My Deligreen LF280 28kW build

[Ampster]

My order of 32 LF280 cells which I ordered from April Cao at Changsa Deligreen were dropped off this morning by Fedex. I placed the order on 8 May, it generated a tracking number on 18 May and the ship set sail on 18 May, arriving in the port of LA on 12 June. It took until 21 June for them to clear customs and 3 days for Fedex to moved them from LA to Sonoma. It must have taken 3 days of trying various credit cards for me to finally request Paypal and April split the fee with me. The total for 32 cells came to $3335 or just over $116 per kWh.

 

[svetz]

...just over $116 per kWh...

Holy cow! Is that the world changing?

 

[GMB]

That's a great price. Can't wait to check out your build. Did they all arrive without any damage?

 

[gnubie]

$116/kWh!

If you are a DIY battery builder why would you even blink sideways at lead acid anymore.

 

[Ampster]

Did they all arrive without any damage?

I haven't had time to open more than one box but that one was perfect.

 

[solardad]

@Ampster What kind of voltages are you seeing with the cells? Looks like they packed 4 per box? Thanks

 

[Ampster]

So far 16 of them are within 12 millivolts. (3.321 - 3.333) I am starting to put those 16 into parallel top balance mode at 30 Amps.
For practical reasons, and because I have an extra BMS I changed my plan to start with two 16S packs rather than one 2P16S pack.

 

[Ampster]

Also, I attached photos of the supplied buss bars which came in two lengths. The quarter in the picture is about the size of the terminal top.

 

[solardad]

@Ampster Looking good! I received some bus bars also along with fasteners, posts and nuts. Started a thread on my build: https://diysolarforum.com/threads/battery-bank-build-deligreen-280ah-eve-cells.8983/

 

[solardad]

@Ampster have you figured out how you are going to compress your cells when they are stacked? That is one area that I am noodling on still...

 

[Ampster]

Yes, I am going to use three rod. I am reenforcing the bottom of the cabinet and the thread rod will be verticle in the spaces between columns of cells. I will use aluminum plate on the top with angle stock.
I do think I am going to have to drill out the buss bar holes to 9/32" just to parallel top balance the cells or temporarily clamp them. Otherwise there is too much side loading on terminals. I am away from the project for the next few days so progress is slow.
The swelling is very much like my experience with Nissan Leaf modules. I have to clamp my Nissan Leaf cells before fitting the 6S buss bars for those modules.

 

[solardad]

What did you end up using as a cabinet, Craftsman example in the video I shared earlier? I purchased one to test out and the clearance is pretty tight though I do like how the bottom is flush with the ground so no need for reinforcement. Not 100% sure I am going to leverage it. One note on top balancing the cells is that once they hit 3.6 they tend to run up fast! My 1st balance attempt with 6 cells in parallel ended up hitting 4.1! I quickly put a load on to reduce the voltage back down (water heating element). My last attempt went well, 10a charge
(max my charger could do) until they hit 3.6 and then dialed it down to 2a for the remainder .05 volts (3.65 final). Now resting +18 hours later at 3.62.

 

[Ampster]

What did you end up using as a cabinet, Craftsman example in the video I shared earlier?

I bought a 30 x 30 cabinet from Global. I hope it passes for NEMA or that the inspector doesn't care.

One note on top balancing the cells is that once they hit 3.6 they tend to run up fast! My 1st balance attempt with 6 cells in parallel ended up hitting 4.1!

I got lazy and didn't check my power supply and 8 of mine went to 3.8. I did the same as you and rapidly drained them down to 3.5. Volts and will combine them with another group of 8 to do the final stage to 3.6. That second group of 8 will get a first stage charge to 3.5 volts.

 

[Ampster]

I got 16 of my cells top balanced in paralell at 3.58 volts. At that point I didn't want to mess with incrementing my power supply any further so I unplugged it and pulled off all the buss bars. My cabinet still needs work so I am setting them up temporarily below my inverter next to where my cabinet will be.

I got delayed by a staph infection but today got them connected to my inverter and BMS and they are all doing well. The voltage has settled at 53.2. (3.32 per cell). The largest cell delta is 7 millivolts and the Internal resistances are all equal at .7mOhm. My BMS calculates IR. That may be a plug number since I don't have the shunt connected yet and it does say it uses current to calculate IR.

 

[JoeHam]

8 of mine went to 3.8.

You know you don’t have to top balance.

It’s not a riskless procedure and most any BMS will do the job as you charge and discharge a few times.

Or perhaps you’re tired of hearing me say that ?

And seriously, glad your cells were not permanently damaged.

 

[Ampster]

You know you don’t have to top balance.
It’s not a riskless procedure and most any BMS will do the job as you charge and discharge a few times.
Or perhaps you’re tired of hearing me say that ?
And seriously, glad your cells were not permanently damaged.

I don't mind you repeating the warnings for others.
If you are going to do that I only ask that you be a little more precise about calling it parallel top balancing, because that is the process that can cause problems. We agree that there are risks doing it that way mostly from operator error. That was why I mentioned my own experience. Also, I continued with the parallel top balancing with no incident. At the next full charge I am curious to see how close they are. They were within 7 millivolts of each other when they settled.

There are two other ways to top balance. The top balancing that your BMS does has very few risks.

 

[Ampster]

This is how I got all 32 in a 30 x 30 cabinet. I have a 1/8 " aluminum plate on top and bottom and allthread clamping them between columns 1 & 2 and 3 & 4. I still have some buss bar fabrication to do to eliminate the multiple buss bars. There are angle pieces of aluminum on the top and the underside of the cabinet to strengthen the thin aluminum and even out the pressure on the aluminum plate. Also I have the case bolted to the wall and the top of the pack is tied back to the wall for seismic security. {I'm in California)

 

[Ampster]

I had parallel top balanced the pack but after increasing the Amperage charging limit when I swung my other GT inverter over to be AC coupled I noticed one pair of cells start to creep up over 3.6 so I cut back the Amperage and put a 5 Ohm resister on those two cells because I did not want to shut of the system and it would take too long at 200 mA for my BMS to bring it down. I was in the last part of the Constant Current stage of charging and I will watch it again tommorow to see if that did the trick. I did order some spares and thos two cells are at the top so If they don't settle down I might swap them out and give them a thorough capacity test.

 

[JoeHam]

This is how I got all 32 in a 30 x 30 cabinet. I have a 1/8 " aluminum plate on top and bottom and allthread clamping them between columns 1 & 2 and 3 & 4. I still have some buss bar fabrication to do to eliminate the multiple buss bars. There are angle pieces of aluminum on the top and the underside of the cabinet to strengthen the thin aluminum and even out the pressure on the aluminum plate. Also I have the case bolted to the wall and the top of the pack is tied back to the wall for seismic security. {I'm in California)

View attachment 19737

Now that’s a battery!

Nicely done ?

 

[solardad]

This is how I got all 32 in a 30 x 30 cabinet. I have a 1/8 " aluminum plate on top and bottom and allthread clamping them between columns 1 & 2 and 3 & 4. I still have some buss bar fabrication to do to eliminate the multiple buss bars. There are angle pieces of aluminum on the top and the underside of the cabinet to strengthen the thin aluminum and even out the pressure on the aluminum plate. Also I have the case bolted to the wall and the top of the pack is tied back to the wall for seismic security. {I'm in California)

View attachment 19737

Looks good. Are you in a flood plane, appears you have you bank raised a foot or so above the floor..?..?