Lithium Ion Batteries

Topics about Class Rules and the RRS.

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Dan Corcoran
Posts: 134
Joined: Sun Jan 29, 2017 4:32 pm

Lithium Ion Batteries

Post by Dan Corcoran » Thu Jan 02, 2020 4:51 pm

The industry is getting closer to providing affordable lithium-ion battery replacement for lead-acid batteries, these batteries are currently excluded by the J/109 class rules.

It could be helpful to have an alteration of the rules to allow such batteries in 2023 or later, so owners can plan in advance as lead-acid batteries have 4-10 year lifetimes.

I open this thread to start a discussion that can continue through 2020 if anyone is interested.

I am not in the market for such batteries, but as an electronics evaluator/marine electronics editor for practical sailor magazine, I may become interested in testing these batteries on my J/109 in 2021 or later.

For others in our class, there could be an interest in having much more power available for cruising or the desire to make their boats even more environmentally friendly by eliminating the diesel engine altogether. as at least one J/121 has done
Link: ... oats-j121/

Some initial thoughts:

(1) Two approaches
- Increase the minimum amount of Ahr for boats with Lithium-Ion. E.g. Required Ahr = Ahr of Lead Acid + 1/2 * Lithium Ion Battery capacity.
- Swap the current minimum of Amp Hrs with a minimum weight of battery plus battery management system (BMS) and other stuff needed to make lithium batteries safe and effective to use on a 109.

(2) Weight issues - Ideally the rules would be neutral to the user's selection of solutions to deal with lithium challenges.
- The rule could perhaps allow additional safety components to be counted in the weight.
- Some batteries have an internal BMS, while other designs put the BMS and components like relays external. The rule should not favor one approach over the other.
- BMS's have protection systems that can cut-out all the power on the boat without warning. Some owners may want to keep a mix of lead-acid and lithium while others may choose to have two lithium-ion batteries.
- Potentially our alternators will not be up to the task of charging some types of batteries and need to be replaced.
- Potentially our shore chargers will not be up to the task of charging some types of batteries (for example charging a mix of lithium and standard lead-acid batteries may be somewhat restricted, as our current shore charger requires you select the same battery type and voltages for both battery banks of batteries.
- Diesel replacement. Potentially there would be no diesel engine, the owner could opt for a massive battery bank and electric motor. Perhaps then the owners choice of engine is added into the weight equation.
- Allow owners to make up for a deficiency in achieving weight minimums, with a bolted in weight in their battery compartment.

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Vento Solare
Posts: 257
Joined: Wed Dec 31, 1969 8:00 pm
Location: Newport, RI

Re: Lithium Ion Batteries

Post by Vento Solare » Mon Jan 13, 2020 10:12 am


I've read this over and thought about the implications that should be considered for any proposed rules change. In general, my feeling is that the One Design class rules are in place to provide a uniform baseline for all boats. Recognized that there are some differences between the US and French built boats, and the options offered, the class rules do a pretty good job defining a baseline owners may work in to keep the OD configuration. The OD rules also prevent an "arms war" so that owners feel they do not need to modify their boats to stay competitive with other boats.

Being a techy, I am aware of the advantages a high density energy battery has for distance races. I am also aware of some pitfalls and know of two boats with lithium batteries that had fires due issues with the battery management system malfunctioning, most recently a J/121 that was participating in the New England Solo Twin race (read the log in the link) that I did on Vento Solare last summer. Here are my thoughts for any considered rules change.
  • I am not in favor of any change that removes the diesel engine and associated systems
  • Replacement Batteries must fit in the volume of the existing battery compartments and must have corrector weights in the same location so the equivalent total weight is the same as standard lead technology batteries at the capacity listed in the class rules/interpretation.
  • Unfortunately, changing to Lithium batteries requires a different voltage regulator / battery management system and may require a different alternate to charge at the higher rates.
I suggest that before this is considered, that "system design" alternatives with the pieces and associated costs be created for a notional design. This would then be available for owners to evaluate and comment on whether is is worth while to propose a rules change.

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