Extending battery array - levelling charge

[xanld]

Sounds like a plan, if running 4 x 3.3 batteries are you going to run two double battery cable runs? I seem to recall the cables are available with 2 batteries or 3 on a single connection to the inverter.

Have you already added any batteries to get it to its current status?

So no, three batteries were installed by the installer and I'm looking to add a fourth. Thank you for raising the point about connections. This is hopefully the last thing I'm looking to get absolute clarity on before proceeding.

You're right that the existing three batteries connect together with an inline connection, and I can't simply add a fourth. The installer said that to add a fourth you connect with a junction box. Attached is a page from the manual which also confirms this.

The parallel battery cables are 16mm2 and they connect to a common inverter cable which is 25mm2. I was hoping there would be explicit spec in the instructions, or that the battery would be supplied with cables or that there would be an obvious cable pack available for this extension, but it appears that none of these things are true.

Nonetheless, it appears pretty clear that connecting four 16mm battery cables into the existing common 25mm cable to the inverter via a junction box is the way to go. Am I right that the load in these cables will not be any higher when I add a fourth battery, it will be the same charge/discharge current distributed across four batteries rather than three?

I was planning on using a couple of these 300A bus bars as junction boxes, one for positive and one for negative.

I am still waiting for advice from the battery supplier on this, but I believe all I need is the two bus bars and two extra 16mm2 cables with the radsok connectors, plus the data patch cable.

Any further advice or confirmation welcome.

 

[xanld]

See attached SPH6000 inverter instructions. There is only one battery terminal on the inverter.

 

[yozhughes170]

You could wire the batteries in two pairs using two twin connecting leads, the inverter will take two cables

 

[xanld]

You could wire the batteries in two pairs using two twin connecting leads, the inverter will take two cables

Good shout. So 4 x 16mm2 into 2 x 25mm2 into the positive terminals on the inverter, and the same for the negative.

The "Two Holes" gland currently takes a single positive and single negative 25mm2 cable, I'm not sure I can get 4 x 25mm2 cables in this (2 for positive and 2 for negative), even if the terminals inside can take two cables each.

Either way, it sounds like this is a physical issue, and connecting the 4 x 16mm2 into 1x 25mm2 via a 300A bus barinto the positive terminal inverter, and the same for negative would achieve the same thing.

 

[yozhughes170]

I have at present 2 batteries and both are wired separately to the inverter, each terminal can take two ferrules. Just alter the gland if need be

 

[xanld]

I have at present 2 batteries and both are wired separately to the inverter, each terminal can take two ferrules. Just alter the gland if need be

Thanks. Presumably I could bote a couple of extra holes in the gland.

I already have the busbars, but could return these if your suggestion is cheaper/better/simpler/necessary. Unless there's a reason not to, I'd probably just stick with my plan using the bus bars.

Do you have a link to the connectors you'd use to couple each pair into the single cable?

 

[yozhughes170]

This link was posted by someone else
https://www.tradesparky.com/solarsp...rowatt-65kwh-cable-2-way-2cat-for-2-batteriesOr another idea that was suggested to me by an electrician was to connect your batteries to a Henley Block and then to the inverter, so you could use your existing 3way cable and a additional single from your new battery

 

[xanld]

This link was posted by someone else
https://www.tradesparky.com/solarsp...rowatt-65kwh-cable-2-way-2cat-for-2-batteriesOr another idea that was suggested to me by an electrician was to connect your batteries to a Henley Block and then to the inverter, so you could use your existing 3way cable and a additional single from your new battery

Thanks again for your thoughts.

What's the difference between a Henley block and one of these 300A BusBar Boxes: https://amzn.eu/d/9NiJCAw, which is what I have?

I could retain the existing 3way connection, but I'm not sure the point if I just connect the 4 batteries individually into the bus bar?

 

[xanld]

Thanks again for your thoughts.

What's the difference between a Henley block and one of these 300A BusBar Boxes: https://amzn.eu/d/9NiJCAw, which is what I have (not yet installed)?

I could retain the existing 3way connection, but I'm not sure the point if I just connect the 4 batteries individually into the bus bar?

 

[karlboldy0]

So no, three batteries were installed by the installer and I'm looking to add a fourth. Thank you for raising the point about connections. This is hopefully the last thing I'm looking to get absolute clarity on before proceeding.

You're right that the existing three batteries connect together with an inline connection, and I can't simply add a fourth. The installer said that to add a fourth you connect with a junction box. Attached is a page from the manual which also confirms this.

The parallel battery cables are 16mm2 and they connect to a common inverter cable which is 25mm2. I was hoping there would be explicit spec in the instructions, or that the battery would be supplied with cables or that there would be an obvious cable pack available for this extension, but it appears that none of these things are true.

Nonetheless, it appears pretty clear that connecting four 16mm battery cables into the existing common 25mm cable to the inverter via a junction box is the way to go. Am I right that the load in these cables will not be any higher when I add a fourth battery, it will be the same charge/discharge current distributed across four batteries rather than three?

I was planning on using a couple of these 300A bus bars as junction boxes, one for positive and one for negative.

I am still waiting for advice from the battery supplier on this, but I believe all I need is the two bus bars and two extra 16mm2 cables with the radsok connectors, plus the data patch cable.

Any further advice or confirmation welcome.

How are you getting on with this?

I’m about to press buy on a couple of batteries and the cable pack to connect 3 up on one string.

From chatting to growatt the additional batteries above 3 on one string is to add another string and match. Eg connect 2 strings, each going to 2 batteries. Using the growatt cables you can purchase.
Surprised to hear the individual battery didn’t come with cables! You need the power and network cables for the BMS .

 

[binky]

Thanks again for your thoughts.

What's the difference between a Henley block and one of these 300A BusBar Boxes: https://amzn.eu/d/9NiJCAw, which is what I have?

I could retain the existing 3way connection, but I'm not sure the point if I just connect the 4 batteries individually into the bus bar?

Henleys are rated for 100Amp

 

[xanld]

Well I'm in limbo because tradesparky where I bought the battery from have told me that the cable pack listed on the thread above which I was about to buy is not the correct one, and that they promise to list the correct one for me soon.

In the meantime lr-renewables had a picture showing what looked to me to be the cables I needed with 2 of the 16mm2 cables with radsok connectors, plus the cat5 data cable, and without the 25mm2 cable. But this was part of their package here, and when I enquired about whether the cable pack could be supplied on its own the picture mysteriously disappeared. I will chase.

As we discussed above 2 strings makes sense, but I've already got the bus bars, so this still seems like a good option for me. It all ends up as a parallel connection to the same ports so I don't see that it matters.

But I'm waiting to see what cable pack tradesparky come up with and go from there. I'll try and chase it on Monday.

Thanks for staying in touch.

 

[xanld]

Here's the cable pack that tradesparky have just started listing which consists of 2x16mm2 power cables and the data cable. Just what I need to connect my 4th battery in parallel to th inverter via my busbars.

https://www.tradesparky.com/solarsparky/batteries/growatt/growatt-33kwh-cable-2-way-2-cat2-batt

Locked to prevent being resurrected (again)