The Offshore Voyaging Reference Site

Lithium Ion Batteries Explained

There’s a good chance that you are currently sharing the room with a half-dozen or more lithium ion batteries. The computer in front of you has one, your camera has one, your phone has one, the R/C car your kid is racing around your ankles has one. Lithium battery technology is almost everywhere. And, soon, it’ll be coming to a boat near you.

Before we start, let’s (temporarily) forget everything we know from the lead-acid world: charge profiles, cycle life, equalization, voltage setpoints, monitoring, and so on. Lithium is a completely different animal.


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More Articles From Online Book: Electrical Systems For Cruising Boats:

  1. Why Most New-To-Us Boat Electrical Systems Must Be Rebuilt
  2. One Simple Law That Makes Electrical Systems Easy to Understand
  3. How Batteries Charge (Multiple Charging Sources Too)
  4. 5 Safety Tips For Working on Boat DC Electrical Systems
  5. 7 Checks To Stop Our DC Electrical System From Burning Our Boat
  6. Cruising Boat Electrical System Design, Part 1—Loads and Conservation
  7. Cruising Boat Electrical System Design, Part 2—Thinking About Systems
  8. Cruising Boat Electrical System Design, Part 3—Specifying Optimal Battery Bank Size
  9. Balancing Battery Bank and Solar Array Size
  10. The Danger of Voltage Drops From High Current (Amp) Loads
  11. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 1
  12. Should Your Boat’s DC Electrical System Be 12 or 24 Volt?—Part 2
  13. Battery Bank Separation and Cross-Charging Best Practices
  14. Choosing & Installing Battery Switches
  15. Cross-Bank Battery Charging—Splitters and Relays
  16. Cross-Bank Battery Charging—DC/DC Chargers
  17. 10 Tips To Install An Alternator
  18. Stupid Alternator Regulators Get Smarter…Finally
  19. WakeSpeed WS500—Best Alternator Regulator for Lead Acid¹ and Lithium Batteries
  20. Smart Chargers Are Not That Smart
  21. Replacing Diesel-Generated Electricity With Renewables, Part 1—Loads and Options
  22. Replacing Diesel-Generated Electricity With Renewables, Part 2—Case Studies
  23. Efficient Generator-Based Electrical Systems For Yachts
  24. Battery Bank Size and Generator Run Time, A Case Study
  25. A Simple Way to Decide Between Lithium or Lead-Acid Batteries for a Cruising Boat
  26. Eight Steps to Get Ready For Lithium Batteries
  27. Why Lithium Battery Load Dumps Matter
  28. 8 Tips To Prevent Lithium Battery Black Outs
  29. Building a Seamanlike Lithium Battery System
  30. Lithium Batteries Buyer’s Guide—Part 1, BMS Requirements
  31. Lithium Batteries Buyer’s Guide—Part 2, Balancing and Monitoring
  32. Lithium Batteries Buyer’s Guide—Part 3, Current (Amps) Requirements and Optimal Voltage
  33. 11 Steps To Better Lead Acid Battery Life
  34. How Hard Can We Charge Our Lead-Acid Batteries?
  35. How Lead Acid Batteries Get Wrecked and What To Do About It
  36. Equalizing Batteries, The Reality
  37. Renewable Power
  38. Wind Generators
  39. Solar Power
  40. Watt & Sea Hydrogenerator Buyer’s Guide—Cost Performance
  41. Battery Monitors, Part 1—Which Type Is Right For You?
  42. Battery Monitors, Part 2—Recommended Unit
  43. Battery Monitors, Part 3—Calibration and Use
  44. Battery Containment—Part 1
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David

Interesting post. I have been “noodling” on this same concept for a few months. On thought that you didn’t address is the charge “profile” vs lead/acid. With the more aggressive charging capability I wonder about the need for a separate gen set vs charging off the main engine.

It would seem that a main engine high-capacity alternator could charge lithium ion batteries much quicker. Thus, eliminating the need (advantage) of a slower charging low horsepower gen set.

I’ve just started to play with the math. See this link for some good info on charging acceptance rates (http://batteryuniversity.com/learn/article/charging_lithium_ion_batteries). But, it the math pencils out then the cost savings of eliminating the gen set could more than make up for the additional battery costs.

I’m interested to hear others thoughts on this. I think it could really be one of bigger “game changers” in the yacht industry since roller-furling.

Douglas Pohl

Matt – Deep depth of discharing lead-acid batteries will shorten their life – to extend the lead-acid battery life keep the depth of discharge (DoD) limited to a max of 50% , even less is better.

Example:
Lead-acid battery DoD vs Cycles: (lifetime)
DoD Number of cycles
=== ============
80% 100-200
50% 400-600
30% 1000+

LiFePO4 and Ni-Fe cells can both be deeply discharged (80% DoD) with a problem.

LiFePO4 (DoD 80%) 2500-3000 cycles lifetime
Ni-Fe (DoD 80%) 2500-3000 cycles per electrolyte change. 50+ year lifetime

(Check with your battery manufacturer for specific DoD vs Cycle graphs)

David

Thanks for the reply Matt. Many of the comments below are very valid regarding the dangers, but nothing will change that faster than the entire automotive industry putting big $$$ into these systems. Eventually, the math always wins.

GUILLOT

Currently sailing around New Caledonia in the South West Pacific I had to change my dead service batteries recently. I had thought to LFP batteries but eventually decided to stay with Lead batteries (12V-150AH-C10 Gel batteries) for several reasons :
– they are locally available for shore solar grid power supplies ;
– LFP batteries are still not available in the area and all the small islands around ;
– most lithium batteries are classified as dangerous goods and their transportation by airplane is strictly prohibited ;
– transported by ship, as it takes a long time to get them they may arrive dead here (this happened to me with a Torqeedo battery which took six months without any maintenance to arrive from Europe) ;
Maybe the situation will be better in 5 years or more next time I must change my batteries.
Jean-Claude – S/V Bauhinia

Fuss

This maybe a sweeping statement, but in my experience, only a very small percentage of boaters care about their batteries and charging equipment to the extent that it is all working at 100%. So often do we see bad connections, undersized cabling, non industrial, non robust alternators, output undersized alternators running with special regulators that reduce the amps produced.
LIFEPO4 batteries will stress these systems beyond the limit.
LIFEPO4 batteries, to optimise their fast charging capabilities, require alternators to be at least twice the capacity or maybe even 3 times the capacity currently.
Currently LIFEPO4 systems need you to love batteries nearly more than anything else in the world.
Unless you are one of the few…I would suggest waiting 5 years.

Laurent

1)- I don’t think that you can make any kind of saving using main engine at full load for lithium-ion batteries charging if you still use classic main diesel + mechanical inverter instead of an adapted genset. To do that you would need an alternator large enough to accept main engine’s full load, which means about 2500 amp. at 12V. for a 40 hp (#30kw…) engine. Cost of this alternator should be substantially more than the cost of an additional 4kw small dedicated diesel + #340 amp. 12V alternator (plus : this dedicated engine could use tax-free diesel…)

2) – This question is very different if you use diesel-electric transmission instead of a classic main diesel + mechanical inverter.
Diesel-electric transmissions without any kind of battery in the way, provide a continuously variable transmission between engine & propeller, and allow to connect efficiently and easily multiple engine to one propeller shaft. Those points are good or very good for motor-sailing because:
– you can install two 20hp engines + alternators instead of one 40hp engine and run on one engine only at a correct load-ratio when motor-sailing instead of using the 40hp engine at much too low load-ratio.
– you can precisely adapt transmission ratio to your motor-sailing needs, including dynamic fine-tuning according to the current wind & sea conditions.
– you can reduce engine size. Engine size is generally decided considering low-speed high-load needs (“bollard pull” requirements…) and high-speed low-load needs (motoring-only required speed in normal wind & sea conditions…). With a continuously variable transmission, those needs can be satisfied with a smaller engine size than when using a classic fixed ratio mechanical transmission, because in this case the transmission ratio will be a very poor compromise between very different needs.

3)- If you have a diesel-electric transmission, you can obtain additional advantages using batteries in the circuit. Those advantages are mainly :
– the capability to use some shore energy (“pluggin capable”…) or green energy (photovoltaic, windmill, sea-energy….) instead of using only diesel.
– the capability to motor quietly (electric-only) in some circumstances (maneuver, low-speed…).
– the capability to be more efficient with diesel-oil & save diesel engine life expectancy, running it part time at full load instead of longer time at limited loads.

I think that diesel-electric transmissions for sailboat aux. propulsion is very promising and is mature enough for educated DIYer (a significant issue is maintenance in current boatyards, so diesel-electric yachts transmissions early-users still need to have serious capabilities to maintain those systems by themselves….).

Introducing batteries and other energy sources in the circuit (shore-energy, green-energy etc….) is not a big issue per itself, but, might be easy or not depending the amount of energy you want to store. If you want only limited quantities (enough to enter or leave harbors..) lead-acid batteries are a reasonable and very mature choice, although heavy and not very efficient.
If you want more energy storage ( several hours at motor-cruising level engine power), you need better technologies than lead-acid. It looks like things are moving rapidly in that field, mainly due to electric cars. Technically correct solution should be available either today or in a very near future. Commercially available packaged solutions for sailing yachts might have to wait a little longer, but I think that those things are not that much complex, and that educated DIYer don’t need to wait for those packaged solutions if they accept to be early-adopters and if they can make most of their maintenance themselves.

Considering fire/explosion risks with non lead-acid batteries, I understand that :
– Apple and Boeing had some recent well-publicized problems with very high-specs batteries
– Tesla seems to have developed volume production without big well-publicized problems, but there is still a slight doubt about 2 recent fire-accidents concerning their cars,
– And that Bollore, in France and Canada, has developed a different (less ambitious ?…) technology (“lithium metal polymer”) with volume production for some time and without any battery-related fire-incident to-date. Those batteries are commercially available.

—> So I am convinced that educated DIYer can install reasonable diesel-electric plugin-capable transmission today, perhaps using Bollore batteries, and that other yachts users will be able to do the same as soon as boat-industrialists, maintenance yards etc. will allow them to do so, which might take “some” time….

John Harries

Hi All,

I really don’t want to go down the long winding path of debating the benefits and drawbacks of diesel electric drive for voyaging sailboats yet again on this post. We have already done that subject to death…several times.

I will move any further posts on diesel electric to the appropriate post on that subject.

Thanks

John Harries

Hi Matt,

Great post that answers many of the questions I had. I had really hoped that lithium batteries were ready for yacht use since their energy density would solve the problem that we have on “Morgan’s Cloud”, and many other voyagers are struggling with too: our electricity needs have outgrown the space we have for batteries.

Your post makes it clear that we will have to continue as we are by carefully managing lead acid batteries for some years to come since there is absolutely no way that we would install any technology with the inherent dangers, that even Boeing has had trouble managing properly, on our boat.

Bottom line, it’s one thing to experience a “exothermic excursion”—you engineering types have such great euphemisms for things like “you are going to get fried”—in a car, where you simply pull to the side of the road and stop, and quite another to experience the same mid-Atlantic, or even 10 miles off the coast.

Simon Wirth

Hei Matt
This sounds a bit like an emergency eject system would be needed to make them save. Something along the line of the batterie beeing mounted in a colum, say before tha mast built massivle into the boat. If you now make a ventiolation of some kind on top of it, and some form of fast release hatch on the bottom, you could, if done right, “just” pull the handle and the entire thing would dropp out of the boat and away.
Regards Simon