I am building a custom ITX PC to replace my old laptop. The laptop measured 16.5 x 11.5 x 1.5 inches. After a lot of measuring and comparing, and even more searching, I am fairly certain I can get an i7-7700K CPU with water cooling, and an Nvidia GTX1080 into a space about 17 x 12 x 2 inches. I will have a custom case made for it all once I have the final exact measurements.
One of the biggest hurdles has been the power supply. At current I am leaning towards a Meanwell EPP-400-24 that will run an HDPlex 300w power supply (if they ever become available again). The Meanwell has a peak of 400 watts at 24 volts. The HDPlex can take voltages between 18 and 24 volts. Now to make this new system truly replace my laptop it needs to have some kind of a battery power option. Currently as I sit here typing this the system is staying under 65 watts (with an AIO), at boot up it hits 90+ watts, and for gaming its all over the board, but generally under 200 watts. But I am not necessarily looking to play games when running on the battery. So I am thinking I can get 24 (4 banks of 6) of the 18650 (3.7 v at 3.4ah) into the system. If I am calculating right, that should get me just over 300 watt hours (3.7v x 6 x 3.4ah x 4 banks), which should yield almost 5 hours of battery life for normal usage. If I tweak the system some or even underclock, while on the battery, I likely can improve that time some.
So to my question, the Meanwell power supply will provide power to the HDPlex PSU and power to charge the batteries (with a protection circuit). So the big question is, can the batteries provide the power back through the same wires that are used to charge them? The wires for charging will feed off the same point, on the Meanwell, as the wires that power the HDPlex PSU. Or should I use some other control circuit to engage to batteries when power is lost?
And while I am asking about battery power I have 3 other related questions. First is batteries, so far the best one I have found is by Panasonic (3.7v at 3400mah). I figure stick with reputable brands as some companies seem to exaggerate on the capabilities of their batteries. But if anyone knows of a better battery option I would be very interested. Second, is the protection circuit for controlling the charging and discharging of the batteries, I have never bought one. I have found them in several places but wouldn't know a good one from a bad one. And as I don't wish to ruin the batteries or worse fry $1500+ in computer parts I want to pay extra attention to the one I get, so I would really appreciate some recommendations. Third, I have seen a few USB battery level indicators around. I have not looked into them too much, but the one's I did see didn't seem to support the voltages I am dealing with. While not absolutely necessary, these would be very handy for letting me know when the battery is getting low. I am kind of hoping someone knows of one that would work.