Unsure how to configure my battery setup. Looking for guidance.

[hwy17]

I did too many hours of research and came across the previously mentioned 3 cells. Shipping and taxes....etc 18650 cells would not be as cost effectively unless I scavenged for awhile and on top of that, the amount of them I would need for 125kWh...making that array would take many many man hours.

I think you are at risk of getting new old stock though. How long ago were these weird cells manufactured and what's their provenance, etc. The 280/304 stock is moving fast and fresh and we've honed in on these vendors who have actually established a reputation to uphold for good product supply.

I won't tell you not to do something different, nothing wrong with it, but I will still say there's a good thing that's going on in the retail EVE cells.

 

[CamTech]

I think you are at risk of getting new old stock though. How long ago were these weird cells manufactured and what's their provenance, etc. The 280/304 stock is moving fast and fresh and we've honed in on these vendors who have actually established a reputation to uphold for good product supply.

I won't tell you not to do something different, nothing wrong with it, but I will still say there's a good thing that's going on in the retail EVE cells.

Looking at some of the EVE cells it looks like they are 10%-30% more expensive than the other options I am looking at. They do have a better energy density both by weight and size however this setup will be stored in a storage closet that is climate controlled that has plenty of space so both of which are very low on the totem pole for me.

kW/cu ft is 13.37 vs (6.19 CAM72 / 5.09 LEV60F / 4.64 Nissan Leaf).

kW/kg is also better 154.75 vs (121.52 Nissan Leaf / 121.26 CAM72 / 109.12 LEV60F).

$/kWh is $137.67 vs ($124.79 LEV60F / $121.96 CAM72 / $105.45 Nissan Leaf).

Are the LEV60F bad? I haven't been able to find much from a negative aspect online.

 

[robbob2112]

That was my fault, 33P16S is correct.

Black is the negative bus bar. Red is the positive bus bar. Red outlined in blue are the 15a fuses. This is only 6 however there would be 33 per row and 16 rows.
View attachment 207923

Why would you fuse each individual cell?

I would expect each 16S to have a fuse where it attaches to the bus bar. And, I would also ask what size bus bar are you using? Back of the napkin says you total up to 495amps. The other side of the napkin says 1/4" x 2.5" pure copper.



(asking for knowledge verse suggesting anything, I have never gotten past reading about battery builds because the commercial batteries are cheap enough and UL listed.

 

[robbob2112]

I absolutly agree. I only had to drill 48 holes in the bus bars for my 3P16S pack.

When researching bus bars I found one online company that would cut to any length and puch holes at any interval with a CNC machine. Prices were very reasonable and cheaper than the naked copper off ebay and of guaranteed quality.

 

[Partimewages]

When researching bus bars I found one online company that would cut to any length and puch holes at any interval with a CNC machine. Prices were very reasonable and cheaper than the naked copper off ebay and of guaranteed quality.

Do you have a link?

 

[CamTech]

Why would you fuse each individual cell?

I would expect each 16S to have a fuse where it attaches to the bus bar. And, I would also ask what size bus bar are you using? Back of the napkin says you total up to 495amps. The other side of the napkin says 1/4" x 2.5" pure copper.



(asking for knowledge verse suggesting anything, I have never gotten past reading about battery builds because the commercial batteries are cheap enough and UL listed.

Its setup as 33P16S. Doing it this way means I only need 1 BMS rather than 33 for something like 16S33P.

If an individual battery fails, the pack will continue to function. With glow fuses, I can easily see which battery failed and replace it. I obviously would not do this while the system was active, disconnect the battery, perform maintenance and reconnect. The maximum amp load per bus bar will be 416 amps (20 kW discharge from inverter AC draw or 20 kW charge from solar at peak saturation). That is 12.62A per battery, if one fails it jumps to 13.02A for that specific row while the rest of the rows would have their batteries charging/discharging at a max of 12.62A. The batteries are rated for 180A charge/discharge (600 surge) so either way I am well under 0.1C.


Thickness of 0.25" and a width of 1.5" should allow 572A of current draw. That's >=25% Safety Factor which is generally calculated at 25% of the load.

Resources used :

Bus Bar Size Calculator

Current carrying capacity and budget as under size busbar can cause heating and damage in busbar while over size busbar can affect the cost of project. By using BUSBAR Size Calculator we can prevent these issues by predicting them in the first place.

www.allumiax.com

Electrical: Busbar - DC Copper Busbar Ampacities

The following tables have been provided by the Alliance for Telecommunications Industry Solutions (ATIS), T1 Committee, and represent ampacities for busbar sizes and arrangements typically found in the telecommunications industry.

www.copper.org

 

[Ampster]

Looking at some of the EVE cells it looks like they are 10%-30% more expensive than the other options I am looking at.

I am surprised at that if you are comparing cost per kWh. Is that the metric you are using? Just one quote from 18250 puts them at $100 per kWh versus $130 you quoted for the LEV cells

 

[CamTech]

When you include taxes, shipping and hardware it's never that cheap. As this will be specific for me I am getting shipping quotes for all parts and totaling everything that comes out of the Lynx Power In. I then use this number as the total cost of the entire battery system. Then divide that number by the total kWh of the entire pack to get my $/kWh figure.

The reason the LEV60F are so appealing to me is 4 main reasons.
1. High C rate (180A continuous, 600A surge)
2. Competitive when comparing alternatives
3. High supply
4. LiFePo4 chemistry

From everything I have read, keeping the maximum charge at 90% and minimum at 10% with very low charge/discharge rates ensures longevity. In every day use, the SoC will rarely if ever drop below 50%. The extra capacity is there for not only consecutive garbage weather days but also longevity.

 

[robbob2112]

Do you have a link?

I can poke around, it has been 6 months or so since I found, I was googling 'custom copper bus bars' Here are some

I think this is the one I remember

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

This is another

Custom Copper Busbar Assemblies | Conex Copper Busbar

Manufacturers of Custom Copper Busbar Assemblies, Exporters of Custom Copper Busbar Assemblies, Suppliers of Custom Copper Busbar Assemblies, Fabricated

www.conexcopper.com

 

[CamTech]

I can poke around, it has been 6 months or so since I found, I was googling 'custom copper bus bars' Here are some

I think this is the one I remember

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.

www.mcmaster.com

This is another

Custom Copper Busbar Assemblies | Conex Copper Busbar

Manufacturers of Custom Copper Busbar Assemblies, Exporters of Custom Copper Busbar Assemblies, Suppliers of Custom Copper Busbar Assemblies, Fabricated

www.conexcopper.com

McMaster-Carr is who I have linked for the bus bars.

 

[Ampster]

The reason the LEV60F are so appealing to me is 4 main reasons.

Sounds like you have done your reseearch and may have discovered another value.

 

[CamTech]

Sounds like you have done your reseearch and may have discovered another value.

Just a little :D