DIY Offgrid Project – Batteries

A couple of years ago I bought a Tesla and put vanity plates on it that say OFFGRID.

Ever since then I have been trying to make the dollars make sense to install some batteries, an inverter and a bunch of solar panels in an attempt to charge my Tesla and keep my pool clean with free solar electricity.

About five readers are about to leave a comment that I don’t need a battery to achieve that and indeed I don’t but why have a simple life when I can add technology?

Recently some associates found a stash of 460 AmpHour Lithium Iron Phosphate storage cells being disposed of and I managed to get 16 which means I now have a 52 volt, 460 Ah, 23kwh battery. You can cycle these cells to 80% discharge thousands of times. If you keep them between 20% and 80% State of Charge (SoC) they should last much longer. 60% of 23kwh is still 14kwh which is more than my overnight electricity consumption.

It seemed appropriate to put the batteries in the boot of my Tesla.

LiFePo4 cells are great technology. They don’t need water and don’t produce hydrogen gas. If you over charge them or allow the terminal voltage to exceed 4.2 volts you will damage the battery and the classic failure mode is to catch fire. If you over discharge the cell, to below 2.8 volts you will damage the battery and the classic failure mode is to catch fire. I’m obviously going to need some sort of battery protection or management system.

Before the project is finished I’m also going to need solar panels, mounting frames, isolating switches, fuses, circuit breakers, an inverter and some sort of overall monitoring and control system.

I’m going to try to do as much of it myself as I can but there are some parts which will need an electrician.

Welcome to my solar storage adventure!

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