I’ve been looking at lipos for my Super Cub, so I measured the battery compartment to see what can fit without mods, and these are the dimensions I came up with: 66.6x36x41 (LxWxH). The 8-cell pack which fits perfectly is 66.6x35x30 (LxWxH). I checked out cheapbatterypacks.com and using their super-cool li-po finder tool I came up with three 1320mAh 3S 11.1V packs that are a direct fit and offer at least 15A of continuous current capability. The most expensive being from Thunder Power costing $55 is a popular choice, the second most expensive runs $48 and is made by Hyperion. However the cheapest way to get an 11.1V lipo into a Super Cub is with the Apex APX1350-3S which runs a cool $35, is a 1350mAh pack and actually offers the highest discharge capability over the other two packs with a 20A constant current capability. That should be plenty to run the stock brushed motor, as well as just about any brushless motor available. Not only that but the pack weighs 1/2 what the 8-cell 2/3A pack weighs coming in at 97 grams vs. 184 grams. The first lipo I bought for my RC18T I couldn’t believe how light it was, I kept think there’s no way this thing is going to power my car, there’s nothing inside! But undoubtedly, it worked out amazing.
The other option to get lipo power in the SC is to modify the battery compartment to fit a bigger pack, or rather something with more mAh like a 2100mAh or 2200mAh pack. These are available in a 3S configuration (3 series cells, none in parallel) however, you can get even more mAh by going to a 3S2P pack, which takes a smaller pack like the 1320mAh and doubles up on the cells giving you a pack that’s basically twice as big as the 3S version and twice as heavy, since it’s made up of 6 identical cells instead of 3. There are two downsides to this approach in my book: one being cost and the other being if something happens to the pack from damage of some kind (overcharge, under voltage) then the whole pack is done, where as if the extra money were just put into a spare pack, it would still be good.
One downside to li-pos is charge time. Lipos can only be charged safely at a 1C rate but you can charge an 1100mAh NiMH pack at 2C (which would be 2.2A) without damage. At that rate the pack will be charges in less than 1/2 hour. By contrast a 1320mAh lipo will take over an hour to reach full capacity. You can get away with charging a lipo to 80% of its rated capacity, which it can do in about 1/2 the time it takes to fill it up the other 20%. The ICE charger gives off a beep when it’s about at the 80% point where it switches from CC to CV. It’s not the “done” beep though. I like to wait till the charger says the pack is done and not remove it beforehand just because the pack is “charged enough”. Either way, expect to wait for longer charge times for lipos over NiMH/NiCAD batteries.
After tearing apart the stock battery compartment and seeing how it all goes together with the receiver/ESC unit I feel pretty confident that I can modify it along with the fuselage to fit a bigger lipo pack. I’d really like to have longer flight times, it seems like 10 minutes just isn’t enough anymore, and neither is 9.6V. The cheapest pack I can find that would require the minimalist amount of mods is the Apex APX2100-3S which runs 100x34x20, so it’s basically just longer than the stock battery but still comes in under in weight at 158 grams, offers 2100mAh and 31A continuous discharge, well above what we need in the SC, and the best part is it only costs $40. By contrast, the brand name Thunder Power TP2100-3S is $70, almost twice as much for basically the same battery. Is one better than the other aside from just the listed manufacturer’s specs? Only someone whose run both packs could probably tell. I suspect that the Apex pack is just as good as any other, but that’s just my opinion, and based on its excellent price point, I’d be willing to pick one up and check it out. Unfortunately all Mike’s Apex packs are out of stock right now. We’ll have to wait and see…
