Upgrading battery bank + mantus goodies

As mentioned in my last post, one of the things I was doing was a cheap increase in battery bank size to tide me over to next year (and lithiums).

Originally, I was going to get two 6v golf cart batteries from costco but their 12v deep cycle were actually a little bit cheaper and more capacity. They won’t last as long as the 6v, but I don’t really care as I will probably replace them next year anyway. It was $130 CAD for a 115AH group 27 12v battery, and I got two of them.

Installation was fairly easy, I just had to connect the new batteries in parallel (this combines their AH, connecting in serial would add their volts together making a 24v system) and then hook everything up to them, making sure that the positives all connected off one battery and the negatives off the other.

Basically this

Battery Connections - 2x12VoltinParallel

Notice that it says 120AH and not 115AH, this is a test and defiantely not because I put the number on the diagram wrong and am too lazy to change it.

This arrangement meant I had to make two more jumper cables, luckily I had short lengths of cable lying around so it wasn’t hard


Heat shrinked etc etc.

Then I had to remove the starter battery box (it’s the wrong size) and install the new group 27 size battery box, then plop down both batteries in their cases and strap em down


Note they are also attached at the bottom of the battery box as well to the bottom of the hull.

Then it’s just wiring them back up. And enjoying the 2x-3x extra battery! The trickiest part was reaching everything, as they are outside under a lazzerette in case of gassing off (this is where the battery is overcharged and starts venting hydrogen. Not unlike me eating lot of burritos! (yes that was a fart joke. going highbrow up in here)). Anyway, both those things are things you don’t want happening in the small enclosed space of a cabin.

I also got a couple of goodies from Mantus – mainly because Bruce from http://neverforever.ca/ (another local liveaboard blog but with better webdesign) reads my blog and won a competition and gave me a 50% off voucher! Thanks again Bruce!

I got a holder for my second anchor to hang off the stern, and an anchor bridle. This is used if I had an all chain anchor rode but more importantly for me, can be used on mooring buoys as well. This is a step up from my usual ‘old line I found hanging around I’m not using for anything else right now’, since it has chafe protection and proper sized line etc. Very nice!




  1. Enjoy the Mantus goodies! We’re fans of their anchors 🙂 Are the batteries flooded lead acid or AGM? Any reason you don’t think they’ll last that long? And I’m curious about your potential switch to lithium – read a little bit about it but haven’t researched that thoroughly.

    • Yeah, I have the 45lb one! They are flooded. The ‘year long’ thing is just cos I am really set on moving to a 400AH lithium bank next year but didn’t have the budget/time this year – on the other hand, my 70AH house bank wasn’t cutting it anymore!

      400AH lithium gives you around the same potential as 600AH of lead acid, as you can draw it down faster, but weighs a lot less, is a lot smaller and the peukert effect is basically not existent. I don’t really have the space for a big bank of LA batteries.

      Also I am a huge geek and lithium batteries (when installed as part of a system) are just so cool! Definitely lots of rethinking and relearning needed though

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