Can a 50hp outboard charge AGM type battery bank correctly?

[opie]

I have a Honda 50HP with a 10amp output and a rectifier/regulator. I may soon need to buy two batteries. I have read everything I can about AGM batteries and most often am told that the AGM battery can not be charged properly with a dumb charging system found on smaller engines. In fact one site set the requirement of having a minimum 100hp inboard engine with minimum 100 amp alternator and a three stage electronic charging system plus a frequent shore-side 110v charging system before AGM can be effectively accommodated.

Should I stick with the normal non-gel or non-AGM marine battery choices? Anyone with good AGM experiences while charging with a older 50hp outboard?

[Paul S]

I charge a agm with my other boats alternator with out a problem. No doubt many here do too..

I am in the wet cell camp when it comes to batteries. Far lower cost, more amps per pound, servicable, long life. Not worried if they leak if the boat turns upside down..if that happens.. I have other things to worry about at that moment!!

Check with that battery mfr for their recommendations on charging. I think you would be OK though.

[Hardcrab]

Great question.
I have pondered this on my installation as well.
I have two parallel AGM's (Optima) as house/start and one flooded cell as backup only.
(all three fit in the M's normal battery spot!)
My "smart" charger does charge AGM's at 15.4 volts, but my outboard only charges at 14.5.

After running the motor returning to the dock (14.5v), then plugging up the smart charger (15.4v), the batteries are fully charged; the smart charger will display "Full" and shut down.
Hmmmm.

So my take on this, in my situation, and IMHO, is it doesn't seem to matter.
Besides, these AGM's are intended for many "standard" charging systems in vehicles and other applications.
The makers do not restrict installation into existing systems due to the 14.5 volt "limits".
If you have to upgrade the regulator in your car/boat to support these AGM's, then some shine is lost on making any switch.
Not many sales if headaches are going to be seen by using standard charging systems.
Optima, for one, makes no such suggestion that I have seen on their site.
It works for me since Feb of this year.
The up side to these AGM's is hard to argue against, also IMHO.

[JustSail]

I have 2 of these in my 26M with a Honda 50 and have never had a problem. I do charge them up twice a year with a regular battery charger.

http://www.optimabatteries.com/optima_p ... /index.php

Mine are 3-4 years old. I let it one go all the way down this year. I've charged it up and we'll see if it continues to hold a charge. I'm pretty sure its going to be ok for at least another season.

I previously had standard lead acid batteries. They only lasted 2 seasons, tops.

[Paul S]

I previously had standard lead acid batteries. They only lasted 2 seasons, tops.

Funny in 20 years in boating, over 3 boats, never had a marine wet cell last fewer than 10 years. My powerboat had 2 batteries in 15 years (first lasted 10, second was sold with the boat). The wet cells in my Ohlson are something like 15 years old. My Mac batteries (Rolls wet cell group 27) are babies at 6 and can charge to 13.x and hold the charge no problem.

[Don T]

Hello,
Next spring I will be getting new batteries. 3rd set for my mac. I use a load tester and when the reserve capacity gets down I replace them. While the batteries charge fine, start the boat fine, they currently only have 60% of the original energy storage of new. At some point I no longer trust them on a 2 week cruise up in the San Juan Islands. It's just not the kind of trouble I want to have. Yes, I can pull start the Tohatsu so I wouldn't be stranded but our sailing lives are more electronic now. I like anchor alarms, anchor light running all night and charging the cell & laptop from the house Batt. Lynn and I watched our first movie the last time out this year. Normally I would say "Bah Humbug" we're here to enjoy nature but creature comforts seem more friendly now. I must be getting old or maybe just married too long.

[DaveB]

You can charge your AGM or Gell batteries with you Honda. Gell and AGM have lower voltage readings than wet cell when fully charged. The advantage of AGM or Gell is that you can run them down to 30% battery capacity with little or no harm to them. The wet cell deep cycle you can run down to 50% before recharge and even down to 35% if you recharge them quickly.
Sulfate is the major problems of wet cells and can often be desulfate over a large 30-50 amp charger for short time.
I have had all types in my boats and for a week trip or two would go with the far less expensive deep cycle 27 or 30 series.
I have 2- 27 wallmart deep cycle in parrell ($85 each) for house batteries and has more than enough power to last for 10days without going below 50% capacity. We run TV,CD's movies, radio,4 fans and all our elect. includeing chargeing laptop,rechargeable batteries thru 75 watt inverter.
I do not have these house batteries hooked up to Honda engine charger (Just my starting Battery).
The other option I liked on my Compac was 2-6 volt Golf Cart Batteries @ $85 each.
I had 1 gel battery in my Potter that was 7 yrs old and still going strong.
It's all in how much you want to spend, most sailer want more for less and those Wallmart batteries will last at least 7 years if you take care of them.

I have a Honda 50HP with a 10amp output and a rectifier/regulator. I may soon need to buy two batteries. I have read everything I can about AGM batteries and most often am told that the AGM battery can not be charged properly with a dumb charging system found on smaller engines. In fact one site set the requirement of having a minimum 100hp inboard engine with minimum 100 amp alternator and a three stage electronic charging system plus a frequent shore-side 110v charging system before AGM can be effectively accommodated.

Should I stick with the normal non-gel or non-AGM marine battery choices? Anyone with good AGM experiences while charging with a older 50hp outboard?

[trip01]

Opie,

To charge, they like high amps - The 10% rule applies. IE to charge a 60AH AGM you require at lease 6amps. (Your 10amp output charge from motor should do {on it's own} a 100AH AGM)
AGM's not so popular with solar charging re high amps charging requirement.

http://www.fridge-and-solar.net/batteries.htm
http://www.fridge-and-solar.net/agm.htm

Above site - Aussie site, Aussie dollars.

Rgds
Dave
2008 Mac 26M / Landcruiser HDFT

[Kelly Hanson East]

Ive replaced one of my wet cell batteries on Catigale in 7 seasons - and that was because I let it discharge and freeze. It still met my electrical needs, but it wouldnt crank the motor.

My electrical needs are minimal, so the wet cell (deep cycle type) is the right approach for me. Remember NOT to follow the mantra of 'starting' and 'house' batteries for our puny outboard motors (Billy can take a possible exception with his 140 HP)