The Avalons report what your PSU is feeding them. Check Status > CGMiner API log. Near the top you will see:
[Firmware Version] => Avalon Firmware - 20180305
luci: 62d814c
cgminer: b5b497e
cgminer-packages: 960e108
Reply was 'STATUS=S,When=1552405632,Code=70,Msg=CGMiner stats,Description=cgminer 4.10.0|STATS=0,ID=AV80,Elapsed=7644723,Calls=0,Wait=0.000000,Max=0.000000,Min=99999999.000000,MM ID1=Ver[8411802-1e73b80]
DNA[0130a561fa8de79c]
Elapsed[7644726]
MW[2363602990 2363604773 2363605616 2363606435]
LW[9454419814]
MH[4221 4182 4394 4095]
HW[16892]
Temp[43]
TMax[87]
Fan[5760]
FanR[100%]
Vi[1203 1203 1212 1212]
Vo[3773 3798 3825 3827]
GHSmm[13748.50]
WU[190936.23]
Freq[768.59]
PG[15]
The line
Vi tells you what the PSU is feeding to each of the PMU's (Power Management Units) and PG is a generic Power quality value.
In my above example the PSU is feeding 12.03, 12.03, 12.12 and 12.12v to each of the PMU's and PG is the typical value of 15 (very good). If PG goes below 13 or so you will have problems with boards dropping out.
Using the Code tag (looks like
# ) post your API log here.