Tag Archive: repair


I have two keyfob cameras from Hobbycity, the old SD resolution ones. Their code is #7, the worst of the lot actually. #3 was far better.

These cameras have a built-in battery, that is a 1-cell Li-Po with 140 mAh capacity. You charge it from USB-port. As far as I know traditional USB ports supply maximum 500 mA current. So this would charge up in roughly 17 minutes. I am very unsure how good the battery charging circuitry is in the unit. I would assume not so good. The premature death of my battery underlined this thought.

I was reluctant to just dispose the unit. It costs 15 USD, so quite cheap. But why dispose something if there is a chance of mending it. So I tried.

The idea was to buy a small Li-Po battery (done), and some JST connectors. So that I could remove the small battery, solder on the JST female connector and then use the external battery with some adhesive velcro tape. Brilliant 🙂

I tried to solder the contacts onto the wires. These wires are very thin, so use a fine grade soldering iron. Mine is very coarse, had to be very cautious.

When you have soldered the wire onto the metal pin you have to push together the last portion that forms an open U-shape. Otherwise it will not enter the plastic connector housing.

Then I had to remove some material from the other half of the housing. To have a good support for the connector I removed a rectangular area.

The connector fits nicely.

I double checked the polarity to be sure. Then I could assemble it and glue in the connector. It will be subject to some force when connecting and removing the outside battery. I used CA glue.

Just a size comparison, the new battery next to the camera unit. I will use adhesive velcro to fix it on top.

Maybe I will have the battery on the plane and the camera will sit on the battery. This way I will get better (less) drag coefficient. Important in flight.

I will need to do this on my other camera, that has reduced battery life. Probably will throw in the towel soon. Since this new battery is 240 mAh (vs 140 for the original) I will get significantly better battery life. And I can monitor the cell voltage with my Cell Voltage Monitor device. Important factor in keeping batteries healthy.

Best regards,

Sir Crash a Lot



I had to do emergency landing last time (on my 3rd flight), lost power totally. I tried to find the problem, I got huge help from my colleague who remembered a similar issue from the past. It was a cable connection that failed.

The symptoms were quite alarming, the ESC booted up normally, I could even steer the plane. But for any power input the propeller just stuttered. When it happened and I was in the air I did not notice the stuttering since air passing by rotates the propeller even at no power. Just upon the very last moment when I wanted to adjust my gliding angle became it appearent. Quite scary it was.

I checked first if the problem persists. It did persist. Then I replaced my 25A ESC to my helicopter ESC that is 40A. Same problem. This helped to rule out quite a lot of items. The only one remaining was the electric motor. This gave me a bit of headache. I just glued it back to its place since it became loose.

Maybe I broke the connection there, where it is in the fuselage? Hope not. I started to peel away isolation from the contacts that are easy to access. The first one was okay, the second one actually was so broke that when I removed the isolation the connector just falled away. The cable just broke.

I decided to resolder all 3 of them. This item was not done by me, the connectors were on from the factory. Maybe they used some wrong parameters upon soldering, I don’t know. Anyhow during last time when I disconnected the motor and glued it back the cable broke and only that stiff black isolation held it together. At low power there was some current flow there, but after 2 flights and higher current draw the electrical connection got severed and the motor just quit on me. That explains the steering also, since it happens on a different circuit it was unaffected.

Now it is fixed, I tested the motor on the balcony. There was much rejoicing on part of my wife who tried to watch TV 🙂

I put some decals on the plane, now it is easier to see it in the air. I shall test this next time when I fly.

Best regards,

Sir Crash a Lot