Build finally finished - 8 x 280Ah pics and discussion

[mr_ed]

Finally put the finishing touches on my battery this weekend which I've discussed in various threads and had some great support/help from the community members here in planning. It's been functioning since around Christmas, but I've slowly been adding all the nice to haves.

This weekend I added some beefier home-made busbars (from crushed copper pipe which I've tinned myself - I've outlined the process in detail in another thread) and a perspex cover over the cell terminals which were the finishing touches.

Key points of interest:
- The cells are 280Ah EVE cells from Basen. Total tested capacity of the pack from 3.6V down to 2.5V is a touch over 270Ah which I'm happy with for the price. The main reason I don't quite get full capacity is differing resistance between cells, meaning I get low voltage disconnect on one cell while a couple of others still have capacity remaining.
- My inverter is run straight off the battery rather than via the BMS due to the amperage rating of the BMS being too low. To protect against over-discharge, I cut the remote switch cable to my inverter and ran it via a low-voltage disconnect board (relay). The relay switch is then connected to the BMS - therefore once the BMS cuts the discharge the relay cuts and turns the inverter off. This is functioning great. I had a couple of members raise on here that some inverters may not like being switched off under load - my manual doesn't say anything about this and the inverter doesn't seem to mind. Aside from this consideration, this solution seems to be a great alternative to more expensive pro latch / battery protect type products.
- My inverter is a 4000W/8000W pure sine wave from a 4x4 company here in Aus. It works great and provides the rated power no worries, however in setting up the A/C system I realised the inverter is actually split phase (both L and N are 120V with respect to ground). This is apparently relatively common in inverters, however the manual doesn't say anything about it. Just a bit of a watch-it for others. Annoying for my as I now can't have neutral bonded to ground. I will make sure my next inverter has a true neutral.

Anyway - I just thought I'd put up some photos as a thanks to those who helped point me in the right direction on the build.

 

[Steve_S]

A Very nice & tidy setup in that cabinet too, I like it, Well Done !
Only concern would be temperatures in there, I see you have vent holes bottom & top but will it be enough ? Once the solar is charging and the inverter is running along, it will most certainly get warm in there, so I'd keep an eye on it, may have to supplement it with a small PC Box-fan for input & output airflow.

 

[iamrich]

Really nice setup! Are you worried at all about the cells expanding?

 

[Boondock Saint]

My inverter is a 4000W/8000W pure sine wave from a 4x4 company here in Aus.

When I read that sentence I immediately thought of the REDARC products. > https://redarcelectronics.com/produ...cle-dc-battery-charger?variant=29494631727217

Great finished project - I like the clean compact installation and the way you were able to select different brand products as part of your system plan and design. I'm supposing you can just keep an eye on the temp of the main components and determine if in the future you care to add a quiet 120mm PC case fan to push air in.

I would personally like to see other pics from a lower angle of the inter-connectivity of your cabling, if it isn't too much to ask :D

I'm interested in the parts (part numbers) you used and how you conjured your relay switch from the BMS etc.

 

[John Frum]

Kudos on the fire extinguisher.

 

[sid the seagull]

There must be room for a green and gold Australian made sticker .

 

[Steve_S]

Gotta at least put a Flag Sticker on there somewhere !
Then send a Photo to Rupert Murdochs news corp with a Thumbing ! hehehe...

 

[mr_ed]

Sorry all - busy week. Thanks for the comments!

@Steve_S - agree I'll need to keep an eye on temperature. I've done some stress testing on the battery running about 130A through it for a decent period of time and it was fine, but that was in relatively cool weather. My plan is to wait for a hot day and do the same thing to check how it holds up. I like the PC fan idea - hadn't thought of that!

@iamrich - I'm not too concerned about cell expansion - I have the voltage limits on my BMS set pretty conservatively - but I'm certainly interested to see what happens. If I see any expansion I'll add a frame. Although that timber frame around the base does provide some restraint as do the busbars on top (not that you'd want to load the terminals too much).

@Boondock Saint - I wish it was Redarc!- their stuff is really nice but $$$. I don't have any other photos at the moment and I won't be near the system for a while, but see attached for the wiring schematic which shows the whole setup. You can see that the inverter being split phase has made a bit of a mess of my 240V wiring - had to put breakers on both L and N and can't bond N to G which is annoying, but really probably not a huge deal for the application.

@smoothJoey - always better to be safe than sorry!

The only other things I'd like to do which I may get around to at some stage is to put a midnite solar SPD on each of the two panel array cables before they come inside and to put a midnite solar GFPD on. But it's expensive to get them to Aus, we're not in a hugely lightning prone area and I just check the fuse I have between battery negative and ground each time I go up to make sure I don't have a ground fault.

In terms of part/part numbers:
- Cells are 280Ah EVE cells from BASEN via Alibaba.
- Shunt is the cheap 350A AiLi that quite a few people have. With my time again though I'd probably spend the extra money on the version that shows watts as well as amps. But this one does the job.
- Orange cables are welding cable. 25mm2 going to the BMS/busbars and 50mm2 going to the inverter. It's great stuff - super flexible and easy to work with. Also bought a hydraulic crimper to put the lugs on these which I would highly recommend - so nice to use and the crimps are great.
- BMS is the JBD 100A 8S (same as overkill solar I believe, but much cheaper through AliExpress, particularly to Aus)
- Low voltage disconnect board is by CZH labs - really well put together. I've tested it and the cutoff works perfectly.
- The relay between the LVD board and the remote switch is just a small PCB relay like this. Uses extremely little power.
- Inverter is this 24V 4000W (8000W peak) pure sine wave. Works great but as I said I probably wouldn't recommend for this application due to the split phase power.
- Both the MPPTs are Renogy Rover 40A. I like them. I was worried that having them in parallel would create issues with one seeing the voltage from the other and thinking the battery was fully charged, but it hasn't been an issue - I've seen 70A+ going into the battery so they're definitely both providing charge at the same time.
- The DC breakers are Noark. A bit expensive but I bought some of the cheap ones first and they were just crap.
- Busbars are mostly DIY - tinned squished copper pipe
- Step down converter and fuse block are just from Ebay.

 

[Steve_S]

@mr_ed You've done such a nice job, I will toss this link in for you to check out. I use AC-Infinity products, they ARE the Rolls Royce of their universe ! They may look like something you'd find in a PC made out of plastic, NOT ! Ballbearings and perfectly silent, cast aluminum housings etc...

I use these for a few different things. These are USB power equivalent Axial Fans which can also use Thermal Controllers. They use so little power that it amazes ! They work amazingly well AND NOT EXPENSIVE compared to other solutions.
Main LINK: https://www.acinfinity.com

CONTROLLER 2, INTELLIGENT THERMAL FAN CONTROLLER,
SINGLE ZONE $39.99

MULTIFAN S1, QUIET USB COOLING FAN, 80MM $10.99​

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