Starting my LFP build.

[Hayden Watson]

Thank you! Ugh, the height might prevent me from implementing this on my Tartan 3800. This boat was designed as if all that anyone needed was a couple of group 27 FLAs - and even those were a tight squeeze! I might have to start looking for an alternate location for the batts. It will be tough to find a place that will handle the size of your pack.

Do you happen to know what it weighs?

Thanks,

jv

My battery box in the C30 Mk2 is also designed for a couple of group 27. The height could probably be trimmed down to about 9". It weighs 120lbs with everything. The eight cells are 12.5lb each. The length can be reduced by putting the BMS and the class-T fuse on the outside of the box. You can also make it as two 44s packs but that would require a BMS for each pack at $122/each.
Because they are DIY, there are lots of ways to position them.

 

[Hayden Watson]

Wow, that's awesome. I mean, the battery system, and your reporting on it!

My "dream" system would have a way I could tell the system to go to storage mode, and somehow burn Ah's to get to 85%, or 50%, or whatever I tell it - maybe hearting water - like the ocean?

I don't worry much about the SOC during the season. If I am running by fridge, I will set the float at 13.4v and forget it. To bring it back to full charge before a cruise, I just need to turn off the charger and restart it to put it back into bulk to top it off.
When I am ready for long term layup, I will run the fridge without charger and set the BMS low voltage cutoff for 3.325v which is just a bit higher than the cells were when I received them and let them discharge. After it shuts off, I will turn off the BMS which is equivalent to disconnecting the ground wire and let them sleep happy. I have leads to switch my emergency bilge pump to the AGM start battery during storage so the LFP will be unneeded.

 

[jviss]

If I can manage the height, the length and width are no problem. I have plans to break out the existing glassed-in wooden strips defining the battery boxes in the bottom of the hull (under the aft bunk) and building new, to accommodate the LiFePo4 bank of my dreams.

 

[Hayden Watson]

If I can manage the height, the length and width are no problem. I have plans to break out the existing glassed-in wooden strips defining the battery boxes in the bottom of the hull (under the aft bunk) and building new, to accommodate the LiFePo4 bank of my dreams.

The other thing to consider is do you need a 2p4s 560A bank like mine or would a 4s 280A battery give you all you need. My boat is an energy hog with a complex multizone hydronic system, built-in 12v icebox conversion and 52qt 12v deep freeze plus the normal lights and electronics. In spite of that, I never dropped below 70%SOC in a week long cruise with 6 aboard.