Newbie here. I am known among my friends as a flashlight junkie but what they don't know is that the real experts are on these forums. Almost everything I know has been learned searching these forums over the past few years. As it happens, my first question has nothing to do with flashlights:
I am trying to figure out an economilcal way to power my portable ARB fridge/freezer (http://store.arbusa.com/Fridges-C11.aspx) with lithium batteries. It runs off of a car's cigarette lighter socket at a fairly low current, so it might be possible. Some background info might be helpful. When the compressor comes on, it draws an initial 5.36 amps and then settles down to a constant 4.86 amps within about 30 seconds. Because the compressor is off much more than it is on, it will run about a day drawing 20 amp hours from the battery. It also has serveral built in protection circuits. One will shut the unit down, and trigger an error light, in an under current situation. This most often happens when plugged into a low current cigarette lighter. It also happened when I put three 3000mAh 18650 batteries in series and tried to power the fridge. Another protection turns off the fridge when the battery hits either 10.1, 11.4, or 11.8 volts. This function is set by the user.
I searched the forums and leaned that there are high current 18650 cells that can handle up to a 10a current. But I am not sure that would be needed because I am thinking I would like to build a battery pack that could run the fridge for at least a day. As I understand it, when you hook the batteries together is parallel, you pretty much add the amp hours together assuming all the cells are the same. So, as an example, if I used 3000mAh cells in goups of three (series, 12.6v), I would then need eight of these units to make a 24 amp hour battery pack. But would that solve my undercurrent situation? This is where I am getting to the limit of my understanding of all of this. I know there are people here who know, but I have no clue.
My mind is kind of stuck on the 18650 cells because that is what I am familiar with. But I don't know if that is the best way to go or if there is even a way to do this without getting into serious bucks. I do know that a lithium deep cycle RV battery is out of my price range because they generally cost over $1000. Ideally, I would like to keep costs under $300. Any ideas you have will be greatly appreaciated. I've done an extensive net search and, apparently, no one has tried something like this with these fridges. Assuming there is a way to do it, the benefits are pretty obvious in terms of weight savings and the fact that lithium batteries can be safely discharged further than lead acid/AGM batteries. I'm also thinking there might be a way to charge them faster, but that may not be true. You guys would know.