Battery short circuit protection?

[SJ-Chris]

I've been working on a solar system and 2000w inverter install. Lots of wiring. Lots of heavy duty cables (inverter to batteries). I've also got a battery monitor set up which uses heavy duty cabling. It got me to thinking....What is the potential danger of shorting the 12v battery(s) and how can it be prevented. In the back of my mind, I'm always thinking about the potential bad scenario of accidentally touching Pos to Neg (or someone else accidentally doing this somehow) and creating a disasterous short circuit. I try to be extra careful. So far, no issues.

It made me wonder if I should install a large fuse at the battery terminal for each of my 2-3 coach batteries. At least this way, if me (or someone else) accidentally shorted across the battery at the inverter or anywhere else there would be some protection.

So I was trying to think about how large of a fuse I would want/need. During a 12v lead acid battery short. Does anyone know approximately how many amps are flowing in that sort of scenario?

On one of my RVs I have 3 batteries (installing the 3rd now). I was thinking about installing something like this on each battery:
https://www.amazon.com/TopstrongGear-Solid-Brass-300Amp-Holder/dp/B07XRLN8JY/ref=sr_1_1_sspa?dchild=1&keywords=battery+terminal+breaker+400+amp&qid=1615193884&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUExU09CVjRBNDJUVjJCJmVuY3J5cHRlZElkPUEwMTM1NzA4M1cyNzZFRkxKRlVUQyZlbmNyeXB0ZWRBZElkPUEwODgzMDI4MlU1RjRLNlIzVlBMNSZ3aWRnZXROYW1lPXNwX2F0ZiZhY3Rpb249Y2xpY2tSZWRpcmVjdCZkb05vdExvZ0NsaWNrPXRydWU=

My RV (2015 Thor Magestic 28a) does have an Emergency Start switch (in case the chassis battery dies/etc) so it is possible that the coach batteries would be used in that scenario to start the engine. Does anyone have any idea how many cranking amps in general the v10 Ford e450 uses?

What are your thoughts? I try to be overprotected and put fuses anywhere that has the potential to be dangerous. I'm always on the lookout for ways to avoid potential problems.

Let me know your thoughts.

Happy (and safe) camping!
Chris

[Old-Biscuit]

POS Cable from battery bank to the RV should already have a DC Fuse or DC Circuit Breaker close to the batteries

That will trip if battery AMPs exceed the fuse/CB rating

Individual on each battery not necessary

[2oldman]

Shorter link so all your post can be read without scrolling.

Not sure someone would hook up a battery using cables as a dead short, but dropping a wrench can be a disaster.

[ndrorder]

Fuses are selected based on the wire size and expected loads, whichever is less. Any short circuit will result in higher amperage through the cables and will blow the fuse.

For example, you mentioned a 2000W inverter. However, most inverters will tolerate some level of surge. If 2000W is the surge capacity, divide by 12V and get 167A. So a 175A or 200A fuse would be about right. If there are more loads on the cables, add that amperage to the 167A and find the next higher fuse.

Now take the fuse size along with the cable run distance to one of the many online cable size calculators to determine the appropriate cable size.