Opinions on battery type/size

bmax

I need to replace the house batteries on my 2011 310, I think that I want to go with AGM batteries, I currently have 3 105 ah flooded batteries. Our marina has no shore power so we use solar to keep the batteries topped up from weekend to weekend, I have 4 x 20 watt solar panels mounted on the radar arch. What are the opinions on the best AGM battery to use? I'm also wondering if I should look at 2- 6 volt instead. Rolls/Surrette seems to have a high quality unit, does anybody have any experience with them? Do the AGM's work well with solar charging? We do have a generator and we anchor out all the time so we use a lot of battery power.

bmax

Michael T

AGMs accept a charge 40% faster than any other battery chemistry available for marine use. I think they would work great with solar charging as long as you have a charger that reads AGM feedback profiles - as many people damage batteries with improper solar charging. I purchased East Penn Deka series 31 AGMs through my marine dealer. There is a distributor in Ottawa. West marine also sells them.  bmax, I believe you live in Canada but if you found a Sam's Club in the USA I believe they have some good prices on them. I do not like the ones at CDN Tire as, in my opinion, their amp hours are real low. If you have a good relationship with your selling dealer (if you bought new) I bet they would give you a discount. I would not get involved with 6 volt batteries and I think two series 31 AGMs are better that a 4D, as they are easier to handle and place. BTW all of your battery chemistries have to match - so all AGMs. My series 31 AGMs are great starting batteries too. As well, to get your biggest amp hour punch make sure to wire those two house batteries not just in parallel, but in the "correct" parallel manner. Good luck :-) MT

bmax

Thanks for the info MT, I'm in Canada, upper Ottawa Valley. My Charger does convert to the AGM profile but I read in the manual that all the batteries need to be the same, I was hoping to leave my 2 starting batteries in place, they are still working fine. When my boat was wrapped last fall the house battery switch was left ON, I usually leave the batteries in the boat over the winter and plug in the shore power to top them up once a month, but with the circuit left live the draw was too much and 2 of the batteries now have dead cells. I understand the AGM charges with less voltage than the flooded will this mean the 2 starting batteries will not charge to full capacity or will they be damaged from the lower charge? My solar is only hooked up to charge the house bank and I hoped the alternators would be able to keep the starters up to snuff???? I can buy East Penn from a local supplier, I bought the boat new from a dealer in Chatham so it is a long trip for 2 batteries. I have read MT's previous posts on the proper way to parallel the the batteries for best performance.

Michael T

Penn Deka says that all the batteries should be the same chemistry - unless you are using two battery chargers which would be a bit complicated but doable, in my opinion. If flooded and AGMs were mixed I think that the AGMs would charge a lot faster than the flooded ones and the charger would shut-off - starving the two flooded starting batteries. Although your starting and house batteries may be own different circuits I believe the charger only reads them all as a group. I guess you have a decision to make whether to stay with flooded and replace your house batteries with flooded now then all your batteries when they go or "bite the bullet" now and go AGM for all of them. Having used AGMs I would never use flooded again. I had four series 31 AGMs in my last boat (2 starting and 2 house) and they were awesome. In particular the house batteries really outlasted - by a very wide margin - my friends' flooded house batteries. On our new boat I have 2 starting and 3 house Series 31 AGMs in parallel. I was thinking of using 4 house AGMs but when I calculated the output of three there was no need. Even two Series 31 AGMs wired "properly" in parallel are real beasts! Good Luck bmax. MT

 

Cableguy Greg

I just bought 2 Duracell AGM Group 31 batteries from Sam's Club. They are made by EastPenn, the maker of Deka batteries. The guys on the Hull Truth seem to like them, time will tell. The price was right, $179, so I am not going to complain too much. I just need to wire them 'properly' since the current ones on my boat are not. Heck, the second house battery is wired with 4 gauge wire, which it clearly the wrong size wire.