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My friend Russ put one of these together in 2019 and it's still going strong today. The moment I saw it I knew it was the solution. It only took me four years to get around to making mine. I fly aerobatic electric models up to 6000W/50cc size, so I've bought more than my fair share of LiPos over the years. There had to be a better way - and there is. It's a 40,000mAh (just scale it to suit your needs) Li-Ion pack at 24v connected to one or two ISDT 20A chargers, to allow a pair of 6S 5000mAh LiPo packs to be charged simultaneously at 4C, all housed in a Screw-fix metal carry case. For a single charger system it cost £285 including various delivery charges but not including my time. Each pack took about 2 hours to solder up, with about the same again to sort out the cases & wiring. I should note here that I'm a known incompetent relating to all building matters, so Russ supervised me and very kindly finished off the wiring and cases when I fell over exhausted at the end of the day due to inhalation of too many solder fumes. I made three packs in all - two for me and one for my mate Pete. Final pic is the 12S flying day version but usually it's just one charger and a pair of LiPos for 6S flying. I'll try and get some better pics of how it's wired in the box. There be fuses. I've got the component list knocking around somewhere if anybody wants to make one. It doesn't take much to spend £285 on LiPos, and the advantages are huge: you can leave it charged up all the time and it doesn't complain. This totally changes how you go about flying. Charge the box as soon as you get home, leave the LiPos at storage charge at the field (I generally land at 3.75). The Li-Ions will last forever because they're barely breaking a sweat - Russ built a 2nd box a year ago and can't tell which one he's using. So you can go flying at the drop of a hat, and leave all the decisions about which plane you're going to fly until the minute before you leave the house. No more "Oh if I knew the weather was going to be like this I'd have charged those other batteries." It's like having a can of petrol, only less smelly. And the bit I was nervous about - the high C rate charging - has proved to be worry free. At the moment I'm flying 6S 3300mAh Heavy Duty Turnigy packs and charging them at 12A, which takes about 10 minutes. I cap my flights at 7mins30 so you can pretty much fly non-stop if you don't mind being a patch-hog. Previously I've always, always, always charged at 1C or below, like I was a member of some death-cult, but I'm 250 charges in and I see no performance issues or increasing internal resistance - the Zippy 4500s hover around 0.9 and the Turnigys around 1.3 per cell. Happy batteries - and they had a couple of hundred cycles on them pre-chargebox. Only charging to 4.17 makes an amazing difference to battery life. That Phil Lewis knows his onions. I've been using this for 4 months now and waited to see how things turned out before posting. I can honestly say that, for me, there is no other way of going about electric flight. Just my two 4 port chargers would have paid for this box, let alone the dozens of LiPos. This is the first topic I've started so please excuse the mess. Long time lurker. Thought I'd contribute for once. Oh... and definitely use the balsa sticks to assemble the initial cells all nice and tidy. The masking tape was like herding cats.- 66 replies
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