[Nut-upsuser] Cyberpower CP850PFCLCD 120% battery charge

Arjen de Korte nut+users at de-korte.org
Thu Mar 31 19:09:55 UTC 2011

Citeren Justin Ellison <justin op techadvise.com>:

> I have a CyberPower Systems CP850PFCLCD that I'm hooking up to NUT 2.4.3
> from apt running under Ubuntu 10.04.  Using the usbhid-ups driver, things
> *seem* to work at first glance, but there are some odd issues.  The most
> notable issue is that the battery.charge indicator reads 120 when at full
> charge.  I came across this post here:
> http://lists.alioth.debian.org/pipermail/nut-upsuser/2007-September/003222.htmlbut
> it looks like the user never supplied the necessary data.

For whatever reason the people that made the UPS firmware decided that  
they didn't need to follow the USB HID PDC specifications. From the  
data you sent, it looks like the value for battery charge that is  
reported by the UPS needs some conversion (coefficient and/or offset)  
to get to the true battery charge. Most likely, this is present in the  
bundled software for the UPS, but sadly we don't know them. So unless  
you're going to change that, the situation is unlikely to improve. It  
looks like '120' means 100% charge, but one data point is not enough  
to find (at least) two missing parameters.

> The other issue that I found was that the LB flag is sent way to early when
> I unplugged the UPS from the outlet.

I don't think so. The data you posted indicated that about the time  
the UPS started reporsing LB (low battery), the runtime fell below the  
battery.runtime.low, so this is about right. If you don't need 5  
minutes to shutdown your system, you might try lowering this value (if  
the UPS supports that) and see if this increases the useable time on  

Best regards, Arjen
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