Do you mean the silver box on the tail boom? or the yellow boxes on the landing skids? How do you build the box? by 3D printing or using some boards and screws?
Thanks.
@steveross1234
Hi Steve,
if you are only interested in the longest possible flight times, then this is also possible with Lipo batteries.
To save costs when buying batteries you can also use LiFe batteries. These are more cycle resistant and can be charged up to 5000 times without losing much capacity. In our operation 1000 cycles are realistic in any case. Also the aging process over the years is much lower than with LiPo batteries.
I myself have two battery packs in my scale helicopters in use. One of them is already over ten years old and still works very well.
In the German heli community you will find many examples of helicopters that achieve very long flight times with low head speed. Of course, you canât do 3D flying style with it. However, normal flight and simple aerobatics are possible. Especially the Mikado Logo mechanics can easily be converted to âlow RPMâ flying. I would search the popular heli forums for the term âLow RPMâ. Iâm sure youâll find enough posts there.
30 minutes of flight time and more are easy.
BR
Heri
1 Like
Hi Heribert,
Does a regular LiPo ESC work on LiFe battery or do you need a special ESC to work on LiFe battery? Do you have to use a 4S LiFe battery instead of 3S LiPo battery to compensate the voltage differences or you just use 3S LiFe battery to power the heli to get a lower performance/headspeed?
I searched using Google and Amazon in USA, itâs hard to find LiFe batteries. Where did you buy the LiFe batteries from?
Thanks.
@steveross1234
Hi Steve,
it depends on the ESC you are using. With many ESC the cut-off voltage (the voltage at which the ESC switches off or down) can be adjusted by reprogramming.
If the ESC is not programmable, then you can usually disable the shutdown.
If this is also not possible, then you can choose cell pairs that give the same final voltage.
In general, a cell voltage of 3.7 volts per cell is calculated for ordinary LiPo batteries. A LiFe battery is calculated with 3.3 volts. Now you can simply run through calculation examples, with which combinations you come as close as possible to the same total voltage. The better these match, the more the ESC will ârecognizeâ the LiFe batteries as LiPo batteries. Very good is e.g. 10 cells LiFe replace 9 cells LiPo. You can also work well with this. Prismatic LiFe cells are often offered as 5S1P pack. These can be connected serially to a 10 cell LiFe pack and the ESC ârecognizesâ a 9 cell LiPo pack.
I have exactly such a battery pack in a 700 scale helicopter in use.
BR
Heri
May be use this âA123 LiFePO4â to search. These are round zells. Here in Germany I have dealers for the prismatic typ too. But they do not export to USA.
ZIPPY Compact 4200mAh 3S1P 30C LiFePo4 Pack
ZIPPY Compact 4200mAh 4S2P 30C LiFePo4 Pack
You can connect them to 10SP1 Pack.
Hi Heribert,
Thanks for the answers. The ZIPPY LifePo4 batteries are in Backorder in HobbyKingâs Global warehouse. The A123 LiFePo4 packs are available in USA, but the price is 5x that of a similar capacity/voltage LiPo packs. LiFePO4 Prismatic Cells are huge in capacity and volume. Otherwise, LiFePo4 is an excellent choice (with more weight).
I havenât tried using LiFePO4 cells in an aircraft yet myself but I purchased some 32700 cells to use in various experiments. I purchased the cells from this seller.
https://www.aliexpress.us/item/2251832800184911.html
I purchased a balancing circuit from this seller.
https://www.aliexpress.us/item/3256802431292758.html
I donât know enough about this topic to know if I got a good deal or not.
I havenât used the cells enough to know if theyâre good quality or not. The cells all had voltage levels in the expected range.
Hi Duane,
The price of the A123 LiFePo4 cells or balancers from Aliexpress sellers is more reasonable than that from USA sellers, except that the shipping will take 2 months from China to USA (by Sea and Land routes). After the cells arrive, it will need spot welder to make these cells into a pack with shape that the helicopter can accommodate.
There is a US seller of the A123 LiFePo4 cells with very reasonable price and shipping. But they will charge a very expensive shipping for a customized pack (due to the regulation).
Overall, the LiFePo4 is good for longer Life Spans, longer flight time, but the the heli will have much smaller payload left due to the weight of the battery. Also, the CG of the heli will be changed due to the extra weight of the LiFePo4 pack (need to add some lead on the tail boom).
It would be better to adjust battery or even payload position than to put deadweight.
@steveross1234
@LupusTheCanine
I canât quite tell from the post what Steve is most concerned with. In the first post I read that he probably wants to have long flight times and save the expensive lipos.
If Steve also wants to fly 3D with a gasoline helicopter, which in principle he can, then he probably wants to keep the sleek aerodynamics of a 3D fuselage.
If he only wants to have long flight times to make long autonomous flights, for example, then the aerodynamics should not play a significant role.
In this case, converting an electric helicopter to mount the batteries elsewhere is relatively easy. For example, one can construct an intermediate floor (between the chassis and the skids). In the intermediate floor you can mount the batteries in the center of gravity and you still have space for the electronics.
So you have to know more about Steveâs goals to give him the best advice.
BR
Heri
Hi Heribert,
Thanks for the suggestions. I like the gas powered heli UAV because of its long flight time, heavier payload, cheaper fuel, and longer lifespan. But its noise level is also a big issue (I have to find a field that tolerate it). The LifePo4 powered heli UAV have no noise issue, but the payload suffers.