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Marine Electronics Journal Blog
Lithium-ion battery swap: a few issues to consider

Ed Sherman, vice president/education at the American Boat & Yacht Council, writes a regular column in Marine Electronics Journal called Ed’s Electro-Tech Tips. The purpose is to keep electronics dealers and installers up to speed on a variety of electrical issues related to their work. While most of the information is very technical, Ed’s recent comments about lithium batteries are more general. Since we’re seeing more and more of the technology work its way into the marine world, we thought you’d like to tap into the conversation. Here’s how he introduced the topic to MEJ’s trade readers: 

I’m getting a lot of queries lately about switching to lithium battery technology and I’ll bet that many of you are too. The question is, how to advise your customer about this battery option. Is it safe? Do I need to do anything beyond swapping out the existing batteries? They are expensive, but will they significantly outlast my current collection of lead acid batteries? Are there any ABYC or ISO (International Organization for Standardization) standards that apply to this technology? Are boat builders using this technology as original equipment?

I’ll start with the easy answers first. As of this writing there are no specific ABYC or ISO standards in place addressing lithium technology batteries. That said, ABYC has been working with a group of experts from the lithium sector to develop a technical information report. I’m told that ISO is now working to develop a standard as well. 

As for OEMs (original equipment manufacturers) using the technology, the only installs I’ve seen to date were on very custom boats that were built as requested by their owners who were typically engineering types who wanted the latest and greatest. Last fall, however, I entered the Jeanneau booth at the Annapolis Sailboat show and snapped the lead photo for this article. Turns out Jeanneau was offering an option for lithium tech on their new boats. When I asked the sales reps what additional upgrades came with the option, they weren’t exactly sure what was involved, but they were certain there were additional modifications involved in the upgrade. That was comforting, because as I’ll discuss here, upgrades are needed if this is going to be a successful change.

The operative phrase to associate with lithium battery technology is "current density.” The bottom line is lots of battery amp-hour capacity for the physical dimensions and weight. Additionally, lithium tech batteries have a significantly higher recharge acceptance rate than any other technology available to us in the marine field these days. This translates to rapid recharge of the batteries when depleted. Additionally, all the vendors I’ve queried tout the deeper level of discharge these batteries can take without reducing cycle life, 80% vs 50%. 

Ok, so what are the negatives to this technology? For a customer that simply wants to swap out their existing batteries, they are many. Early adopters have learned the hard way that the alternator that helps to recharge the batteries when the engine is running is going to be working hard. It’s going to need to be of a heavy-duty variety and equipped with a temperature sensor that shuts it down when things get too warm. On one of the installations I’ve inspected, the builder added a forced fresh air cooling system aimed right at the alternator to help keep things cooled down. 

Management system is essential

Additionally, whatever battery you select MUST be equipped with a battery management system (BMS). This is imperative to ensure proper cell balance and even discharge and recharge levels. We’ve seen lithium tech for sale at places like eBay and Amazon from unscrupulous vendors that are not properly equipped. The BMS is a minimum safety requirement that the ABYC group developing our tech information report all agree on. 

Selecting name brand equipment could make a difference as well. The process for manufacturing the cells that make up a lithium battery requires hospital-level cleanliness to ensure inherent safety of the cells. Dirt or other contaminates in the cells are known to trigger what is known as thermal runaway, whereby the battery catches on fire and the fire can’t be put out with any known current extinguishing agent. I’ve seen lithium installations where the builder had installed halon or equivalent extinguishing systems in the battery storage compartments thinking this might actually do something. Well, that system might slow down the boat from catching fire, but once those batteries go into thermal runaway, they are going to burn until all the fuel is consumed. The only way we know of to extinguish these fires is with plenty of cold water. This is of course counter-intuitive with electrical fires. Several builders I’ve checked out have installed the batteries in dedicated compartments whereby if the batteries were to go into a runaway mode, they would literally burn their way right through the bottom of the compartment and fall into the ocean. These were multi-hull boats and the compartments were located between the hulls. This of course would be a bit difficult to design for a monohull. 

New standards that apply to batteries in general apply here as well. Over-current protection for the battery bank is now required. The August release of ABYC E-11 outlines the new requirements. Finally, in addition to the alternator issues already mentioned, the installed battery charger may be an issue. How programmable is it? Does it have a lithium setting? Can it be calibrated to match the battery vendor’s recharge specifications? In many cases the answer here is ‘no’ and this would necessitate replacement.

So, to sum this all up, lithium technology is great, but a simple swap with your existing batteries may not be the answer. To maximize both safety and cycle-life, your customer may need to upgrade their alternator and battery recharging systems to maximize the cycle-life needed to get the maximum amp-hour per dollar from this technology.

In addition to his work at ABYC, Ed Sherman writes a blog called Ed’s Boat Tips—click HERE for a look.

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Comments | Leave a Comment
Page 1 of 3 ( 13 comments)

Jp:(8/11/2018 5:28:29 PM) "I have a 2018 Yamaha f40 la and Humminbird helix 7 di , I would like to leverage the nema 2000 capability of the helix 7 to display engine info, what do I need , Humminbird does have a gateway and lowrance makes a Yamaha nema cable, but I'm reading connectors are proprietary . How can I get what is needed?

Since these products are not NMEA 2000 certified there is little assurance that they will share data with each other.

1. Here is the link to see all NMEA 2000 certified products:

2. The NMEA 2000 cables and connectors are from many manufacturers: Here is the link for approved cables and connector manufacturers:

AC/DC grounding distance:(8/2/2018 1:29:35 AM) "What about the grounding points of AC /DC systems? can they be grounded at the same point?
If one system has both AC and DC can they both be grounded to a common buss-bar that has only one conection to the hull?

Here's what Ed Sherman, electric tech guru at the American Boat & Yacht Council, said:

The ultimate goal should always be to tie ac and dc grounds together on board at a single point. In ABYC Standard E-11, it is described as “the engine negative terminal or its buss.” It is most commonly done at a buss."
Hard-Over with Brushed APilot Pump:(12/18/2017 5:37:05 PM) "Jim.
What do you mean by ...."Garmin GHP 20 with SmartPump...Because it is a brushless system, it is fail-safe and won’t execute a hard-over turn the way a brushed pump can."

Thanks for the note. Since the description came from Garmin I contacted the company for an explanation. Here's what one of their engineers told me:

On brushed DC actuators, a single-point failure in the drive circuit (shorted wire or blown component inside the controller) could cause the motor to run full speed in one direction and take the rudder all the way to one rail. A brushless actuator relies on timing-controlled commutation, so a short or component fail would cause the actuator to stop moving rather than moving at full speed.

Hope this helps,

trawlerdeejay:(10/13/2017 3:46:51 PM) "Excellent article. I had no idea what the differences were between o183 and 2000, Thank you so much."
Darryl:(3/27/2017 10:17:15 PM) "Putting the MSRP with each unit reviewed would have been helpful. If each unit was actually tested, the reports on each unit would have been helpful too.

Thanks Darryl---we generally don't mention prices due to confusion over so many variations---MSRP (mfg. suggested retail price), MAP (min. advertised price), MRP (min. resale price) and then there are internet prices on some websites that go their own way. But your point is well taken--buyers need to know if something is in their price range. We'll work on it.
There is independent testing of some of these products on sites like but the information we receive from manufacturers rarely cites the results of any shootouts they may conduct against the competition's products. "
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