Agreed, the current those small black wires will surely cause havoc and not vaporize if a short develops
What gauge wire and fuse for 48v battery and 48/3000 inverter
- Thread starter beowulf
- Start date
Those little wires though look like they power something like the cerbo OR they are the small wire that comes with the Distributor? I think I saw one in mine.. and I thought I saw some "hack" to enable the LEDs or something. In fact I bought something from amazon per a video that shows how you "fix" the issue of the LEDs not working when not connected to a shunt or something. I will have to find that video now. That is anyway what I thought that small black wire was for.
Brucey
Solar Wizard
Looks like they are running to a tire pressure monitor box. Doesn't have the circuit board with LEDs that the distributor has
So an odd slightly off topic but in line with my wiring questions.. when I connect my battery (which is charged to 56.3v right now) pos/neg to the victron (via distributor).. I assume that it wont spark/etc cause I'll have that switch in line and turned off. But once I flip it on.. does the battery essentially power the victron? What if the battery was basically dead? Would it use the AC IN to power it? I am guessing it only is powered by the battery +/- wires whatever those are attached to and the AC IN has no bearing on the unit turning on since that is optional and programmable?
Alarchist
New Member
The contacts of the switch will spark when turned on if you haven't used a pre charge resistor to charge the inverter capacitors first.
Multi's/Quatro's will power up from the battery being connected, but they can stay on powered by AC in without it.
So.. is that BAD if they spark.. is it yet another thing we DIYers should know how to do.. e.g. pre-charge resistor thingy? Or is that just some knowledge some pick up along the way but it wont affect anything? I am guessing the spark is IN the 48/3000 unit itself.. or is it at the switch.. any danger to worry about?
So can I lay the unit flat? I have a shelf I want to put it on. I can't mount it on wall or anything. Does it get hot? I have this sort of plastic liner (not sure its plastic but came with my cheap 4 shelf metal 2x4 shelf that I got at Costco for like $60 or so) that covers the "gaps" on each shelf (made of thing metal design). Not sure if I can lay it flat on this.. if it gets really hot on the bottom of the unit, etc?
Long story short, I need to sort of "hide" this from the wife.. she blows up when I spend money (dont ask.. long story) so trying to put this and my rack battery in a location not easily seen. The rack battery I assume is fine since you can put several of them on top of one another. I can wire up some 12v fans if need be to blow across the units if that helps. But basically the 48/3000, distributor, switch, cerbo gx and the 48/24 DC/DC (if I can use it) will be on a shelf and the battery on the shelf below about 1 foot or so apart. Plan on running about 2 feet of wire at most from distributor to battery and so forth.
Alarchist
New Member
Please read the Multi manual.
It will not disperse heat as well when mounted horizontally, depending on if you have any regulations or codes to comply with, normally electronics like this should be mounted on a non flammable surface (cement board etc), but many just mount on wooden ply.
Large enough battery banks and certain BMS's can cope with the inrush an inverter takes, but it can trip and stress the BMS if they're too small, and constant switch arcing if turning on and off regularly will also cause pitting and eventually a poor connection or weld together. There is no DIY manual, we've all had to read up and ask questions, but there is a good resource section here, and Victron docs are comprehensive and need to be read thoroughly before installing anything.
P.S. Leave your wife now, if you think you can hide a whole inverter and battery system from her.
Brucey
Solar Wizard
I think it was Dexter from current connected who had posted about how he upgraded his office/server ups, basically tucked a multiplus on the back of a cabinet with a rack server battery. That was vertical.
That is basically what I am doing, but horizontal as my shelf where it will go isn't tall enough between shelfs for it to fit vertical and definitely not able to be mounted. It's temporary too.. few months or so that's about it. Then I plan on moving it to a portable stand of some sort. The battery itself is long so I'll need some longer dolly like setup for it to be portable. At any rate, ideally I want it all mounted in the garage and power everything, but things are a bit chaotic right now so not sure wth the future holds.
S Davis
Solar Enthusiast
- Joined
- Sep 25, 2021
- Messages
- 607
I am laying a 12/3000/120 flat in a tight spot and I am installing a ventilation fan to exhaust the heat.
I just bought two server racks and put them in the garage “for a work project” if I leave them there long enough she won’t notice when they start filling up
Love it! Yah.. in my case they are in a ventilated area so should be fine. But I have a few fans I can wire up if need be. Eventually the goal is to move all this in to a garage and set up whole house storage/etc. But for now its just starting out. Build it little by little.. given the costs of all this. Supposedly the sodium ion batteries will start to be mass produced by next year and should be 1/3 the cost of LFP for similar storage capacity, but we'll see.. famous last words right?I am laying a 12/3000/120 flat in a tight spot and I am installing a ventilation fan to exhaust the heat.
View attachment 202109
I just bought two server racks and put them in the garage “for a work project” if I leave them there long enough she won’t notice when they start filling up
View attachment 202110
yabert
Solar Enthusiast
That usually true for large capacity battery pack (let say 280Ah or more) or highly powerful cells.
Here we are talking about 74 Ah cells who would give 2000-3000A during a short.
The Mega HP fuses are rated to break 2500A @ 70Vdc, so a bit more at 51V (around 3800A).
There is also the AMX fuse rated to break 8000A at 63V as a safer and good low cost choice (8$).
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So these LEV60 cells claim up to 600a of peak output (or input?) I think. It's been a damn long time since my electronic class in HS, so I cant remember if you have 16 of them if that multiples, stays the same or what lol. But assuming I will be building a 2nd one soon (have everything but the cells right now), I plan to run two of them.. hopefully I just add it to the second one (e.g. parallel the pos/neg wires) and it all works righty tighty with the victron setup. But if there is a concern that 1, or more so 2 can push too much amperage definitely rather error on the side of safety. That said, with the AC OUT running a couple computers/office stuff, I wouldn't think it would ever push (at least that path) past 25a. From the inverter to the battery how would it ever pull more than the 100a the BMS on each unit (once I run 2) use? Does that mean running 2 in parallel will pull up to 200a of power?
When you say break at 8000A.. is that that way above what could happen in my setup and thus I'd want to much lower to ensure no overload to the BMS on each of the batteries? Man.. insane how much I still have to learn and memorize with all this.
FWIW the Bussman 185 and 285 spec sheets say they are good to 48V, not above.
You will hear they are good for to 48V nominal LiFePO4 charge voltage but again, the spec sheets do not say that.
So that means a 48v pack that is 56v max is too much for those? I would rather go with better fuses.. I suspect they seldom if ever blow anyway. But definitely want something that isnt going to blow/trip when my battery is charged up to 50+v.
I would suggest Midnite for breakers then. Good to 150V if I recall correctly.
You’re talking about AIC.
Here is one thread about it :
Calculating AIC for fuse selection.
Folks, As we get bigger capacity LiFePO4 cells and then put them in parallel, the internal resistance is going from very small to crazy small.... That means the fault current it getting crazy high. Has anyone seen a good analysis of how to calculate the AIC (Amp Interrupt Capacity) needed...
diysolarforum.com
yabert
Solar Enthusiast
This is without damaging cells during a discharge of 10 seconds.
During a fraction of second short circuit, the amps can go very high (2-3kA). Hopefully, the fuse will blow and stop the short or the wrench, who caused the short, will melt then stop the short circuit
Keith Andrews
New Member
I'd say you're on the right track with the 2 AWG cable for your setup. Since your BMS is 100A and the distances are short, it should handle things fine. For the inverter, considering the 3000W max output and the short distances involved, 2 AWG seems like a solid choice. If you ever upgrade to include more batteries or solar, you can reassess then if you need to beef up the wiring.
So in terms of adding my 48v to 24v dc to dc inverter.. or.. converter.. is that wired up to the distributor as well? Or would that come directly off the battery? Unsure where that goes now in this setup so I can power (charge) my river 2 pro 768wh unit.
