The tragedy happened to my 1st 2m plane ,Tempest ( named as Wizard), on last saturday morning.
As an novice of the pattern flying, I was wonder using 1100 mA NiCD battery for 5 Futaba standard high torque servos and one S148 is a bit risky. However, I did not do a good job regards that concerns. It was happening during the 3rd fly of that morning. Each of previous 2 flying time is 7 minutes. I use Quick field charger charging 10 minutes between each fly, and check the voltgage with voltmeter and make sure it is in the green zone before taking off. But, the 3rd fly last only one minute, and I totally lost the control over the plane. It went straight down and disappered in the swamp area around the flying field. I was shocked and my heart went down with the plane.. I tried to retrieve the plane after that, but all in vain.

I made such a huge ......... mistake about the battery and the charging procedure, which caused my fortune. I guess, 1st, the quick charging burned the battery. 2nd, Even thought the voltmeter shown the voltage is in the green zone, it does not mean it has enough power to fly.
.........................
Please give me your best comments and suggestions. I lost my best plane (biggest and most $$$ ever to me) already, but I don't want to loose any other plane in the future. Thanks !
Here is the Wizard in my memory only.

In my humble opinion you made many mistakes in the charging and care of your batteries. I've seen it time and time again where guys think they have to charge their batteries after every couple flights and somehow these same gentleman are the ones who really haven't taken the time to find out anything at all about batteries at all. They have no idea of what the discharge curve of a Nicad or Nimh battery looks like and no concept of how to properly maintain a battery. The internet is full of information for anyone who will take the time to look up everything there is to know about care and feeding of batteries. Before you invest in another plane I would suggest you avail yourself of the vast wealth of information that costs nothing but a little of your time.

On another note I'm sure you will be advised somewhere along the line to switch to LIPO's and to use regulators. That's not the solution either. Throwing a more expensive battery in your airplane is not the solution. You should have been able to fly at least 8 seven minute flights on that 1000mah battery if it had been properly slow charged the night before. You leave out a lot of detals about the complete life of that battery, without which nobody can really say what the problem could have really been. Lack of education is very expensive isn't it??? That was a beautiful airplane. [&o] [&o] []

Good luck in your future Pattern Planes



[/quote]

Good luck in your future Pattern Planes

Hate to hear of anyone losing a plane......Sorry for your loss.

Did you retrieve the wreckage?
Was it a new Battery pack?
Are you sure the battery pack was the cause of the crash?

Many other things could have been the culprit, and some are more likely than a bad battery pack such as:

battery came loose and unplugged in aircraft.
bad On/Off switch.
Receiver failure (bad crystral).
Outside interference (especially if PCM, because hard lockout is very similar result as radio failure).
Receiver switch left on between flights, discharging pack.
etc...

A 4 or 5 cell, 1100 Mah NiCad would have been plenty for 5 or more seven minute flights without recharging on a healthy 2m plane, no problem. I flew seven flights on Saturday and Sunday at contest on 4 Hitec Digitals and a throttle servo on a 1400 mah NiCad with plenty left in the pack. Just check volts between flights. You may be right, that the quick charge was harmful to the battery...but I don't think the battery capacity was the culprit.

Richard

Thanks Guys!

You were all right. I made too many mistakes. I need to be educated more about "battery" as well as radio setup.
The battery I use is 3 years old. I charge it the night before, but with only 6 hrs. I believe it is not fully charged, and I miss believe the field quick charger can fix that problem, which is a very very bad idea.
The radio is my 1st brand new 9cap PCM. I did not specific setup the fail safe and I am not even sure is it on or off for that function. It did looks a bit like lockout in the air....cause none of the stick movement wroks.. anyway. it is too late. I still can not locate where it crashed. The chance of retrieveing the rackage is very samll. There are too many "long grass" swamp and trees around the field. I am more planning on saving money for building another one. It is gonna take me another year or two. Sigh!


Mike Shih

Maybe you can get some guys at the field to help you look for it. Sounds like you could salvage some of the equipment out of it. Good luck.

Don't feel too bad about having to learn about batteries. Charging by guesswork isn't a good idea. You need a home charger that detects peak and takes care of all of the for you. Cycling batteries is something you can learn from the manual of a decent charger.

Ouch......just ouch.

I usually change my batteries once a year, whether they are acting fine or not. It sounds to me like the pack was just worn out, possibly.

That really sucks. Well, they all have expiration dates......and unfortunately, we can't read them. That just sounded like a mistake though.

-Mike

Mike,

Sorry to hear of your loss.

I've been using a Sirus fast charger for the past ten years charging a 5 cell 1,500 mAh ni-cad pack without any problem. I do cycle my batteries with the Sirus Super Tester every other month and record the discharge rate. As long as the battery discharge rate is at least 75% to 80% of the battery's capacity, I will continue to use that particular pack. However, I do replace all of my Rx batteries once a year regardless of their condition.

Good luck,

Adrian

Sorry to hear about the loss of your plane, that baby was beautiful.

You didn't mention whether or not the batteries had been used frequently over the last three years or if they'd been sitting for a while. When NiCADs or NiMH batteries have been sitting around for a long time (or when they're brand new) it's very important to slow (trickle) charger them at about 50 mah for a good 24 hours. This will bring all the cells to generally the same level of charge, assuming they are all in good shape.

The next step should be done whether the batteries have been sitting around, have been in use, are old or brand new. After the trickle charge you should perform a discharge test with a charger/discharger that will tell you exactly how many mah were pulled out of the battery. Sometimes with older batteries the first discharge will only pull out a very small amount but after three or four charge/discharge cycles you'll begin to get a more consistent amount of discharge. Regardless of whether the batteries are old or brand new if you don't see a discharge amount close to the rated capacity of the battery throw the batteries in the trash and buy new ones. Note: I said throw them in the trash, not put them aside... throw them in the trash!

Here's my guess (assuming the batteries were the cause for the crash). When you quick charge batteries even bad batteries can show a high voltage (in the "green") but will taper off very quickly when under load. This could be why your test after the quick charges showed the batteries as good. This is why, in my opinion, it's critical that the charger/discharger you use displays exactly how many mah are put into and pulled out of the battery. Otherwise it's like the fuel tank in your car just says Full and Empty, but you don't know if it holds 16 gallons or 16 oz.

I also agree with the others, batteries should be replaced every year or two. They should also periodically be checked for capacity by cycling (this does not apply to Lithium batteries).

Don't feel bad, we've all learned things the hard way. When I was in college in 1982 I'd been flying about a year and in my excitement to fly a new radio system I did much the same as you and flew after only short night of charging of my RX battery. I lost that plane and being a college student was unable to build a new, which ended up knocking me out of the hobby. I didn't get back in for about 18 years!

Now I'm older, wiser and have more money to spend than when I was in college, but I still make mistakes

Keith B

Sorry about the loss of your plane. First, you don't know for sure that it was a battery failure that brought it down. So many things can go wrong. The 1100 mAh nicd packs are very good and durable. Did you use a loaded voltmeter to check your pack? I check before every flight regardless. A loaded meter will place a load on the battery and give a better indication of what it's voltage will be while working. At what rate were you quick charging between flights. I've seen a lot of guys put their planes back on a peak detect charger after every flight.

My theory with battery packs is to get to know them well. Know what the reading should be after a full charge. Know how it behaves after one, two or three flights. Check the useable energy once in a while using a battery discharge tester. If you start to see a deviation from regular behavior, get a new pack. A new pack is a small price to pay to save a plane.

I too am sorry for your loss.
I agree with others...it could have been something other than the battery pack.
I field charge with a Sirius Pro Plus. In fact the manual recommends charging between flights. I occasionally cycle my packs to check capacity and fly with a 5 cell SR pack.
Without the remains it's just guess work as to the cause.
Good luck!
JLK

Mike,

Hindsight is always 20-20... one makes mistakes and one learns from them (unfortunately).

Batteries are a very cheap investment considering the amount of money one throws at a plane these days - so I am now using 2 batteries and 2 switches in my planes now. I'm using 4 cell 1500 mah Cermark packs - cost is $24 each and I've used these packs extensively for a number of years now.

-Derek

I have to agree with some of the folks who said that the problem may not be the batteries. It could be interference, the switch, a loose connector, loose crystal, who knows. But about the batteries. I don't know how you fly or how you take care of your stuff but you were using Nicads which, if you have been charging them and discharging them for three years like how you mentioned, will get "memory". Basically, if you only get to charge the 1100maH pack for 100ma, after a while, your batteries start to think they're only 100mA batteries. Also, I don't know how long you've flown or how prolific you are but to us who have been in the hobby for a long time have learned a lot of lessons the same way. Maybe it's from ignorance, mechanical breakdowns, or stupidity but we've been there. We tend to learn everything that's going into our planes, whether we talk to experts or read from honest reviews. It would seem odd that you would have a very expensive plane with an expensive engine and if you even consulted a pattern competitor, he/she didn't bother to say to change to a lighter pack, even a NiMh, which doesn't show memory from undercharging.

In any case, it really sucks to lose a plane, especially if it's something as nice as you had. Hope you learned from this. Good luck on your next plane.

Thank you all and appreciate all the positive comments and suggestions !!
I tried the last time today to retrieve the wreckage, but fail again and I almost got lost in the woods. I think that is it. It will rest somewhere in the woods or swamp for good.
Well, the radio is brand new, so I think other than the interference, it must be the battery. I flew it 7 times before the crash and it flew great with no radio problem. luckily, Andrew Jesky flew the maiden fly for me three weeks ago...
The battery I used has been sitting there for almost a year without properly charge or discharge. I was not a frequent flyer. I only use it 3-4 time is past 2 years. I charge it 16hs at previous trip using standard futaba wall charger. Other than that, it has not been through the cycling nor the discharge test . in past few years, I squeeze out all my spare time building planes other than watching two little kids . Clearly, I lack all the knowledge you guys brought up regards battery ! Anyway. Never too late. I still have two other samller size plane, 60 and 40. I already had the multiplex charger/discharger, just too lazy to use it, which caused me big time. Just order a new pack battery for the other plane. I learn this by hard way, just so I won't forget..

I look forward to learning more from you all. I think I have chance to build Mike's black magic when I am ready.

Thanks again

Mike