enginstar portable power station, 300watt portable power bank with ac outlet for outdoors camping travel hunting emergency use, 80000mah power supply for cpap machine enginstar kindly noted: <br>1. you may hear some sound of rattling inside of the unit, please don't worry, that is the cooling fan working to cool down the unit.<br><br>2. when you need to power a 12v fridge, please use the ac output, get an ac to dc plug to plug in your 12v fridge. the problem will be solved. when thermostat on refrigerator is satisfied, the dc output will shut off to save the power, then you need to turn it on by hand. but the ac output will stay on.<br><br>3. please press the ac button to turn on the function of ac power output.<br>trouble shooting: 1. the unit does not work. red triangle lights up. if the customer don't use it correctly, this unit will turn to self-protection mode. they only need to turn it off and turn it on again, then the unit will work again. <br> 2. the product did not last enough time with cpap. there are many types of cpap machines on the market, and the working hours we have provided on the product details page can only be used by customers as a general reference. in order to avoid such complaints, we have updated the product page with the working times for two specific cpap machines, so that the customer can know more precisely how long his product can work. <br> 3. this unit can't be charged well by the solar panel. our products can be charged with solar panels, but not all solar panels can be used. you must have the solar panels with 12-25v output and the dc plug 5.5 x 2.1mm male. <br> 4. turn on but don't work and turn off itself. our product has a design to help save power. when the product does not detect any load in about 20 seconds, the product will automatically shut down to save power. in addition, if customers use high-power products that our products cannot support, this will not work. we have updated the description page. <br> 5. get hot when charging. normally all batteries get hot when being charged. we have strict tests in production, and the charging temperature will not exceed 140 °f, which is safe.