Redundency Batteries

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Trex600
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Redundency Batteries

Unread post by Trex600 » Sun Jul 29, 2012 7:49 pm

To have or not to have is the question here. I learnt the hard way this weekend that one needs to HAVE two batteries that power your receiver. My 30cc Sbach342 has been flying now since March2011 until yesterday July2012 with one LIFE battery pack on the receiver and one NiMh battery pack on the ignition. I Did not have a back-up for the receiver at all.... MY Fault. I wrote off my plane due to this mistake.

I hope others read this and DO NOT DO AS I DID Please. :( :(

I however did have over 320 flights with the plane and did have lots of fun with it............... I will be buying a replacement some time soon as this plane is a lot of fun to fly. (GoldWing 30cc Sbach342 Red/White/Black) Here is the plane I am on about .......... :wink:
S342.jpg
This is all I have left of it ...sad so sad :( :(
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Re: Redundency Batteries

Unread post by RocketMonkey » Sun Jul 29, 2012 8:25 pm

Trex, sorry about your Sbach. She was a beauty in the sky!

I saw the whole thing going down, in slow mo. This week I will be looking onto the redundancy in the battery system for my 50 cc Extra. All of us gas flyers definitely learned from your loss yesterday.

I took some pictures of your Sbach on the last turn, will post them later.
Forget all that stuff about thrust and drag, lift and gravity, an airplane flies because of money.
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Re: Redundency Batteries

Unread post by Brettp » Mon Jul 30, 2012 10:38 am

Eish...... sorry to hear about the loss of this stunning plane.!!! Hope you can re-use motor and electronics?

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Re: Redundency Batteries

Unread post by Trex600 » Mon Jul 30, 2012 1:20 pm

Brettp wrote:Eish...... sorry to hear about the loss of this stunning plane.!!! Hope you can re-use motor and electronics?

Regards
Yes, I can use the equipment again. I was fortunate that the plane went in right wing first then the right-hand side of the body this saved my motor. The only damage was the airframe, one servo lost it's mounting ear and of course the life battery pack that caused the crash. :(

I am pleased the No one got injured or the no other damage was caused due to the plane crashing. [-o< =D>

It was a nice plane to fly and I Will be getting a new replacement, the same as that one. :D :D :D

I have Learnt a HARD Lesson, I will NOT repeat it again. Battery Redundency is the right thing to DO :wink: :wink:
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Re: Redundency Batteries

Unread post by RocketMonkey » Mon Jul 30, 2012 6:36 pm

Trex,

Could you tel us more on how to prevent this, the redundancy of batteries.

A few questions come to my mind:

If using LiFe cells, how would you connect to your receiver if using two packs?
How would the voltage from the two packs influence the the servo compatibility?
Do one need a special switch/box/converter to run two packs simultaneously?
Forget all that stuff about thrust and drag, lift and gravity, an airplane flies because of money.
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Re: Redundency Batteries

Unread post by clivem » Mon Jul 30, 2012 9:12 pm

trex - sorry to see that your sbach is no longer.

dual battery redundancy is not a necessity but a good idea. almost all my planes have it, that said with the advent of LiFe even i have gone back to single Rx packs in some cases. what was the failure? specifically, bad cell? poor connections? do you monitor the LiFe battery input after each flying session / prior to the next?

Even if i use one Rx pack ( only sometimes with LiFe i do this) i always run 2 leads off the LiFe battery into 2 switches and then into 2 ports on the Rx. you can plug a battery into any Rx port and it will supply the whole rx. my feeling is the weakest part of the system is the switches used. second is the plug connections on the rx, so by doubling these up can help. this is not a foolproof way as it does not have a true battery share facility. should one battery or switch or something short, it can take down the second pack too. however remeber that we are dealing with electrics and most common is that when a circuit fails it will 98% of the time fail open circuit, so the second system will keep you running. as the systems are in parallel it has no effect on the servos and their voltage.
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Re: Redundency Batteries

Unread post by Trex600 » Tue Jul 31, 2012 12:05 am

Hi Clive, Thanks but yip it is no longer a Sbach but rather a scrap plane now :( :twisted: . The battery in question was a single battery pack and was a LIFE battery, one of the cells went totally dead and I mean zero volts out. The total supply to the receiver was 3.1v and I was using a AR9000 Spektrum receiver, total BLACK OUT. I also had a Opto kill switch in-line with the supply to the engines ignition. First the motor died and I thought OK, fuel problem. I tried to level out in the turn I was in, but nothing. It just kept on going, wing over to the right, and in it went, bye bye Sbach.

I WILL SOON be looking for the same to replace that one, Any suggestions Clive :D :D :D :D :lol: =D> =D>

Thanks in advance

Trex600. :D
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Re: Redundency Batteries

Unread post by Spacey » Tue Jul 31, 2012 1:33 pm

Been there done that, had that happen to me twice with a dodgy batch of the old A123 batteries. Charged fine all's well, few minutes into the flights things get sluggish...landed the plane twice without me being in any sort of control, batteries just died.

Did you balance charge the pack all the time? Our experience is the Life packs really have a bad habit of going out of balance, best to always balance charge so you can keep an eye on the cells.
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Re: Redundency Batteries

Unread post by SYBOT » Tue Jul 31, 2012 2:42 pm

Life technology took the rc world by storm. Not long after the OEM, A123 released their batteries, every dick tom and harry jumped on board when this technology was introduced to rc. Result: compromised quality.
I have extensive experience with Life batteries. When it was released in the US i have ordered cells and build my own packs. One pack is still powering my 100cc Sbach ignition.
What I quickly learned is that the good branded packs seldom requires balancing. The not so good ones have to be balanced every single time. A cell which takes longer then the other to balance is a clear sign that something is wrong. Also, who have ever flown 'till the pack is very low? Some will charge after every weekend, I charge every second. I have enough power in each plane to fly three consecutive days 3x a day. Every second month I'll cycle the packs fully to make sure they take the full charge (the best way of testing A123).

Packs with which I have had problems are Hyperion and Desire Power and some of the funny name things flooding hobby shops.
Packs with which I do not have had any problems are Life Source (Tower Hobbies)
and Iron Corps from Fromeco

I am glad to see that CMC Hobbies are going to import Batteries from Fromeco. Their Li ION packs are also extremely good. Good for up to 100cc planes running HV servos. I prefer however, A123 for my big plane as Li IoN may not provide enough punch (low discharge rate).
In the old days of nicads we used one pack with two switches for 50cc and lower. My standard setup now is two Life packs, battery backer with one fail safe switch. Gives me a fussy warm feeling of being protected, and I don't have to charge that much or can fly a lot when I am not to busy at the club. I will not ever plug two bats into the RX without some method of isolation between them. My backing system also balance the packs (switch between the lowest and highest all the time)
Remember to unplug all batteries after a days flying when u use regulators. They continue to draw power although the plane is switched off (switch between reg and rx. Over time it can draw the pack down and hurt a cell. :wink:
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Re: Redundency Batteries

Unread post by Trex600 » Wed Aug 01, 2012 12:06 am

Hi to All here :D

Spacey YES I did balance charge the pack. I always balance charge the pack as I lost my Trex600 Gasser also with a LIFE pack and it was the Desire Power pack, which I did NOT balance charge. I learnt a hard lesson there......... I thought until now that I lost my Sbach as well. The modified Trex600N to a Gasser puts the weight up by somewhere around 1.6Kg and space is little so I could not afford the extra battery pack for redundancy. The Gasser heli already has two battery packs, one for the RX and one for the ignition.

Sybot please explain how one can go about reducing the risk of Failure with the LIFE packs. I want to try avoid this from happening again to me or even ANYONE that read this thread. I will go out of my way next time to reduce the risk of loosing another plane or heli. I am very lucky that NO ONE was injured in this case, I would like to keep it that way. One hears of accidents that happen were people get hurt at the club, I hope to never be in that situation and will go out of my way to not be in such a predicament. I must say I was just lucky on Saturday as not to have hit anyone or anything except the ground.

Whats the best way forward here to prevent this happening to anyone is the question here................ This is what this thread is all about. :D

Thanks to All for your input here.....

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Re: Redundency Batteries

Unread post by Spacey » Wed Aug 01, 2012 8:44 am

Wow that sucks. As a last thought, highly doubt this is a problem but, maybe check your charger also. Sounds odd, and it's certainly not common but chargers have been known to do some strange things also. Maybe have a friend charge the pack with a different charger to just check what it does. I would charge a pack on your charger and then take it to a buddy to do the same and see if his charger doesn't put more into it etc.

We honestly haven't had many failures with the LiFe packs that I can recall, only ones happening due to faulty chargers and folks not balance charging them ever. It's one of those situations like a good friend experienced also on Sunday, took off with his 35% Extra running a DA120, engine is fairly new so we're keeping an eye on things. On take off it stutters, no problem he throttles back and it jumps to life again and he flies off, no problem right? I tell him to rather bring it home so we can richen it up slightly just for safety sake. Lands, we adjust it a little, rev it up on the ground properly and it's happy. Next take off, 10 meters up, silence! Nothing he could do but land out in the rough, write off. This stuff just happens...bad luck. #-o
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Re: Redundency Batteries

Unread post by SYBOT » Wed Aug 01, 2012 10:49 am

Woh, Spacey touch on something which is very important. Your battery is as good as the charger.
When cycling a pack min voltage is very important. If a cell is dropped to low, then it will be hurt also if over charged. Also balancing is important. There is a huge difference between
3.558 and 3.600. What I am trying to say is get a good charger which display and balance up to 3 decimals. Also not all chargers balance at the rate they can charge - be careful.

TREX, Don't cycle without making sure that min and max values are exceeded. If one cell takes much longer than then 5 minutes to balance, then something is wrong. Higher charge rate values for LIFE works better. Apparently they like it it it will quickly show if something is wrong - I charge mine at max rate every time.

A good source for batteries http://www.fromeco.org/
and check this https://www.screencast.com/t/MjcxZGVkY2It

I am not going to start a charger war and will not discuss what I use, but do yourself a favor and read on Flying Giants about Life charging etc.

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Re: Redundency Batteries

Unread post by danie.e » Wed Aug 01, 2012 3:17 pm

Maybe the time has arrived for a separate section where LiIon, LiFe, and LiPo batteries are discussed in depth - something like a knowledge database. This topic started with redundency and is currently about the failures of LIfe batteries and how to charge them etc.

So maybe we should try to reach concensus about the use of a single battery or more in a RC model. So the question here is, is the use of a single battery a "dangerous practise" or should people only be warned?

I would like to agree with Clive in that most RC accidents happen because of some electrical "mechanical" issue such as switches, bad solder joints, too thin wire used, etc. etc. Batteries are quite often mistreated by most RC pilots purely because of ignorance and yet, sometimes they last quite a long time before actual failure. Obviously there are the ones that fail when new, but that is the exception rather than the rule.

So here goes: In my opinion, the use of one battery is OK when the owner has done the trouble to gain the required knowledge how to maintain his batteries. In all other instances the best practise would be to use two packs each with its own switch.
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Re: Redundency Batteries

Unread post by SYBOT » Wed Aug 01, 2012 4:54 pm

Danie, question is: Can you separate power to the rx into different topics?
Redundancy was the question, but it may and be not the only answer.
Mistreating packs, maintaining them using the right equipment is very much part of the problem. Even redundant setups is not always practical and will not avoid disaster always. It is a personal choice but no guarantee. I'll fly any plane up to 50cc happily with one battery, but then I make sure about everything else in that configuration.
There is a warning by some manufacturers not to use certain chargers on their packs.
If certain packs fails, and that failure is experienced by yourself and others then surely you have to ask questions. It is no secret in this hobby - don't risk your priced possession with second rated equipment. I always ask around, and further away to make sure I am not the only one. Before I slams something, I am always open enough to question myself.
Thirdly, I don't think most people are pedantic enough about battery maintenance( A123 IN QUESTION), and most reading here and who have watched the link to the vid I posted will approach the issue differently. I this saves one plane, then this thread has achieved its purpose.

Yip maybe its time to split things into topics, but then again topics only arise when a certain question is asked and somebody suggest a look at the wider picture?
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Re: Redundency Batteries

Unread post by Chrisvn » Wed Aug 01, 2012 5:07 pm

Trex600 wrote:To have or not to have is the question here. .......... I Did not have a back-up for the receiver at all.... MY Fault. I wrote off my plane due to this mistake
Trex when was the last time that you checked the battery pack - did you check it prior to the flight ?

Best practice could also be to check before each flight ?

I had a similar incident - but check the voltage before every flight nitro or gas .(I do not make use of a back-up pack)
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