[Nut-upsdev] Trying to fix "Unsupported combination of battery voltage / nr. of batteries" error

[Charles Lepple]

On 5/1/07, Frank van Wensveen <frankvw at myconnection.co.za> wrote:
> Hi, everyone,
>
> I've recently bought a UPS from Mecer. This is a South African brand
> that basically resells Mustek hardware, and this UPS is no exception;
> it's a Mustek product. It does come with software for Linux, but that
> is terrible (the background process that monitors the UPS is written
> in Java and needs a terminal to start properly, so you can't run it
> from a startup script... that sort of nonsense). So I was very happy
> to discover NUT.
>
> However, while NUT does recognize the UPS as using a Mecatec type
> protocol and can communicate with it, I get the following error
> message:
>
> "This UPS has an unsupported combination of battery voltage/number of
> batteries"
>
> The UPS has 3 batteries of 12V each. The nominal voltage is 36V but
> the UPS reports 40.8V (which is correct; the float charging voltage is
> 13.6V per battery).

It looks like the existing battery table has some odd per-battery
voltages for other 36V UPSes:

http://boxster.ghz.cc/projects/nut/browser/trunk/drivers/megatec.c#L106

> - How can I get debugging info (e.g. the raw data reported by the UPS)
> out of the driver or other portions of the code?

You can start the megatec driver (or any other driver, for that
matter) with at least one "-D" on the command line to enable debug
output. One "-D" should print the voltages used to determine the
proper charge parameters.

> - Can I change set_battery_params() in megatec.c with impunity?

You might want to see if you can get away with just adding to the
aforementioned table.

(These are just some starting points - Carlos (the driver author) or
others with specific megatec experience can weigh in with more
authoritative information.)

-- 
- Charles Lepple