I've got a L20 which I bought from USA a few years ago but only
installed in the last few months and it seemed to work really well. A
couple of weeks ago it light up like a Christmas tree and apart from
the voltage reading, all the other functions were complete garbage.
Discovered that during its CPU attack it had set itself to LOC, so
once I had unlocked it it started to behave a bit better. Any amp
reading is still odd - indicates charging on the "t" function when it
is discharging. Have done the basics of disconnecting it and leaving
it for 24 hours and resetting. Xantrax FAQ also suggests grounding
the shunt sense terminals, which I have yet to do.

There are voltmeters that can do essentially the same job - www.smartguage.co.uk
- but I like the ammeter function of the L20 to see what is using the
power. I guess a Smartguage and digital ammeter to use the L20 shunt
would do the job and probably be more reliable.