Enough Solar for conservative boondocking?
Hey Guys, I looked for the "Dumb Questions" thread, but didn't see it, so I'll post my question here. I want to be able to boondock for 3-4 nights with my family of five on our 28 foot TT. I don't p...
Forum Discussion
Kudos to Mr Wizard for pointing out confusing misuse of electrical units. Pardon this old school teacher for repetition.
Electrical energy is measured in units of watt hours or kilowatt hours (kWH). A KWH on your home electricity bill costs about ten cents. An ordinary RV battery stores about 100 amp hours which is 100 amps x 12 volts x 1 hour = 1200 watt hours or 1.2 kWh. Note that discharging a battery below half charge damages it.
Electric power is the rate of energy use; energy per hour. The unit is watt hour per hour or just Watt. It is never correct to say “watts per hour” because the watt is already a watt hour per hour.
I ruined our first pair of RV batteries by relying on engine charging and the voltage method of measuring the per cent of full charge: 12.6 volts means 100 %, 12.0 means 50%. This method is tricky because the battery voltage indicated is charging voltage while charging ... and for some time after charging ceases, depending on the power drawn. So a 50% charged battery can be at 13 volts a few hours after charging which lights up all the indicator lights on the RV panel making you think all is well.
After installing a 100 watt solar panel, we find we can camp without hookups indefinitely in summer. We don’t use electricity hungry appliances like incandescent lights, microwave, TV or coffee pot and we don’t run the furnace at night. We cannot camp now (March in northern Alberta) when it is -10 C, 15 F most of the day.
Electrical energy is measured in units of watt hours or kilowatt hours (kWH). A KWH on your home electricity bill costs about ten cents. An ordinary RV battery stores about 100 amp hours which is 100 amps x 12 volts x 1 hour = 1200 watt hours or 1.2 kWh. Note that discharging a battery below half charge damages it.
Electric power is the rate of energy use; energy per hour. The unit is watt hour per hour or just Watt. It is never correct to say “watts per hour” because the watt is already a watt hour per hour.
I ruined our first pair of RV batteries by relying on engine charging and the voltage method of measuring the per cent of full charge: 12.6 volts means 100 %, 12.0 means 50%. This method is tricky because the battery voltage indicated is charging voltage while charging ... and for some time after charging ceases, depending on the power drawn. So a 50% charged battery can be at 13 volts a few hours after charging which lights up all the indicator lights on the RV panel making you think all is well.
After installing a 100 watt solar panel, we find we can camp without hookups indefinitely in summer. We don’t use electricity hungry appliances like incandescent lights, microwave, TV or coffee pot and we don’t run the furnace at night. We cannot camp now (March in northern Alberta) when it is -10 C, 15 F most of the day.
