Battery Size and Weight Options

[Valiente]

Hey, it's Chatty Cathy back from a long weekend of boat commissioning, repair and modifications, and I'm looking for yet more free advice. This time it concerns sizing batteries.

I have plenty of space in my engine compartment. Let's say for argument's sake I could put one 8D AGM on starboard and two 8D AGMs on port. Let's say I could weld angle iron frames to hold them at about 15 degrees so that I could haul them out instead of directly up, thus facilitating removal.

Now add the advice of a friend with a similar metal boat. He has 2 8D Deka-brand AGMs, side by side under the floorboards in his saloon. While he is happy with the batteries, he thinks he made a horrible mistake getting 170 pound/75 kgs. 8Ds, because they are a horror to install and remove. And he isn't talking about lifting them over an engine, but simply lifting them straight up and then up a companionway. He is strongly urging me to get 4Ds or even Group 31s because they are easier to handle...or relatively so.

That's one advantage. Another is that if I get a bad battery, or one that goes bad, I can more easily and cheaply replace it and/or diagnose it.

A disadvantage to my mind is the greater number of short lengths of expensive copper wire and lugs, plus the greater potential for failure in a larger number of connections. Regardless, I want the amp capacity that two or preferably three 8Ds can store, so I can be on the hook with solar and wind charging for a week or so before I have to run the diesel.

Rolls makes a modular 8D wet cell battery: 12 HHG 8DM Rolls Marine Battery
that has a great design. Is there an AGM modular equivalent that anyone knows of? If I could get an 8D AGM that came apart into six 30 pound "bricks", that would be the ideal.

[Freesail99]

How are you planing on charging these batteries ?

[sailingdog]

That's basically the reason I went with Trojan T105 golf cart batteries... the batteries are far more manageable in size. They do make golf cart type batteries in AGM, so it could be a good possibility for you. Good, tinned marine wire, with properly installed battery lugs don't really go bad, so that's a fairly minor worry.

Valiente, take a look at the AGMs at this link. I have been using the 8D equivalents and the group 31 batteries for about 10 months now and they have worked well so far. A number of boats here went to these batteries last year and all are reporting good results so far. Sorry I can't provide any long term data on them for you.

The weight and form factors were big factors in my decision. The ability to orient the batteries in all positions except upside down was useful.

Might be worth a look as you do your research. Not knowing about your current charger I can only suggest you make sure it is compatible with AGMs if you decide to go that way. When I moved to AGMs my existing charger was not compatible and I replaced it with a Xantrex 5012 unit.

Regards, John

Added link: .: Battery Specifications : Energy 1

[capn_dave]

I gave up on hauling those 8D's out of my boat years ago. They would make a man out of you, taking them in and out. I am sure you don't want hair on yer chest. The T105's are about 70 lbs apiece and one person can carry them with little problem.
Yes you have to make up lots of little cables to connect them, however the cables are light and you can make them yourself for alot less than buying them.

Fair Winds

Cap'n Dave

[btrayfors]

Wrestling an 8-D battery -- or a 4-D battery, for that matter -- in or out of your boat could cause a back injury which would end your sailing career. Period. Why would you, or anyone, want to take this risk? Especially, since there are good alternatives.

Alternatives:

(1) Golf-cart sized batteries, like the T-105s; easy to handle; powerful; robust; cost efficient; just be sure to make good connections;

(2) Slightly larger "golf-cart" or industrial batteries, like the L-16 size;

(3) Large battery banks made up from individually removable 2V cells (like those from Rolls/Surette); an excellent alternative, if a bit costly up front.

How much is your back worth?

Bill

[Cruisingdad]

Oh Val!! You have hit my hot button!!!! I am running right now but I will tell you what I would do tomorrow. DONT BUY ANYTHING YET!! HAHAHA!! Just sit back, pull out the credit card, and enjoy the ride (well, tomorrow!).

- CD

[Cruisingdad]

PS DO NOT BUY THAT ROLLS!!!!! HOLD OFF UNTIL TOMORROW! Ole CD will set you up and you will be able to power small islands like me!

- CD

[DeepFrz]

Trojan has just announced new smaller sized AGMs. Get in touch with them and find out what they have. I believe one is T105 sized.

Edit: they are 6 volt AGMs. I see that Lifeline have them also.

[Valiente]

Originally Posted by Freesail99

How are you planing on charging these batteries ?

2 or 3 130 W Kyocera panels, a KISS windgen (and a Honda EU 2000 as necessary), plus a 100 amp Balmar on a 52 HP diesel. If on shore power, 60 or 100 amps into a Xantrex RS2000 charger.