Rate my battery: 280ah 24V

[ShaneC]

Hi all,

Just wanted to show off my battery as I'm quite proud of how neat it's turned out while also double checking that I haven't messed anything up as its my first go.

It consists of 8x 280ah Eve B-grade cells, about £950. Bought from fogstar.co.uk they came capacity tested, batched and balanced. I am using a JBD SP22S003B 100A BMS. Yes it came with just 8awg cables, I have another thread here asking about that, yet to hear back from JBD.

Sheets in between cells are recycled HDPE, foam at the top is some of the PE foam the batteries came packed in. I'm not going for serious compression but it does hold them well in place. I've taped each 2 sets of cells with heavy duty packing tape then 2 of those into each of the 4x cells. The two sets of 4 are not taped together just pushed together by the case. Went with a flexible 4awg cable in between in case of movement.

This is for use in my office so isn't designed for lots of movement or vibrations, I'd definitely pack it out with more padding if so and tape the two columns of cells together if I wanted to put this in a van.

All in this came to just over £1000 for a 7kwh+ battery. Not bad!

 

[ShaneC]

I hope the lack of replies means there's no glaring problems people can see ?

 

[740GLE]

Looks pretty straightforward. How are you charging it?

Have you capacity tested it?

 

[John Frum]

Just wanted to show off my battery as I'm quite proud of how neat it's turned out while also double checking that I haven't messed anything up as its my first go.

Sheets in between cells are recycled HDPE, foam at the top is some of the PE foam the batteries came packed in.

I like the way you did the separators.
I'm stealing that

 

[GSXR1000]

you need more isolation between bms and battery post

 

[ShaneC]

you need more isolation between bms and battery post

It's on a cutout of the same HDPE sheet that I used between the cells, might not be that obvious from the photo. Do you think it needs more?

 

[ShaneC]

Looks pretty straightforward. How are you charging it?

Have you capacity tested it?

Charging at the moment with a 450w mean well charger. I've got that setup on a smart plug to charge when electricity rates are low. I'll be adding solar when I can afford it or find a cheap second hand deal. No rush during UK winter.

EDIT: And no I haven't capacity tested, I don't have any specialised equipment to do so, it hasn't even been up to 100% charge yet. The cells did come capacity tested with 4 around 277Ah and the other 4 at 279Ah so I'm pretty confident this battery should be around 278Ah assuming their capacity tests were accurate.

 

[GSXR1000]

It's on a cutout of the same HDPE sheet that I used between the cells, might not be that obvious from the photo. Do you think it needs more?

I would have done it bigger so it covers the battery terminal.. looks like it could slide and fall down..

 

[ShaneC]

I would have done it bigger so it covers the battery terminal.. looks like it could slide and fall down..

It's double sided taped quite strongly to the HDPE, I wanted to keep access to the terminal in case I needed it.

 

[740GLE]

Charging at the moment with a 450w mean well charger. I've got that setup on a smart plug to charge when electricity rates are low. I'll be adding solar when I can afford it or find a cheap second hand deal. No rush during UK winter.

EDIT: And no I haven't capacity tested, I don't have any specialised equipment to do so, it hasn't even been up to 100% charge yet. The cells did come capacity tested with 4 around 277Ah and the other 4 at 279Ah so I'm pretty confident this battery should be around 278Ah assuming their capacity tests were accurate.

So what’s the difference between off peak rate and peak rates?

How long is your payback? Or is it more for fun?

 

[Bud Martin]

You should use tinned copper ring lugs making contact with battery Aluminium terminals

 

[ShaneC]

So what’s the difference between off peak rate and peak rates?

How long is your payback? Or is it more for fun?

We're on Octopus Agile so it changes every half hour, some days it maxes all day at 35p/kWh other days it can even go negative. Usually get a few hours through the day at <15p, few more at <25p. Payback with just this scalping would take... a while. I'm going to add panels though and get a quicker return that way though. That will be more important when our fixed term at these rates runs out in the summer and they stick us on the rates that can max out at 80p or even £1/kWh.

 

[ShaneC]

You should use tinned copper ring lugs making contact with battery Aluminium terminals

What's wrong with pure copper? Does it react with the aluminium?

 

[740GLE]

Corrosion, green death.

If you use some “anti ox” and slather everything after it is nice and clean during assembly, you should be fine.

 

[ShaneC]

Corrosion, green death.

If you use some “anti ox” and slather everything after it is nice and clean during assembly, you should be fine.

Interesting thank you, I'll look for new lugs and replace the ones I have, I assumed pure copper would be the best conductors.

 

[Sky-HHI]

Nice build and very clean wiring. One small thing I see is the short jumper wire between battery 4 and battery 5 has the black end on the positive terminal and the red end on the negitive of the other battery. Just turn it end for end or change the heat shrink. But it is still a clean and will planned battery.

 

[ShaneC]

Nice build and very clean wiring. One small thing I see is the short jumper wire between battery 4 and battery 5 has the black end on the positive terminal and the red end on the negitive of the other battery. Just turn it end for end or change the heat shrink. But it is still a clean and will planned battery.

Thank you, the heat shrink colour is intentionally that way round as it indicates the negative side of the battery on the left going towards positive on the right.

 

[GSXR1000]

I hope the lack of replies means there's no glaring problems people can see ?

my build started off 12v but rewired for 24v

Thread 'Just ordered Lifepo4 prismatic cell 3.2V 280Ah lithium lifepo4' https://diysolarforum.com/threads/j...smatic-cell-3-2v-280ah-lithium-lifepo4.14955/