New to solar, just bought 71 kWh of batteries for DIY some help please :)

[doox00]

Don't cut the pack like David Poz did. You can separate cell interconnect between cell 16 and 17 and keep the pack assembly intact. You then have 16S and 4S packs in each module. Connect those 4S sections across 4 modules and you have another 16S pack without physically destroying the module.

Yep I had planned on leaving all the cells in the pack, just cutting the battery bar out to leave a 16c pack.

 

[Browse]

His latest video goes over the BMS for these packs (with links in the description):

 

[OffGridForGood]

I said I assumed I need a BMS, my question is more of which kind and if the kind I need matters depending on which inverter I get. Yep I am new at this and I knew I was going to diy the batteries shortly after starting to read up on things as its half or less the cost of prebuilt ones and I am a diy kind of person. Also I am not separating the cells, just cutting the bar to remove 4 of the cells from the 20 cell packs. The extra 4 will physically remain and I will connect those 4 extra from each of the 4 modules to make a 5th 16c pack.

My loads are a well pump, shop with some 15-20 amp 220v circuit equipment, like a table saw, dust extraction, air compressor etc. 5 small mini splits (1 ton max each), 3 in the house and 2 in the pole barn. As of now the water heater, stove, dryer are on gas, I may swap them in the future. I figured the eg4 18k would be sufficient to start with or if there are other inverters that can connect to the panels, grid, generator and batteries and seamlessly swap between them I would consider those as well.

Thank you!

For me the JK BMS is my go to control, I started with the Daly (and still use some for separate 24v system).
Some of the guys say the JB is also good, I have not tried that one.
For controlling and communications, I like the Victron 500A shunt and Solar Assistant, mine operates off-line LAN only.
Some of the guys like Home Assistant, but I can't say, never tried it.

Shop loads:
Using a new toy, Klein CL900 - I have measured the inrush current to start a 240v 3Hp Tablesaw =68Amps
even a handheld skillsaw (120v) is 38Amps to start it. Once the motors are turning the amps drop back to normal, but you need enough capacity to get them going.
For bigger stuff I use VFD's to start the motors.

Having enough battery behind the inverters to hold the voltage under the start up in-rush seems to be half the battle, the other half is enough inverter output. I have been eyeing up the EG4 18k's as one option to expand my own set-up to 24kW, which would be two of those inverters. Remember the "18k" is 12kW output, the "18" is PV input.

 

[Bleedingblue]

They are about 300 pounds a pack, I have pallet jacks and a few people who can help put them into a rack once they are built. I bought 4 modules of 20 cells so that will be enough to make 5 16c packs. I considered the eg4 18k inverter but have not decided on that yet. I would like it to seamlessly connect to the panels, batteries, grid and generator.

I have 4 EG4 6500watt inverters and they have never given me a problem so far. I have had them almost a year.
Lot of good brands out there

And yes the BMS would have to be purchased separately if that case doesn't have one already built in it.
I'd highly recommend getting an active balancer or buying a BMS with one built in it. That is something I'm dealing with now. Packs become out of balance over time and need to be top balanced or bottom balanced again.

 

[Bleedingblue]

For me the JK BMS is my go to control, I started with the Daly (and still use some for separate 24v system).
Some of the guys say the JB is also good, I have not tried that one.
For controlling and communications, I like the Victron 500A shunt and Solar Assistant, mine operates off-line LAN only.
Some of the guys like Home Assistant, but I can't say, never tried it.

Shop loads:
Using a new toy, Klein CL900 - I have measured the inrush current to start a 240v 3Hp Tablesaw =68Amps
even a handheld skillsaw (120v) is 38Amps to start it. Once the motors are turning the amps drop back to normal, but you need enough capacity to get them going.
For bigger stuff I use VFD's to start the motors.

Having enough battery behind the inverters to hold the voltage under the start up in-rush seems to be half the battle, the other half is enough inverter output. I have been eyeing up the EG4 18k's as one option to expand my own set-up to 24kW, which would be two of those inverters. Remember the "18k" is 12kW output, the "18" is PV input.

And it's always a very good idea to double what you need. If your using a lot of current that inverter is working overtime in keeping up with demand. Having 2 cuts the load in half in between them making the inverter much happier. Also if something goes wrong and your down an inverter you have another one still working while the other gets repaired or another one shipped out.
And these days it could be weeks before you get a part or inverter

 

[OffGridForGood]

Off topic: just a question:
I see this layout quite often so I just have to ask: where I live, I am not permitted to have comms or DC cables in the same trough as the AC cables. I see a lot of parallels between the Canadian Electrical Code and the NEC on solar related items, so I wonder - is there no restriction for AC, DC and communication cables all in one metal trough?

 

[G00SE]

Good luck with the build! I’ll be tuning in for sure.
I ordered cases for my cells with seplos BMS but I also ordered a REC BMS to try and run my cells 2p16s and communicate with SMA

 

[DIYrich]

Off topic: just a question:
I see this layout quite often so I just have to ask: where I live, I am not permitted to have comms or DC cables in the same trough as the AC cables. I see a lot of parallels between the Canadian Electrical Code and the NEC on solar related items, so I wonder - is there no restriction for AC, DC and communication cables all in one metal trough?

You can partition in the trough.

 

[OffGridForGood]

You can partition in the trough.

I guess you can!
just not sure how all the cables can cross one-another.
I used a small PVC wire organizer just below the inverters, for comm cables,
Then used AC cables for the DC next below the comms, for the PV,
Then the wire trough below that with metal conduits up to the inverter.
They were happy with that.

 

[1201]

His latest video goes over the BMS for these packs (with links in the description):

They sold out of those batteries within two days of David poz uploading that vid

 

[Bleedingblue]

Off topic: just a question:
I see this layout quite often so I just have to ask: where I live, I am not permitted to have comms or DC cables in the same trough as the AC cables. I see a lot of parallels between the Canadian Electrical Code and the NEC on solar related items, so I wonder - is there no restriction for AC, DC and communication cables all in one metal trough?

Not here there isn't. I'm sure it's different in some areas. You can watch guys like Engineer775 and see him putting his 1/0 in same trough.
Give it time and the code will change and we will have to have everything done a certain more expensive way and have to have it inspected etc

 

[Quattrohead]

I guess you can!
just not sure how all the cables can cross one-another.
I used a small PVC wire organizer just below the inverters, for comm cables,
Then used AC cables for the DC next below the comms, for the PV,
Then the wire trough below that with metal conduits up to the inverter.
They were happy with that.

You can mix the cable types but your low voltage DC cables must be rated to the maximum ac voltage in the trunk, quite a few low voltage DC cables are rated to 300 or 600 volts insulation for this very reason.

Now whether it's a good idea to mix them as far as interference is a whole another subject and as some people have found out the inverter parallel cables are quite useful at picking up noise and making inverters go nuts.

 

[Partimewages]

We mix control voltage <48 and high voltage 120 or greater as long as the jacket insulation has the higher rating. In some instances it will mess with the DC control signal. Where you have real problems is with VFD wires. They will cause all types of issues. Sometimes depending on the application you will need different types of VFD'S to counter that. Inverters are like VFD'S with the exception they don't change Hz or voltage to change speed.

 

[Disturbedfuel15]

His latest video goes over the BMS for these packs (with links in the description):

These are not the same battery packs.

 

[Hedges]

I considered these cell packs, but didn't pull the trigger.

I would have left them physically intact. Possibly cut busbar to make separate 4s & 16s.
I wanted the sealed case, would have had to do additional feed-throughs.

My first thought was 40s or more for HV battery, but don't know what BMS for the HV SMA inverters I would consider.

Alternative idea was to leave busbar intact. Ground one of the busbars to make +12V and -48V batteries. Parallel 2 or more. Issues were I prefer 12V battery at a different location for comms backup power, don't need parallel for more Ah at 12V either.

Choices of several expensive REC BMS for my Sunny Island, or connecting cells 5p16s, need robust cross ties.
Any of those midpoint connections difficult to do well, should be laser welded.

I started by asking about BMS for 20s to use with SI. SI's max votage would be part way up the upper knee. It would jack the BMS cost higher, 2x and need master.

 

[OffGridForGood]

I considered these cell packs, but didn't pull the trigger.

Darn - we could have learned a lot - with you paying the cost!

Choices of several expensive REC BMS for my Sunny Island, or connecting cells 5p16s,

I looked at those REC BMS's - they look very well made. but the cost !!
yeah I decided to stick with JK's for now, but happy to follow along anyone's posts to learn.

 

[1201]

These are cheaper and already 8s, so, much easier to do 48v.

25.6v 280ah 7.16kWh Lifepo4 8 Cell Modules

Just 1 module left at the moment. You can pick up from our Bensalem, PA location for free or we have excellent freight rates which include residential and lift gate service. We also have a shipping calculator at the bottom of this page to quickly estimate your shipping costs. Each module has 8x...

batteryhookup.com

 

[Batronca]

These are cheaper and already 8s, so, much easier to do 48v.

25.6v 280ah 7.16kWh Lifepo4 8 Cell Modules

Just 1 module left at the moment. You can pick up from our Bensalem, PA location for free or we have excellent freight rates which include residential and lift gate service. We also have a shipping calculator at the bottom of this page to quickly estimate your shipping costs. Each module has 8x...

batteryhookup.com

This one is used

 

[Rednecktek]

Waiting for those to come back! Just finished checking out for 2 of them! $500 in shipping hurts and the DavidPoz discount is only 10%

 

[1201]

This one is used

It is but it's a smoking deal and almost testing as new, in terms of capacity.

43kwh shipped to my door for less than $5k, and already in a compression pack, is hard to beat