"It's only 12 volts" starts fires
The danger was never the voltage.
The danger was never the voltage.
Twelve volts won't shock you through dry skin, and that fact has convinced a lot of people a 12V system is harmless. It's the most dangerous misunderstanding in DIY off-grid.
A dropped wrench across two terminals doesn't give you a tingle. It gives you an arc flash, molten metal, and a fire in under a second.
The non-negotiables:
Fuse every positive conductor as close to the battery as physically possible. The fuse protects the wire, not the device. Any unfused length between battery and first fuse is a bomb the length of that cable.
Size wire to current AND length. Undersized wire doesn't trip anything — it heats up inside a wall where you can't see it.
Use the right fuse class. Every fuse has an interrupt rating: the maximum fault current it can safely break. A cheap blade fuse facing a lithium bank's fault current can arc internally instead of clearing. Class T exists for exactly this.
Take off the metal. Rings, watches, bracelets. Tape your wrench. One terminal at a time.
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