Battery to busbar to Multiplus 12 300w, wiring help needed

I'm getting very confused by my internet research, by my calculations to get the max draw from the batteries to the busbar 700a to the invertor and the 12v system is roughly 600a so my cabling needs to match that the the busbar. Is this correct. So 120mm2 cable or would running two 90mm2 cables be better advised or at risk from melting...

The rest of the system is in place and just confusing myself with this last little bit... undoubtably the most important which is why I am 2nd guessing what I am researching.

If anyone can help that would be great

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Besides the inverter, do you have any other loads?

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yes 12v system max which is max of 100a.

This is more a question on the cable coming from the battery bank to a bus bar which would then feed the rest of the system. I have seen wiring diagrams which use the same spec cable that would go to the 12v MP which can't be right, can it?

In my head, this cable should be spec'd to handle all possible pulls from the battery bank. Would I be correct in thinking that?

Sorry for the confusion :)

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You still have not clarified the inverter model...

klim8skeptic

sorry 12v 3000w – 16a

Look at the chart I uploaded.

klim8skeptic

I've already got cabling to the MP I'm trying to work out what cable needs to go from the battery to the bus bar, before the MP. If you see what I mean.

Do I need to factor in the pull of the 12v which is seperate to the MP which is only supply 240v (uk)

Hi @CeeCee

There is multiple ways to work this out, but a quick solution is always to match your busbar area with your cable area.

Just take you need to derate your cables if you have multiple cables in parallel, this is because if they are kept close together they will heat eachother up... And I highly doubt you are going to space your power cables 100mm apart. So to explain if you need 100mm^2 , you cannot use 2x50mm^2 cables, You need to probably use 2x70mm^2.

I hope this helps.

Regards Ewald

You seem to have missed the point regarding the tables I have posted.

You can go up to 5m (one way) with 2 x 50mm sq cable per DC pole BEWTEEN the battery and multiplus, and still be within recommendations.

If your battery cables between the battery and multi should exceed 5m, thicker cabling would be required.

ALSO if you had more than ONE multi connected to your battery, you would need proportionately thicker cabling between the battery and buss.

klim8skeptic

How much thicker from battery to bus bar as this is what I'm trying to find out. Twice as thick to take both MPs current if both are on?

You have 2 x multiplus?

klim8skeptic

no but the load form the 12v system and the 240v MP is what I am trying to workout what cable size I need from the Battery to the busbar only, for distribution. If you see what I mean.

klim8skeptic

Yes please :) All the other cables are in place so my question is should cable ( battery to busbar/lynx distribution) be super beefy to cover all expected loads. This is what I believe it should be.

If you were to use 2 x 70mm sq cable per DC pole between your battery and DC buss, that would cover your inverter current, and 100a DC loads.

If your total distance between your battery and inverter goes over 5m (one way) you can go thicker.

klim8skeptic

Thank you :)

Your title and questions are not clear.

You have a 12v multiplus, with an output of 3000w? AC voltage???

You can search Victron Products, for manuals for your particular product.

As to if your 2 x 170ah batteries are able to withstand 600a drain, dunno.

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