While new technology is fun to watch I think it would be best to watch from the sidelines at this point. Like AGM technology, that made HUGE claims before entering the marine market, then got slapped in the face with the "reality",I think we'd be best to take the claims with a grain of salt at this point.

I remember when AGM's first hit the marine market. I jumped in with both feet then got bit in the arse, hard. They claimed discharges to 20% SOC were fine, we now know they are NOT. They claimed many more cycles than wets, we now know these claims were "lab derived" and nowhere near reality when applied to cruising boats..

The reality, in the real world [B]Disclaimer:[/B] ([I]I base the "real world" from the eyes of a marine electrical systems specialist who owns and uses industry standard test equipment to determine end of life for batteries[/I]) is that I regularly see wet cell batteries outlast AGM batteries on the order of about 9:1 yet AGM's still out weigh wets in price by double to triple, depending upon brand.

AGM's have their pluses but can also carry some pretty big minuses so any purchasing decisions need to account for the whole system and overall life cycle cost, in a marine installation, not just the increased cost of the batteries..

[B][URL="http://forums.sbo.sailboatowners.com/showthread.php?t=124973"]AGM's Making The Choice (LINK)[/URL][/B]

LifePo4 batteries need BMS systems and in fact the ABYC is mandating as such after studying this for well over four years. Buying cells off eBay can be very dangerous for a boater without a very, very in-depth knowledge of this technology and how to keep the cells balanced..

I have two colleagues who are in the LiFePO4 business one as a distributor for a LiFePO4 brand and the other is launching a LiFePO4 company as we type. I have watched banks costing over 12k each be replaced under warranty already, ouch! Suffice it to say the industry has not agreed on which BMS system is best and they are still very much in their infancy. How would that have gone down had these banks been out of warranty? It would have gone down like this $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$......;)

Some of these companies claim the banks can be discharged to 0% SOC. So, if we know they can safely be discharged to 0%, and still get the claimed cycle life, why are the current warranties no better than AGM or wet cell technology? Surely this superior performance/technology should carry a 5, 7, 10 year warranty, right?

Considering I am on my third Li battery (not technically the same technology as LiFePO4) in my phone in a year and replace the Li battery on my MacPro about every 13 -14 months it is still tough for me to swallow the "claims" without seeing them in action for many years to prove them out....

Over current protection with these batts is also currently an issue as they can exceed even the highest rated AIC for fusing technology we currently have. If you have a dead short in LiFePO4 your wires will flsh to flame and ignite your boat in mere seconds. Up till now the closest we've had to delivering a short circuit current that even gets close to LiFePO4 has been TPPL AGM's (Odyssey).. A 400 Ah bank of TPPL/AGM batteries can deliver 20,000 amps into a short circuit. LiFePO4 can be multiples that number..... Class T fuses at a minimum...

For now I would advise letting this technology mature a little bit and be time proven in the marine market, not the "lab" like AGM's were.. Having been dealing with AGM's for well over ten years I now have a pretty good handle on how they survive, or don't, on cruising boats and what to do to get the most out of them.

My buddy Bruce has twice been around the world with this technology but this was in a go fast, go very light, offshore racing boat where this technology works well and is a great fit regardless of price, longevity or other considerations a cruiser may need to account for.. Lots of tech trickles down from racing but it can take time to work through all the "bugs"...

This is very cool and promising technology that some day we will all likely be using. However, I would advise not being a "pioneer" and getting the arrows in your back. Let others take the arrows and work the bugs out then when the prices drop, and the technology is proven in BOATS, that would be the time to jump in...

Kudos to Maine Sail for giving the real world side. I use an AGM for starting battery but will be sticking with the silly old 6Vs for house duty until the horror stories about AGMs and new tech batteries in a house bank stop outnumbering the praise singers. We do need the early adopters though so I fully support anyone brave enough to take on new tech of any kind. I'll supply a band aid for the arrow hole in the back, in the form of a cold beer and sympathy, that the early adopters inevitably get.

[QUOTE=Rockman;14188]A quick google search for LiFe batteries (used most commonly in electric cars).

Golf Battery
Trojan 6V & 225Ahr $151 each, discharging to 50%, with 700 cycles
so, (225 x 0.5 x 700) / 151 x 2 = 261 Ahr/$

LiFePo4 Battery
HiPower 3.2V 160 Ahr, $192 each, discharge to 70%, with 3000 cycles
so, (160 x 0.7 x 3000) / (192 x 4) = 438 Ahr/$

So big saving for the new technology

And good modern versions can support traditional chargers.[/QUOTE]

Hmmm, 3.2 volts at $192 each. You would need 4 in series to get to 12v and 160 Ahr, so double that for 2 banks to come close to my 4 GC batteries. You would still be at significantly less capacity than my system. You would also be up to around $1500 to $1600 with tax compared to around $70 X 4 for me. Don't quote the highly inflated Trojan price as typical. My GCs are still going great after 5 or 6 seasons.

'Splain to me again how it is a big savings for new technology.

[QUOTE=gforaker;14198]Hmmm, 3.2 volts at $192 each. You would need 4 in series to get to 12v and 160 Ahr, so double that for 2 banks to come close to my 4 GC batteries. You would still be at significantly less capacity than my system. You would also be up to around $1500 to $1600 with tax compared to around $70 X 4 for me. Don't quote the highly inflated Trojan price as typical. My GCs are still going great after 5 or 6 seasons.

'Splain to me again how it is a big savings for new technology.[/QUOTE]

The real problem is that this is for bare cells. The last thing a DIY wants to do is install LiFePO4 batteries without a good BMS. These are not like regular lead acid batteries and keeping the cells balanced is important.

A 360Ah bank from a reputable manufacturer, with BMS system, is roughly $7700.00.... Like LED bulbs there is a lot of snake oil and junk out there right now so one really needs to know exactly what they are getting...

When shopping to replace my current battery ("A"), what size do I specify?

8D 12V ?

4D 12V?

I've never had electrolyte leak out of my batteries and I do keep them topped up. It's a Catalina, not a rail down boat so when we exceed 20 deg it's reef time, stand the boat up and go faster and more comfy. I have them in a leakproof tray deep enough to contain the electrolyte, I consider a split case from a hard pound more of a risk than leaks due to heeling.

Good on ya (that's Aussie, right?) if the new tech stuff works for you, but with what I hear and read about issues with AGMs as house banks I consider GCs the most proven and reliable option for now. As a starting battery the little AGM I have outperforms a wet cell by far and is so flexible for mounting in tight spaces, but for house bank I'll stay with the GCs for a few years yet.

I guess you are choosing to ignore the comments of Maine Sail that question your optimistic cycle data or the true cost of your LiFe installation.

I don't recall saying that I only discharge by 25% to 75%. Lets say I do though, in that case your figures showing only 1000 cycles would be completely off. At 25% discharge my batteries would have many times 1000 cycles of life.

Battery acid leaking out when we heel? Just how much actual sailing experience do you have? AGM batteries were not available 20 years ago, did we all sail around with acid sloshing in our bilges? What kind of races are you talking about?

Yup, I guess we can just chalk it up to us Americans being resistant to change, you have now made that charge in 2 threads.

[QUOTE=RPowers;14204]When shopping to replace my current battery ("A"), what size do I specify?

8D 12V ?

4D 12V?[/QUOTE]

Your boat came with 2 4D batteries. I don't think 8D would fit, but am not sure.

Make sure you have plenty of strong help when replacing the 4Ds off your boat - they weigh around 120 Lb. each. I moved mine alone. That was one reason I switched to 6v golf cart batteries. They weigh about half and I can move them easily alone. Some slight work modifying the compartment is required.

This from Catalina Yachts:
___________________________________________________________
We use Exide Nautilus Commercial Dual-Purpose Starting & Deep Cycle Batteries, group 4D, type NG-4D. Give Karen a call at 800-423-9433 and she can give you a number for a distributor in your area. They are lead acid batteries. If you want to switch to an AGM battery, the dimensions to match are 20 11/16" in length, 8 11/16" in width, and 9 7/8" in height.

Good Sailing,

Kent Nelson
Engineering Department

Dual purpose battery really means "not the best for either purpose". 4Ds are lame IMHO, they store way less amps than a good set of 6V GCs, the ones in our boat were only 170 per battery vs 232 for 2 6V GCs in series I replaced them with, we now have 464 amps total vs 340 before. There is another GC battery same size as ours that will get you just over 500 amps.

Four 6V GCs of the correct height will fit in the same space the 4Ds do but not in Catalina's tray, you have to make one to fit but that is no big deal. The weight of 4Ds is, as Gene pointed out, a big issue, that and their lack of capacity is why I went to GCs with a separate AGM starting battery. Haven't regretted it for a second.

Bud's right. You can go 4 6V golf carts for over 400 ah or go simple Group 31 wet cell 12V at 130 ah each, your choice of quantity. We have three 12V for 390 ah, pretty close to the 400+ for local sailing and a known electrical and charging system. Either way, you can put in the batteries without having to hire a weightlifter. :eek:

[QUOTE=Rockman;14224]Wow, the market in the US must be different to Australia, a full setup here, from a leading EV supplier, with warranty is less than a 1/3 of that.
I looked at these batteries 12 months ago, and the cost was high, but with technology moving so quickly, the prices have dropped. It might be time to check local pricing again.:cool:[/QUOTE]

Do you have a link? Mastervolt, Genasun and Victron are all in a similar price range for marine LiFePO4 systems with BMS....

My friend who is going into business to sell LiFePO4 marine batteries, and hopefully for less $$, has been experimenting for multiple years with BMS and without and with all the cell manufacturers..

He's come down to one cell manufacturer worth even using and it is the same cell maker all the big guys use so he has to try and beat them on price with his BMS cause the cells all come from the same place.....

In experimentation and product testing he has destroyed thousands of dollars worth of LiFePO4 packs without a decent BMS. His main goal was to try and build a battery at a price point with a very minimal BMS, enough to satisfy requirements, but after years of testing he has finally admitted it can't be done.

I will probably be doing some field testing for him but would not spend my own money at this point..