Category Archives: Plane Components

Proper Discharging and Disposal of LiPo Batteries

Here’s my personal experience in discharging a LiPo pack.  I found this how-to scattered all over the inter-webs but the main source (Thunder Power?) seems to be lost forever. At any rate, I’m cross-posting it here for posterity.


Unlike NiCd batteries, lithium-polymer batteries are environmentally friendly. For safety reasons, it’s best that LiPo cells be fully discharged before disposal (however, if physically damaged it is NOT recommended to discharge LiPo cells before disposal – see below for details).

The batteries must also be cool before proceeding with disposal instructions.

To dispose of LiPo cells and packs:

1. If any LiPo cell in the pack has been physically damaged, resulting in a swollen cell or a split or tear in a cell’s foil covering, DO NOT DISCHARGE the battery.

Jump to step 5.

2. Place the LiPo battery in a fireproof container or bucket of sand.

3. Connect the battery to a LiPo discharger. Set the discharge cutoff voltage to the lowest possible value. Set the discharge current to a C/10 value, with “C” being the capacity rating of the pack. For example, the “1C” rating for a 1200mAh battery is 1.2A, and that battery’s C/10 current value is (1.2A / 10) can be used, such as a power resistor or set of light bulbs as long as the discharge current doesn’t exceed the C/10 value and cause an overheating condition.

For LiPo packs rated at 7.4V and 11.1V , connect a 150 ohm resistor with a power rating of 2 watts (commonly found at Radio Shack)to the pack’s positive and negative terminals to safely discharge connecting it to an ESC/ motor system and allowing the motor to run indefinitely until no power remains to further cause the system to function.

Json Comment:

My first attempt at discharging was using a Turnigy Reaktor 250W, I used NicaD setting instead of Lithium so I can set the minimum discharge voltage to 0v.  My first test was a 3S 2200 which I discharged at 1A with a preliminary target of 6v.  After 20minutes the LiPo warmed up and puffed more (it’s already puffed to begin with and has 250-300 internal resistance across the cells)  creating a small tear in the packaging.  So yes, there’s a reason why the suggested discharge current is 10% of the effective C (i.e. I should have discharged it at 0.20-0.25A).

4. Discharge the battery until its voltage reaches 1.0V per cell or lower. For resistive load type discharges, discharge the battery for up to 24 hours.

5. Submerse the battery into bucket or tub of salt water. This container should have a lid, but it should not need to be air-tight. Prepare a plastic container (do not use metal) of cold water. And mix in 1/2 cup of salt per gallon of water. Drop the battery into the salt water.

Allow the battery to remain in the tub of salt water for at least 2 weeks.

6. Remove the LiPo battery from the salt water, wrap it in newspaper or paper towels and place it in the normal trash. They are landfill safe.

Reposted from these sources (there could be others):

The HobbyKing HKPilot32 Stripdown

I decided to bite the bullet and go with the HobbyKing HKPilot32 instead of the Pixhawk for the reincarnation of my Skywalker FPV rig.  By most accounts the HKPilot32 works as advertised and why shouldnt it? it has the same design and uses the same chips as the open source Pixhawk.  Thank you open source and market forces!

Here’s the content of the packet (L to R: USB cord, Servo wire, Power Module, the HKPilo32, cables for the gps, buzzer, arming button, stickers and vibration pads, free memory card/usb adapter and extension board) and a 4MB sd card pre-installed in the device. The only major downside is it does not come with the 6-pin cable needed to connect the HKPilot to the  Quanum Lea-6H GPS.

HobbyKing HKPilot32
HobbyKing HKPilot32

What surprised me is the size of the HKPilot. it has the same dimensions as the APM 2.6 which is great.

HobbyKing HKPilot32
HobbyKing HKPilot32

I’ve heard about the poor quality of the soldering and board layout of the HKPilot.. personally, for the price, I couldnt care less  as long as it works reliably.  Anyway, out of curiosity I checked the board.

HobbyKing HKPilot32 board
HobbyKing HKPilot32 board (back)

and front:

HobbyKing HKPilot32 board
HobbyKing HKPilot32 board (memory card on the left)

In my opinion, the board design and layout is not bad, a bit dirty to be honest but not bad. The soldering while not topnotch seems to look solid  enough at any rate.. of course I’m comparing this to the usual hardware I see (computing and networking appliance’s boards).  You can judge for yourself above.

So does it work?  so far yes, I was able to load the latest ArduPlane firmware and didn’t really have an issue connecting MissionPlanner (except I had to set the connection speed to 38400)

HKPilot32 with MissionPlanner
HKPilot32 with MissionPlanner

Looking forward to setting this up for flight!



The Aero-naut (aka TBS) Folding Pusher Prop Set

Finding the right pusher propeller set can be frustrating, specially if nobody can be certain if it will “work” in a pusher configuration.  It turns out, Team Blacksheep has exactly the propeller set I’ve been looking for which they stock for their Zephyr flying wings.  It’s the Aero-naut Folding Prop Set which seems to packaged specially for Team Blacksheep.   At $29.95 it’d be better worth it.

Here’s how  it came in:

The TBS Prop Kit

And some very sound warning for folding props.. which I’m posting here.  My main issue really with my old SW set up was that the one piece prop was bulky when putting the rig in its box for transport.


Ok on to the description of the set.. the prop centerpiece has a 6mm hole (for the shaft) and 8mm space between the prop arm for the prop attachments. The CF props that comes with the kit is 10×5 size. The two black stopper strips which goes to the front and back of the centerpiece to help prevent ‘over folding’ is made out of some plastic, which looks tough enough and which I think is unique to this set.


Here’s the measurement of the prop arm spacing using a high tech device.


And the prop set compared to a regular 10x5e prop.



I’m not so sure how much “push” this particular set can provide compared to the one piece prop. The folding prop seems to have 10-15% less surface area.  We’ll know soon enough. Anyhow, the manufacturer of the centerpiece and the props,, has bigger sized props just in case.