AGM batteries

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CCHer

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Jul 7, 2010
230
Beneteau 37 Cranes Creek, VA
For those 12 volt battery experts out there....I recently purchased a B37 with fairly new AGM batteries-both house and starting-my first experience with AGMs. In my prior boats with flooded batteries I kept the charger on 24/7 year around which served me well in terms of batteruy life. Is that advisable with AGM's? The boat has a 3 stage Xantrex charger set on the AGM voltage. Thanks.
 
Sep 25, 2008
6,356
Alden 50 Sarasota, Florida
Not sure what purpose you intended by limiting your post to just Beneteau readers. Regardless, I'm no expert but have read about everything there is regarding the care and feeding of batteries and your plan to charge them continuously will not damage them any more than doing the same thing with any other type battery. That is, any battery type may suffer premature sulfation even when fully charged if not exercised periodically.
 
Jul 20, 2011
4
Beneteau 373 Kemah, tx
I have a B373 with 4 odyssey agm's which are now about 4 years old. I have used a rather sophisticated battery condition meter . The SPX OTC Sabre HP - to periodically check battery condition and remaining life ( the SPX cost about $400 and has a two stage load recovery load cycle) which showing them a about 80% of new. The boat came with the standard 2 flooded lead acid batteries which were near the end of their life at 4 years. I also have the stock Xantrex charger set on AGM (good unit). But here is the key piece of information- the stock Yanmar with Hitachi alternator has a voltage regulator designed for flood cell lead acid batteries which does not have the right charge profile for AGM ( can remember but I think over charges them). Thus I then replaced the alternator with a Balmar with external regulator with an AGM setting. This set up should give me 6-9 year of battery life versus about 3-5 of flooded cell per my boat electrican mechanic. Why did I do all of this? Well first I am an engineer but more importantly I hated having to check the batteries very often under the rear berth cushions. I also added a bow thruster which required a large power source near the front of the boat and the 4 th battery is up under the forward berth (for windlass too). Hope this helps.
 
Feb 6, 1998
11,454
Canadian Sailcraft 36T Casco Bay, ME
I have a B373 with 4 odyssey agm's which are now about 4 years old. I have used a rather sophisticated battery condition meter . The SPX OTC Sabre HP - to periodically check battery condition and remaining life ( the SPX cost about $400 and has a two stage load recovery load cycle) which showing them a about 80% of new. The boat came with the standard 2 flooded lead acid batteries which were near the end of their life at 4 years. I also have the stock Xantrex charger set on AGM (good unit). But here is the key piece of information- the stock Yanmar with Hitachi alternator has a voltage regulator designed for flood cell lead acid batteries which does not have the right charge profile for AGM ( can remember but I think over charges them). Thus I then replaced the alternator with a Balmar with external regulator with an AGM setting. This set up should give me 6-9 year of battery life versus about 3-5 of flooded cell per my boat electrican mechanic. Why did I do all of this? Well first I am an engineer but more importantly I hated having to check the batteries very often under the rear berth cushions. I also added a bow thruster which required a large power source near the front of the boat and the 4 th battery is up under the forward berth (for windlass too). Hope this helps.
Actually the Odyssey batteries will take more voltage than the Hitachi is capable of in absorption mode. Also the internal Hitachi regulator is temp compensated to "protect" the alt from over heating. As it heats up it will drop the voltage thus reducing currernt.

Keep in mind that for the best life with Odyssey batteries they want to see LOTS of charge current. EnerSys/Odyssey want to see 40% of "C" or capacity in bulk mode. Lifeline has a minimum of 20% of "C"..

Eighty % of new is technically, by industry standards, nearly dead. Odyssey batteries should last longer than 4 years but with the TX heat, that may be what you get. I do strongly suspect you'd have done far better had they been "properly" charged.

The OTC testers do not have the best algorithm for TPPL batteries. The only analyzers I know of that do are Midtronics, in their very expensive analyzers. The tools however can very successfully be used, but, you need to start with a good baseline from "new" for them to be accurate. If you are not comparing current readings on your own batteries, to physical when new readings, the batteries could be in better or worse shape..

It always saddens me to hear of marine electricians not doing their job well.:doh: Your batteries are EXPENSIVE and thus really need to be set up properly, for the best life, with a custom program NOT the factory "AGM" Balmar profile.

Odyssey batteries should be charged at 40% of "C", or as close as you can reasonably get but I don't like to drop below 30% / "C" if it can be avoided. The charging voltage should be 14.6V - 14.7V in absorption and this is contrary to most "AGM" settings which are most often 14.4V or less.. These regs, and battery chargers for that matter should also be custom programmed for much longer "absorption" than the factory profile allows or they will enter what I call "premature floatulation", or go into float far to early. Float voltage should be at 13.6V, though on a sail boat you should really never get to float unless doing the ICW or running the motor for hours on end..... These batteries also NEED temp compensated charging especially in the TX heat.. Make sure your shore charger AND your Balmar regualtor are taking full advantage of this.

There is no pre-set program from Balmar that charges Odyssey AGM's properly so the installer should have gone in and chosen to set it up with custom parameters. These regs NEVER stay in absorption long enough when you just accept the factory programs and they also go into float mode waaaaaaaay to early.

Your electrician did you a disservice by selecting the factory AGM profile and by NOT READING the Odyssey technical manual.. There is a big difference between 14.38V and 14.6V - 14.7V for charging Odyssey batteries. If he is not competent enough to do a custom program as an engineer you can easily figure this out..
 
Apr 30, 2010
54
beneteau 331 victoria
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