New Polyquest XF packs: 45C discharge, 5C charge
By Adrián Muiño
The LiPo technology has taken another big step and now we can enjoy packs rated at 45C or more. I have been testing the new Polyquest XF 45C packs over three platforms and here are the results.
The packs come with the cables isolated and fastened. The main cables are multifilament and have a generous section. Under the external black covering, there is a hard plastic protection that makes them more resistant to eventual scratches—a welcomed improvement. The weight of the packs is higher than the previous ones, but in the air, the difference can not be felt.
First test: Polyquest XF 14.8V 3700mAH in an AJ Extra 330
I already made 200 flights with my Extra 330 using both LiPo packs and A123 packs. I have to say that I did not expect to have a better performance than with the A123, but the differences were clear from the take-off to the landing.
Pack 4S1P: Polyquest XF: 14.4V; (3700mA; 45C; 420g/14.8 oz.
ESC: 60 A U-BEC
Model: AJ Extra 330S (1.28m @ 1.8kg), (50.5 in. at 4 lb.)
Propeller: 13×6.5 APC-E
I am used to throttle management, but speed-down, during the vertical climb amazed me. Part of this change was due to the extra volt the LiPo has compared with the A123, but another part was due to its great performance. Compared with the past LiPo generation, the differences were significant.
These packs are so powerful, that now the weakest point seems to be the motors that gives 9,800 rpms at 680W, so I had to change the 13-inch prop for a 12-inch, to keep the motor in the safe side.
Going to the figures, I measured that the difference in voltage at the end of the routine was only 1V (0.25V per cell), and the temperature was increased from 24°C to 31°C; these facts represent a very good performance. In this not-so-demanding application, the output voltage was very flat and a bit higher than the old LiPo packs, giving some extra rpms.
Second test: Polyquest XF 22.2V 4400mAHr + AXI 4130-14 in a 1,6m F3A style plane
Next, I tried a 6S pack in a more demanding platform than used in the 4S test, a plane where some old 18C packs did not pass flight number 15. The Matrix is fast, and even with a 16×12 propeller needs the rpm high all way long, so if the pack is not proficient, it will enter in thermal runaway and the landing will be sooner than planned.
Pack 6S1P: Polyquest XF: 22.2V; 4400mA; 45C; 740g / 21.16 oz.
ESC: Jeti Spin 99 (90 A opto)
Model: Matrix F3A-style (1.6m at 3.7kg) (63 in. at 8.15 lb.)
Motor #1: AXI 4130-16 (409g; 385rpm/V), 16×12 APC-E
In this test, it was revealed that under load, the battery drops its voltage quickly, but soon it starts to flatten out. This gives a constant voltage during flight, except in the taking off, when a bit more of power is available, ideal for super safe take-off in ducted fans.
The performance was very good, vertical climbs were unlimited, but at its end there was only enough power to make gently maneuvers, with peaks of 1280 watts at 6600rpm during vertical climbs. The surface of the pack did not get hotter during flight.
Third test: Polyquest XF 22.2V 4400mAHr + AXI 5320-18 in a 1,6m F3A style plane
But, to take the most from the pack a bigger motor was needed. So, I choose the new AXI 5320-18 for the third test. It is the perfect match for the new 6S 45C packs because it is the hottest AXI motor in this size (495g) and it can handle easily an 18 inches propeller.
The power was increased to 1600W at 6000rpm and the result was a very firm flight. The powerplant showed a remarkable authority nevertheless the speed was moderated. The efficiency and robustness of the AXI 5320-18 plus the Jeti Spin 99 were notable too. It wasn’t hard to fall in love with this setup.
Pack 6S1P: Polyquest XF: 22.2V; 4400mA; 45C; 740g / 21.16 oz./FONT>
ESC: Jeti Spin 99 (90 A opto)
Model: Matrix F3A style (1.6m at 3.8kg) (63 inches at 8.37 lb.)
Motor #2: AXI 5320-18 (495g; 370rpm/V), 18×12 APC-E
The profile of the discharge was again very flat, passing from 21.5V to 20V, giving the same power during the whole flight, except in the first minute when it was noticeable greater. Nevertheless, values showed in this article were not taken in this first “golden minute”.
With this configuration (6 feet, 11 pounds). aerobatic models can be effortlessly powered, i.e. a 1.20 size plane, avoiding the use of two 4S packs and the subsequent cost in packs and charging logistics.
But to speak about the discharge is only half of the history. The XF generation is rated to be charged at 5C, something that will challenge more than one charger. For example, to charge the first tested packs at 4C demands 200W, and to do the same with the second one 350W. The critical point seems to be the balancing time and not the power availability. Safety measurements should be reconsidered too, because at 5C there is not a lot of margin for errors.
The final time between flights is not cut to 1/5th. First, we need to let the pack temperature fall before start to charge. Then we can start to charge at 5C, but it means to cut to 1/5 the first part of the charging process (constant current), but not the second part (constant voltage), so the final time is shorter, but not 1/5th. Using a flotation voltage of 4.15V per cell and charging at 2-3C, the procedure takes 10 minutes to let the pack cool down after the flight and 30 minutes to charge it. In my case, with the Extra 330 and the Matrix at the field, I only needed one pack of each size and a big charger to be happily airborne all day long.
As the specification states, the performance of the Polyquest XF 45C is superior to the past generation; that was already very good. New motor configurations, as the AXI 5320-18, will take full advantage of the huge available power. Ducted fans and applications at the competitive level will appreciate the improvements a lot.
Besides this, for me one important aspect is to go to the field with only two packs (or one) plus a charger; and flight as much as if I were using three or four of the old ones. If you are thinking of buying packs, Polyquest XF can be a good investment; and motors as the new AXIs are their perfect match.
Polyquest packs are available at:
AXI motors and Jeti ESCs are available at:
Notes about the author
Adrián Muiño has almost 30 years of experience in the hobby, and he has written hundreds of articles for magazines around the world. Today he specializes in electric flight. He also is Electronic Engineer, has an MBA and is a certified Project Manager Professional and teaches at one of the most prestigious universities in Argentina.