[Nut-upsuser] false low battery alarm

Kris Jordan nut.kj at sagebrushnetworks.com
Thu Feb 28 17:55:14 UTC 2013

Vieri wrote, On 2/28/2013 9:41 AM:
> --- On Thu, 2/28/13, Manuel Wolfshant <wolfy at nobugconsulting.ro> wrote:
>> Good batteries ( for instance Yaesu, as seen in APC UPSes )
>> last 4
>> years. Normal ( usual ) ones last 2. Do the math yourself
> Thanks for that information.
> Just a side question:
> Will the ups.mfr.date value be updated automatically by the APC ups firmware when I change the battery or will I need to set it manually? I'm asking because I'm not sure if the current battery was really installed at the time indicated by this field.

Where APC has provided a value for battery mfg date, it has always been 
the same as the UPS mfg date. The value isn't automatically updated and 
NUT doesn't (from what I've seen) provide a way to update it manually.

Before getting new batteries, you might want to check the float voltage 
with a good multimeter. 55.65 is rather high (~2.32/cell), but I 
wouldn't trust what the UPS says. Smart-UPS's can be bad about 
overcharging their batteries. It can be adjusted by software in some cases.

> I also have another (maybe related) problem. I have another 2 APC devices I'd like to monitor (apparently same model and serial numbers). However, whenever I connect a serial cable to the port on the UPS, the whole device shuts down immediately. This happens only if I connect the other end of the serial cable to either a ttyS0 port on a running motherboard or a port on a rs232-to-usb adapter (even if the usb end ISN'T connected to a NUT monitoring server). What could be happening here?
> This is obviously slightly off-topic because it doesn't seem to be related to the nut ups drivers.
> I'm just wondering what could be happening and if old batteries on relatively high load (approx. 75%) could be a reason the UPS shuts down abruptly on connecting a serial cable on both ends. IT sounds really strange though.
> Also, the UPS won't switch on while the serial cable is connected even if I press the UPS power-on button several times.
> I have to disconnect it (or at least the far end of it) in order to "boot" the ups.

Are you using APC's supplied serial cable? They have special wiring and 
it varies depending on UPS model.

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