about half.

On this swap I remained w/ flooded cell.

[Hot Rod]

Does anyone know if it's possible to direct the alternators' output to a high capacity battery isolator and then to the starter bank and the House/Electronics bank? This would produce a .6V lower alternator max charge rate by going through the isolator's diode. That would provide the reduced (desired) output for the AGM batteries in the House/Electronics battery bank. The reduction in the max. charge rate for the cranking battery bank could be corrected when the batteries are charged by the onboard battery chargers without going through the isolator. Will each alternator need a separate isolator, or can both alternator-charge-outputs be attached together to the isolator's charge-source-terminal?

If this works, it may be simpler than having my internally regulated alternators, converted to alternators with external regulators.

[Capt J]

Originally Posted by Hot Rod

Does anyone know if it's possible to direct the alternators' output to a high capacity battery isolator and then to the starter bank and the House/Electronics bank? This would produce a .6V lower alternator max charge rate by going through the isolator's diode. That would provide the reduced (desired) output for the AGM batteries in the House/Electronics battery bank. The reduction in the max. charge rate for the cranking battery bank could be corrected when the batteries are charged by the onboard battery chargers without going through the isolator. Will each alternator need a separate isolator, or can both alternator-charge-outputs be attached together to the isolator's charge-source-terminal?

If this works, it may be simpler than having my internally regulated alternators, converted to alternators with external regulators.

Yes, you can run your alternator's output directly to a high capacity battery isolator. I would think that you can run both alternators to 2 different isolators and 2 different battery banks. I wouldn't worry about your engine alternators producing too much voltage for the AGM's.