Home made cables, watch the voltage! (uk)

[Fingers]

I've been looking on ebay.co.uk, Aliexpress and online vendors for 50mm2 cable for my battery breaker box to inverter.
Unfortunately a lack of information & disinformation is order of the day.

The cables that I have found are only for automotive batteries and low power welder cables at 50 to 60 volts! Yet look the same as 650 to 700volt cable.
The 25mm2 inverter cables that I have just bought are rated at 1000volts; if I could get those in 50mm2 I'd be a happy bunny (fat chance).

As my 48 volt battery pack operates up to 57.6v, a 50 to 60 volt cable is out of the question. I need a healthy margin for error, for peace of mind if nothing else. Here's the typical 60volt cable on ebay: Oh, before I go, if anyone knows where to get decent cable at a good price in the uk please let me know.

 

[Leeds]

The voltage rating has to do with the insulation on the outside, it has nothing to do with the wire itself.
I suspect its a very bad idea and I think it should not be done, But- I do wonder if anyone has bought a roll of shrink tubing and encased an entire length of wire to increase its insulation?

 

[Fingers]

I did think of that but, if the insulation starts to melt or burn at 60+v

 

[Leeds]

I did think of that but, if the insulation starts to melt or burn at 60+v

It's not a temperature thing, that's what current rating protects against.
This is more of a high pot thing where the insulation could cease to be effective in preventing it from shorting against any metal surfaces it's laying up against.

 

[Fingers]

For the extra few £20 -£30 I'd rather get it right with the correct item. It's just a a matter of finding it.
Anything else is just a codge job.

 

[DrJoe]

Since you are in the UK, you might be able to get NSGAFÖU cable, which is basically a german thing (made for internal wiring in buses and trains): https://products.lappgroup.com/onli...conditions/rubber-cables/nsgafoeu-183-kv.html

pros
- rated for UV/oil/ozone exposure
- tinned conductors
- spec'ed to at least 1kV
- relatively flexibel (it's no welding cable, but workable)
- wide selection of gauges (up to at least 300mm²)

cons:
- technically only rated for "dry" use
- thick insulation
- no AWG sizes

 

[Fingers]

Aha! I have seen this for sale here in the uk.
I'll re trace my web viewing steps.
I think it was a custom EV builders place in Bristol, that doesn't reply to emails lol.

Cons: No AWG sizes LOL.
Oh no! Now we will have to use those strange confusing mm things
AWG, arse wear gauge?

 

[DrJoe]

I guess its not really a problem over on this side of the atlantic :D

Oh another thing: You can't get those in red, it's gonna be black only

 

[SeaGal]

The 25mm2 inverter cables that I have just bought are rated at 1000volts; if I could get those in 50mm2 I'd be a happy bunny (fat chance).

You could always wire two of those in parallel.

... Oh, before I go, if anyone knows where to get decent cable at a good price in the uk please let me know.

We used this company... no association apart from being a customer.

Battery Cable 50mm 345amp High Quality Extra Flex Cable

simplysplitcharge.co.uk

 

[octal_ip]

Welding cable typically has very thick and durable insulation, as it's expected to be used in harsh environments. The cable in @Fingers spec sheet has PVC insulation a bit over 1mm thick, the breakdown voltage of which would be best measured in kilovolts (e.g. plasticized PVC itself has a breakdown voltage of about 10KV/mm). It would have to be astoundingly bad insulation to be a risk at 57.6v.

So while the cable is marketed at 60V, I personally wouldn't be concerned about using it all the way to its limits, and well beyond. I have two kinds of welding cable in my setup, one with a rubberized sheath, the other with PVC. Both are rated to 600V according to the labeling on the cable itself.

 

[Fingers]

You could always wire two of those in parallel.

I planed to do that but then realized, two cables per pole, and two batteries, eventually four cables per pole would have to join each other.
50mm cable means I don't have to use a pair of buzz bars.

Also unfortunately the sunsynk inverter terminals are not suited to two cable connectors.

 

[Fingers]

We used this company...

It doesn't say what voltage it is.

 

[brum]

Go with welding cable. The one I used was rated at 100V, common, flexible, and at least where I took mine they had up to 70mm2 available. The price was better than the alternatives I considered - silicone cables for car audio.

A cable rated at 60V is also perfectly fine for a 16S LiFePo4 battery. 60V means that it will have no issues at that voltage. Above that and you'll have issues with the batteries first, not with the cable.

 

[Fingers]

I personally wouldn't be concerned about using it all the way to its limits, and well beyond.

I don't want to be a goody two shoes here, but going beyond the manufacturers stated limits is well dangerous
This is mass produced junk, which is why the manufacturer has limited the use to 60volts.

 

[Fingers]

I have at last found 50mm2 100volt 228amp cables here: https://www.bimblesolar.com/extras/cable/50mm-2m-cable-M8 £60 delivered for four meters.
It's not the 1000v that I wanted but it will do.


I was quoted £140 by another company, yep that just isn't going to happen
Because of the power crisis, so many people have rushed to buy, and everything is in short supply.

 

[Fingers]

60V means that it will have no issues at that voltage.

I wonder how many inverter company cables have 60volt written down them.

 

[Delphinus]

I buy my cables here, you cant go wrong with them, EV cables seems to be welding cable in orange.
http://eveurope.nl/

 

[Fingers]

Thanks for the info.
I tried to buy two solar charge controllers through ebay from Germany, but they refunded me, saying it was just too painful and expensive to export to the uk.