siclick33

I recently had a couple of flameouts with my P-80 powered Flash. The first one occurred right after take off and resulted in a snapped retract unit. I was very lucky with the second one to make it back to the runway. Both times the ECU said 'fuel fail'. Whilst testing on the ground I received a couple more flameouts with 'power fail' messages.

The turbine battery I was using was a 4500 mAh Nimh battery straight out of the packet.; however, it had been sat in the packet, in my house, for about a year. Although the pack still tested perfectly well I replaced it with a new Lipo and all the problems went away

I thought I would post here as a reminder that it isn't worth risking your model for the sake of a battery. I am just about to take all the Nicads and Nimh batteries that I haven't used for a few months to the skip for recycling/disposal.

Andrew Bird

Had a similar problem with a Li-ION pack when the weather was really cold and it was unable to keep pumping out enough juice for the turbine resulting in various flameouts. Went to a good quality thunder power Li-po with a good C rate and never looked back.

GSR

My Feedback: (145)

Now guys remember that you can not let a NiMh battery sit for extended periods of time and then expect it to take a charge at anything over 300 Ma or so. If you try and charge it at a higher rate you will get a false peak at about 4-500 Ma in. I will bet you a quid that you charged it at a rate higher than 300Ma-it took about 4-500 ma and then said full. You know the rest. You must charge a Nimh that has been sitting at no more than 300 Ma for a couple of cycles to bring it back. Once done you can fast charge away 2-3 C etc. I once saw a 18K plane go in for just this reason. Sitting for about a half year, threw the Nimhs on a fast charge -packs took about 300 Ma- THe plane flew for about 4.5 mins and then boomdead. Scotty

thunderceptor

I always install LIpo batteries for Turbine and receiver, so I prefer to spend 30 or 40 bucks more and save a $6000 jet.

Eddie P

My Feedback: (4)

I'd say the single best thing anyone can do for their jet is to know the type of battery they are using, and know them well. Know the strengths, weaknesses, and most importantly, the condition of their individual packs. That's a lot more important than the specific chemistry one chooses to use. If you have Nimh's or Nicd's, they need to be cycled with a quality charger and condition checked: check for voltage during an amp draw (NOT static voltage). A123's are my favorite for turbine and radio ops. Good all weather performance and solid capabilities. But know how to keep them happy too, they have their own quirks (not as much as say Nimh or Lipoly, but they have their ways too). Keep in mind, Lithium Polymer batteries also DO NOT perform at their best at low temperatures (same as Nimh) in low amp draw conditions where they stay cold in a cold environment (don't warm up with use like when used as a EDF power pack for example). Even high C rated packs. It's to do with the chemistry.

I'd agree that a relatively fresh RX/ECU pack (but more so the knowledge of how they need to be handled) is the cheapest insurance for a big $$ turbine jet project. True, most Nimh packs are probably all getting a little long in the tooth these days.

BaldEagel

There are so few people into jets or any sizable airframe in the UK that use A123's it beggers belief, some still consider it new technology that is unproven? The newer Nimh's on the block have a habit of giving false Delta peaks whilst being charged the chemistry inside has been changed without fanfare to make them more environmentaly freindly upon dissposal.

Mike

jetnuno

I just don't use Nimhs anymore....

They have to be cycled every month to perform well and if not induce false peaks upon charging. I am using lipos for about a year and expecting a 2year period usage.

Also they can be seated for more than a month without loosing capacity.

Regards

Nuno

highhorse

My Feedback: (2)

Thanks for the reminder and the lessons learned. I am curious though: Did you CYCLE the battery and measure the total amps it took to drain it and than how many it took to re-fill? That's my version of a "test" and I do it periodically on all battery types to check the overall health. Just FWIW......

siclick33

For what it's worth the battery went through a triple discharge/charge cycle on a Schulze Chameleon charger and the capacity checked fine before it was used. It may well be that I didn't do it properly or that the pack was faulty but I won't be using NiMh again.

I wasn't aware of the point that GSR brought up about charge rates. It's a good reminder to me to be more thorough with my understanding of the battery technology that I am using.

highhorse

My Feedback: (2)

If the capacity was checked and found to be OK thru 3 cycles then I'm at a loss as to the eason for the failure....If it took in it's rated amps on the final charge, then it should have been good, right?

Either way, It's an excellent reminder to be veeeeeeeery careful with whatever batts we have. Thanks for sharing !!!

GSR

My Feedback: (145)

I see that you had the Schulze set for the three cycle mode, but -at what Mah rate did you have the charge set at?????? If it was anything above 300 Ma It probably went through three cycles just fine- The only problem being it charged and discharged about 400 Ma or so each time. You cant fully charge a NiMh that has been sitting for a long time at any charge rate over 300 or so or you get a false peak after 3-400 Ma input. Scotty

Gregdonaldson

Hi Guys
Im having flame outs every 6 or 7 flight on my euro with a P-160 and everytime it says power fail,Iv replaced the battery with a 5000 LIPO but still the same result.
Iv checked every connection from the battery to the ECU and from ECU to reciver.Everything is in perfect working orderinside and out.
Any suggestions?
Thanks Greg

Eddie P

My Feedback: (4)

I have a Schultze Chemelian charger too. If you select a 3X Charge-Discharge cycle program, EVEN in Auto mode, it will often false peak with a Nimh. It will even do it three times in a row and act like it did you a favor If you do not follow up and make positively sure how much Mah is put into and taken out of the battery, you'll never know as sometimes the auto mode will take hours to put in a quarter charge. You have to know what buttons to push and then do it or it just says "complete". The result is an even more "messed up" Nimh battery pack as it will not have fully charged (will have even worse memory effect). And it will certainly not be charged and good to go, either.

Now, I really like my Chamelian. I've had it for about five years but this is one area where it does not shine particularly well. I blame the battery chemistry more than the charger though, as all other charge types work great.

Eddie P

My Feedback: (4)

Go to the Jetcat forum or call them directly.

On the off chance, you may have a cold solder joint on one of your connections giving you a bad power delivery. If you have changed out your battery then you know as long as you can look at your battery on the charger then it's OK. It's gotta be in your distribution lines or your ECU. A partially loose connection, cold solder joint, partially damaged power lead somewhere. Double check you don't have corroded or oxidized plugs somewhere, clean everything up and safety strap it all. My money is on something like that. If not, you may have a loose "something" inside your ECU but my money is on the installation wiring.