DIY lithium battery, 12 volt lithium battery, build your own lithium ion battery, build your own lithium ion 12-volt battery, lithium ion 12-volt sailboat house battery

A surveyor wouldn’t touch it with a ten foot pole (I know this because my friend’s a surveyor and said so), but that’s a legit home made 12-volt lithium battery for $300 vs. the $700-1000 you’ll pay for a “marine” one.

Each cell is about three volts and that little red box is a battery management system (BMS), which keeps it all distributed evenly. The wires off the BMS are soldered to the positive end of each cell . There’s even a fuse on the battery to limit risk of fire in case the battery shorts out. Plus, it’s lithium ion vs. lithium iron. Lithium iron is apparently the more dangerous one, and if one cell melts or gets too hot it can start to burn any cell that is next to it.

It’s the way of the future, and lithium 12-volt batteries are way more efficient and longer lasting than lead acid. But of course like anything it comes with risks and consequences.

Where did the lithium in my batteries come from? Probably some horrible mining practice. I’ll look into that. It seems we just can’t escape the environmental impacts that come with being a human and consumer.

In the meantime I’ll be getting lots of work done on my computer because I can finally plug it in on board. This is the first time ever I’m able to have sufficient power on a boat I’ve owned. I even have a food processor. Hummus anyone? Plenty of solar aboard to charge everything and this battery can easily be disconnected and brought to land to charge! They’re also so much lighter than lead acid, and if you’re really clever you can swap them back and forth with your electric bicycle which is all these cells are anyway. Electric bike batteries.

I am not that type of clever, however, so just leave me to some basic carpentry and fiberglassing. This addition to Sohund is definitely not my creation, but I’ll take it!

Hang in there folks. Spring is almost here. I came out of the boat and I didn’t see my shadow, so– I’m sure of it. 

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  1. That’s an awesome array of batteries!!! Alittle bit jealous but I’m good with what I have for now, even though my batteries are huge and heavy….. the plus of agm deep cycle is affordable and one can often find a used set from a solar company who is upgrading a commercial venture. Another source of lithium ion batteries is the hospital suppliers because they replace the portable oxygen and other monitoring devices regularly…. so go for it gulls n bouys!
    Light up your life….

  2. I love that you did this. What BMS did you use? Which lithium cells? I’ve been considering doing this kind of thing for my own boat. It’s great that you’re doing the DIY thing to get it going. There’s no reason not to do that!

    The only thing that I really find fault with (no pun intended) is that the fuse is soldered directly to the lead, rather than in a fuse holder. Minor.

    Great work.

    P.S., Lithium iron phosphate is the safer of the two. Lithium ion is the one that can suffer thermal runaway / catch fire.

  3. It’s more RV and home off grid than marine, but learned a ton about LiPo batteries from this YouTube channel:

    • Don’t worry, They left their van for 6 month unattended an charging a huge battery bank……

      • The charging in cold was likely a contributor …. though old cells with lots of internal resistance couldn’t have helped.

        There are also new batt issues especially relating to proper charging. Can’t use cheap tech with these Li Batts!

  4. I tried to sign up but it says my email already exists. Which notification system are you using? 8m trying to setup the same thing. Thanks !