After experiencing for years with several small scale UPSes that are mainly used for desktop computers or small offices I decided to up the game.
As you may know from the top sticky post this blog is self hosted in a home rack. Adding a proper rack UPS was on the agenda for a long time.
After investigating the market I finally decided on NJOY brand. It is a low cost brand that uses batteries that are easily available on the market. My final set-up is at a fraction of the price if I was using for example APC UPSes.
The setup
- A 2 unit rack NJOY Balder 1000 with 3x7Ah batteries. Batteries are in a series set-up so a total of 7Ah capacity should be considered).
- A 2 unit rack NJOY CA0312GX-AZ with 6x9Ah batteries. Note they are 2 series of 3 batteries each so 18Ah capacity should be considered.
The calculation of the capacity is crucial as seen in the manual because when adding an extender to the UPS the “Battery total AH setting” and “Maximum charger current setting” must be updated for the UPS to work correctly. The factory settings are fine just for the 3x 7Ah set-up.
So to calculate the total capacity of the UPS with the extender I have to do:
7Ah(UPS)+ 2x9Ah(extender)= 25Ah
Note that the manual has a wrong calculation :). Also note that I reported this to the vendor.
Then to calculate the maximum change current by looking at the table we get 4A.
Note that in the end I moved back to 2A setting at the recommendation of the vendor. The reason I got for this from the vendor is:
“Because you use a mixture of 7Ah and 9Ah batteries, the 7Ah will charge too fast and the 9Ah will be charged with a higher current than the recommended one. Please roll back to the 2A setting. The producer recommends that you use the same capacity batteries if possible and also with the same date of installation so to have a uniform wear of the batteries in time.”
The fun part is that I got this nice recommendations from the vendor because I signaled the issue from the manual and asked them for recommendation for my set-up. Thumbs up to NJOY for that.
Now I have plenty of capacity to spare in my UPS.
