Adding Inverter for dry camping
I would like to add an additional battery (have one group 27 now), possibly a solar charging system and an inverter. I hate that the 120V outlets don't work on battery power. Seems crazy you can't...
Forum Discussion
Some large and expensive motorhomes use whole-house inverter-chargers that do what you want. 4-10 KW inverters to feed the whole 120v system, autoswitching to mains when connected, and converter-charger section to recharge the battery bank and supply the 12V side when hooked up. Many also provide for auto-start of the generator when battery bank is drawn down. Cummins-Onan has even produced a 'hybrid' sytem in which genset, inverter, high density storage are a single large package, and there are all-electric coaches that use the main engine and a beefed up alternator system for auto-start charging. It is also common to use solar power for charging.
What is common to most of these systems is adequate storage of energy in the battery banks for use through non-charging periods. This would be a lot more than two Group 27 lead acid batteries, smallest systems maybe eqiuivalent of four batteries this size, the more robust eight or more.
You need to understand your energy needs (how much power for how long) to size the storage and charging, and your power draws to size the inverters.
If all you need is to charge a cell phone, power for that can be readily drawn from one of the 12V outlets. Typical draw is 300-500 milliwatts, maybe 1200 for the most power hungry tablets, and they usually charge in less than two hours at that rate. All phone devices work with less than 12V, and the 12V to USB adapters limit voltage to what is needed. No need to invert to 120V AC, then reduce back down to 4.5-6V to charge a phone.
What is common to most of these systems is adequate storage of energy in the battery banks for use through non-charging periods. This would be a lot more than two Group 27 lead acid batteries, smallest systems maybe eqiuivalent of four batteries this size, the more robust eight or more.
You need to understand your energy needs (how much power for how long) to size the storage and charging, and your power draws to size the inverters.
If all you need is to charge a cell phone, power for that can be readily drawn from one of the 12V outlets. Typical draw is 300-500 milliwatts, maybe 1200 for the most power hungry tablets, and they usually charge in less than two hours at that rate. All phone devices work with less than 12V, and the 12V to USB adapters limit voltage to what is needed. No need to invert to 120V AC, then reduce back down to 4.5-6V to charge a phone.
