Bob,

Need some advice. Three times, while setting up my new PAU Dalton 300ML, the power just stopped. Had power from the batts, but the Smart Fly Competition 12 (bought used by the way) just shut down. Nothing. Once while setting up the rudder (push pull in the tail) and I thought I had one servo dragging and then nothing.Power was low so I charged the batteries since I hadn't charged them since storage. Thought it was a bad servo but wanted to give them a chance. Waited a little while after charging then came back everything was okay which to me "says" heat buildup or weak batteries. Now I'm leary. When I went to hook up the ailerons I was exercising the servos to check direction and it shut down again. Now I'm scared. Hooked up the aileron servos to the horns and using a Fromeco quad checker and was working connections and it shut down again. No load to speak of and certainly less than flying. Hate to risk a 40% plane. Any suggestions? Replace the Smart Fly? The batteries are fine. Mechanically the connections are very, very close. I've never run into this type of electrical issue before. Using one Futaba 6014 receiver and a pin and flag smart fly switch with two 6800 ma batts if that makes a difference. Thanks for any insight or suggestions. I'm perplexed.

Start eliminating points of failure. Maybe send the SF in for a checkup.

Agreed, remove one item at the time starting with the small stuff. This could as simple as a switch or even a wire. You can easily unhook one battery, or hook up another battery and remove the ones you have in it. You can unhook one servo at a time and so on it goes until you find the culprit.

I bet it is your batteries. A friend I fly with had the same problem and cost him a 50% biplane. I am sure he will reply once he sees this post as he has some rather "strong" feelings about it due to his loss.

My understanding is the 6800 mah batteries he was using had some sort of reset. He tested it by touching both leads which caused the shutdown. Once switched off then back on they were fine again. He won't use the 6800 mah batteries ever again. (Not sure the brand, so won't comment on that.)

Batteries were charged and tested fine as well. They shutdown on him during a flight and boom, no more plane.... Try different batteries and see what happens.

Thanks for the suggestions. I'm going to go through some eliminations today and have asked Bob via the website to take a look at it. I will be sending it in when I get the RMA number. I bought it used so I don't know it's history. I ordered a new one to be overnighted Monday since I don't want to trust this one until we find out what's going on. Since I'm not the original owner I know it's not under any type of warranty but finding out the reason will be comforting at least. I don't see how it could be the pin safe switch since it fails on, not turns off. I do have another that I'll throw into the mix when I start testing. I don't see how it can be the receiver since there is nothing connected to it other than the board and it's the board that is randomly turning off. The ignition has a switch in it's circuit and it's not on and other than the fiber optic to the cut off it's not connected to the board. If it's a bad servo, it would smoke it or something not turn off the board. I guess it could be the switch but it's a smart fly pin and flag so that makes no sense either. Sure acts like the board is just switched off. Sorry for the rambling...just trying to think it through. Off to the shop...will report back if I discover anything.

Thanks TSter. I remember talking to him about the batteries. He had the same ones and told me about the problem. I will swap out the batteries. That's a cheap fix.

Okay, think I found the culprit. When I went into the shop to begin the elimination process, after turning on the transmitter, I had no power to the board. I had a new pin switch so I installed that and still nothing. So it's not the switch. Checked the batteries at the balance lead and they appeared to be fine. Since a friend had problems with these 6800 batts on the deans lead I took them out and plugged in a new battery I had laying around. Pulled the pin and instant power. I'll get the batteries replaced and do a lot of servo exercising before the maiden but the batteries now make more sense than anything. Got a new board coming just to be on the safe side but I suspect the batteries. I am still going to send the board to Bob to inspect and get a clean bill of health but right now I think it's not a board issue.

I have seen 2-3 (well reputed name)brand new packs with deans connectors that would not make good contact. They had just enough slop to not make good contact.. I stopped using deans for power connections for receivers/servo loads.. they will pull 50amps all day long in an electric plane powering everything but put them on a low load situation and they can let you down.. plug your old battery in and gently wiggle/twist the connector and see if you loose power.

For clarification, do you believe the deans connector on the battery is the point of failure, or the battery itself?

What kind of batt is your 6800? Li-Ion?

Originally Posted by Vapor Trails

For clarification, do you believe the deans connector on the battery is the point of failure, or the battery itself?

What kind of batt is your 6800? Li-Ion?

I would like to know as well. Have deans on numerous packs along with SFB's.

A loose T connector cost me my beloved compy. I've also seen excess Flux swamp the contact area, harden, and hinder a good connection. I still use them, but I'm more mindful now!

I use Anderson Power Poles for all my batteries. 15, 30, and 45 amp versions. Easy to make up, and a solid connection.

Anderson deans testing to failure (2 0f 2) (7 min 12 sec)

Yes the slop was in the connector itself. Plugged in, you could wiggle it and it would loose power. Any misalignment, slop, or debris can cause big problems with deans style connectors.. doesn't help when there are so many clones out there too that may not have the exact dimensions or materials as the original deans..
Anderson power poles don't work well as the vibration of a gasser will wear them out.. Many many DA ignition problems due to the power poles they shipped with originally on the power leads..
I have been shifting to the xt60 connectors on everything- mainly because I have a bunch of them on all my small electrics..

Originally Posted by 2walla

Anderson power poles don't work well as the vibration of a gasser will wear them out..

Weird. I've been using them for years with zero issues. I do take two steps. I make sure they are no flopping around and I use the little plastic deal they make that keeps them locked together tightly.

One thing people should consider when having intermittent connection problems is getting a tube of dielectric compound and using it on contacts. It can help intermittent issues in high vibration areas