Making the Solar
Lithium Iron Phosphate cells are the new stars of the battery world , and rightly so . However , all this star power does cost more ( perhaps 3 to 5 times as much as a similarly rated FLA battery ). However , they have the advantage of being able to be discharged down to 0 % SoC without damage . That ’ s right , when you buy a 100 amp-hour Lithium Battery you can ofen use all 100 amp-hours of its stored energy thousands of times without damage . And it can be recharged much faster than a FLA or AGM battery . So while a 100 amp-hour lead-acid battery ( FLA or AGM ) probably won ’ t be rated to charge faster than 10 % to 20 % of its amp-hour capacity ( perhaps 10 to 20 amps of charging current that could take 5 to 10 hours to completely recharge it ), many Lithium batteries can be charged with an amperage rate up to 100 % of their amp-hour rating .
That means a 100 amp-hour Lithium battery can often be charged with 100 amps of current , allowing you to completely recharge it from 0 % to 100 % SoC in about an hour or so . Of course , you need a battery charger capable of providing that current . But don ’ t think that will require a 100-amp connection at 120-volts AC . Luckily because this is 12-volts of charging , it will only draw around 1 / 10th of that amperage from your generator or shore power line . So maybe 10 to 12 amps of 120-volt AC from shore power will charge a lithium Battery at 80 to 100 amps at 14.6 volts DC .
This is also why you don ’ t want to wire a Lithium battery directly to your vehicle ’ s alternator . It may not only draw enough current to burn-out your alternator . The alternator won ’ t provide a high enough voltage to charge your Lithium battery to 100 % SoC . It might charge your Lithium battery to 80 % SoC before the alternator burns up from pulling too much charging amperage .
Inverters : Making 120-volts from your batteries
Not all RVs have inverters , and even if you do have one it might not be large enough to supply all your 120-volt AC needs . They come in a variety of wattages , sine-wave types , and features . Most new installs are using 3,000-watt pure-sine inverters since that ’ s enough AC power to run a few high-amperage appliances at the same time . Without a large enough inverter ( and a battery bank to supply it ) you ’ ll have to closely monitor power usage , turning on only one high power appliance at a time . Monitoring power usage is especially important when running on solar power alone since you ’ ll need to save enough battery power to get you through the night .
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