Batteries

Time to replace our batteries. Currently have 850 amp batteries and thinking of going to agm type. Very pricey. Worth it? 46 gb Europa and planning on Alaska this season.

There are lots of fans here of AGM batteries. I'd be a fan, too, if I had lots of cash. IIRC, they require a different charging profile than lead acid (LA) batteries. I like that fact that they can accept a much higher charging current than other types.

Being the cheap SOB that I am, I stick with the LA batteries. I use the golf cart 6V batts and wire them in series/parallel for 660AH at 12V. I can get them at Costco for under $100 per battery...$600 for my bank of 6. If they last 6 years, that's just $100/yr...good value. But mine are located where servicing them is not a problem. Not all have it so good.

I just replaced my battery bank in my sailboat this last fall. Like Al, I am a cheap SOB (oh, I guess I already mentioned I had a sailboat) and decided against the significant cost of AGM. I replaced my 2 x 4D batteries with a bank of 4 Costco Golf cart batteries.

For certain applications AGM have some real advantages of course, but the Golf Cart batteries were cheap, used the same charging system as my existing batteries, and are pretty bullet-proof.

As Al pointed out, one consideration is ease of servicing. My bank sits right under the cabin sole in the galley and super easy to access to check. I run a dehumidifier in the boat so always have condensate to use to top off cells if needed.

Depending on the age of your boat, I would also suggest you take this opportunity to review how your DC system is configured. I added the appropriate fusing to the batteries and changed the way my alternator output was routed to the house bank for example. Standards have changed since my boat was built 11 years ago.

Before leaving on our trip to the Broughtons last summer we switched to new Oasis carbon foam batteries from Bruce Schwab at Ocean Planet Energy. Nigel Calder calls these AGM-style batteries a "game changer". They are definitely not cheap, but check out all the specs and the $/kWh comparison.

Firefly Oasis Battery - Carbon Foam AGM

The simplified bottom line perspective for us is this: while on the hook we went from running the generator two or more hours a day to a couple of hours every two days. We went from a lead acid bank of four 6V golf cart batts (480 Ah) to four carbon foam batts (440 Ah). Since the old bank could not go below 50% rated capacity, we essentially only had a little over 200 Ah available. The Oasis batts can be discharged 80% or more of their capacity without harming them, so we effectively doubled our available amp hours in the same footprint. Needless to say nine months later we love 'em!

Forgot to mention that while the Oasis carbon foam batteries do require specific AGM charging profiles, our nearly 4-yr old Magnum inverter/charger was easily programmed to charge them properly.

My boat came with AGM batteries five years ago. (No complaints.) Hope they'll last another five as my cars' batteries have.

Just picked up our 'cheap SOB' batteries today on our way here. Eight GC15 batteries from a busy golf cart dealer in Goldsboro, NC and three Group 24 dual Purpose as start bank. Date stamp was L5 (Dec. 2015), so they are pretty new. Still have boxes and cables to make since we are tossing the three 8D cells installed from the factory.

I don't know much about higher end batteries, but we aren't going to anchor out but a handful of times per year. I see nice batteries as the realm of the sailor (or any cruiser) that plans to be out for many days or weeks. Perhaps a bit of a generalization, but I just don't think I will get the return on the investment with a few thousands bucks in batteries.

Tom.B said:

I don't know much about higher end batteries, but we aren't going to anchor out but a handful of times per year. I see nice batteries as the realm of the sailor (or any cruiser) that plans to be out for many days or weeks. Perhaps a bit of a generalization, but I just don't think I will get the return on the investment with a few thousands bucks in batteries.

Click to expand...

Excellent point. The OP mentioned going to Alaska, so having a quality house bank for extended periods on the hook will probably be pretty important. For marina hoppers, not so much!

In 2010 I bought a ride-on mower and a used RIB. Both used motorcycle sized batteries. The mower came with a new lead acid battery, the RIB with a used (age unknown) AGM, but the RIB was 7 yrs old at the time I bought it. In 2015 I replaced the battery in the mower. I haven't had to worry about the battery in the RIB yet. The mower gets used a lot in May and June, less in July and August, hardly at all in Sept and Oct, not at all from Nov to March. The RIB, slightly different, but comparable. From year 2 on, I couldn't use the mower without a recharge, even mid season. The RIB, still starts the 40 Honda on the first turn each spring and performs flawlessly all summer.
So the mower got treated to a new AGM, even though it never gets inverted. I am hoping for better performance from now on.

Moonfish said:

Before leaving on our trip to the Broughtons last summer we switched to new Oasis carbon foam batteries from Bruce Schwab at Ocean Planet Energy. Nigel Calder calls these AGM-style batteries a "game changer". They are definitely not cheap, but check out all the specs and the $/kWh comparison.

Click to expand...

I've been watching those for quite a while now, hoping the price comes down with more efficient manufacturing or maybe a licensing deal with a well established battery maker by the time our golf cart batteries need replacing.

Thanks for sharing...you're the first person "I know" who's gone carbon foam

I think if you have easy access to the battery tops so you can check the fluid level every month or so, and you have the discipline to actually perform the checks... then I'd definitely go with flooded batteries. They are still the lowest cost per amp-hr over their life, but they do require regular maintenance. I've got big flooded batteries powering a house and add about 10 gal of distilled water every 3 months or so. It's a pain, and unless you can easily access the batteries, you are unlikely to do it.

Otherwise, I'd cough up the $$ and get AGMs.

Here in Ft Myers the 6v Trojan golf cart , true deep cycle is about $80ea cash with core.

Better than most off brands.

twistedtree said:

I've got big flooded batteries powering a house and add about 10 gal of distilled water every 3 months or so. It's a pain, and unless you can easily access the batteries, you are unlikely to do it.

Otherwise, I'd cough up the $$ and get AGMs.

Click to expand...

I agree!

I liveaboard and only add water maybe 2x a year....not sure why others need more other than when I switched to more modern charging tech...I went from 3 to 4 times a year to 1 or 2 times filling flooded batteries with water.

I am sure different setups could be the cause and not just chargers or usage...but it is not a given.

I use standard auto type flooded 12 vdc batteries, and I get good used ones from Advance Auto for half the price. I used to buy expensive marine flooded batteries, BUT my experience was they wore out just like used batteries. So why bother paying so much more.
I have a gen with its own battery, a starting battery for both engines, and 2 house batteries. Maybe a sailboat makes more sense to get deep cycle battery. But big powerboat is just like my cars.

All my flooded batteries live in the lazarette. If I had batteries inside, like under the bunk on a previous boat (for the bow thruster), I used AGM.

FF said:

Here in Ft Myers the 6v Trojan golf cart , true deep cycle is about $80ea cash with core.

Better than most off brands.

Click to expand...

That is an amazing price. When I was shopping this last fall I could not find anything near that good.

All good points and I agree. I bought my boat 3 years ago with wet batteries. I then replaced them with AGMs and no trouble so far.

My charger was OEM 2001 so no AGM profile. It is a Charles 80 amp. I called Odyssey(batter maker) and asked them if the Lead Acid setting would be sufficient. They said that it would be fine. The biggest issue was that AGMs desulfate by a rapid charge rate and the LA setting is a little bit slow. Anyway, they said it was a nominal(theoretical) issue and shouldn't worry about it.

There is a good thread on here that I started when I was shopping batteries. I will see if I can dig it up.

Here you go....same questions and some good stuff!!!

http://www.trawlerforum.com/forums/s4/batteries-11513.html

Gbonas said:

Time to replace our batteries. Currently have 850 amp batteries and thinking of going to agm type. Very pricey. Worth it? 46 gb Europa and planning on Alaska this season.

Click to expand...

Last April I replaced all the batteries of my GB 42' MY (twin caterpillar 300 HP 3116 TA) with AGM and I'm happy about that.

"I've got big flooded batteries powering a house and add about 10 gal of distilled water every 3 months or so."

Sounds Like the charge voltage is too high , or charging too long.

Measure all the voltages to see whats happening.

Hydro Caps will save most of the watering if you cant correct the hassle.

Hyrdocap | Home

www.[B]hydrocap[/B]corp.com/


Hydrocap - Reduce Battery Maintenance & Save Money! By reducing explosive hydrogen gas and virtually eliminating corrosion, HYDROCAPS create a safer ...

Why not just go all out and replace the lead batteries with lithium. Less space, less weight, faster charging, can be drained by 100% and , oh yeah, MORE money.

I'd take a serious look into Lithium Iron Phosphate batteries (Note: These batteries are not for the self-proclaimed "cheap SOB's").

Here are a couple of links to get you started:

https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery

12V Lithium Ion Marine Batteries | Deep Cycle Batteries | Smart Battery®

Li batteries catch on fire all the time!!!!

Baker said:

Li batteries catch on fire all the time!!!!

Click to expand...

That, sir, is a gross exaggeration of the facts!! They only catch fire SOME of the time.

OK...I might even give you MOST of the time, but ALL of the time is going just a bit too far.

FlyWright said:

That, sir, is a gross exaggeration of the facts!! They only catch fire SOME of the time.

OK...I might even give you MOST of the time, but ALL of the time is going just a bit too far.

Click to expand...

I replaced flooded lead-acid batteries that were quite new during my refit. The main reason was that the Odyssey AGM's have a much higher charge-acceptance rate.

I have 2 x 200 A alternators on the engines, and needed that charge-acceptance rate benefit. Another plus is that the Odyssey's can have 80% DoD, so much more of your installed AH is usable.

Side benefits were not having to do water top ups, no mess mess or off-gassing.

I might go to LiFePO4 once the price comes down. They don't catch fire, like some of the other lithium chemistry ones are infamous for. But they don't have as good as power-density as some of the others either. That's no big deal for cruiser.

"I have 2 x 200 A alternators on the engines, and needed that charge-acceptance rate benefit. Another plus is that the Odyssey's can have 80% DoD, so much more of your installed AH is usable."

This is the key!

If short charge times are THE requirement AGM , is the way to go.

It wasn't in a boat but in my motorhome. I installed 1000 amp hours (800 usable) of LiFePO4, lithium iron phosphate, batteries. Very pleased with them over the 2 years then pulled them out when I sold the motorhome and sold them to a friend who is still very pleased after 2 years usage.
These will not catch fire, in fact 1 cell came in with a cracked leak and a small leak. Being the inquisitive person that I am before I sent the cell back to the dealer I collected a few ounces. I poured some on cement outside and used a small butane torch to try and ignite it. It just evaporated. I also poured some into water and it just mixed in with the water. There is a video from Australia that shows someone rigging up a cell and causing a direct short. It smoked and the case melted down but never caught fire. I would not be concerned using these in a boat.

Isn't there several different chemical formulations of Lithium batteries? One is like working with nitro but some of the others are proven yet limited tech?