Symmetra PX All-In-One 48kW, 400V Externa "'Non Smart" Battery Pack

[Brukutu]

HI all.

I have installed "non smart" batteries into this UPS.  

THe bank is made of 32x 105AmpH batteries.   +, CT, - connect to UPS.

All working very well. However I am not sure what to put into the External Battery Cabit capacity setting.

Common sense would tell me to put in 105amh. However, although the bank is 384 nominal Voltage DC, the UPS seems to report Center Tap voltage. Ie 221 fully charged (442V) or 192 fully discharged (384V).  This makes me think that it threats the top and botom as 2 banks,. ie. My amp hour should be 105 + 105 = 210. 

However, after reading a extract on this forum, i am VERY confused. If i had to follow this, my amph would be 32x 105 = 3360ampH which is most definatelly not correct. 

Quote:  (https://www.apc.com/us/en/faqs/FA156609/) 

"
In order to setup the external battery packs, please key in as (Ah of battery) x (total number of batteries).

Example 1:   If there are 16pcs of 5Ah battery in series (for 5kVA), the total Ah number is 5Ahx16pcs=80Ah.
Example 2:   If there are 16 pcs of 100 AH batteries in series(for 5 KVA), the total AH number is 100 AH x 16 pcs=1600 AH
Example 3:   If there are 2 strings of 16pcs of 5Ah battery in series (for 5kVA), the total Ah number is 5Ahx16pcsx2 strings=160Ah.
  
The 80Ah inside the table is the default setting for 5kVA/6kVA (1 EXB: 16pcs of 5Ah battery)
The default setting for 8kVA is 140Ah (1 EXB: 20pcs of 7Ah battery)
The default setting for 10kVA is 180Ah (1 EXB: 20pcs of 9Ah battery).
  
If “Ext total battery Ah” is set as 0, it means there is no external battery connected. "

[SESA85534]

Hello,

You are not the only person to be a bit confused with this. The high value seems strange but the calculation is straightforward.

Basically, it is is 32x 105 = 3360Ah which may seem high but it is correct. After all this UPS can provide up to 48KW so on full load we would have over 100A on full load so you should expect about the 3 hours runtime depending on the state of the batteries.

What can be confusing is when you think that this will deliver 1A for 3360 hours. However that would be at 12V but the DC Bus in a Symmetra is about 400V DC so when that is considered it makes more sense. 

For set up with non Schneider Electric batteries, refer to the manufacturers spec for the 3^rd party batteries and program in the AHR into the “Ext Bat Cap: 0000Ah” menu.  

I hope this clarifies the issue.

Regards,

Joseph King

[Brukutu]

Thank you for the response. 

I was working under the assumption the ampH value requested is relative to the bus voltage being 384. Ie. 105Ah at 384v.

i would calculate 480000W at 400V equals current of 120A. 120A draw on 400v dc making 52 minutes runtime assuming discharge to 0%. Please correct me if I am wrong here.  

however if what is asking is ampH relative to a 12V, then it makes sense to say 3360Ah

please clarify above. 

thank you. 

[SESA85534]

Hello,

Apologies, my error.  Yes, you are right, 52 min is correct, however as the batteries get older this would reduce a bit.

I hope this clarifies the issue.  Thanks.

Regards,

Joseph King