General information on PowerWise UPS from HP (L600, L900 and L1250)

HP made a series of UPS in the mid 1990s that included power boosting, intelligent communications port and long run time.   HP subcontracted the support of these units to American Power Conversion.

APCC does not actively support these units.  There is almost no mention of the units on their web site.  They sent me what documentation they had, and I've posted extracts below.

The name of the UPS is not as important to HP as the Model number. I'll only address the 120 volt units, though HP makes a 230V equivalent for each.:
Unit Name (on front Panel) Model Number (on back panel)
L600 HP C4775A
L900 HP C4776A
L1250 HP C5225A

I've only got the L900, so I've only posted the specifications for that model.  The general operating sequence and the communications port are common to all three units. All three use the same batteries. The L600 uses 2 batteries in series, the L900 and L1250 use 4 in series.


I've done a bit of experimenting with my L900 and the Powerwise Assistant software from HP. I was able to reverse engineer parts of the communication protocol. I've used this information to create a small script that will poll the L900 and print its status.