Battery power onboard hundreds of ocean-crossing skippers share their secrets

Our great annual ARC equipment survey focussed on power on board, its usage and generation. Jeremy Wyatt quizzed the 234 skippers who made the 2024 crossing

Power on board is a key equipment issue for all bluewater cruisers, whether preparing a boat for a first transatlantic passage or considering comfortable liveaboard cruising. We asked the 234 skippers who took part in the 2024 ARC and ARC+ rallies detailed questions about their electrical systems, how they generated power and their power consumption at sea.

Crucially, we also wanted to find out what went wrong for them and their tips for how to ease anxiety about power management.

[Note: 220 skippers responded, fully or in part, to our survey. Not all respondents answered all questions]

Yacht Battery Types

As any electrical expert will tell you, having good batteries is the key to a reliable marine electrical system. Most boat owners will want to replace or upgrade their batteries at some point during a yacht’s life. When that time comes should you take the easy option and just swap like-for-like, or should you take opportunity to upgrade? If that’s the case, what might be best for your boat?

We looked at which battery types were fitted within the ARC fleet, their ages and capacities, and the results showed a clear trend towards lithium batteries.

At around three times the cost of lead-acid or AGM batteries, installing lithium batteries is a big investment. Wayne Prevett, technical support manager at Advance Yacht Systems explained how to get best value: “The benefit of a lithium battery system is that you can use 80% of the capacity, and the speed with which they can be recharged, makes them ideal for a service battery bank.

“An engine start battery, on the other hand, needs to deliver a large burst of energy over a short period followed by time to recover. Traditional battery technologies do this well and are much cheaper to purchase.”

Just over 38% of skippers had changed or upgraded their batteries since owning their yachts, most opting to switch over to lithium. Generally, but not exclusively, those opting for lithium tended to use a professional to do the work, whereas a like-for-like swap was usually done by the skipper.

Prevett explained why this is important to have a properly designed system. “There are aspects of the way lithium batteries work that might cause problems for a self-installer with insufficient knowledge. Lithium batteries should be installed as part of a properly designed system – it’s not a simple swap in/out with traditional batteries. The system needs to be protected from overcharging, which can cause overheating in under-specified cables and the engine alternator.

“In fact, insurance companies may decline your cover if the lithium system is not designed and installed by a certified person.”

We asked the skippers to rate their satisfaction with the performance of their batteries during the ARC, on a low-to-high scale of 1 to 5. Of the 87 boats with lithium service batteries, all bar three skippers rated their satisfaction at 4 or 5. Those who marked down their satisfaction did so primarily because of associated equipment such as battery monitors not working as intended.

The skippers scoring their lithium system a 4 on our scale generally commented on having underspecified the amount of battery capacity that they’d require for the crossing rather than the batteries not working as expected.

Swede Anders Fredholm, sailing his 16-year old Hallberg-Rassy 54 Aglaia, (lithium, 500Ah, 24V), had swapped from lead-acid with a professional installation and commented, “it is like buying a new boat for usability”.

Canadian Lloyd Smith had done a self-install upgrade from lead-acid to lithium in 2020 on his 34-year-old Tayana 47 Apres Ski (lithium, 800Ah, 12V) and explained that the upgrade had allowed him to switch from gas to electric cooking, saving hassle looking for gas refills and enhancing safety on board.

Wilhelm Klass from Germany, sailing Bluewater Mooney (lithium 24V) on his third ARC, has owned his Hallberg-Rassy 54 from new in 2008 and is now on a world circumnavigation, and thinks that adding lithium batteries was “the best change ever made” to his boat.

Less satisfied were the nine skippers who rated their systems as a 2 (all non-lithium). Of these, seven had not made changes to their systems since owning their boats.

Alan Soukup commented on the need for seven to nine hours of charging per day aboard his four-year-old Privilege 510 Full Circle III (gel, 1,040Ah), while Chris Allen attributed his batteries’ poor performance to two of five units being damaged aboard his 2002 Rustler 42 JolieF (AGM 650Ah). Fellow UK skipper Peter Williams said that his batteries “just didn’t hold change at night” aboard his Malø 37 Rosiere (lead-acid, 315Ah).

Yacht Battery Monitoring

The key to successful power management is the ability to monitor charge levels and consumption for the system. We asked skippers to rate their satisfaction with the performance of their battery management equipment.

The leading brands Victron and Mastervolt were suppliers of a significant majority of the monitoring equipment within the fleet – representing 49% and 28% respectively of the 158 boats that declared their brand, and most skippers were very satisfied with the performance of their equipment.

While the numbers fitted for other brands were too low for statistical comment, the only satisfaction scores of 1, the lowest mark, were both for self-installed equipment described by the owners as ‘Chinese brands’. It would seem that, at least for monitoring equipment, the old adage that ‘you get what you pay for’ holds true.

Investing in a professionally installed, well-designed monitoring system will be worthwhile in terms of usability and in obtaining the best performance from the batteries and charging systems.

And while you may not necessarily wish to be checking your phones at sea, several skippers commented on how useful they found the bespoke battery management app from Victron.

Power Management

We looked at how power was generated by ARC boats and then asked the skippers about their power consumption at sea.

Of the yachts fitted with diesel generators, 23 also had some form of renewable electrical generation via solar panels, hydrogenerators or wind turbines. Within this group we wanted to know which system gave the best value for power generated. There was a clear split within the sector, but more skippers commented favourably on renewables. Of the 17 skippers in this group who responded, five preferred their diesel gensets. These were usually for reasons of renewable equipment failure, such as Swedish skipper Christer Sjö, whose “hydrogenerator blade fouled” on his Lagoon 380 S2 Helios.

However, 12 skippers preferred their renewables and, in general, hydrogenerators were praised by skippers for their continuous 24/7 power delivery. “Our Remoran Wave 365 kept the batteries at 100% overnight in strong winds and it allowed us not to run the engine,” said Steve Bax, British skipper of the 2016 Roberts 532 Santosa.

Of the 191 skippers who responded on generation, 74 had set up their boats to charge via the main engine; eight of them had no alternative, while the other 66 had renewables, mostly solar panels or solar with a hydrogenerator (25 boats). Those with sufficient solar capacity were happy with their choice.

The Bavaria Ocean 38 Avanti (from 1998) for instance, had 1,000W of installed solar, 600Ah lithium service batteries and a Victron Lynx BMS plus Cerbo GX management system. Skipper Jonathan Grün from Germany commented: “We didn’t use our engine to charge at all. This is on a boat using an electric autopilot, a refrigerator, electric hob, radar, and navigation displays.”

Diesel gensets were well liked, although there were often caveats from skippers that they needed to be installed and maintained correctly. Those with reliable installations praised their gensets in preference to main-engine charging for being quieter – an important consideration when the off-watch crew are likely to be asleep – and for their lower fuel consumption.

Off The Grid, a new Southerly 42, had a 460Ah lithium service battery with Mastervolt monitoring and a 1.4kW genset. American skipper Patrick Whatley commented on fuel consumption: “Our generator when working used 0.75 lt/hr and we typically ran it for two hours per day”.

Power Consumers

Yachts in the ARC fleet are typically well equipped for bluewater voyaging, with many crews aiming for long periods as liveaboard cruisers. This is reflected in the typical equipment fit we found when looking at power consumption at sea.

Among the big power consumers, most skippers would not be without an electric autopilot – with these in use on average 20 hours per day, including 83 boats where they were used 24/7. There were 10 yachts relying on hand or wind steering alone.

Radar was another often-used power consumer, with an average of 7.7 hours per day usage, and 11 boats reported running their radars 24/7.

A surprise for some skippers was the power consumption of their Starlink satellite communications systems (up to 75W) when left running all the time: 15 skippers commented specifically on this equipment as being a power drain and needing to change their usage patterns, only powering up the equipment when needed.

Fridges and freezers were another source of power anxiety, as typically they are run constantly.

“We had to abandon the freezer,” said US skipper Bill Whidden of Kaimana, a six-year-old Jeanneau Yacht 51 with 650Ah of AGM batteries. They used the main engine plus solar for charging.

Desalinators were generally managed well; yachts with gensets co-ordinated making fresh water with the battery recharge during a three-hour run time. Those with electric cooking likewise cooked and arranged meals around ‘generator on’ periods.

The combination of solar panels with a hydrogenerator provided sufficient power for some boats to manage without running their main engines. “Our Remoran Hydrogen gave 7A 24/7 during sailing; super during nights,” said Arto Alnehall from Sweden aboard the Dufour 405GL Dagmar (360Ah lithium).

He explained further: “The generation and consumption were in balance without fossil energy, which allowed our crew of four to make water and take showers every second day. We also had a Hydrovane for self-steering.”

Of the boats using diesel engines, either the main engine or a genset, the median daily run time for charging was three hours and across the fleet the range was between two and nine hours per day. Boats relying on hydro or solar were charging constantly during daylight hours and when sailing above 6 knots.

Lessons Learned

We asked skippers how their charging routine altered for ocean sailing compared to coastal sailing.

The skippers’ comments reflected the need for more charging hours compared to coastal, where typically they might motorsail more often and put the engine on for manoeuvring and docking, which doesn’t happen offshore.
Norwegian Christian Thjømøe, sailing his five-year-old Beneteau Oceanis Yacht 62 Oda Julie, said: “We found that the large ocean swells caused our autopilot to work much harder than for coastal sailing, which meant longer charging to keep our batteries up.”

Morgan Hayes aboard the formidable new MC75 catamaran Jack, added: “You may well sail with a larger crew for your Atlantic crossing, so be prepared for the knock-on of more power consumption than usual and longer charging.”

Rob Peters, a Dutch skipper also sailing a new catamaran, the Outremer 55 Balavu, learned another valuable lesson: “We were caught out by the level of shading from our sails onto the solar panels. When coastal cruising you are not on the same heading and sail plan for days on end.”

And American Peter Goldich, aboard the 2018 Jeanneau Sun Odyssey 440 Gone With The Wind had this to say: “We helped cut our consumption by turning off the freezer at night; we didn’t open it at all overnight, which kept it cool enough.”

Final thoughts

In conclusion, we can see that most ARC skippers have been satisfied with the performance of their batteries and power generation. Where problems have occurred, they have only affected crew comfort and not the safety or seaworthiness of the boat.

Spending preparation time and refit budget on a well-designed power management system is a good investment, even if skippers decide against an expensive upgrade to lithium service batteries. Replacing batteries before going bluewater voyaging will save hassle and stress later; having multiple ways to charge, and a good battery monitoring system will cope with the variation in power consumption caused by different types of sailing.

---

If you enjoyed this….

Yachting World is the world’s leading magazine for bluewater cruisers and offshore sailors. Every month we have inspirational adventures and practical features to help you realise your sailing dreams.

Build your knowledge with a subscription delivered to your door. See our latest offers and save at least 30% off the cover price.

Note: We may earn a commission when you buy through links on our site, at no extra cost to you. This doesn’t affect our editorial independence.

---

The post Battery power onboard hundreds of ocean-crossing skippers share their secrets appeared first on Yachting World.