Some things just won't sink in.

[Mrjmegson]

I'll start by saying sorry for this question.

Some things just don't make sense to me.

My batteries came today. Yay. They came with battery cables, the type used with Pylontech, so seriously thick ones, and they also sent me a few meters of what I think is 12mm² cable, which I assume they intend for me to use between the battery disconnect and inverter, however, the inverters use MC4s to connect the batteries, which only take a max cable size of 6mm², so these cables don't fit at all.

Anyway, with this cable dilemma, I decided to work out what size cable I needed. This is how I went about it.

The max charge/discharge rate of the batteries is 50A, as I'm connecting them in parallel, this increases the Amps, which I took to mean, 5 batteries connected in parallel at 50A a battery, would mean 250A, at 51V. So when I put that into a cable calculator, it said I needed 70mm² cable.

So that's clearly not right.

Can someone try to explain this to me?

 

[johnb2713]

Whats the capacity of the inverter and the maximum input voltage on the DC?

 

[Murdoch]

Ask the people that sold it to you?

 

[Andy1733]

If your setup is SIM to mine then You need to use a isolator between the battery's and Inverter so the cable that connects to your inverter should have a connector that came with your inverter on one end and a crimped fitting on the other. And the cables that connect to the battery's should have the battery connector on one end and crimped on the other.. then between them it should go into a isolator like the Kato ones.
I will send a video of mine as ref.

 

[Andy1733]

Kato isolator

https://www.itstechnologies.shop/products/keto-battery-disconnector-with-80a-fuses-32-50-vat

Battery cable with crimped ends

https://voltaconsolar.com/batteries...duMscAxxc_s65MmZzMlTa1q0XiqXSKwsaAvKYEALw_wcB

Inverter cables

 

[Andy1733]

 

[Mrjmegson]

Ask the people that sold it to you?

I have. They just ignore that question.

 

[Murdoch]

I have. They just ignore that question.

Leave them a very negative review.

Companies selling this stuff should be able to give basic guidance

 

[Mrjmegson]

Whats the capacity of the inverter and the maximum input voltage on the DC?

Here's the inverter spec. Figured it would be best to post the image from the manual. Mine is the 6kw on the right.

Cheers.

 

[Mrjmegson]

View attachment 14249View attachment 14250View attachment 14251

Andy, cheers for that. My inverter is like yours, it uses MC4 connectors for the batteries, so I'm limited to 6mm² cable.

My worry is that the 5 parallel connected batteries will output more than the 6mm² cable can take, especially as the company have provided the 12mm² cable (not the actual battery cables you've linked to, the 12mm² is separate to those).

 

[Mrjmegson]

Searching for the current rating of 6mm² single strand solar cable gives results from 50-70A Max. But of a difference.

My inverters have a max of 80A.

 

[Andy1733]

Andy, cheers for that. My inverter is like yours, it uses MC4 connectors for the batteries, so I'm limited to 6mm² cable.

My worry is that the 5 parallel connected batteries will output more than the 6mm² cable can take, especially as the company have provided the 12mm² cable (not the actual battery cables you've linked to, the 12mm² is separate to those).

Won't the inverter company only supply cables adequate for the inverter DC input. IE 6mm Binky is the man to confirm

 

[Sharpend]

Won't the inverter company only supply cables adequate for the inverter DC input. IE 6mm Binky is the man to confirm

I think he’s taller than that?

 

[Mrjmegson]

Won't the inverter company only supply cables adequate for the inverter DC input. IE 6mm Binky is the man to confirm

You'd think wouldn't you.

They told me they would provide the battery link cables, and the cables to the isolators, as well as the isolators themselves, which they did.

But they also provided this random cable, and a Chint DIN surge arrester, neither of which I requested, or was told about, or feel I can use.

Very strange.

Binky is actually 5.8mm, but rounds it up to 6mm.

 

[johnb2713]

Searching for the current rating of 6mm² single strand solar cable gives results from 50-70A Max. But of a difference.

My inverters have a max of 80A.

I thought the maximum rating of MC4's was 50A which is inline with your 6mm2 cable size but not with your inverter capacity requiring 80A?

 

[binky]

Andy, cheers for that. My inverter is like yours, it uses MC4 connectors for the batteries, so I'm limited to 6mm² cable.

My worry is that the 5 parallel connected batteries will output more than the 6mm² cable can take, especially as the company have provided the 12mm² cable (not the actual battery cables you've linked to, the 12mm² is separate to those).

Output from the batteries is controlled by the inverter. You could have 10 batteries, but the output will be the same.

 

[binky]

Searching for the current rating of 6mm² single strand solar cable gives results from 50-70A Max. But of a difference.

My inverters have a max of 80A.

80A for how long?

 

[johnb2713]

Output from the batteries is controlled by the inverter. You could have 10 batteries, but the output will be the same.

What about under fault conditions????

 

[binky]

Won't the inverter company only supply cables adequate for the inverter DC input. IE 6mm Binky is the man to confirm

Not necessarily, most of the batteries I've fitted use solar cable, which has always seemed rather odd given the size of the cables they supply for the batteries themselves.

 

[binky]

What about under fault conditions????

That's what you're inline fuses are for, to prevent overloading the cables.

That's why I'm not keen on batteries without inline fuses.