Date   time Range Waterconsumption
1/1/01 0300 31km  2.0liters
2/1/01 0800 30km  1.8liters
3/1/01 0300 33km  1.7liters
4/1/01 0600 32km  1.8liters
5/1/01 0800 28km  1.7liters
6/1/01 0300 35km  1.6liters
7/1/01 0800 31km  1.8liters

Date   time heatlost weight
1/1/01 0300 0.27     61.5kg
2/1/01 0800 0.33     62.0kg
5/1/01 0800 0.69     61.7kg
6/1/01 0300 0.15     61.8kg
7/1/01 0800 0.63     62.0kg

set.seed(10)
df1 <-
  data.frame(
    id = c(1:4),
    time = c(1:4),
    range = runif(4,0,1),
    watercon = runif(4,5,6)
  )

df2 <-
  data.frame(
    id = c(1,4),
    time = c(1,4),
    heatlost = c(11,7),
    weight = c(10,10)
  )

dplyr::left_join(df1, df2, "time")

1   0.5074782   5.085136    1   11  10
2   0.3067685   5.225437    NA  NA  NA
3   0.4269077   5.274531    NA  NA  NA
4   0.6931021   5.272305    4   7   10