Battery Charging VERY high Values 6353kW for 20 kWh Battery

Hi SAM Forum:
1st post, novice SAM Users.Tried using 20kWh battery storage with Li ion. When looking at power to/from battery I see really high (seemingly random) values like (-6353,-5426,-2744) these are all at 2100 hour. 2100 is odd because charing from grid is allowed starting at 1900 hr, and data shows correct discharge/charge upto 2100hr. Sample shown below
hr power to/from battery
1300 0
1400 3.00

Hi Tom,

I believe the reason you are seeing the high charge rates is two-fold. First off, for the bank capacity of 20 kWh, you have a bank voltage of 13.2V. This leads to a very high maximum current of about 1500 A. This is because the maximum C-rate is equal to 1, that is, the battery is allowed to discharge its full capacity over 1 hour. Thus, 20 kWh/1h = 20 kW/13.2V = 1515A.

I'd recommend you increase your bank voltage to 1000 or 2000, or reduce your maximum C-rate of charge/discharge until the amperage is lower. I don't know precisely what voltage a 20 kWh bank would be kept at, but I suspect it's in the hundreds or thousands of volts. If you make this modification, the large power spikes should reduced to lower levels. Let me know if that doesn't address your issue.

Best,
Nick

Hi Nick,
Yes this does the trick!!! Many thanks. I thought the problem was related to the Cdischarge rate. I went to the equipment specs and found Rated input/output voltage = 86.4; Max input current = 16.5 A and Max output = 26.0 A; I back calculated C-rate charge = 0.145 and C-rate discharge = 0.23 . These values seem low, but OK. Thanks again Tom !!!

Tom,
Great, I'm glad that helped. That's interesting to know the specs of a 20 kWh system. With those voltage and current levels, it would seem the maximum power output is about 2.2 kW, implying the system can last for about 9 hours. Just let me know if you run into other issues.
Thanks,
Nick

Nick,
Your correct the specs I quote just above is for the standard Tabuchi EIBS 5kW inverter/10kWh Battery storage. (the 20kWh mentioned previously was just a sim). So I agree with the 2.2 kW but at 10 kWh the discharge time is 4.5 hr. The 2.2kWh max discharge is a problem for me bc the BatStor is backingup a 5kW-DC PV system which (mostly stops producing at 1700 and my high residential demand charges (APS -ETC-2) are in effect until 1900. (i.e. it doesn't discharge fast enough to offset the PV load). Tom