Connect Magazine

28 TECH TIPS I need to cool down with A/C over short bursts. How do you get customers to consider juggling comfort and power use when they’re not plugged in? A/C units are power guzzlers at the best of times. A standard battery cannot produce enough power to run a 120V A/C unit. However, when a 120V air conditioner is paired with 200Ah of Lithium batteries, customers get the option to run the A/C for about an hour to cool down the RV. This leaves just enough power for overnight needs like lights, fans and charging electronics. Adding solar improves the picture significantly. 400W of solar, an appropriately sized inverter and two 100 Ah batteries is a good starting point here. I go off-grid for days at a time; efficiency is key for me. Those going off-grid for more than 2-3 days at a time will need a much more robust setup. This build will vary largely on personal use and how the customer travels. The leaner they are with power use, the smaller the system can be. It’s recommended to start with no less than 600 W of solar and pairing that with at least 300Ah of lithium batteries. This keeps up with basic use, keep a 12v fridge running, the lights on, devices charged, and run the A/C for a short time on a perfect day. More available power is better. Trying to put too much solar on a small battery bank can create problems. When upgrading a mobile power system, adding another battery is almost always a better investment than adding more solar. AC vs DC Fridge The type of refrigerator will make quite a difference in energy consumption. Look at an AC fridge for example: every 1 amp of AC power coming out of an inverter, takes 10 DC amps from the battery to produce. DC refrigerators are much easier on the battery and, some fridges can run for up to 48 hours on a single 100Ah lithium battery. If you have a 120-volt residential refrigerator in the RV, an inverter is required to operate it off battery power. Running through the inverter, it will use between 200 & 600 Amp-hours (Ah) per day. In contrast, the 12-volt DC refrigerator has a much smaller power requirement, i.e. 60-200 Ah per day.

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