SGP/EBBR/E22 - Low Battery - Resulting In Incorrect Data

A low battery condition (less than 10.5 volts) caused a number of data
fields to be incorrect at some times and all data fields to be incorrect
at a more limited number of times.  All data fields are suspect when the
battery voltage drops below 10.5 volts because the CR10 cannot operate 
properly.  Some sensors are affected slightly (i.e. pressure) at slightly
larger voltages.  The low battery condition resulted from an initially 
weak battery and a week of extremely low solar radiation (from heavy 
cloudiness) on the solar panel that provides most of the charging of the
battery.

Comments added by Marv Wesely: 
David Cook has been working with Dave Breedlove to try to assess the age
of the batteries.  The dates on the batteries needs to be read during 
site visits and provided to David C.  It's quite possible that they need
to be replaced.  It's work in progress, though slow at times.

• Wind direction vector mean (mV)(wdir_vec_mean_mv)
• Left air temperature(temp_air_left)
• Soil temperature 4 (resistance ratio)(soil_temp_4_rr)
• Left T/RH sensor temperature (resistance ratio)(temp_trh_left_rr)
• Net radiation (mV)(net_radiation_mv)
• AEM position indicator(home_signal)
• Soil moisture 3 (resistance)(soil_moisture_3_r)
• -180.0 - +180.0(alt)
• North Latitude(lat)
• Time offset from base_time(time_offset)
• Soil heat flow 1 (mV)(soil_heat_flow_1_mv)
• Soil moisture 4 (resistance)(soil_moisture_4_r)
• Soil temperature 1 (resistance ratio)(soil_temp_1_rr)
• Soil heat flow 4 (mV)(soil_heat_flow_4_mv)
• Battery voltage(battery_voltage)
• Reference temperature in enclosure (resistance ratio)(temp_reference_rr)
• Right relative humidity (mV)(rh_right_mv)
• Left relative humidity (mV)(rh_left_mv)
• Soil moisture 5 (resistance)(soil_moisture_5_r)
• Soil heat flow 3 (mV)(soil_heat_flow_3_mv)
• Soil temperature 3 (resistance ratio)(soil_temp_3_rr)
• Soil moisture 1 (resistance)(soil_moisture_1_r)
• base time in epoch(base_time)
• Wind speed arithmetic mean(wspd_arith_mean)
• Atmospheric pressure (mV)(atmos_pressure_mv)
• lon(lon)
• Soil heat flow 2 (mV)(soil_heat_flow_2_mv)
• Soil temperature 2 (resistance ratio)(soil_temp_2_rr)
• Soil heat flow 5 (mV)(soil_heat_flow_5_mv)
• Right air temperature(temp_air_right)
• Soil temperature 5 (resistance ratio)(soil_temp_5_rr)
• Right T/RH sensor temperature (resistance ratio)(temp_trh_right_rr)
• Soil moisture 2 (resistance)(soil_moisture_2_r)

• Reference temperature in enclosure(temp_reference)
• Wind direction vector mean standard deviation(wdir_vec_std)
• lon(lon)
• Top vapor pressure(vapor_pressure_top)
• Top relative humidity (fractional)(rh_top_fraction)
• Bottom T/RH sensor temperature(temp_trh_bottom)
• Wind speed vector mean(wspd_vec_mean)
• Wind speed arithmetic mean(wspd_arith_mean)
• Bottom air temperature(temp_air_bottom)
• Top air temperature(temp_air_top)
• Top T/RH sensor temperature(temp_trh_top)
• Net radiation(net_radiation)
• Wind direction vector mean(wdir_vec_mean)
• -180.0 - +180.0(alt)
• North Latitude(lat)
• Time offset from base_time(time_offset)
• base time in epoch(base_time)
• Atmospheric pressure(atmos_pressure)
• AEM position indicator(home_signal)
• Bottom relative humidity (fractional)(rh_bottom_fraction)
• Bottom vapor pressure(vapor_pressure_bottom)

• Surface latent heat flux(latent_heat_flux)
• Top vapor pressure(vapor_pressure_top)
• Wind speed vector mean(wspd_vec_mean)
• Wind speed arithmetic mean(wspd_arith_mean)
• -180.0 - +180.0(alt)
• Top air temperature(temp_air_top)
• North Latitude(lat)
• Bottom air temperature(temp_air_bottom)
• Change in energy storage 3, 0-5 cm soil layer(energy_storage_change_3)
• Change in energy storage 2, 0-5 cm soil layer(energy_storage_change_2)
• Change in energy storage 5, 0-5 cm soil layer(energy_storage_change_5)
• Change in energy storage 4, 0-5 cm soil layer(energy_storage_change_4)
• Wind direction vector mean standard deviation(wdir_vec_std)
• Wind direction vector mean(wdir_vec_mean)
• Atmospheric pressure(atmos_pressure)
• Soil heat flow 1, corrected for soil moisture(corr_soil_heat_flow_1)
• Soil heat flow 2, corrected for soil moisture(corr_soil_heat_flow_2)
• Bowen ratio(bowen_ratio)
• Soil heat flow 3, corrected for soil moisture(corr_soil_heat_flow_3)
• Soil heat flow 4, corrected for soil moisture(corr_soil_heat_flow_4)
• Soil heat flow 5, corrected for soil moisture(corr_soil_heat_flow_5)
• AEM position indicator 15 to 30 mins(home_signal_30)
• Net radiation(net_radiation)
• Soil heat flow 1(soil_heat_flow_1)
• Soil heat flow 2(soil_heat_flow_2)
• Soil heat flow 3(soil_heat_flow_3)
• Bottom relative humidity (fractional)(rh_bottom_fraction)
• Reference temperature in enclosure(temp_reference)
• Soil heat flow 4(soil_heat_flow_4)
• Soil heat flow 5(soil_heat_flow_5)
• lon(lon)
• Change in energy storage 1, 0-5 cm soil layer(energy_storage_change_1)
• Soil heat capacity 5(soil_heat_capacity_5)
• Soil heat capacity 4(soil_heat_capacity_4)
• Soil heat capacity 3(soil_heat_capacity_3)
• Soil moisture 4, gravimetric(soil_moisture_4)
• Soil heat capacity 2(soil_heat_capacity_2)
• Soil moisture 3, gravimetric(soil_moisture_3)
• Soil moisture 2, gravimetric(soil_moisture_2)
• AEM position indicator 0 to 15 mins(home_signal_15)
• Soil heat capacity 1(soil_heat_capacity_1)
• Surface sensible heat flux(sensible_heat_flux)
• Soil moisture 1, gravimetric(soil_moisture_1)
• Surface soil heat flux, average of fluxes 1-5(surface_soil_heat_flux_avg)
• Soil moisture 5, gravimetric(soil_moisture_5)
• Half hour averaged soil temperature 5(soil_temp_5)
• Half hour averaged soil temperature 4(soil_temp_4)
• Soil temperature mean 3(soil_temp_3)
• Soil temperature 2(soil_temp_2)
• Soil temperature 1(soil_temp_1)
• Bottom T/RH sensor temperature(temp_trh_bottom)
• Top T/RH sensor temperature(temp_trh_top)
• Time offset from base_time(time_offset)
• Bottom vapor pressure(vapor_pressure_bottom)
• Top relative humidity (fractional)(rh_top_fraction)
• Surface soil heat flux 2(surface_soil_heat_flux_2)
• Surface soil heat flux 1(surface_soil_heat_flux_1)
• Surface soil heat flux 5(surface_soil_heat_flux_5)
• Surface soil heat flux 4(surface_soil_heat_flux_4)
• Surface soil heat flux 3(surface_soil_heat_flux_3)
• base time in epoch(base_time)