Nov 11, 2021

Last issue, The Boat Nerd, Mike Wheatstone, introduced us to lithium batteries and explained why they are important. This time, we dig deeper into the technology inside them.

The Science Behind Lithium Batteries

All lithium-ion batteries, as their name suggests, are based on the movement of lithium ions driving the reactions within the battery.

Think of a battery as consisting of:

1. Two electrodes that can absorb lithium ions at either end of the cell. One of the electrodes is called the Anode and is made of carbon, typically graphite. The other electrode is the Cathode and made of a metal oxide.

2. A liquid electrolyte sits between the two electrodes and carries the positive charge lithium ions between the anode and cathode if being charged and visa-versa under discharge. More recently a solid polymer electrolyte is replacing the liquid one resulting in a lighter and safer battery.

3. A separator in the middle of the cell that blocks the flow of electrons within the battery but allows the passage of ions.

The type of lithium-ion battery is dependent of the chemical composition of the cathode, for example lithium cobalt oxide, lithium manganese oxide, or the one will are most interested in, Lithium Iron Phosphate (LiFePO4). The battery terminal voltage also varies slightly with the chemistry involved.

Lithium cobalt oxide batteries have the highest energy density and are what you will find in mobile devices where long charge life, small size and light weight are paramount concerns. However they are also the most thermally unstable. You may remember stories of Boeing’s 787 Dreamliner battery fires or some Samsung mobile phones catching fire.

The phosphate in LiFePO4 can tolerate high temperatures and makes for a very thermally stable battery. While Cobalt based chemistries have a higher energy density, LiFePO4 with its lower but still very respectable energy density is the only chemistry that should be used on boats due to its thermal stability. Fires in cobalt lithium batteries are extremely hard to extinguish. Not what you want on a boat.

The terminal voltage of LiPo cells is 3.7V compared to that of LifePO4, which is 3.2V per cell.
Lithium Battery Diagram


What Reaction Takes Place in a Lithium Cell when Charging or Discharging?

(You can skip this section if you’re not interested in the gory details)

Electrodes in a lithium battery work because the lithium ions can be held in the lattice structure of the electrode material without materially disturbing it. To preserve electrical neutrality, each positive lithium ion is coupled with a negative electron within the structure of the electrode.

Upon fabrication a lithium-ion battery is in a completely discharged state. All the lithium ions (and attendant electrons) have been absorbed within the cathode. Before any electricity can be obtained from the battery it must be charged.

During charging, the charging source causes an oxidization reaction to occur at the cathode whereby it loses some of its negatively charged electrons. To keep electrical neutrality in the cathode, an equal number of the positive charge lithium ions stored in the electrode, migrate into the electrolyte solution. These ions travel through the electrolyte to the anode where they are stored in the graphite lattice. The electrons pulled off the cathode by the charging source are combined with the migrated lithium ions in the anode, preserving electrical neutrality.

During discharge the opposite happens. When an external load is connected to the battery, electrons flow from the anode releasing the ions that were tied to them, into the electrolyte to travel to the cathode. At the cathode the electron are then tied with the ions again to preserve electrical neutrality. Without the external electrical connection to the electrodes, no electrons are free to travel and there is no reaction in the battery. It’s the negative electron movement through the external circuit that allows the balancing positive ion movement through the electrolyte.

When the cathode has absorbed all the lithium ions it can, the battery is flat and no further energy can be taken out of it. The battery must then be recharged by connecting an external voltage source, pushing the lithium ions from the cathode back to the anode.

The electrolyte is typically a mixture of lithium salts in a mixture of solvents. The dissolved lithium salts create free lithium ions in the electrolyte. These electrolyte ions mean the ions released from one of the electrodes do not have to travel the entire path to the opposite electrode to complete the circuit. During discharge, ions leaving the anode enter the electrolyte while ions in the electrolyte near the cathode surface are absorbed into it. During charging the reverse happens.

Lithium-ion batteries get their high energy density because Lithium is molecularly small and light resulting in lots of it being able to be stored in the electrode material lattices. For example one lithium ion can be stored with six carbon atoms in the graphite. The greater the number of ions stored in the material, the more ions are available to travel between the electrodes and a corresponding greater electron flow in the external circuit.

The movement of ions between the electrodes in a single lithium-ion cell occurs at a voltage of 3.2V or higher, depending on the chemical makeup of the cathode. Contrast this to the 1.5V typically obtained from a single alkaline cell or the 2V from a single Lead-acid cell. Thus for marine use we typically stack four lithium cells in series to get a nominal 12V battery.

Next time, Part 3 looks at the packaging of lithium batteries, battery management systems, implications for insurance and charging characteristics.

Mike Wheatstone the Boat NerdCYOB’s Boat Nerd, Mike Wheatstone, has enjoyed sailing since he was in his mid teens. He bought his first boat in 1980, a Shark. With the growing family’s 2-foot-itis saw upgrades to a Grampian 26, CS34 and finally a Hunter36. A retired electrical engineer, Mike and his wife spend summers on the Hunter (Dragonfyre) and winters in the Caribbean on their Leopard 43 cat (Peregrine).

Got a question or comment for Mike? Please send them along to This email address is being protected from spambots. You need JavaScript enabled to view it. and put “Nerd” in the subject line.

Related Articles

Tuesday, 09 November 2021 21:00

Hi Mike, My name is Sergey (59 y.o.) and I'm cruising on Georgian Bay on Jeanneau SO379 for 7 years (late starter), considering owning a cat on the Caribbean somewhere upon retiring (~5 yrs.)

Tuesday, 09 March 2021 14:46

How do you know what’s happening with your boat when you’re not on board? This is especially trying in the Covid world we find ourselves in when many of us may not be able to get back to our boats!

Wednesday, 27 October 2021 00:38

What is my interest in Lithium batteries? We spend three months of the winter on our Leopard43 “Peregrine” in the Caribbean (at least we did pre-covid!) When our 630Ah AGM batteries died...

Monday, 16 November 2020 20:08

There's nothing that we like to do more than talk "nerd", especially when it comes to boats! Your new feature "The Boat Nerd - the boater's guide to the newfangled" sounds like an outstanding...

Tuesday, 26 January 2021 23:37

For anyone cruising on a boat that will be away from the dock for any appreciable time keeping the batteries charged becomes an important consideration. The silent and on-going cost-free nature of...

Tuesday, 25 May 2021 15:57

All marine batteries require regular maintenance, even AGM and lithium-based models. Put maintenance on your calendar so it’s automatic. Consider storing safety and maintenance equipment near your...

Boat Reviews

Video Gallery

 

 

Oakley 245 CCBy Andy Adams

The multi-generational island cottagers of Georgian Bay and serious fishermen are just two of the groups most attracted to the new Oakley Boats models.

Brad Oakley has been around the boat business his entire life and he said to me that he has long admired durable, seaworthy welded aluminum boats. His company WMW Vacuum Pumpout Systems in Waubaushene, Ontario on Georgian Bay, builds highly regarded vacuum pump-out systems and Oakley’s equipment is in so many marinas that he knows a lot of people in the business.

Read More

 

 

 

Fountaine Pajot Astrea 42By Katherine Stone

On a beautiful summer morning in July, I hopped aboard a new-owner delivery from the Outer Harbour Marina in Toronto to the Port Credit Harbour Marina in Mississauga, with the President of Navy Point Yacht Sales, Steve McPherson. I don’t know if I have ever referred to a boat as pretty, but this adjective fits the Fountaine Pajot Astrea 42 to a tee.

The transitions and communication from interior to exterior spaces are seamless and well-thought-out with functional ergonomics. 

Read More

Destinations

  • Prev
Following the War of 1812, a battle that Canada narrowly won against the United States, the ...
You’ve weathered COVID and you’re ready to book your charter to paradise. You’ve done some ...
If you are looking for an interesting destination for a weekend trip or longer, Quebec City will ...
A holiday often is defined by the experiences we make in unique and beautiful settings. But what ...
St Vincent and the Grenadines is open to tourists and Horizon Yacht Charters are looking forward to ...
We bobbed in the brisk winds while rounding the breakwater into Victoria Harbour, then lowered sail ...
Over the course of four days in September 1864, representatives from Prince Edward Island, Nova ...
The new owners of L’Orignal Marina offer boaters a new destination. Located in a charming ...
Commemorating 100 (+1) years of through-navigation on the Trent-Severn Waterway National Historic ...
On Friday, April 2 at 7 pm ET on TVO and streaming anytime after that on tvo.org and the TVO ...

The Ottawa Flight LocksFollowing the War of 1812, a battle that Canada narrowly won against the United States, the boundaries of Upper Canada were held and the British army realized that the St. Lawrence River was no longer safe as a supply route. A more defensible route was needed to bring supplies from Montreal to Kingston and on into other Great Lakes settlements.

This new, more secure route revealed itself through the travel and trade of the Indigenous peoples. Surveyors learned that one of the Indigenous trade routes began at the mouth of the Cataraqui River in Kingston (Canada’s first national capital) and connected a series of lakes and rivers all the way through to where the Rideau River meets the Ottawa River in the heart of Bytown (known today as Canada’s national capital: the City of Ottawa). 

Read More

Lifestyle

  • Prev
Thanks to Louise from Gyles Sails and Marine for catching us up on this weekend’s massive parts ...
The marine industry provides exciting opportunities for Canadians. Every month CYOB will introduce ...
There are two POTWs this time. The reason? Guilt. We are picking up the first one from the internet ...
So, I’m at Mobility Cup in Nepean, across the river from Ottawa. I’ve participated in Mobility Cup ...
Emirates Team New Zealand, who introduced foiling to America’s Cup competition in 2012, is ...
Our own Ask Andrew ‘floated his Fanny down the Ganny’ in the annual boat race held on Ganaraska ...
While there’s all kinds of discussion, particularly in NZ, about the plan to defend the 37th ...
How a young woman who was encouraged by her father to enter a contest, became a member of the ...
We got this beauty from Don Snell of the Sea Spray Class in Alberta who proudly reminds us “the ...
This past June I stepped aside as Publisher of Canadian Yachting Media after a ten-year run. It was ...

Marine Products

  • Prev
The club's first digital guide is the collaborative effort of dozens of CCA members and now ...
The days are lovely and what better way to celebrate than heading to the engine compartment. Here ...
While collapsible bimini tops offer boaters a welcome escape from direct sun, deployment and ...
Volvo Penta is launching its Assisted Docking system as a retrofit upgrade for many yacht owners ...
Don’t let offshore emergencies turn into disasters. SeaKits help to prepare you for emergencies at ...
It’s one of the best things about sailors: we hate to give up on our equipment. But if you’re like ...
Furuno has announced that Navionics cartography is now available on their GP1871F and GP1971F ...
With the boat back in the water it’s time to refresh our boating skills after a long lay-off. ...
I’ve been doing powerboat reviews for Canadian Yachting magazine for over 40 years now and I want ...
Many boaters prefer the clean appearance and greater safety of modern pull-up cleats that retract ...

News

  • Prev
SailGP, the international racing series featuring high speed F50 wingsailed catamarans, is ...
First, they were closed - as of May 2, many of the Canada Border Services Small Vessel Reporting ...
According to their Facebook page, TSN is on onboard as The Canadian SailGP’s entry’s broadcast ...
According to International Boating Industry magazine, the BRIG factory near Kharkiv, Ukraine ...
After a two-year hiatus the 53rd edition of Antigua Sailing Week wrapped up on Sunday, brimming ...
When SailGP Season 3 commences on May 14 in Bermuda, it will mark an historic moment for Canadian ...
Georgian Bay boaters are familiar with the prehistoric landscape of the Bruce peninsula and are ...
Canada SailGP Team has unveiled a three-year partnership with the Algorand Foundation. The ...
Note: this information applies to Lake Ontario but indicates what is expected by US authorities ...
At the 2022 Palm International Beach Boat Show, BoatTEST founder Jeff Hammond met with Boyd ...

Fuel EconomyI filled up last week at $1.90. Pundits are suggesting that prices will stay high throughout the summer. Radio and TV news have been flooded with ‘man on the street’ interviews that show the impact on the average driver. How will these prices affect the average boater this year? Will we see more hours spent on the docks and fewer on the water? Will fuel efficiency become a top-of –mind selling point? Will we see a shift toward electric marine engines?

Time will tell – but for the majority of us, we’ll need to weather the storm as best we can. There are a number of tips and tricks we can employ aboard to make the most of our boat’s fuel. BoatUS published an excellent article this week that I’ll break down...

Read More