DIY 28kw/h Storage : EVE LF280k x 32 LiFePO4 Batteries

[Pink7]

Is time to get the batteries for my DIY solar project built. There will be 2 batteries with 16 EVE LF280k and a JK 150A BMS on each battery. The LiFePO4 will be placed with the largest side down, not standing up. The rack is made and up now, its made for some airflow and for compression. I will also use some 3mm EVE foam between the cells. and also to cover some steel.

 

Pink

[Crossy]

Looking good.

 

I would have some sort of plate on top of the steel shelf elements. You need to ensure the weight is evenly spread on the batteries. Also insulate, insulate, insulate, the outer case of the cells are connected to one terminal of the battery and the blue insulation is very thin.

 

The shelves our packs are on are faced with 10mm Shera board, it's cheap, spreads the load and is insulating.

 

[Pink7]

3 minutes ago, Crossy said:

Looking good.

 

I would have some sort of plate on top of the steel shelf elements. You need to ensure the weight is evenly spread on the batteries. Also insulate, insulate, insulate, the outer case of the cells are connected to one terminal of the battery and the blue insulation is very thin.

 

The shelves our packs are on are faced with 10mm Shera board, it's cheap, spreads the load and is insulating.

 

Good points Crossy. I was considering using some white ceiling boards/plates i have from build home, but i might get something stronger then. I plan to isolate all steel with 3mm EVE foam glued on the steel.

 

Pink

[Crossy]

3 minutes ago, Pink7 said:

Good points Crossy. I was considering using some white ceiling boards/plates i have from build home, but i might get something stronger then. I plan to isolate all steel with 3mm EVE foam glued on the steel.

 

Yeah, I think the ceiling stuff will be too compressible.

 

Foam should be fine, but don't use it as insulation that's in contact with live parts. I've seen some foams that are slightly conductive and can actually get hot at 48V!

 

[Pink7]

11 minutes ago, Crossy said:

 

Yeah, I think the ceiling stuff will be too compressible.

 

Foam should be fine, but don't use it as insulation that's in contact with live parts. I've seen some foams that are slightly conductive and can actually get hot at 48V!

 

I will be use shrink tube on all connectors. The front Im plan to use clear acrylic sheet. I want visibility to easy see all ok.

 

Pink

[Crossy]

1 minute ago, Pink7 said:

I will be use shrink tube on all connectors.

 

Also, put heat shrink on your spanners, socket ratchet etc. We all drop stuff and it gets very hot very fast even on one 280Ah cell!!

 

[Pink7]

3 minutes ago, Crossy said:

 

Also, put heat shrink on your spanners, socket ratchet etc. We all drop stuff and it gets very hot very fast even on one 280Ah cell!!

 

I will, thanks Crossy

 

Pink

[degrub]

I would vote for the Shera board for insulating as well. Non-combustible, which can be important around batteries and wiring. EVA foams melt at moderate temperatures (130 - 200 C)  and are combustible if exposed to flame.

 

Polycarbonate sheet should be better than acrylic due to its  scratch resistance, higher melt point,  and impact resistance,

 

[Seeall]

What a great topic, and I am impressed people contibuting..  but batteries are expensive and loose their charge capacity, as for CN batts.. we all seen how rubbbish most are...  so what on paper looks like a good plan, comes crashing down when need to replace the batts 5 x more than you planned....

but its still a great topic..  and yes, sure, some have no choice but off grid...  so hopefully if people find good products they share it here...  I heard the indian solar parts are better than CN ... all the best ye all...  thanks

[Pink7]

3 hours ago, Crossy said:

Looking good.

 

I would have some sort of plate on top of the steel shelf elements. You need to ensure the weight is evenly spread on the batteries. Also insulate, insulate, insulate, the outer case of the cells are connected to one terminal of the battery and the blue insulation is very thin.

 

The shelves our packs are on are faced with 10mm Shera board, it's cheap, spreads the load and is insulating.

 

Do you have a link to the shera board?

 

Pink

[Crossy]

17 minutes ago, Pink7 said:

Do you have a link to the shera board?

 

We've used several flavours of similar stuff both with and without the "decor". This one happens to be in-stock (it's actually conwood, same-same). For a shelf install it with the decorative side down so you get a nice flat surface.

 

[Pink7]

3 minutes ago, Crossy said:

 

We've used several flavours of similar stuff both with and without the "decor". This one happens to be in-stock (it's actually conwood, same-same). For a shelf install it with the decorative side down so you get a nice flat surface.

 

Great, Thanks for that.

 

Pink

[JBChiangRai]

Are you going to connect your 2 batteries in parallel?

 

Cable lengths to each inverter need to be identical.

 

Charge your packs separately to exactly the same voltage before joining them in parallel or you will have a massive equalisation current that will goose your BMS’s (ask me how I know)

[Pink7]

27 minutes ago, JBChiangRai said:

Are you going to connect your 2 batteries in parallel?

 

Cable lengths to each inverter need to be identical.

 

Charge your packs separately to exactly the same voltage before joining them in parallel or you will have a massive equalisation current that will goose your BMS’s (ask me how I know)

Yes they will be paralleled at the inverter side of the battery breakers.

 

Pink

[Bandersnatch]

On 4/12/2023 at 1:49 PM, Seeall said:

batteries are expensive and loose their charge capacity, as for CN batts.. we all seen how rubbbish most are..

“We all seen how rubbish most are” can you post what batteries you are using. My nRuit LFPs have a 6,000 cycle life and I haven’t seen any capacity loss in 2 years. 
 

If you have discovered a battery that others shouldn’t buy that information would be helpful to others.

 

As for expensive, I paid ฿7/Wh for CATL cells which I think is very reasonable, but @Seeall what do you consider expensive?

[Pink7]

Currently struggling to get batteries in level, the foam between complicate the leveling. Im on my 3th round now, this time i tried to use the busbars to temporary help leveling.. Next round i might throw out the foam.

 

Pink

[Crossy]

1 hour ago, Pink7 said:

Next round i might throw out the foam.

 

I would avoid running with no insulation between the cells. The outer metal of the cell is connected to one pole, the blue plastic is very thin and any breach could result in a short!!

 

You could use thin (I used 0.5mm) acrylic or FR4 between the cells, it's rigid and may be more friendly than the foam.

[Pink7]

5 minutes ago, Crossy said:

 

I would avoid running with no insulation between the cells. The outer metal of the cell is connected to one pole, the blue plastic is very thin and any breach could result in a short!!

 

You could use thin acrylic or FR4 between the cells, it's rigid and may be more friendly than the foam.

I just did another test where i used shera after 4 levels up, then i got better leveling and stability. If i end up doing it it means some custom busbars. Even im happy with the quality on my cells its not as easy or exact to build this way as if i just used to "normal" side down.

 

Pink

 

Pink

[Crossy]

Yeah, you are in somewhat uncharted territory stacking your cells like that rather than the conventional "terminals on top" arrangement.

 

EDIT By the way, you will need some insulation between the two vertical stacks too.

[BritManToo]

1 hour ago, Pink7 said:

I just did another test where i used shera after 4 levels up, then i got better leveling and stability. If i end up doing it it means some custom busbars. Even im happy with the quality on my cells its not as easy or exact to build this way as if i just used to "normal" side down.

 

Pink

 

Pink

No need for expensive busbar!s! 

I just strip 2.4mm twin and wrap it 3x around the terminals with a flat washer on top. 

6x 16-24A = 96A to 156A

As its uninsulated in air I should be good for the higher amps. 

[Pink7]

51 minutes ago, BritManToo said:

No need for expensive busbar!s! 

I just strip 2.4mm twin and wrap it 3x around the terminals with a flat washer on top. 

6x 16-24A = 96A to 156A

As its uninsulated in air I should be good for the higher amps. 

Good idea. I have a 16mm2 solid copper wire i could use that way.

 

Pink

[eddysacc]

How is it going on?

[Pink7]

47 minutes ago, eddysacc said:

How is it going on?

Been to busy and hot latterly to work on this but its not much left and it should be all ready. Hopefully sine progress and updates soon.

 

Pink

[Pink7]

4 of my wires to BMS is a bit short to reach the batteries in bottom of my build. Extend the needed 4 wires or get a JST extension for the whole set of wires?

 

 

Pink

[Crossy]

I just extend the BMS wires, but a JST extension is also viable.

 

How's your soldering?

[Pink7]

1 hour ago, Crossy said:

I just extend the BMS wires, but a JST extension is also viable.

 

How's your soldering?

More experienced than skilled. So i was thinking of join the wires together with some soldering. I will be ok but i know it could be done more beautiful than i do. Usually i will twin the wires together and fold the joint then solder it then shrink tube. In this case might not fold it, just twin together and wire.

 

Pink

[Crossy]

Just now, Pink7 said:

More experienced than skilled. So i was thinking of join the wires together with some soldering. I will be ok but i know it could be done more beautiful than i do. Usually i will twin the wires together and fold the joint then solder it then shrink tube. In this case might not fold it, just twin together and wire.

 

Like the angle-grinder and paint, heat-shrink can hide a multitude of evils

[Pink7]

So now its time to get the batteries and JK BMS mounted together. I think I have a quite small contact area between battery connector an the battery pole. Any thoughts on this?

 

Pink

[Pink7]

32 minutes ago, Pink7 said:

So now its time to get the batteries and JK BMS mounted together. I think I have a quite small contact area between battery connector an the battery pole. Any thoughts on this?

 

Pink

I consider cut some pieces of the extra bars who i get with the batteries with a exact drilled hole and place between the pole and connector as a washer.

 

Pink

[Crossy]

Does the hole in the BMS connector fit over the "shoulder" on the battery terminal?

 

Otherwise, I'd modify one of the inter-cell strips with exact size holes and fasteners.