Batteries for Beneteau 40

[Goingsouthsoon]

I just sold my Jeanneau 36i, and bought a Beneteau 40, as we are heading for an extended sail to the Bahamas this summer.
It has two stock 4d house batteries on it, which i believe are about 150 amp hours each.
I am replacing the stock alternator (80 amps) with a 140 amp electromax.
As well, i plan to install a small wind generator and 270 watts of solar panel.
my Question is about batteries. I would like to have about 600 amp hours of capacity in the house bank. looking at going with six 6 volt golf cart type batteries, flooded, or agm. The 6 volts provide 220 amp hours each, so that would give me on the order of 660 amp hour capacity, at 12 volts.
AS the AGM's are double the cost of flooded, i was looking for feedback about the agm versus the flooded. Considering flooded batteries from Crown, agm's from Lifeline.

 

[joker460]

Actually the 4 x 6 volt 220 amp/hr batteries will give you 440 amp/hr @ 12v total plus your 2 x 4D 150 amp/hr will give a grand total of 740 amp/hrs @ 12volts.

Putting 2 6v 220 amp/hr batteries in series still only gives 220 amp/hr @12 v.

Also make sure your charging system can handle AGM's otherwise you could destroy them quickly.

Added Note: Golf Cart batteries are usually taller. Make sure they will fit.

 

[Goingsouthsoon]

thanks, to clarify , i plan to remove the 4d's to make room for the 6 volt batteries, so i will have six of them, with a total of 660 amp hours.(as pointed out, 2 6 volt batteries give 220 amp hours. )
I am switching to the 6 volts, as i can get more amp hours in the same physical space, and i understand the plates are thicker, resulting in better life.
My interest is really in the performance of the agm's in cruising conditions
The batteries are under the aft bunk, so the low gassing property of the agm's is attractive

 

[Stu Jackson]

AGMs aren't for everyone

http://forums.catalina.sailboatowners.com/showthread.php?p=848465&highlight=darn agm

http://forums.sbo.sailboatowners.com/showthread.php?t=124973

I'd stay with wet cells unless your access is soooo horrible you can't ever get to them.

 

[Chuteman2]

FYI - Info From recent Diesel Class
1) Before installing Hi-Output Alternator check w/ Mfg - Dealer to ensure compatibility
and will not affect engine performance - Have Engine Model & Serial # for inquiry
2) Increasing Charging and Battery capacity should be coupled with increase of Wire(s) size to safely and properly carry higher loads

 

[Mike B]

Goingsouth, I changed out the 2 4Ds that came with our 43 with 4 6V Trojan wet cells. Although a little tall they still fit in the old 4D battery boxes. The original 4ds couldn't handle the power needs for more than a day or two. The 4 6V Trojans do a much better job and makes me wish I had gone with 6 rather than 4, something I'll deal with later. You should have space under the aft bunk for the additional set. I thought of going with the AGMs for the gassing issue and due to the fact it's a pain to get under the aft bunk, but was put off by the price. FWIW not issues with gassing as of yet. Not sure what you're power needs are but with your solar and wind generation the HO alternator may not be needed. If you go with it anyway the 140A unit may put a bit of stress on the engine bearings, not to mention the potential belt issues trying to drive it. Perhaps twin belts or a serpentine drive? No doubt you'll get more input on the AGM vs Wetcell question. Good luck deciding.
Mike

 

[Rick I]

DO NOT GET AGM's if you're cruising the Bahamas. I made that mistake a few years ago. They lasted two seasons. I'm now back to flooded batteries. Most of the time I'm using the band between 50% and 85% charged. It takes too long to get the final 15% in. AGM's do not like this. 600 amps is a good size bank. Mines a tad over that. I have 4 Trojan 12v flooded batteries, they're about 160 amps or so each. I did not have the height to put 6v in.

 

[Goingsouthsoon]

Thanks folks for the great input
I am changing the belt to a serpentine, to support the higher "pull" of the 140 amp alternator. Haven't put it on yet, but went through a demo at the electromax booth at Toronto boat show, looks easy enough. I have the larger motor (54 hp) so i think it will handle it ok.
I do have enough room (just ) to put four of the 6 volts behind the motor, and two more up under the front of the aft bunk, replacing the 4d that was there.
The 6 volts i am looking at are from Crown battery, my supplier feels they are as robust as the Trojans
I think i will take the advice and stick with flooded. Doesn't seem to be worth the effort to keep the agm's fully charged
I do plan to increase the wire size from the alternator to the batteries, current is up quite a bit

thanks again
Randy

 

[Mike B]

Randy, since you're a B40 owner you should check out the B40/43 owners site in www.seaknots.ning.com Not to take anything away from SBO, it's a great site, but the people that created Seaknots have a B43 and there's a number of 40/43 owners from all over the globe that post on the site.
Mike

 

[Gunni]

I have batteries in my (hot) engine compartment and in my (cool) lazarette, there is a problem with proper charge control. I am addressing that with an improved AC charger with battery temp sensors. Ideally, I would put them all in a cool location, but that is not possible. In your case, I think you will find that your alternator output drops off big when the engine heat rises. So providing greatly improved ventilation there (where 1/2 of your battery bank is located) may pay double dividends.