Battery upgrade

[philmac]

Hello All,

One of our local stores (Canadian Tire) just put Exide group 24 AGM deep cycle batteries on sale.  I have been flirting with the idea of changing my conventional flooded lead acid cells because they are located in the rear cabin under the bunk, are a huge pain to get at and are in a cramped space.  We are mostly weekend cruisers with the occasional longer cruise in the summer and pretty small power demands but we do enjoy our showers, the onboard stereo and my son recharges his collection of electronic gadgets. The batteries went low a couple of time last year.   This would be a straight swap for the conventional batteries as my current batteries and the AGMs are both rated at 75 aH.  I have also acquired a 30 watt solar panel and a new Xantrex smart charger in the off season.  My alternator is rated at 60 amps but is internally regulated.  Is this worth the effort/cost and am I asking for trouble trying to recharge AGMs with a standard, internally regulated alternator.  Thanks for any input.

Phil 

[Ivars]

AGM batteries are very good and meant to be used...  their downfall is if left in a discharged state  and in occasional use they will fail faster than a standard wet cell... in applications where there is a possibility of them being left discharged,  I would avoid them... the standard wet cell is more forgiving in those situations and much less costly to replace when they fail...  it is possible to get a group 24 wet cell with better performance specs than the AGM... 

 

75Ah rating is meager for any  group 24 battery... Interstate battery model  SRM 24 is a group 24 that rates at 140Ah... almost double of the AGM at about 1/3 the price...    

 

become an informed battery buyer... battery purchases are dumbed down to "what year car"... there is more than correct voltage and physical size  to a battery... read the fine print and understand what one is getting...

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From: benetea...@googlegroups.com [mailto:benetea...@googlegroups.com] On Behalf Of philmac
Sent: Tuesday, May 14, 2013 5:36 PM
To: benetea...@googlegroups.com
Subject: {Beneteau Owners} Battery upgrade

Hello All,

One of our local stores (Canadian Tire) just put Exide group 24 AGM deep cycle batteries on sale.  I have been flirting with the idea of changing my conventional flooded lead acid cells because they are located in the rear cabin under the bunk, are a huge pain to get at and are in a cramped space.  We are mostly weekend cruisers with the occasional longer cruise in the summer and pretty small power demands but we do enjoy our showers, the onboard stereo and my son recharges his collection of electronic gadgets. The batteries went low a couple of time last year.   This would be a straight swap for the conventional batteries as my current batteries and the AGMs are both rated at 75 aH.  I have also acquired a 30 watt solar panel and a new Xantrex smart charger in the off season.  My alternator is rated at 60 amps but is internally regulated.  Is this worth the effort/cost and am I asking for trouble trying to recharge AGMs with a standard, internally regulated alternator.  Thanks for any input.

Phil 

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[Ivars]

ooops forgot to comment on the charging system... there is more to it than 12volts

 

standard wet cell charging systems have a different charge voltage and profile from an AGM... a std 12 volt charging system should get any type of battery out of trouble and get a start out of it....  on going use and maintainance is where the problems begin... an AGM may not charge to 100% and not using a charger designed for AGM can lead to early failure as well...the charging profiles are very different for an AGM using a std charging system will not allow for optimum use...  again read the fine print to understand what is going on

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From: benetea...@googlegroups.com [mailto:benetea...@googlegroups.com] On Behalf Of philmac
Sent: Tuesday, May 14, 2013 5:36 PM
To: benetea...@googlegroups.com
Subject: {Beneteau Owners} Battery upgrade

Hello All,

One of our local stores (Canadian Tire) just put Exide group 24 AGM deep cycle batteries on sale.  I have been flirting with the idea of changing my conventional flooded lead acid cells because they are located in the rear cabin under the bunk, are a huge pain to get at and are in a cramped space.  We are mostly weekend cruisers with the occasional longer cruise in the summer and pretty small power demands but we do enjoy our showers, the onboard stereo and my son recharges his collection of electronic gadgets. The batteries went low a couple of time last year.   This would be a straight swap for the conventional batteries as my current batteries and the AGMs are both rated at 75 aH.  I have also acquired a 30 watt solar panel and a new Xantrex smart charger in the off season.  My alternator is rated at 60 amps but is internally regulated.  Is this worth the effort/cost and am I asking for trouble trying to recharge AGMs with a standard, internally regulated alternator.  Thanks for any input.

Phil 

[philmac]

Thanks for the input.  My current Deka FLA deep cycle batteries are also 75 aH.  I thought that was pretty standard for group 24 deep cycle.  I certainly take your point about charging but I have just installed a Xantrex smart charger and it has an AGM setting as does the charge controller I have for my solar panel.  I worry about stress on my alternator as we do not have power at our slips so I will have to park at the service docks and run the onboard charger. I guess I am going to have to give this some more thought.  I really hate digging under the bed in the aft cabin for the batteries.

Phil 

[Bill Jarvis]

Phil,

 

Before you think about replacing your batteries you really need to do an energy budget for your boat and use it to determine what capacity you need in your storage bank.

 

If you are not familiar with an energy budget here’s what you do.

 

Go through a full 24 hour day and write down everything that you use and how long you use it. Then look at the usage in ampere hours. To do that you  need to determine how many amps each piece of gear uses. Some will have the amps stated on a name plate others will show watts. To get amps from watts divide by 12.

 

Once you have all that data set up a spreadsheet and multiply the amps by the minutes of use. Sum all of those and then divide by 60. The answer is your total ampere hours usage for a day.

 

Your battery bank should be a least three times your daily usage. That’s because battery life is seriously shortened by discharging below 50% and it takes forever to recharge from 85% to 100%. That means that the effective capacity is about 35% of the nominal. Your solar panels may well get back to 100% when you leave the boat for a week but in doing the energy budget I would recommend ignoring its contribution since you may well have a day with severe overcast when the contribution will be minimal.

 

Frankly while 2 75AH batteries may well be normal that is usually totally inadequate for today’s boat with lots of electronics and creature comforts.

 

Bill

 

 

From: benetea...@googlegroups.com [mailto:benetea...@googlegroups.com] On Behalf Of philmac

Sent: Thursday, May 16, 2013 10:21 AM
To: benetea...@googlegroups.com

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[Mark J Wilme]

Also if you are switching to agm's be sure your charging source(s) are putting out the right voltage to effectively charge them - agm's, gel's and lead acid's all take different charging regiments.

[Luis Sá]

Hello,

 

Another thing to consider is the other batteries you may have (engine starting, bow thruster, ...) In my case the charger (Dolphin 25A) has 3 separate outputs and 8 types of charging programmes. The problem is that the charging programme is common to all the 3 outputs and so I can not choose, say AGM for the servicing bank and, say lead acid for the starting battery.

 

Luis (Oceanis 40, Portuguese flag, presently in Croatia)

 

From: philmac

Sent: Tuesday, May 14, 2013 10:36 PM

To: benetea...@googlegroups.com