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Details of how to disassemble the Syma S026 Chinook model helicopter, in order to replace the Lithium Polymer 3.7V 185mAh battery. Note that you try this at your own risk - I've carried out this operation on a couple of models, but your mileage may vary. All photos here

Background

The Syma S026 model helicopter is a great toy. Easy to fly and almost unbreakable. However, the battery that is fitted to these models does not have a very good capacity. In fact, I've had one model that only held sufficient charge to allow flying for one minute.

So, after trying a few charge/discharge cycles - which didn't improve things, I decide to open up the helicopter & see what sort of battery it contained.

Opening the helicopter

Before starting, run the model until the battery is completely discharged.

The fixings that hold the two halves of the helicopter together are very small, crosspoint, screws. You will need a jewellers screwdriver to remove these. Be sure to work on a tabletop where the screws won't get lost. Remove all 8 screws. Then prise the two parts apart.

Removing the old battery

Do handle LiPo cells with care. There are lots of worrying stories telling of LiPo cells catching fire/exploding. Be sure to read all about the characteristics of these cells before attempting to work with them.

The battery is held in place by a tie-wrap. Use a pair of wire cutters to snip this. Then cut the positive and then the negative leads between the battery and the PCB. Be careful not to short the battery connections. Leave some of the battery wire attached to the PCB so that you don't get the polarity of the connection confused. Remove the battery - it might be stuck to the body with a sticky pad. Remove and dispose of the old tie-wrap. Don't throw the old battery into the bin - recycle it properly.

Points to Note

Looking at the PCB, I had expected to see 'jumpers' to allow the selection of the channel that the model would operate on (the remote control has an A/B/C selector switch). However, I didn't see an obvious option for this. Looks like the PCB is 'factory programmed' to respond to a specific channel. There is a red sticker on the base of the model with the letter A/B/C.

Not so good if you end up with two models which use the same channel.

Reading about LiPo cells, it seems that they can get hot whilst the model is flying. Apparently, it's best to let the model sit for a while (to cool down) before recharging. RC experts recommend charging the model whilst it is sitting on a fireproof surface - just in case the LiPo battery catches fire. They also recommend keeping an eye on the model whilst it is charging.

Fitting the new battery

I bought a couple of LiPo cells from a Chinese seller on ebay.com (not the UK site). These cost < £2 each and had a better rating than the ones that shipped with the Syma (2.8mA Hours). They weigh a little more than the 'as shipped' ones, but this doesn't seem to affect the ability of the model to fly. In fact the larger capacity of the cells allows for a much longer duration of flight.

To fit the new cell, you will need a soldering iron and some solder. Start by removing the two tiny screws that hold the PCB to the body of the helicopter. Then carefully lift the PCB out of the model - be sure not to break any of the very thin wires that run from the PCB to the four motors.

Place the new battery in position and cut the wires on the new battery to length. Then strip back the insulation on each wire - a 1mm length of stripped wire will be enough. Again, be sure not to short the battery wires. Tin the ends of the wires with some solder. Now, desolder the red and black wires that were left from the old battery and solder the new wires in place - do observe the correct polarity.

Refit the PCB and run a new tie-wrap around the replaced battery. Tighten this & cut off the excess plastic. Then refit the two tiny screws that hold the PCB to the body of the helicopter. This can be a bit fiddly - I used a blob of 'blue-tac' to help hold the screw to the end of the screwdriver - note that it the screw falls off of the driver, it might well adhere itself (magnetically) to one of the motors.

Now, charge up the battery. 10 mins should be sufficient to allow a quick test. Unplug the charger, then turn the model on & check that the rotors turn when the remote control is operated. If all is well, fit the two halves of the model back together & refit the 8 screws.

Charge up the battery until it is fully charged.

Enjoy flying your rejuvenated model!