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Tools & equipment needed for first battery build

Abromavich

I know this has been asked somewhere but I cant find which thread…

Im going to order battery box today. Can anyone advise any tools & parts such as cables/busbars/breakers etc. that are needed for the battery build. Im planning on 3 battery boxes (15kwh each):

https://www.alibaba.com/product-detail/YIXIANG-V2-BOX-New-Design-15kwh_1601281929575.html?spm=a2756.order-detail-ta-ta-b.0.0.5f37f19cAMjlN4

I think everything is included in for the battery itself in the above box (ordering cells seperately) but please advise other components for putting these in parallel with busbar and connection to inverter.

Thanks a mil!

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graememk

Multi meter, cable, cable lugs, heat shrink, busbar (pricey but the victron lynx power in(unfused) or distributor(fused) is very good)

Hydraulic crimp tool, small torque wrench (if you don't have a calibrated arm 😜)

Cable lugs are numbered say 50-10, first number is the cable size in mm², second number is the size of the hole in mm.

Abromavich

Thanks a mil!

So this busbar can take up to 4 batteries fuses can be added:

https://eu.nkon.nl/victron-energy-lynx-lyn060102000-dc-distributor.html

What fuse size would be ideal:

https://eu.nkon.nl/search/power-supply/48v?q=fuses

For the lugs and cables, 2 each needed for each battery. What size is best?

graememk

https://www.boards.ie/discussion/comment/123111811#Comment_123111811

Fuse size is determined by cable size, (fuses protect cables)

Cable size is determined by current draw.

Whats the current draw?

Abromavich

https://www.boards.ie/discussion/comment/123112208#Comment_123112208

Of course, that makes sense.

The Inverter has a max battery charge/discharge rating of 250A. So I will need a cable between the inverter and busbar rated for 250A - 70mm2 copper cables? Does this cable normally come with the inverter?

I am paralleling 3 batteries so I assume that equates to a max of 80A per battery. So I would need 3 sets of 83A rated cables - 25mm2 copper cables?

Manual specifies 55mm2 copper:

oaklands

Consider the case when 1 or 2 batteries are offline temporarily. You could get the full Amps going in/out of 1 battery unit. However, the BMS should have a setting for the max charge/discharge amps.

slave1

Why 3, is there not 50kWh cases on wheels available now?

oaklands

I got one of these recently…pretty solid with M8 nuts.

I cut the busbar in 2 and used it to fuse both Pos & neg cables. This should be better than daisy-chaining the 2 batteries.

with 3 fuses (1 pos, 1 neg &1 spare) came to 107 euro delivered from NKON.

graememk

https://www.boards.ie/discussion/comment/123112977#Comment_123112977

There you go, possibly 60 or 70mm2 cable.

And Oakland has a valid point, the batteries themselves can pump out 200 amps, while they will likely only see 1/3 of it, you need to account for 2 of them offline, so would run the same cable to each battery and fuse accordingly.

Inverter is likely a 10mm bolt.

oaklands

ooops forgot to post the link earlier (post #8 above)

https://eu.nkon.nl/victron-zesvoudige-zekeringhouder-voor-mega-zekering-met-busbar.html

Abromavich

https://www.boards.ie/discussion/comment/123113122#Comment_123113122

I think the biggest accomodates 16 prismatic cells so yeah 15kwh is the biggest DIY case

Abromavich

Thanks so, just stick with the 60mm2 copper cables for everything. Makes sense as I get your point with batteries going off line.

I'm unsure the best way to wire 3 batteries to avoid different discharge rates. I understand daisy chaining is bad. Can you please elaborate on you setup?

Also is this busbar superior:

https://eu.nkon.nl/victron-energy-lynx-lyn060102000-dc-distributor.html

graememk

https://www.boards.ie/discussion/comment/123113420#Comment_123113420

Everything to a common busbar eg inverter, batteries etc.

(Not that it really matters but it's the proper way to do it)

https://youtu.be/n1F0IhkxdHI?si=MKFBmr_l0uWzqB3C

Abromavich

Thanks - very informative video.

For the distributor, would below be the setup. Would you go with 300A fuses?

Ill use 60mm2 copper for everthing

graememk

https://www.boards.ie/discussion/comment/123113671#Comment_123113671

Red actually goes to the lower nut, with the fuse to the main bar

Abromavich

https://www.boards.ie/discussion/comment/123113722#Comment_123113722

Ah ok. So this is ideal way to wire it? Keep all cables the same length and no need for direct wiring between the batteries as they are connected through the busbars? Equal current should charge/discharge to/from the 3 batteries with this setup?

Abromavich

Have ordered 48 x Eve MB31 cells (314Ah) from Nkon - ships end of the month. Ill likely order 3 of the YIXIANG V2 BOX - unless anyone can recommend something better.

Please critique my planned setup. I plan on 70mm2 copper wiring.

My logic is as follows:

Max inverter charge/discharge is 250A
3 batteries paralleled so nominal current is 83A max for each battery
If one battery goes offline then the other 2 batteries have max 125A current each.
If 2 batteries go offline, I will have a limit of 150/160A on all BMS.
If the software 150A limit somehow fails then the BMS is hardware limited to 200A and failing that, the 200A megafuse on the battery will blow.

The battery boxes come with 250A breakers installed. The inverter will have a 250A megafuse (in the lynx). What should be used for the breaker for the inverter - Jean Muller breaker or is this even necessary?

SD_DRACULA

That's basically exactly what I have right now (but I have the lynx power in not the distributor) and will add a fourth pack shortly.

Only thing "not right" in the diagram is that the mega fuses go on the + not the -

Also you will need to double up the +/- cables going from the JM to the inverter or it will trip at 200a (speaking from experience) doesn't mention it in the manual iirc.

I just doubled up the 70sq cables between inverter and JM and has been solid since.

But good luck bending 4 x70sq cables 2 times around that magnetic ring 🤣

Abromavich

https://www.boards.ie/discussion/comment/123228462#Comment_123228462

Ah so the current from JM to inverter is split. Is it necessary to always have the current split going to the inverter (i.e. 200A breaker inside inverter)?

Surely it makes sense to use 50mm2 between inverter & JM if the current is split (i.e. 125A max on each wire)

Can you link the JM you use? Is this not just another fuse? Is it necessary as I will have a mega fuse for the inverter in the lynx distributor

SD_DRACULA

You only need to split it if you go over 200a charge/discharge, the inverter has 200a breakers so they will trip at over that.

I'd say skip it since you already have the mega fuses and yes the JM adds another two fuses, needed for me since I have the fuseless lynx.

It's just nice as a quick disconnect if you ever need it but you can always add a switch on the lynx + before it goes to inverter like this

I added the shunt too since with multiple packs the JKBMS soc will be useless.

Only went twin 70sq because I already had a single pair of them cables with the sunsynk so I just used the same. Twin 50sq will be plenty

Abromavich

https://www.boards.ie/discussion/comment/123228608#Comment_123228608

Thanks - this is very helpful. So I can go straight from the inverter to distributor. You reckon the distributor terminal is big enough to accomodate 2 x 50sq wires? Maybe makes sense going with the JM…

I like the shunt idea - do you feed this back to HA to monitor battery SOC?

SD_DRACULA

https://www.boards.ie/discussion/comment/123228665#Comment_123228665

Yeah the distributor block is pretty beefy, 8mm x 30mm, rated 1000a but if you get the M8 version you will need to drill out the holes to make it M10 where you connect the shunt (500a version) (or just get the M10 version of the lynx but annoyingly only the ends of the busbars are M10 holes the battery connections are still M8) or get the 300a shunt instead, I think that might have M8 bolts.

And yeah you can get the shunt data into HA easily enough with a BT proxy

Abromavich

Great thank you. Yeah I can find the 300A version of the smartshunt.

Maybe a dumb question - is it ok to put M8 lugs on 70sq wires for the battery connections? Or better to just drill out the holes to 10 or 12…

edit - just realised I should be able to use 50sq wires for the batteries as im using 200A fuses

SD_DRACULA

I'm using 35sq cables from each battery to the lynx since they are limited to around 75a each anyway.

50/70sq is overkill for such a small current.

Abromavich

https://www.boards.ie/discussion/comment/123228984#Comment_123228984

Are you worried if 2 of your batteries somehow go offline, potential for 200A (BMS limit) to one battery?

Im guessing you use 100A fuses for the batteries or something like that?

SD_DRACULA

https://www.boards.ie/discussion/comment/123229046#Comment_123229046

All packs have 200a bms and breakers and I can't see why I would need to draw 200a from one battery pack (just won't) though you could for short bursts safely, usually they are rated 210a at 105C but I would not want a cable that hot 😂

I actually have temp sensors inside my CU on various breakers, at each JM connection and inside the lynx too so if anything gets toasty I can reduce power etc.

BobMcBob

Just thought I'd show my setup, which I completed only a week ago. Deye 10Kw 3-Phase with x2 V3 Seplos, 280ah batteries. I'm not not an expert, but hopefully useful to see other peoples setup.

35mm cable from battery to 160a NH00 fuse disconnects then to busbars (cable rated 240a)

50mm cable to 300a Class-T fuse (cable rated 345a), from there to a Victron disconnect.

Would recommend a disconnect, the on/off buttons on the Seplos don't turn power off to the battery terminals. The on/off button on the inverter doesn't turn the inverter off, think it just stops it running (the screen stays on, and it still alarms if the battery is disconnected when it is turned off

not sure about the cable around the ring, was supposed to be both the pos and neg, but 2 cables wouldn't fit. Might redo but I have run out of 50/10 lugs. I have kept the charge / discharge to 80a in the inverter (is 40a each battery) as this was enough to charge on the night rate and still discharge to 10% during the day. Will increase the discharge once no longer having the heatpump working during the day.

Covers are now on, which made a big difference to the noise (the fans start at around 2-3Kw charge / discharge).

Abromavich

Thats a sweet setup!

Abromavich

https://www.boards.ie/discussion/comment/123231079#Comment_123231079

Hey Bob I think you have exactly what Im missing. Ive orderered the Victron switch - I need the T class fuse and the holder. can you send a link to yours? Are they M10? Also where did you source the 50 mm and 35mm cables?

paddy236

I've used this shop a lot for cables and dc electrical components for solar and other projects. Their products are good quality and good prices.

https://www.ebay.ie/itm/252669189277

BobMcBob

Got the class-t fuse and holder from 12voltplanet.co.uk

The busbar and on off switch are Victron and sourced from etronixcenter.com

A Victron lynx Class T power in might have been a simpler option for the fuse and busbar

The nh00 fuses , disconnect, and cable lugs from bimblesolar.com

The cables are from amazon, but the iscompany was hilltop-products.co.uk

I have relatives in the North so got the UK websites to deliver there

Had a little trouble with the 50mm lugs and the cable, was a bit loose and used a 50mm dye and 35 mm dye on the hydraulic crimper to get a good connection. Not sure if this was the cable or the crimper that was the issue.