Electrical Progress

Due to a strong, cold North Easterly blowing straight at our companionway  we didn't feel like working with the main hatch open all day.

Instead, we collected some stuff from our Storage Container. Then Jane started working on the first Dyneema Chainplate Loop for the main mast. Certainly a lot more difficult with the 12mm dyneema for the main compared to the 9mm for the mizzen. More on that another time.

Meanwhile, I started on a long overdue task: creating proper wiring schematics, pretty important for an electric boat.

First, I needed to settle on what software to use. After a whole lot of browsing I have settled on QElectroTech.org, of course it is free GPL software (why would I use anything else). I'm not interested in using photos of items, coloured/labelled boxes with connectors are fine for me. It is nice a simple to create your own library of elements (eg "Victron Multiplus ii"), each with the appropriate connections. I am sure there are some shortcuts that I'm missing (eg to select multiple connector lines to change the colour together). It exports nicely as PDFs or PNGs which makes sharing easy.

Second, we got ourselves tied in knots over the battery wiring. Yesterday we got confused and in our heads re-wired the each bank as 4 batteries in parallel, they should be in series. Fortunately a follower on Mastodon put us right. That's great as we started worrying that we needed to redesign the top of the battery box and the floor levels.

Third, we revisited the battery banks yet again. For the moment we are settled on creating two 48V banks. One is from 4x12V 300AH LiFePo4 (connected in series) and the other from 4x12V 120AH LiFePo4 (also connected in series). We will connect the two banks in parallel to create a single 48V battery. While we know it isn't ideal to have mixed battery sizes but we are limited by the batteries and space that we have available. We have seen an number of articles saying that while not the optimum configuration, providing the batteries are all at the same state of charge when you connect them up, it should work for both discharge and recharge cycles. Each battery bank will be protected by a fuse, each bank will have it's own load balancing and we are adding temperature sensors to every battery (I am even wondering about adding them to key cable connectors to detect wiring faults). We have looked extensively at keeping the two banks separate and it creates a lot of complexity and expense.

Here is the latest schematic:

Lovely weather today. So back to building the Nook++