In Part 1 of my evaluation of battery options to replace the aging house bank on Morgan’s Cloud, I took an in-depth look at lithium batteries and concluded that they were not right for us.
So that left three types of lead acid batteries in the running:
- Carbon foam (strictly speaking these are a variant of AGM, but let’s keep it simple).
- Liquid filled
- AGM (the incumbent)
As in the last chapter, for the purposes of this discussion I’m assuming a 12-volt 800-amp hour house bank, the size we now have on our boat and a reasonable average capacity for many cruising boats.
Let’s dive in:
Hi John,
One of the appeals to me of gels is that they do not need or demand being equalized to give good to very good service. I have been using gels for 25 years now and have never suffered sulphation problems which, short of cutting open a battery, I suspect would only be shown by a shorted cell. One of the appeals to me of gels is that I install them and more or less forget about them. Not having to equalize for me is a huge bonus. I get 5-7 years on a battery bank.
My best, Dick Stevenson, s/v Alchemy
Hi Dick,
Yes, a lot to like about gells, no question. And, as you say, short of a forensic disassembly, there is no way to know exactly what the eventual fail modality is. As to 5-7 years, that’s great, but it really doesn’t give us the data we need for truly analytical comparison because we don’t know how many deep cycles and how deep they were. As to fail from sulphation, the modality is usually reduced capacity, not a shorted cell. So once again, unless you have done regular discharge tests to accurately measure capacity, we don’t really have the data for comparison.
Hi John,
By the way, I want to note how much work I suspect went into this really superb survey (the whole series of battery articles). I suspect many of your articles have emerged from deeply thinking about everyday life on a boat, but an article such as this battery article must have had you in the “library” for long hours doing research. Your efforts are appreciated.
And I agree with your comments about gels. For a while I kept data records on usage (when I got my first battery monitor), but that got old pretty quickly and once you miss a few recordings of data, all gets suspect.
In any case gels are a compromise that works for me: gels allow me to not worry about attaining a full charge at those times when it is a challenge to do so. Nor do I have equalize. That and their at-rest slow discharge rate and tolerance of occasional abuse has kept me in the gel family. The compromise: I suspect I replace them more quickly.
My best, Dick Stevenson, s/v Alchemy.
Hi Dick,
Thanks for the kind words. Experts in writing, and particularly technical writing, often say “no one cares how much you sweat over a piece, the result is all that counts”, and that’s true, but it sure is nice when someone notices the amount of work I put in.
Any yes, I think that’s a good analysis of gells. I was really in two minds on whether of not to stick with my recommendation not to use them. In the end I went with it because I think that now there are options that will tolerate a wider range of usage profiles, but it was a close run thing and clearly they work well for your profile, and did for me too.
That said, my thinking is constantly changing based on new things I learn. Right now, I’m really liking liquid filled as the best cost/benefit trade off for most cruisers, particularly given the good things we are hearing in the comments about remote watering systems.
Another great article John. We were starting to go through these deliberations last year with a hope to replace the house bank in a slow, deliberate manner when we arrived in New Zealand. This was cut short as the batteries rapidly started dying on the passage from the Marshalls to the Solomons. By the time we got to Vanuatu it was clear that we just needed to replace the batteries and keep it simple as there are limited options even in Port Vila.
We put in flooded 6V batteries again this time going with Trojan due to their good reputation and that ever import criteria of availability. This time though we treated ourselves to the Trojan Hydro-Link system as half of our 980 Amp-Hr (at 12 V) is under the aft cabin bunk. The Hydro-Link was easy to install and easy to use. No problems so recommended so far based our usage over the last six months.
Thanks for all the good work with the website.
Cheers,
Max
SV Fluenta
Presently Tauranga, NZ
Hi Max,
Thanks for the information. Your story makes a very good point: availability can trump everything else!
Hi John, unless i ma All mix-up i thinking Thérèse is a mistake in your spread sheet for The cost. The Banksy gour for surette and Trojan should be 500 and not 1000. Pleasure tell me if i am Wrong.
Hi Serge,
You are absolutely right. Thanks very much for catching the error. I have now fixed it.
must also correct paragraph re costco batteries. 800 AH will require 8 batteries not 4 so cost would be $800 not $400.
Hi Michael,
Thanks, at least when I screw up I’m consistent!
Great article as always. I want to second the concept of separating batteries into redundant banks.
Our FPB64 was originally fitted with a bank of 12 two-volt batteries made by a German manufacturer that did not keep stock in the US and had an 8-week lead time for replacement. Our batteries needed to be replaced when we bought her and we learned over time that multiple FPBs had suffered failures of individual cells, thereby (as you say) impairing the entire bank. So that manufacturer went off our list pretty quickly, even though it was the drop-in solution and we were wary of moving away from the boat’s original specs given the thought that had been put into them by the designer and builder.
After doing much of the same research you describe, and due in part to your earlier recommendation of Lifeline AGMs, we contacted Lifeline and eventually met with them at a boat show. They had excellent (and patient) customer service and it was they who suggested that we change our configuration from 12×2 to three banks of 4 six-volt batteries. Their view was, look, our batteries don’t fail but, if one does, you will still be good to go, plus our six-volt batteries are easier to find than two-volters if you ever need a replacement. Lifeline’s form factor was such that their batteries had the same footprint as the ones we were replacing, but were shorter, so they were essentially drop-in as well.
So we took their advice, did a minor cabling reconfiguration and now have a battery system that we are thrilled with and that is as redundant as all of the other systems on our boat.
We too considered Firefly, even meeting with a member of Bruce Schwab’s team, but they only offer limited sizes and we would have needed 20+ of their batteries to reach the capacity we wanted. Plus we had heard the same quality control, multiple changes of ownership and limited availability concerns you have mentioned. It will be great if/when they get their act together.
We also considered liquid but between maintenance (our batteries are hard to access), the risk of spill (not good on an aluminum boat) and intolerance of vibration, we decided against them. But another FPB owner has gone that route and is very happy. They went with golf cart batteries on the thinking that they are cheap to replace and can be purchased anywhere.
It might also be good to mention the importance of updating the settings on your alternator regulator and inverter/chargers to match the requirements of whatever batteries are installed. Lifeline provides decent information on what settings to use, although not as specific as we would like given all the settings available on our Balmar and Victron equipment that, I assume, if matched to the batteries would provide even better overall performance.
Hi Chris,
That’s really interesting and useful. I always wondered about the source for the “traction batteries” in the FPBs and how that was working out. Now we have the answer. Seems like fault tolerance and availability pretty much trump all else. Something for all of us to keep in mind when we get enamoured with the latest thing.
My thanks as well for providing this experience Chris and wondering if you would be willing to share more details of what caused the Hoppecke 2v cells to fail in your FPB64? You may not know if they were already shot when you found and bought the boat but if you have any additional details on this I would be very interested to know as I’ve been considering using these batteries on a new boat my wife and I are building that is in the same family of boats as the FPB’s. I don’t recall if they were using OPzV (Gel) or OPzS (FLA) batteries in those first FPB64’s? And were all 12 of the 2v batteries failing or just one or two?
Thanks for any additional insights you can provide on these 2v batteries Chris and if you’d prefer I can contact you privately to discuss further.
Wayne
Hi Wayne,
Thanks for your note. I’m happy to help but need a day or so to get back to you, we have a long passage tomorrow to Montenegro that means an early bed tonight and most of the day tomorrow offline. I clicked through to your webpage but (likely intentionally) did not quickly find your email. Mine is moc.yeboorg@sirhc, look forward to hearing from you. –Chris
Hi Chris, Way off topic, but a couple of thoughts that were wonderful for us: anchor off Kotor for an amazing anchorage and rent a car to go up the mountain and inland. Just a fabulously beautiful country.
Enjoy, Dick Stevenson, s/v Alchemy
Hi Chris, thanks for the quick response especially while you are in the midst of heading out. Enjoy your passage to Montenegro and if your travels happen to take you further East to the beautiful coasts of Turkey we are building our new boat in Antalya and we’d love to meet up with you and Carolyn.
Please take time to enjoy your passage and there is no rush with your responses to my questions, would just appreciate learning more from your experiences with the original OPz batteries as well as your new setup.
Thanks too for the reminder that our Emails are not readily available on our Mobius.World blog. Quite unintentional and we will fix that shortly.
Easiest Email for us is dlrow.suibom@enitsirhc.enyaw and I’ll send you a short note from that Email so you have the connection.
Safe and fun travels, Wayne
I installed four Fireflies a year ago and have been cruising full time with them. So far I’ve had no problems. One thing to note though, while you can drive them down to 20 percent, most boat electronics don’t seem to like voltages below 12, so realistically you can’t really go below 50 percent. The issue is mostly irrelevant for me since after installing a big alternator and 340 watts of solar on top of my davits, my charge rarely drops below 85 percent. Bliss.
Hi Gino,
Great to have some first hand information on these. Thanks. Anyone else? And good point about the voltage issue, I had not thought of that.
I too have the Firefly batteries: (6 x 110 Ah) in a single house bank in a Nordic Tug 37. We do a lot of winter cruising with shorter days and often little solar input from our 550 Watts on the pilothouse roof.
The Fireflies seem to be working well but like Gino, I have noted that once in discharge mode they drop their voltage fairly quickly to around 12.75V and then have a flatter, slower discharge from there. (cf with our old LifeLines or Chinese AGM Traction batteries)
IIRC, our deepest discharge to date has been ~ 340A with a Voltage of ~12.2V.
I would be not want the voltage to drop below 12.1V, for the same concerns around the health of the electronics, so the the true useful capacity is probably only down to 50% SOC. It’s reassuring that the bank will not be damaged by a deep discharge but by then I would be worried more about my far more expensive electronics than the battery bank.
On the positive side, they will accept a charge very quickly and are supposedly happy in a partial state of charge so that I do not need to be concerned when at the end of the day, solar or a short generator run only recharges to ~ 80% SOC.
These are expensive. The real cost and the ultimate advantages or disadvantages will be more apparent when we have a few more years of use and a good sense of their ability to maintain their performance.
Hi Evan,
Thanks for the report, very useful.
An update on my Firefly batteries, now going on four years. I recently installed the new Balmar SG200 battery monitor, which includes a state of health reading. It indicates my batteries are still at 100 percent state of health and I have no reason to believe this is not correct. The Fireflies are still going strong and we’ve been cruising full time since we installed them and almost always anchor out. I wish all my systems worked as well.
Hi Gino,
Great news. Please keep updating us as the batteries age.