i think you mean
elif (typ == 'DS2438'):
return DS2438(address, typ, bus, interval=interval, circuit=circuit)
as codeblock, i think it can help to uncomment this part. that show to be the part in evok owclient to give knowing of your batterymonitor-part of the unica device.
maby you have to reload (better restart the system) to load the changed module.
after this check if the DS2438 now be loadet
well i'm not sure, but if this doesnt help you can roll back ;)
one wire are most easy, there was o lot to read online, beginning at wikipedia ;)
PS: feedback after would be nice