563kwh BYD = 52.75kw www.batteryclearinghouse.com/

[Picasso]

See here for starting to collect info on BMS.

 

[Maast]

I appreciate the video - what would be great is if someone could test the batteries for aH LEFT (life left) ... I know the batteries are rated at 200aH (NEW) but what are folks getting out of them now... That's really all I am waiting for at this point ... Basically how much life is left in them ... THX

They're sending me one of the cells you saw on the video to run through my high amperage tester. I'll be able to tell you capacity immediately but lifecycle tests take time and I wont be able to tell the forum what the expected lifespan will be for at least a couple of weeks.

At .5C I only get 6 cycles a day though I may bump that up to .75C just to speed things up but I'll still need a few hundred cycles to firmly establish degredation curves. If they're generous enough to send two I'll do two sets of data: One at 1C at 100% Depth of Discharge which basically abuses the heck out of the battery but is pretty good for establishing absolute minimum life of a cell, and one at .5 at 80% DOD which is a good test for average life of a cell.

I bought a bunch of these modules so I have a deeply vested interest in the results myself. My wife is on a home dialysis machine at night and we're in an area with semi-crappy power stability in winter so this upgrade project has to be done absolutely perfect.

 

[jasonhc73]

After 6 days of charging and using 8 BYD's in 2S4P, they have pretty much equalized themselves.
I charge them at 56.5V@26 amp, the float is set at the nominal voltage (51.2V) after the bulk charge, they stabilize at ~53.0V± 0.1V.

I ran my entire house off them through 2xMPP LV5048's, for 30 hours now...
Today when I switched back to grid, the voltage shown as 52.3V, after 8 hours of house use.

		10	11	20	21	30	31	40	41	System V
12/25/2019		26.73	27.33	27.35	26.70	27.26	26.80	26.98	27.07	54.04
12/26/2019	1:28:36 PM	26.73	28.04	28.03	26.73	27.90	26.86	27.30	27.48	54.75
12/26/2019	7:28:49 PM	26.44	26.37	26.41	26.43	26.38	26.48	26.46	26.41	52.60
12/28/2019	6:48:55 PM	26.53	26.49	26.50	26.52	26.50	26.52	26.51	26.50	53.00
12/30/2019	12:25:09 AM	26.51	26.47	26.49	26.50	26.48	26.50	26.50	26.49	52.96
12/31/2019	12:01:45 PM	26.55	26.52	26.53	26.53	26.53	26.54	26.54	26.53	53.07

 

[Maast]

Nice! Have you opened up the cases to look a the individual cell voltages?

 

[jasonhc73]

Nice! Have you opened up the cases to look a the individual cell voltages?

I did not open the pack, I measured through the connector.
I did that today on one of the packs. (While my house was running off it though)

This is about 3 hours after running my house today(31 Dec, 19) while discharging.
I'll measure the resting voltage tomorrow after charging up.

	Cell
Pack 41	8	7	6	5	4	3	2	1	Average	Min	Max	mV Difference
12/31/2019	26.360	23.070	19.770	16.480	13.190	9.890	6.597	3.297
	3.290	3.300	3.290	3.290	3.300	3.293	3.300	3.297	3.295	3.290	3.300	0.010

Kind of a useless measurement though while discharging.

 

[Maast]

Looks good, not really useless - now you know you dont have any severely weak cells in the pack. But since 3.3 is in the middle of the "power band" of the cells any differences won't start showing up until down in the 3.1-3.2 range.

 

[nwillitts]

i have same mpp-BMS on battery?

 

[maxx123]

like your setup

 

[jasonhc73]

	Cell
Pack 41	8	7	6	5	4	3	2	1	Average	Min	Max	V Difference
12/31/2019	26.360	23.070	19.770	16.480	13.190	9.890	6.597	3.297
Discharging	3.290	3.300	3.290	3.290	3.300	3.293	3.300	3.297	3.295	3.290	3.300	0.010
1/1/2020	26.280	23.000	19.700	16.420	13.140	9.860	6.576	3.289
Sitting idle	3.280	3.300	3.280	3.280	3.280	3.284	3.287	3.297	3.286	3.280	3.300	0.020

I have a Zero Motorcycle DSR - The BMS doesn't even equalize until 35 mV difference, this "old used BYD" is only 20!