Battery & Solar Panel Notes

Definitions

  • Voltage (V) is the pressure from an electrical circuit’s power source that pushes charged electrons (current) through a conducting loop, enabling them to do work such as illuminating a light. In brief, voltage = pressure.
  • Amp (A) – The rate at which electricity flows is measured as an electric current. The electric current is measured in amps.
  • Amp-hours (Ah) – One amp flowing for one hour. It is a measure of the storage capacity of the battery.
  • Wired in Parallel (Positive to Positive, Negative to Negative) – When you wire in parallel you are making a larger battery but the voltage stays the same. RVers generally do this when using multiple 12v batteries.
  • Wired in Series (Positive to Negative, Negative to Positive) – When you wire in series you are increasing the voltage but not the amp-hour capacity. RVers generally do this when using two 6V batteries to provide 12v of power.
How to wire 12v and 6v batteries on a RV
  • Inverter – a device that changes 12-volt battery power to 120 volt AC power. It is used when “boondocking” (camping without hookups) to power certain 120 VAC only devices like a microwave oven. The amount of available power depends on the storage capacity of the batteries and the wattage rating of the inverter.

6v vs 12v Batteries

  • 6v recover faster than 12v batteries
  • 6V batteries are a lot more expensive than 12V batteries
  • 6V less readily available than 12v
  • 6V batteries have bigger capacities than 12V batteries
  • 6V can discharge and recharge more often than 12V batteries, and they are less prone to charge memory.
  • 6V batteries may be more durable

What You Can Run on Batteries

  • The furnace in an RV uses propane to create heat but there is also a fan that blows that heat into the RV.
  • Ceiling lights (10 LED bulbs will use at the most 40W/hr)
  • Ceiling fans (12-24W/hr)
  • Water pump (about 80-90W/hr when running)
  • Range Hood (fan and light)(Range fan uses about 20W/hr)
  • RV propane alarm (1-2 amps of power a day, that’s a max of 24 watts a day)
  • Radio and Speakers
  • RV antenna booster (A traditional RV antenna will use around 12 watts an hour)
  • Slides (a slide-out motor is usually between 30-40 amps which means the watts drawn from the 12V battery will be anywhere from 360-480 watts. Even if the slide motor only runs for a few minutes that’s going to be a high power draw from the RV battery and if you have an electric tongue jack that’s going to be a draw from the battery as well. One way you can save power when using the slide-out is to leave the RV engine on or keep the truck plugged in. The running motor of the vehicle will power the slides and not rob power from the RV batteries.)
  • Awning

What Can Run on Propane

  • Refrigerator (going to use some 12V electricity to run the thermometer and electrical starter. On average an RV fridge will use around 240 watts a day when on the gas setting. That’s only 10 watts an hour but since the fridge has to run 24/7 there will be some drain to your RV batteries and there’s not much you can do about it.)
  • Stove
  • Space Heater (circulation fan runs on battery)
  • Water Heater (expect the water heater to use a tiny bit of electricity to run the thermometer and electric starter.)

What only runs on 120v – air conditioner, wall outlets, microwave, fireplace, TV, coffee maker, CPAP,

Solar Power

There are two ways to look at RV solar in my opinion: as a total solution that powers everything in the RV or as a system for maintaining the batteries so that the 12 volt systems in the RV continue to operate.

Portable Solar Generators

A solar generator is a compact electronic box that encompasses three main components, namely:

  • Battery – A solar generator has to store the energy it captures from the sun for later use. That’s the work of the battery. Lithium-ion batteries are more commonly used in solar generators, but you can also get lead-acid batteries. Lithium-Ion batteries have far more benefits than lead-acid batteries and in the long run, are actually more affordable.
  • Charge Controller – The charge controller is an integral component of a solar power generator. Its primary purpose is to protect and promote the durability of the solar generator’s battery. Charge controllers normally have different characteristics for charging and discharging depending on your battery type. This is the brain of the generator.
  • Inverter – The work of an inverter is to convert the low DC (Direct Current) power from the battery into AC (Alternating Current) power that can be used to power various AC devices in your home. DC items can actually bypass the inverter completely since the electricity doesn’t need to be converted.

It is important to understand how fast the generator can charge. Review the generators battery capacity as well as charge capacity. If the battery is 1,000 watts and the charge capacity is 150 watts it won’t work well. You should count on roughly 5 hours a day for charging. 150 watts charge capacity x 5 hours a day = 750 watts produced a day. That’s not enough to recharge the battery in a day.