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Safety question when working with 48V/300A

wsaharem

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Joined
Jun 14, 2023
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I hope this isn't toooo stupid of a question. <sigh> I'm building my batteries and hooking them up to 2 stacked Rosies. Since I'm working with 48V and potentially 300A, when doing final connections, what is the safe approach so I don't create sparks/arcs in either wire to connections, or wire to devices? (I saw Will jump when it introduced a spark when connecting to a bus bar :) )

I have battery disconnects in the battery, 400A fuses planned for my Victron Bus bar, and 300A breakers for each Rosie Inverter, but when doing the final connections, anything I need to worry about? Should I connect negative first or positive first, then negative?
 
I have a forty eight volt system and I'm considering installing a switch on one of the negative to positive jumpers on one of the batteries. I'll hook up everything else first, then use the switch to energize the entire circuit.

But I'm also a newbie who doesn't know very much at all and has little experience. Stand by and I'll bet you get better answers from others.

I'll be watching as well. If there's a better way, then I'll be glad to learn of it.
 
The spark is from a very large inrush of current that charges a bank of capacitors in the inverter(s). You should have a switch of some sort between the batteries and the inverters anyway, just wire a precharge circuit on it. Just search for 'precharge' on the forum and you'll find all kinds of really simple ideas on how to do it. I personally use a small resistor with a small push-button switch wired across the main switch on the battery positive connection, but I've seen suggestions for light bulbs, #2 pencils, etc. Lots of way to do it.
 
I hope this isn't toooo stupid of a question. <sigh> I'm building my batteries and hooking them up to 2 stacked Rosies. Since I'm working with 48V and potentially 300A, when doing final connections, what is the safe approach so I don't create sparks/arcs in either wire to connections, or wire to devices? (I saw Will jump when it introduced a spark when connecting to a bus bar :) )

I have battery disconnects in the battery, 400A fuses planned for my Victron Bus bar, and 300A breakers for each Rosie Inverter, but when doing the final connections, anything I need to worry about? Should I connect negative first or positive first, then negative?
Stacked Rosie's, nice! I think you're a forum first, looking forward to feedback on them.

Agreed with others; open disconnects, connect everything, jump disconnect with resistor to pre-charge caps, close disconnects.
That's how I've done it with my 760ah bank, no issues.
 
Leave the disconnect open and nothing will be energized. Once everything is connected close the disconnect.

I’m new too however this sounds reasonable.

Michael
The current can be hundreds of Amps, and others on the forum have had issues with tripping BMS’s trying to connect.
It might work fine, but be aware of it if you’re having issues trying to commission the system.
 
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