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I am planning for a 48VDC 8kVA Quattro system. Battery cable length is < 2M.
Documentation I've located on the Victron website shows a recommended battery cable size for this inverter of 95 SQMM.
The Quattro has (2) M8 terminals per (+) and (-). I am assuming I can use either (1) 107 SQMM (4/0) per polarity, or (2) 67 SQMM (2/0) same length cables.
Is this correct?
This is usually explained in the manual for the particular device. This should fit you..
These are quite conservative, and at 2m, the 2x 50mm cables should perform admirably.
I had 95mm2 cables, but they are hard to handle. They don't fit in the MultiPlus (you can't get the cable lug through the chassis cable opening). So you need to clamp the lug at only one and, and then route the open end through the cable opening, and only then you can clamp the second lug. So if you ever need to do any work on your system you need to cut one of the lugs of. Not ideal.
I used 95mm2 because I figured 'I want to be able to upgrade to a max. of 15 kW, so I thought 15.000W / 48V = ~300A', but I never thought of the fact that I use a busbar and one MultiPlus is limited to 70A DC. So 95mm2 is way overkill for cabling to your MultiPlus. For 70A even 16mm2 would be fine.
I have 4 batteries, 2 in parallel, 2 in series. So I have 2 connections to my busbar. So total charging and inverter power is divided by 2 (2 batteries in parallel). So if I have 3 MultiPlus units, 3x70A = 210A. 210A / 2 = 105A. For 105A 25mm2 would be fine.
So equipping your system with 50mm2 would be plenty. Don't overdo cabling. It's very expensive and the big cables are hard to handle. 95mm2 didn't even fit in my battery (cover wouldn't close anymore)
So what you could do is:
- Use some kind of busbar system. For example, I use a MG Master LV.
- Use 16mm2 or bigger to your MultiPlus units from the busbar. 50mm2 if you want to minimize losses. Don't use 95mm2, it doesn't fit.
- Use 50mm2 to/from your batteries, connecting parallel batteries on a busbar.
What huge lugs do you have?!
We use 95mm² with 12/3000VA Multis without any problems.
I use SAFAK Elektrik lugs. I don't think they are anything special. they don't unusually large to me.
I might have been mistaken that they don't fit through the chassis cable opening. But I couldn't get the lug on the M8 bolt after routing it through the cable chassis opening. It couldn't make the angle. The battery connection is too close to the chassis, so I couldn't get the cable to bend enough.
Ah ok I know what you mean now.
Yes, that can be tricky. Here in Germany you have two types of lugs one is very long and the other is shorter.
With the long one it can be difficult to get them on the M8 bolt. With shorter ones it is easier.
You also can use lugs with M10 hole instead of M8 with this it is also a bit easier.
