Lithium Ion Batteries for Boats: Fact or Flame

By: Dean Klein
M/Y "Saltheart", Selene 6203

This article is being re-published from 2014, when Dean Klein owned his first Selene 53. He has since done a similar conversion to Lithium-Ion batteries in his Selene 62 also named "Saltheart"

Just over a year ago we installed lithium ion batteries on SaltHeart, our Selene 53. This was at a time when Boeing Dreamliners were being grounded due to their lithium ion battery woes and the first of the Tesla Motors sports cars were catching fire as fire departments tried to douse the vehicles after accidents. Were we being foolish? On the bleeding edge? Why, of all things, were we choosing this technology and why now?

Allow me to explain!

SaltHeart, S5319, was commissioned for Mike and Beverly Anderson in 2004. She is a 12V boat with a ProSine 3.0/12 inverter/charger, a big Balmar 320A alternator driven off the main and a Balmar MC612 alternator regulator. When we bought SaltHeart in April of 2011 the batteries were in the aft port side of the engine room on a factory-built stainless and Starboard rack. There were 12 telecom-style AGM batteries, each weighing in at 90 pounds in Selene-built boxes. This was clearly not the factory configuration, as much of the DC wiring had been changed and the batteries didn’t really fit the boxes they were in. The biggest change to the wiring was the configuration of the batteries into one large house bank, with independent starting banks for the generator and the main. Mike had made some improvements, including designing an excellent mount for the Balmar alternator.

We like to spend time on the hook and one of the first things we learned was that the batteries we had were not keeping up with our loads as we used the boat. We are fortunate to often have our three boys aboard, with their friends, and our electrical usage is not light. Well, maybe it’s partly light! Incandescent light, that is… It was not uncommon to see 50-60 amps being consumed by just in the lighting of the boat. After converting many of the fixtures to LED bulbs we dropped that a bit, although Theresa still isn’t convinced the lighting is as warm as she would like. Still, we were limited to about one night on the hook before we had to charge. I began to suspect our batteries were not up to the task.

A second thing I noticed was that the batteries did not seem to charge very quickly, especially when we were under power. I was still pointing the guilty finger at the batteries, but this problem would come back later.

Lastly, we noticed that the batteries did not respond well to heavy loads. In particular, the windlass seemed to struggle. This was not compatible with our desire to spend nights at anchor. The batteries had to go.

Replacing batteries isn’t fun. I don’t find any perverse pleasure in bending over in the engine room trying to hoist 90 pounds of lead out of a box it’s wedged into. Twelve times. Fortunately, our son Allen lent a hand and we eventually got the job done. Then we hauled in four 160 pound Full River DC260-12 8D AGM batteries to take the place of the old batteries. Although gravity was working in our favor it was not an easy task.

There are a number of manufacturers of 8D size AGM batteries and the specs are nearly identical. These are a lead-acid type of cell, where the electrolyte (the acid) is safely Absorbed in a Glass Mat that allows the battery to be sealed. Independent of manufacturer, each battery has about 260 Amp-Hours (Ah) of capacity, so with four of these onboard we now had 260Ah*4=1040Ah of capacity. Sounds like plenty, doesn’t it? We’ll see later.

The new batteries did improve the windlass operation, but the Balmar alternator was still not doing it’s job. Considering this was a 320A alternator and a good regulator I expected to see charging currents up over 180A into these batteries, but we were only seeing a fraction of this, at best. So into the engine room I went!

I discovered two critical things when I went through the charging system. The first thing I discovered was that only one of the alternator outputs was connected. In this model of alternator there are two separate outputs for charging two independent banks of batteries. Since SaltHeart was setup as a single house bank these two outputs would have to be tied together to get the full output into the batteries. This mistake is not uncommon and it is easily fixed with a short (and fat!) jumper to tie the outputs together. The second discovery was much trickier. Balmar’s regulators are excellent regulators with many great features. One of the features these regulators have is temperature sensors for the batteries and for the alternator. If the batteries get warm when charging the regulator will decrease the charging current to prevent damage to the batteries. The alternator temperature sensor also reduces the charging current if the alternator gets hot. Great features, but not if the sensors are swapped like they were on SaltHeart! When swapped, the regulator would see the rise in alternator temperature and “think” the battery was getting hot. In response, the regulator would reduce the charging current. I swapped four leads and solved that problem. Was I out of the woods now? Not quite.

Over the course of the next 18 months the batteries preformed reasonably well but we were finding the capacity was dropping off. Some AGM batteries allow occasional equalization cycles, but not the Full Rivers. What else was going on? Several times over that period we had come to the boat to find the batteries very low and the ProSine charger off. During part of this time the boat had been in the yard for some upgrades and it had been moved from dock to yard and dock to dock. For part of the time SaltHeart had been at her slip in Anacortes. I was suspicious of the ProSine inverter/charger at this point and I dug deep into the manual, looking at all the programming settings until I found the lunatic setting. That’s the setting that some lunatic at ProSine put in their firmware to allow batteries to go dead after an AC power interruption. It is only available if you have the deluxe remote panel. If your charger does not come on after shorepower is disconnected CHANGE THIS SETTING!

So, I was staring at another battery replacement, and I wanted to do it right. Clearly I wanted more capacity and I wanted longer battery life. Neither my back nor my back pocket could handle replacing the house batteries at the pace I had been experiencing! So Lithium Ion batteries became the subject of my search. I’ve been using lithium ion batteries in products I’ve developed for well over 10 years. I’ve had lithium ion batteries in power tools and in radio controlled planes, helicopters and cars. I’ve put them in friends high powered rockets and sent them to 30,000+ feet. And I have never experienced a failure, all the while taking advantage of their superior energy density and lighter weight. But what about use in a boat? It was about that time that I read that Coastal Craft was equipping their new boats with lithium ion batteries. So, why not SaltHeart?

Of course, flying in the face of all this lithium ion goodness was the glaring experience of the Boeing 787 Dreamliner. I couldn’t afford to have a catastrophic failure of the house batteries on SaltHeart. In my book fire and boating do not mix – unless that fire is cooking the salmon on my grill! As I talked to more people in the industry two things became apparent:

1. Not all lithium ion batteries are equal.

2. A battery management system would be essential to safe use of lithium ion batteries.

TypeChemistryShort FormNotes
Lithium Cobalt OxideLiCoO2Li-CobaltHigh Capacity; Cell phones, laptop, camera
Lithium Manganese OxideLiMn2O4Li-ManganeseMost safe, Lower energy density than Li-cobalt, but high specific power and long life
Lithium-Iron PhosphateLiFePO4Li-phosphate
Lithium Nickel Manganese Cobalt OxideLiNiMnCoO2NMC
Lithium Nickel Cobalt Aluminum OxideLiNiCoAlO2NCAGaining in importance in EV, grid storage
Lithium TitanateLi4Ti5O12Li-titanate
Different chemistries have different characteristics and thus different uses. The highest capacity and newest technologies were not going to make it onto SaltHeart. We wanted proven technologies and safe operation instead.

Solving the battery management issue was complicated as well. There are as many different types of battery management systems as there are lithium ion battery makers. Each maker has their own recommended scheme, but there are some common threads to all. Everyone agrees that battery cells must be individually monitored and balanced with the other cells that make up a battery unit. And batteries must NEVER be over discharged or subjected to voltages beyond the rating of the battery.

This photo shows four cells in series connected to make a battery unit. You can see the individual cell monitor units on the top of each cell. These units monitor cell voltages and temperatures to keep all parameters in safe ranges. Each of these cell monitor units has its own processor and communication system.

In the end, I selected a battery system from Lithionics. I liked their system as it seemed to address the safety issues best. Lithionics has developed a system that monitors and balances each cell, right at the cell. It is a system that scales well to larger capacities, end to higher voltages. I grilled Steve Tartiglia, the CEO of Lithionics mercilessly over technical issues and I always received answers that made sense to me.

In addition to the cell monitors Lithionics has developed a master control box, of sorts, that protects the battery in case of an internal fault or external overvoltage and over-discharge conditions. They call this box the “Never-Die” box. The Never-Die™ box is connected in series with the output of the battery bank and also is connected to the cell monitor communication network.

This photo shows the configuration of the Lithionics battery system on SaltHeart. Several things must be pointed out. First, note the equal length wiring to each of the batteries and the use of pluss and minus bus bars. Second, note the Never-Die™ box on the output of the battery bank. Lastly, note the green communication wire connecting to each battery and to the Never-Die™ box.

Once I had decided to take the leap into lithium ion batteries there were a couple other changes I wanted to make. I started by planning a move tor the batteries out of the engine compartment and into the commissary. Distance-wise this is only a couple of feet, but it would move the batteries from the heat of the engine room and closer to the inverter/charger. I also made plans to remove the current measuring shunts from the system in favor of Maretron’s DCM-100 DC monitoring solution for NMEA 2K. This system uses a Hall-effect current sensor that doesn’t rob any power from the system, unlike a shunt.

By this time I had spent untold pleasant hours in SaltHeart’s engine room, carefully plotting and planning and figuring things out. So while everything was fresh in my mind I decided I would document SaltHeart’s DC systems and draw plans for the new lithium ion system.

SaltHeart’s Lithium Ion optimized DC system (Click for a larger version)

Even if we could get comfortable with the technology and safety of lithium ion batteries there remained on big question: Economics. Lithium ion batteries are expensive. Some that I looked at were well over twice the price of the Lithionics batteries I had chosen and all were many times the cost of AGM lead acid batteries. But lithium ion batteries have some characteristics that tip the economics in their favor.



Capacity:

Lead acid batteries, AGM and gel-cells included, should not be discharged greater than 50% of their capacity or their lifetime will be shortened. So an 8D AGM battery with a rated capacity of 260Ah, like the Full River batteries I had been using, really have a useful capacity of only 130Ah. In contrast, lithium ion batteries can be discharged to over 90% of their rated capacity without damage. This means I would need to add even more AGM batteries to equal the capacity of the Lithium ion batteries. In fact, it would take three 8D AGM batteries to approach the capacity of one of the Lithionics 8D batteries I had chosen.

Lifetime:

Even the best lead-acid batteries are rated for 1,000 cycles. Discharge more deeply and you’ll quickly cut into this number. By contrast, most lithium ion batteries are rated for 5,000 useful cycles. If you actually cycle your batteries 150 times in a year the lead-acid batteries can be expected to last about 7 years while the lithium ion batteries go for a whopping 33 years!

Cost metrics:

Battery prices are somewhat variable, and I fully expect lithium ion batteries will drop in price as the technology matures and availability increases. Do your own research and figure the cost per battery cycle for equally sized battery banks and I bet you’ll come to the same conclusion I did – that lithium ion batteries are less expensive in the long run.

Other benefits:

A Lithionics 8D battery weighs about 2/3 the weight of the Full River or Lifeline AGM batteries. If compared by capacity per pound the lithium ion batteries are about 1/5th the weight of lead acid. That’s a substantial difference when my back is involved! It also means we are hauling around a lot less weight overall.

Another nice benefit on SaltHeart was that in moving the batteries to the commissary I was able to turn the old battery rack into a workbench, complete with a vice! How sweet is that?!

Installation:

With all of my planning the installation of the batteries went smoothly. Getting the batteries placed down in the commissary was more than I wanted to do by myself. Removing the 165 pound AGM brutes was another problem. These problems were solved by hiring a young football player who moved the batteries around like they were Styrofoam. Wiring went as planned and everything was connected in under a day.

Some parts of the system were simpler to connect than the prior lead-acid system. The removal of the DC shunt was one such simplification. Removing the battery temperature sensors from both the ProSine Inverter/charger and Balmar alternator regulator were other simplifications. (These are not needed for lithium ion batteries.)

The completed system in SaltHeart’s commissary. In the upper right you can see the Never-Die™ box.

Initially I experienced some random trips of the Never-Die™ box which I eventually tracked down to the ProSine inverter/charger. The charging voltage was slightly too high, which I remedied by setting the ProSine to the “Warm battery” setting.

Experiences:

The lithium ion batteries on SaltHeart have been a huge improvement. We can stay at anchor, without heroic conservation methods, for 3, even 4 days. The change in weight did not upset any balance of the boat. I think this may partly be due to moving the batteries outboard, while dropping the weight by over 300 pounds, approximately cancel each other. Nothing beats dumb luck! The batteries charge fast and really do hold their voltage. High load items such as the davit and windlass run a lot better, too.

The bonus! A workbench in the engine room.

Other notes:

Whenever dealing with high current connections you need to make sure you have a good, solid connection. If a connection is poor, perhaps either loose or corroded, it effectively becomes a resistor. When a high current passes through a resistor it generates heat, and potentially lots of it. When working around batteries, bus bars and the like, be sure your connections are of the highest quality. I don’t even trust crimped on battery cable terminals, and will add solder to them as well. I recommend you make it an annual practice to check for loose connections. Remember the old saying: Loose clips sink ships. (Or something like that!)

I mounted a small Fireboy automatic fire extinguisher in my new battery compartment. It’s not that I don’t trust the lithium ion batteries and fear they’ll “go Dreamliner” on me! Whenever you’re dealing with hundreds of amps of capacity there is a potential for bad things to happen. Better safe than sorry!

A note on “C-rating”:

Lithium ion batteries are rated for a maximum discharge rate. This is the “C-rating” of the battery. The Lithionics batteries in SaltHeart have a C-rating of 3C, and therefore can be discharged safely at currents up to 3 times the battery capacity. That’s 1350 amps! I hope I never see that…

Lithium ion battery technology is ready for use in the marine environment. Designed with proper safeguards, a lithium ion house bank can offer safe, high-capacity energy for the most demanding needs and with a lifetime that is truly spectacular.

Lithionics Contact Information

Phil Silberhorn
phil@lithionicsbattery.com
(727)726-4204
Lithionics
2449 McMullen Booth Rd
Clearwater, FL 33759

Editor's Note: This article was derived from a presentation that Dean Klein gave at the 2014 Northwest US Selene Rendezvous in Roche Harbor in April of 2014. The slides Dean used for that presentation are available for download here. Note that the file is in PDF format and is about 3.8MB in size.

 
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