~/.config/taffybar: Add battery display.

.config/taffybar/taffybar.hs

import System.Taffybar
import System.Taffybar.Battery
import System.Taffybar.Systray
import System.Taffybar.XMonadLog
import System.Taffybar.SimpleClock
        log = xmonadLogNew
        tray = systrayNew
        cpu = pollingGraphNew cpuCfg 3 cpuCallback
        battery = textBatteryNew "%d%%" 30
    defaultTaffybar defaultTaffybarConfig {
        barHeight = 15,
        startWidgets = [log],
        endWidgets = [tray, clock, cpu]
        endWidgets = [tray, clock, battery, cpu]
    }