Parrot Skycontroller 2 Battery Modifications

The Skycontroller 2 is a nice quality controller. It is a wonderful piece of tech with a lot to offer operators. It's form factor is familiar and it's functionality is very robust. It's a very portable package post Skycontroller 1 with the same feel but without the larger frame and weight. It is a nice turn. With all of it's perks it does have a drawback in that it contains the balance charger to support its rechargable battery. Many problems with this aspect have been experienced by users over that last couple of years. Some users have reported that batteries are not fully-charging, SC2's are shutting down early and during flights, and others have batteries failing to charge after a realitvely short time. Since the charger is self-contained and the battery has a non-typical circuit the system can run into difficulties keeping the battery healthy. If anything, LiPo batteries are quite touchy and they can behave in ways that create problems for automated charging systems. Include the safety aspects that have high thresholds triggering charge or charge refusal and the system can produce several situations where the battery does not have enough charge to support the Skycontroller 2 as expected by users. This can become evident in a few ways..like, it seems to fully-charge but halfway into the first flight the battery voltage plummets and the Skycontroller 2 shuts down leaving the operator in a state of emergency. A real impact to operator confidence and trust in this control system.

What are the options?

- Option 1, primarily the first option is to rely on the product warranty for a replacement battery. Parrot offers a 6-month warranty on battery packs. However, this option does leave users with the same situation that can end in the same result.

- Option 2, remove the battery and treat it with an aftermarket charger that can provide better charges and more information than the automated system inside the Skycontroller 2. These types of "smart" chargers are inexpensive, they can provide helpful information about what is actually happening with batteries and their internal individual cells, apply different charge levels (full or storage), they can keep a battery pack healthy for a much longer lifespan, they can ensure packs are fully-charged, and they can also charge almost any type of battery..not just LiPo cells.

- Option 3, remove the battery and modify it for Balance Charging. This is the most involved option but also the most rewarding option. Similar to Option 2, the end result is a more stable and reliable battery with a much longer lifespan. But there is an added benefit of fully-charging a battery's individual cells to the same level so that each can also discharge to a similar level...called Balance Charging. The benefit here is that a pack can output the total required voltage for a longer period of time while supporting their devices.

How to fix?  There are a couple of ways to fix a failing system or to prevent it from failing. Each require a new charging system, adapter cables, and possibly a modification to the battery itself. Before I get into the options I need to explain the Skycontroller 2 battery's specific design. The version 1 Skycontroller 2's battery is a rectangle layered 2-cell 2S 7.4 volt 2700mAh LiPo pack. It has a proprietary protection circuit board that attempts to prevent over-charge and over-discharge of the cells inside. The pack is not wired like typical 2S LiPo packs found in the R/C industry. The connector is a 3-wire Molex-Mini with Red & Black wires in typical locations. But, the center Blue wire is actually a Thermistor lead specific to the protection circuit and the Skycontroller 2. This layout prevents typical voltage checks like users would expect with normal 2S LiPo packs. So, only the Red & Black wires produce the total pack voltage when measured by users. As is, the individual cell voltages cannot be measured to determine health and voltage balances. Optionally, charging this battery outside of the Skycontroller 2 with an aftermarket charger will force users to make a decision..weather to leave it as it is and use a 2-wire Straight-Charge adapter cable or to modify it for Balance Charging purposes.

There is a difference in these types of charging and I will explain.

- Straight-Charge is when a multi-cell pack is charged without regard of there being multiple cells inside. Straight-Charging multi-cell LiPo packs will create cells that are not Balanced. The charger essentially treats the pack as one cell..charging it by applying the charge into the pack until the first cell becomes full ahead of the other cells until the charger sees that the pack voltage has reached the preset cut-off charge limit. Essentially, leaving the cells at different voltage levels. This situation can produce a shorter output performance during use. The pack voltage drops during use and one cell reaches its discharge level before the others. The system reacts when the total output voltage level is low triggering alerts or early shutdown. This can actually hurt some cells. During a charge the cell reaching the fullest charge first can become fatigued and wear-out over time. Also, the lowest level battery can become over-discharged and develop inclusions over time that create internal resistance worsening performance and shorting cell/pack longevity and lifespan. In a lot of cases this option is still better than the stock Skycontroller 2 charging setup since packs will become more fully-charged and have longer operational performances. Its one step up from the stock setup. It requires a 2-wire Adapter Cable to match the aftermarket charger used outside of the Skycontroller 2.

- Balance Charge with an aftermarket charger to apply charges to all cells equally during the charging process. This option is by far the best for health and longevity of any LiPo multi-cell pack. The reasoning is that the cells are all fully-charged to the same level allowing them to output similarly down to the discharge trigger level the system expects during use. So, a longer performance is produced and cells are all kept at safe levels at full and discharged without any one cell being over or under. This option will also require a 2-wire Red & Black lead to adapt the stock Molex-Mini connector to the chosen charger's main charge connectors (typically, 4mm Banana Plugs)..this option also requires modifying the battery as detailed below.

What Options to Take?

- Fabricate or purchase an adapter cable to match the chosen aftermarket charger for straight-charging (Mod Part B, below).

- Modify or have me modify the battery for balance charging (Mod Part A, below). This also requires a 2-wire Molex-Mini adapter (Mod Part B, below).

Modify! This option requires some parts, a tiny bit of soldering skills, and a little knowledge and care. I will explain how to make the modification and what parts are needed. I am also offering to make the cables and modifications for a reasonable fee for anyone that would prefer this service. It will void any warranty. I am not responsible for any mistakes anyone will make, though I test my work and verify it to be correct before release into the wild. I have tested this modification and it works. If done correctly it will work for anyone willing to take the leap.

Request the Battery Modification Service Here.
Purchase the Skycontroller 2 Molex Charge Adapter Cable Here.

Skycontroller 2 Battery Modification for Balance Charging (Part A):
Parts Required:
- 1x. 6-inch 2S JST-XH 3-Wire Balance Lead (22-AWG)
- Solder equipment
- Clear Tape

Steps:
- carefully unwrap the battery pack.
- locate the solder points.
- prepare 2S balance lead. stagger the ends to solder point positions. strip the ends. tin the ends.
- tinning..first apply flux to bare wire ends and then solder the ends.
- locate center wire and solder the end to a piece of clipped wire forming the T for the bridge.
- solder bridge across the solder pads at solder point 2.
- solder + red wire to solder point 1.
- solder - black wire to solder point 3.
- route new wires with existing wires and carefully rewrap the battery pack.

Tap on the images to enlarge.

Fabricate a 2-Wire Molex-Mini/Charger Mains Adapter Cable (Part B):

Parts Required:
- one Molex-Mini connector and 2 3-inch pieces of 18-AWG wires.
- small heatshrink, if desired.
- one pair of Red & Black 4mm Banana Plugs.

Steps:
- strip and tin wire ends. tinning..first apply flux to bare wire ends and then solder to the ends.
- remove center contact "X" from connector.
- tin connector contacts.
- solder wire ends to Molex connector onto correct contacts 1 & 3.
- add heatshrink to Molex connector if desired.
- add Banana Plug rubber backers to wire, not onto contacts.
- tin banana plug contacts.
- solder wire ends to the banana plug contacts.
- push rubber backers onto banana plugs over soldered area.


Additional Picture Notes:

Balance Charging Information:

The Skycontroller 2 flat-pack 2S LiPo 7.4V/2700mAh battery requires specific charge settings and charge rates. To maximize the battery performance set the charger to '2S 7.4V LiPo Balance' at '2.7 amps'..which is max. If the charger cannot be set to exactly 2.7A just select the next lower number available. 2 amps is OK also..it just takes a little longer to complete. '8.4V cutoff'. For storage-charging when the pack is not to be used for a week or more, set the charger to '2S LiPo Storage'..most chargers have a default charge rate and cutoff voltage for this process. The storage voltage range is 3.75V - 3.85V per cell. Additionally, it is not healthy for a LiPo battery to be discharged below 3.2V per cell, to remain fully-charged for extended periods, and is to never be drained below 2.8V or below for the battery will become damaged and unsafe for continued use.

I hope you had fun developing this skill..if you want to show me your appreciation by buying me a cup of coffee or a Beer...here's how...click the link below and type in some amount. Its safe and easy as pie!

PayPal.Chris!

Thank You and Have Fun!