Saturday, December 8, 2018

Building a new flight battery for the Lucky 13...

Wow, I'm still checking and repairing batteries. This is a great time of year for this sort of work, since I'm not real keen on flying in cold weather :-) The Lucky-13 flight battery was shot...a 3000 mAh battery that was checking about 800 mAh...not good! I still have a bunch of cells in a RC car pack that cycle nicely. I set my Accu-Cycle up to test single cells, and test them all, one cell at the time. Here, I chopped out a nice 5 cell pack that tests at about 3500 mAh. I installed the connector from the old pack, slipped it in a piece of sleeve, and shrank it down. Here it is, ready to be reinstalled into it's new home. Once that's in place, I'll move on to the next bird and check it's flight battery. 

Two chunks of 3600 mAh NiMH batteries broken apart, testing each cell, separately.

5 cells, all tacked together. Next, it's time to install the power connector.

 A final test, with all 5 cells in series. It cycled out at about 3500 mAh.

Fresh heat shrink covering installed, ready for installation in the airplane.

Dave AMA119484

Friday, December 7, 2018

Still Repairing Stuff...

Well, I picked a good time of year to decide I was gonna check things over and get back active in the local flying club, since it seems I'll be busy repairing stuff for a while... Things have been "parked" over 2 years, and it's amazing how much goes bad from inactivity. While checking over my flight gear, I discovered my glow driver wasn't working. I opened it up, and found the battery had failed and was leaking. No biggie, I've been chopping up a good 16 cell 3000 NiMH RC car pack for batteries to build more receiver packs for my airplanes, so I pulled a sub-C cell from that and slipped it in. Nothing. I opened it up, and saw the center contact was oxidized black. I grabbed the Dremel tool and a small stone, and removed the oxidation to expose the shiny yellow brass contact. Once reassembled, all was well. Another piece of field gear ready to go!

My broken glow driver...
A 3000 mah NiMH salvaged from the RC car pack...

I removed the outer jacket so it would slide into the glow driver easily...

The center contact in the upper housing was oxidized black, and wouldn't make contact with the battery...

After repairs, all was well and ready to go flying!

Dave AMA119484

Tuesday, November 20, 2018

Hangar 9 Twist Battery Check Out!

I can't believe, that after 2 years in storage, the Tenergy 5 cell 2000 mAH NiMH battery in my Twist actually checks out to be good. It looks like the 'Red Neck' battery maintenance system described in my previous post actually worked. Over 2 years of hitting the battery with approximately 25 mAH of charge per day while in storage, and it cycles as if it were new. 

 It's nice to get lucky every now and again :-) Now, it's time to move on to the next airplane and see how it checks out. 

Dave AMA119484

Saturday, November 17, 2018

More from the Mothballs...

Still getting things ready to go after a 2+ year break... I pulled this 12 year old Hangar 9 Twist .40 down, and put it on the Accu-Cycle. It was stored on my "red-neck" battery maintenance system for the last couple of years... That consists of a conventional 50 mAH charger connected to a Christmas tree timer. I have it come on for 30 minutes/day, and then back off. I never bothered to check it, other than to verify that the charge light was still coming on when the timer was passing power. So far, it looks as if the 5 cell 1500 mAH battery is fine. One more cycle to verify, then on to the next bird. So far, so good!

Dave AMA119484

Friday, November 16, 2018

Checking Flight Batteries...

Well, here we go, after a LONG period of inactivity. It's been about 2 years since I've had any of my birds in the sky, other then little park flyers and such. I installed new batteries in everything about 2-1/2 years ago, flew a few times, and put them up. Now, once again, all of my batteries are shot. I'm trying to cycle them and see if they're worth using, but I have a bad feeling they'll all need to be replaced. In these photos, you'll see an old 16 cell NiMH RC Car pack I've cut open to cycle cell groups to see if I can salvage any of it for use as a 4 or 5 cell flight battery. So far, these cells seem to cycle at about the right mAH rating. Next, to leave them sit a few days and see if they loose any charge from internal leaks...

I use a pair of Hobbico Accu-Cycle units on 12 VDC supplies, and keep them cool by pushing air through their ventilated cases with a small 12 VDC muffin fan. These work pretty good, but Accu-Cycle units will generate a lot of heat in the cycle mode with the discharge rate set to .300 mAh.

Dave AMA119484

Friday, November 2, 2018

Building a 20A 12VDC Supply For Field Charging

I'm converting a few more computer power supplies into 12 VDC 20 amp DC power supplies. These are clean, lightweight, and really pump out the current. They're great for running lipo chargers at the field (our club has AC power in the shed and on the flight line). There's more info on this from my old ham radio blog at:

Dave AMA119484


Tuesday, October 30, 2018

Hangar 9 Glow Fuel Pump Repaired...

I had a bit of time to dig into the pump I mentioned in my previous blog. It's really a pretty simple pump, once you get inside. There were a few screws to remove, and the case popped open. The pump is loosely coupled to the motor as seen in the photos below. The drive disc on the pump unit had come loose from the shaft... I cleaned the shaft and the hole in the drive disc with alcohol, let it dry, dabbed a small drop of thick CA in the hole on the drive disc, shoved it onto the shaft, and kicked it with CA accelerator. The pump was snapped back into the enclosure and engaged with the motor, and the case reassembled. I pumped fuel in and out of the flight box tank several times, and all seems well. Time to move on to the next piece of broken flight gear. It's amazing how many things go bad when you don't use them for a while!  :-)


Dave AMA119484

Saturday, October 27, 2018

Hangar 9 Glow Fuel Pump Problem...

Well, after a long break, I'm finally having a little time to get back into my RC stuff. It's been a couple of years since i was very active, so everything I have seems to be broken. First, I'm working on my field support stuff. My glow pump in the flight box quit, just as I stopped flying a couple of years ago. The motor will run inside, but nothing happens... Cracking that open now :-) 

Dave AMA119484