Lithium Batteries


Our #1 recommended upgrade is Lithium Batteries.  Because you want really, really good batteries.


Batteries supply our power for everything and are the heart of all of our electrical needs.  Navigation, refrigeration, lights, computers, cooking, engines, air-conditioning and more are all powered by our batteries.

The absolute best battery option available is lithium.  Not lead acid, not sealed AGM’s but lithium.  It’s the best bang for the buck and we have a video below explaining all the reasons why.

Lithium batteries come in various sizes and Amp Hour ratings.  You’ll want to measure your battery compartment to see which size will work for your space.

We have four 12V 300AH batteries for our house bank and a 12V 100AH battery for each of our engines.

Relion is offering 5% off to all GWTW Fans!  Just click the link below and it will be automatically applied at checkout.



  1. Nicholas

    I have a question about sizing the battery bank for life without a generator. I’ve been watching most of the videos about your life as cruisers and plan to do the same. Jason mentioned that ideally he would like to ditch the Gen set (that’s what I thing he said) if they could get a bigger battery bank. I’m planning to do that.
    Have you got an idea on how many AH the battery bank would have to be and how many watts of solar panels it would take to achieve that?
    I’m looking at a Leopard 45 with almost the same luxuries as you have eg. Air con, washing machine, water maker fridge, freezer etc….

  2. bogdan steiu

    Hello guys, great job with al lthese videos. I also have a Leopard 43 (4 cabin version), and after 7 years of 4x Lifeline AGM 255AMP , it is time to evaluate the new batteries. Just wondering after installing these batteries, if it is a simple swap of my AGM to these, or do I need to consider anything else, like my alternators on the 2 Yanmar 40 HP 3jh4e, or my Westerbeke 7.4TD generator . I am using a Magnum 3000 MSH3012 (i thnk you had that in your RV). Anyfeedback is appreciatted. In a couple of years I am mpving away from the carribean to the Pacific.

    I am also interested in the name of the part on the top of the hardtop traveller, that broke-snapped, and the otehr catamaran had a back-up for you (i would like to purchase a back-up for it)

    All the best and great seas and winds
    Bogdan Steiu– STAY-U Catamaran

    • Curious Minion

      It *can* be as simple as changing the charge profile on your charge controller. Talk to the support team for the lithiums you’re considering buying. Tell them what charge controller you’ll have and they’ll tell you if it has a compatible charge profile for the lithiums. If not, they can probably recommend what controller you should buy and swapping that out should take care of everything else (but ask them to be sure).
      Curious Minion

  3. Per Finnström

    Everyone – Don’t listen to SolarSail – Don’t mix Lithium batteries from Panasonic, Tesla, or DIY etc. with the batteries in the video. It depends greatly what exact mix of metals your battery is made of.
    Most marine Lithium batteries are LiFePo4 batteries, and are MUCH MUCH safer. And safe batteries is what you want on a boat. No one in their right mind would jerry rig their own batterypack etc. on a cruising boat, or any other boat more than 100m from shore for that matter.

  4. Martin Gagnon

    Awsome video and informations! I would like to use Lithium in my RV but I live in Northern Canada and winter can but very cold! What about lithium battery in those condition? Do I have to keep the heater on all winter to protect them?? Thank you!

    • Curious Minion

      Hey Martin. You need to check with your battery manufacturer for their recommended cold use procedures & storage, but as a general rule unless it gets really really cold you can store them *without using them* with no issues. If you are using and charging them, you have a few more things to consider. You can generally discharge them at temps below freezing without damaging them, but *charging* them if they are colder than freezing can definitely damage them. So if you’re going to be using them in the winter it would be easiest to put the batteries in some sort of temperature controlled space where they’ll always be in above-freezing temps. And again, check with your battery manufacturer for their specific operating and storage temperature recommendations.

  5. Chris smith

    Hello guys
    I’d like to get intouch with Solarsail. He seems to have some great insight into lithium’s. I’ve just bought a leopard 46 and would like to upgrade to lithium.
    Thanks ??

  6. SolarSail

    @Brian – Lithium power packs need a BMS (battery management system) to balance, protect, and charge the cells that are in series. This is a must. Some hobbyists don’t bother with that and manually balance the cells once in a while – which is a pain, and only makes sense for small packs of top quality cells. The BMS (balance and protection) card is as little as $20 and a lithium charge controller can be as little as $25, so there is no point of eliminating these. It also provides protection against over-charge, over-discharge, over-current, short-circuit, and thermal protection. Large battery packs contain over 5,000 cells. It is impossible to have individual cell monitors instead of a BMS on so many cells. Balancing is needed whether you charge/discharge slowly or fast, and it does not matter whether you are powering an EV (96 cells in series) or powering a S/V AC or cooktop (4 cells in series). It is normal to mix lead-acid with lithium if the 12V lithium pack has been designed with that in mind. “you need programmable charge regulators (or a ‘lithium’ battery setting at least)” — commercial lithium packs already come with CCCV lithium charge controllers, as part of the BMS – even in your cellphone. Lithium cells can be run down to 0% of their commercial rating (i.e. down to 3.2V). There is ample charge remaining in the cell, that the BMS reserves, and which you don’t see and don’t have access to. Some folks charge it only up to 97% of the rating and down to 5% of the rating, and that adds to the longevity of the lithium pack, but reduces storage by 8%. “Most of the money they currently charge is for the BMS systems which you simply don’t need. ” — Off-the-shelf Chinese BMS are very cheap, and a BMS doesn’t have to be expensive. It is just a bunch of FETs and cheap microcontrollers (for the larger packs). I can see that value-added pack makers want to charge an arm and a leg for a proprietary BMS – but with increased competition the price will have to drop considerably. But you need a BMS and a proper charge controller for lithium packs (they normally come with the pack). It is a very bad idea for example to rely on a solar panel power controller or alternator voltage regulator to directly charge lithium cells without a proper lithium charge controller in between.

  7. SolarSail

    @Paul and @TedOwens – Lithium power packs include their own BMS and charge controller in the power pack (or for larger packs is external to the pack). That makes them compatible to a 12V system that contains Lead Acid. So you can mix Lithium commercial packs with lead-acid (FLA, AGM, etc.). Lead-acid is self-discharging (lithium is not), so unless you trickle charge the system (solar or shore power), the lithium will be depleted trying to trickle charge the lead-acid. So for long-term storage you need to disconnect (all) power packs.
    @Linda Lou – Lithium cells and batteries are environmentally friendly. Lithium is abundant naturally and there is more in a tank of seawater than there is in a lithium cell. There are no heavy metals or toxic metals in a lithium cell (I think you are think of NiCad and not lithium). There is an organic solvent in the cell, but just a few drops of that. This can be incinerated or even let to leach into the ground. A lot less pollution than what you get from a gas station. Perfection comes at a high cost, and humans need not be environmental puritans.

  8. SolarSail

    Also thanks for your wonderful videos, which I absolutely love. Makes me want to become a sailor right away! You surely beat the competition (you know, that couple from Vaga…). Keep up the wonderful smiley and lovingly uploads. Also pls. show a map at the start of your videos. Thanks!

    • Curious Minion

      Hi SolarSail. There’s a Sailing Report toward the bottom of each blog entry with a map, dates covered by the video/post, etc.

  9. SolarSail

    Hi Jason and Nikki – As you know the price of lithium ion batteries has dropped considerably. It is possible to purchase new Panasonic li-ion batteries for a quarter of what you paid for (about $250 a kWh or 83Ah at 12V). Used Electric Vehicle batteries, such as from Tesla or Nissan are even less, and about $150 a kWh (83Ah). Of course this will require some DIY sweatwork – but it is a lot of fun. It is expected that the cost of new li-ion to drop to about $180 a kWh, including the BMS electronics, in the near future.

    You have 14.4 kWh (or 1200Ah at 12V) of storage on Curiosity. Maybe you should consider increasing that to 25 kWh, which is about what a Nissan Leaf has. I plan to build 100 kWh of storage (using Tesla or Panasonic batteries), a lot of flexible solar panels, and 2x 10kW electric drives, and do away with diesel.

    Now that you are in the Pacific, if you plan to come up to Vancouver, let me know.

  10. Bill B.

    When are you guys going to fill us in on the Relion Lithium battery “issue” you eluded to in one of your recent videos? What happened to the Relion batteries? What is your charge voltage? Have you done any capacity testing to ensure they are still meeting their capacity?

  11. Jay Marti

    Awesome .thanks for ,where do I start…Wao ! Everything ?. Called Just Catamarans a few minutes ago. Hopefully get something done soon.
    P.S. you missed one digit on their phone number 954-589-2343. Very inspirational and useful project you guys have. Hope we meet some day. Call me if you are in the Puget Sound area. My wife and I live in Seattle WA. We’ll take you out for dinner there ?

  12. Brian

    Lithium batteries can be used easily and safely in a marine situation and also relatively cheaply. Do away with the BMS and put in a low and high voltage cutoff on the batteries. I also have an individual cell monitor that alarms if any cell goes outside its voltage range. We do not need to ‘balance’ cells as they are charged/discharged very slowly and at low voltages relative to electric car situations. Keep them COMPLETLY separate from any lead acid batteries (e.g. start batteries) and change the charging profile for any inputs; you need programmable charge regulators (or a ‘lithium’ battery setting at least). Do this and they will be very safe and quite cheap. The best advantage is that they charge at full capacity right up to 100% – they do not need to cut back and ‘trickle charge’ the last 10% or so. In addition you can run them down to around 20% capacity with no damage – you can use 80% of the Ahr’s of Lithium batteries compared to around 50% of Lead Acid which again decreases the relative cost. Most of the money they currently charge is for the BMS systems which you simply don’t need. Important bit is don’t mix them with other types of batteries or the charging profile will cook the other batteries. And don’t use VSR’s as they will never turn off!

  13. Linda Lou

    Since lithium batteries have no real way to be recycled and are horrible ly dangerous to the environment, what is your plan when you need to get rid of them and get new batteries? Lead acid can be easily recycled and reused.

    • Curious Minion

      Why do you say they’re “horribly dangerous” to the environment? Their contents certainly aren’t as dangerous as lead and, while it’s definitely not a good thing to do, throwing a LiOn battery away isn’t any worse for the environment than throwing a cell phone or TV in a landfill. A few years ago it wasn’t economically feasible to recycle LiOn batteries, but as more & more electric car batteries are reaching “end of life”, more and more communities are beginning to recycle them. In 10 or 12 years when these need to be replaced (their long lifespan is also better for the environment since it reduces the manufacturing footprint, shipping footprint etc.), hopefully the U.S. will be on par with Europe in recycling them. No matter what though, they’ll be disposed of in as safe a manner as possible.

  14. Bb

    Is the locker that holds your batteries very secure? At that price I hope they are well protected while you are away from the boat and it’s anchored.

  15. Brian

    That’s a nice huge setup. Very good to be environmentally conscious by having that large solar array. Your idea o combining a large bank to support overnight air conditioning is something to consider.

    From information online at the National Renewable Energy Laboratory it seems that storing lithium batteries at elevated temperatures (even 90 degrees) greatly reduces lifespan. Please consider the location of your starter batteries as otherwise they ma not last that long. Same with keeping them near 100% all the time. Lead might actually be good for the starter.

  16. Ted Owens

    I am really interested in Lithium Ion batteries, but I am concerned about compatibility with the rest of my system. I have read that alternators, generators, and battery chargers need to be designed for them. Since LiOn will accept a much higher amperage when charging, they can burn out these components. I have a Leopard 43 just like you guys and I am curious if you changed out these or have had any problems? I believe these electrical charging components are all factory original (2007) and expect they will be the same models as yours.

  17. Einar

    I know this is terribly misplaced, but I guess I do not have the patience to look for the right place, sorry about that.
    I live in Norway and found your channel looking for RV related information. When you changed to sailing – well, that is one of my interests too. I have been messing around in boats since I was born.
    You make great videos, visit great places and all that, but I get more nervous the more I see. You grew up in a car not in a boat.
    You people need to start thinking safety. You are jumping around in you flashy outfits the same way on the boat as you did on land in and about the RV. Man Over Board happens – and it is very very very dangerous.
    You need to think this trough many times more and prepare for a number of worst case scenarios. The only thing you have talked about and done a tiny bit training on, is nice weather recovery from you own boat. I certainly hope you have done a lot more though. When that works it is fine – but this is not always the case. You need to prepare for a series of events, and not being able to recover the MOB from you own vessel.
    Imagine good wind and nice sailing, wind picks up ever so slowly, at some point you realize the conditions are getting more on the nasty side. Then one goes overboard, then a rigging line snaps, as one line goes another snaps => the one person on board are no longer able to fully maneuver under sail. Then starting engines, but one or both will not start => the one person on board have limited maneuverability including engine.
    I bet the MOB really wish she/he have a PFD, and whatevertheyarecalled emergency devise for signaling to the Coast Guard.
    You need to limit the changes for going over board, and you need to prepare for the MOB not being recovered from your own vessel.
    I have lost a friend at sea to the simple reason – no safety line. This person had a PFD. It happened in a storm in Skagerak in Autumn – not at all a bad one but a storm. He has never been found, to date. The boat and the rest of the crew where OK (as much as could be).
    I am sorry if I scare you, but if that can save you in the future – well – you understand.
    All the best, and fair winds, Einar

  18. Paul

    I’m cool with upgrading the batteries, but can I do that without upgrading the charge controller and monitors as well? Lead acid batteries require a constant float charge that lithium batteries do not. Isn’t the charging profile completely different?

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