Do batteries need their own breaker?

[SafetyThird]

Looking in the manual for my Luxpower inverter two which I'm connecting my Pylontech batteries, it's shown to have a 100A breaker box between inverter and battery. However, when I googled for images of LuxPower setups with pylontech, at least half of the installs I could find, including on the pages of several suppliers/installers show the batteries connected directly to the inverter. Even the YouTube video by Infinity Innovations showing how to install and setup the system shows them connecting the battery directly. So, is it optional and would having one be best practice?

Also, are batteries ok on a slate floor or would it be better to have some foam or wood between them. It's in a heated mudroom so won't get cold the way they would in a shed etc.

Edit, just found a bit in the manual that says the breaker is optional if the battery has it's own switch, which the pylontech batteries do. However, would it still be advisable to have a 100A breaker on the cables between the battery and inverter?

[Stinsy]

You don’t need a breaker on the DC side. The batteries have short circuit protection built in.

[nowty]

Arguably with the pylontechs you could just pull one of the phono plugs off the battery stack if you want an easy quick disconnect, like if you want to power cycle the inverter.

I have both a breaker (rated to 250A) and suitable sized bolt down forklift fuses on each of my three battery banks, one of which are pylontech.

Although I don't have them, a Keto fuse box gives a cheap alternative for both a fuse and breaker as they are rated up to 160A.

[cojmh]

On the bottom of Page 20 of the Pylontech manual it says:

"1) a suitable breaker between battery system and inverter is required.
2) all the installation and operation must follow local electric standard."

When I installed mine I used a Keto breaker as mentioned by Nowty. Gives a really fast mechanical way of isolating the batteries.

In my case it was also an easy way to connect the inverter specific battery cable to the Pylontech specific cables.

Hope that helps.

[SafetyThird]

Thanks all, I think I'll get a Keto breaker as mentioned, belt and braces is always handy with this sort of stuff and a fast total disconnect might one day be necessary. It's easy to just split the supplied long cable and terminate into the breaker.

Other question, will they be ok on the tiled floor or is it worth putting something underneath? They'll be on wall mount brackets for security but just resting on the floor.

[SafetyThird]

Also, inverter can charge at 3.5kw, and with a 48v battery pack that's 73A, Luxpower quote 70A. Are 80A fuses a suitable buffer or would I need to step up one. My thought was 80A would be fine but I like to check these things.

[ClockmanFRA]

I fit and use these.

[cojmh]

Also, inverter can charge at 3.5kw, and with a 48v battery pack that's 73A, Luxpower quote 70A. Are 80A fuses a suitable buffer or would I need to step up one. My thought was 80A would be fine but I like to check these things.

Is 3.5KW also the maximum discharge the inverter can do of the batteries?

I went for 100A because that is the maximum the batteries would do (although they could probably do more and even though my inverter is only 50A maximum charge and discharge. My thinking on this was that in the future if I ever needed to replace the inverter (due to it failing) then I would look for an inverter that could match the maximum charge/discharge of the batteries.

Just a thought for the future.

[SafetyThird]

Yes, says 70A is the max discharge and charge.

have decided to go for 100A as the cable is rated to 125A and I'd like the fuse to blow before that