Redundency Batteries

Best practices and Useful tips and warnings that can save property, prevent injury and to keep our modelling safe.

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RocketMonkey
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Re: Redundency Batteries

Unread post by RocketMonkey » Wed Aug 01, 2012 6:32 pm

danie.e wrote: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.
danie.e, what you say make sense.

I for one do not monitor my cells well enough. I do check before each flight and do balance charging time to time. One of the issues and I am guilty as well, we do not understand these different cells (LiFe/LiPo) well enough. The stores we buy from...........well some of the "clerks" also do not know what the proper way is. I have seen quite a number of topics regarding all sorts of battery packs, how to charge, how much to charge, it still do not make sense to me. Yes, I am one of those that think about the battery packs every time I put my 50 cc in the air, I pray and at the end of the day quite while I am still ahead. I would love to see proper SOP on these LiFe/LiPo cells, I would love to see the recommended brands.

In you last sentence, two packs. How would you do this?

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Re: Redundency Batteries

Unread post by danie.e » Wed Aug 01, 2012 8:39 pm

Rocket,

Two batteries, two switches = double protection. If one fails the other will pull you through. You can plug power into any socket on the receiver so there is no problem using 2 switches and plugging into two sockets on the receiver. Important!!! must be two of the same batteries. I have heard many a complaint about how folks battle to balance models because of the light weight of the new Life batteries. So here is a chance to make life a bit easier in that respect by using 2 batteries.

I have often stuggled with why people buy the cheapest switches and then install them in R5000 plus models. How many times have you seen a battery with leads as thick as your small finger with long 26swg extensions soldered to them so that the battery can be stowed away somewhere in the model innards?

Maybe, just maybe, some people will begin to understand why many guys use power boxes in their models.
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Re: Redundency Batteries

Unread post by Gary Lees » Thu Aug 02, 2012 11:21 am

Hi All,
We should all really consider building in a redundancy in all of our planes. The pattern guys are using a dual regulated switch with 2 batteries with 2 power outlets to the Rx. I see the Jet guys are doing the same. Some are using LiFe and others LiPo. On the pattern we wuse 2 X 350 to 450 mAh LiPo's for the Rx. The batteries used for the motor are separate and always make use of the Opto to separate the motor and Rx power.

With the weight of the LiFe and LiPo batts we can afford to carry these and the price of a system is really nothing compared to the loss of an aeroplane.
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Re: Redundency Batteries

Unread post by Trex600 » Thu Aug 02, 2012 10:29 pm

Gary Lees wrote:With the weight of the LiFe and LiPo batts we can afford to carry these and the price of a system is really nothing compared to the loss of an aeroplane.
+++1 Agree with that. I was a fool NOT to have done that in the first place. As the saying goes " We Grow too Old too Quick and Wise too Late" One hard lesson or should I rather say One Expensive lesson. :? :( :(
I will have to replace it some time soon as I already miss my Sbach and it is not even a week ago that it crashed. :wink: :D :D

Maybe we should show what we use in our set-ups as power sources and explain the configurations that are used and why. This way we can learn from each other as to what will be the best for that certain application. As was mentioned to save only ONE plane will be worth it, not only that It can prevent some one getting injured in the process.


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Re: Redundency Batteries

Unread post by SYBOT » Fri Aug 03, 2012 9:21 am

Most of our knowledge regarding setting up a redundant pack are based on past practices when 4 cell NiCads and NiMh batteries were the only thing. No isolation was used and it was not necessary. Generally this was seen as just another point of failure. If one cell fails it will effect that pack and cross charging will not be a factor as does so at a very low rate. With 5 cell packs, Red Scholefield suggest it would be a safer option to use a diode. Red is a rc battery guru and allover respected for his knowledge.

For some of us the game has changed, we use 7+ volt packs even 9+ plus driving Seiko servo's. We are also using different chemistry LiPo, LiIon and Life (A123's and I am not saying that Life is the same as A123, in fact they are not!). Li based batteries has one common failure which resulted in lots of fires before it was well understood, unbalanced cells destabilizes packs and the result is catastrophe. A huge common warning is also displayed on these packs display is not to sort them out directly. Do it with a charged old pack, and see what happens. Do it where you are protected and no fires can be started. The pack will go critical and directly short internally will act as a direct sort on the other pack. Most of the times the leads of the bad pack will fuse together. Now do it again with a pack in paralleled on the same bus, scary nogal ne? Other failures externally of the pack can result a short: scuffing of leads against the structure of the plane etc.

Now knowing this, will u directly put two batteries of into your rx? I will not take that risk. What I use is a battery backup system with some advanced technology.
It is a regulator with its own switch. The switch does not carry any major voltage and when it fails, the system stays on 'till the two battery packs are disconnected.
The regulator has also two leads out to the rx and is equipped with "smart sense technology".It balances the draw from two packs under normal condition and isolate a pack if a voltage drop occurs. Should this circuit fails, power will still go through and should the reg fails, it keep on powering the rx up till being switched off.
Yes it can fail in such a way that I lose total power. But so can the switches most use on non isolated packs, I don't have that worry. In fact on my big planes I have only one external switch (as described above) powering up all the systems inside. Main thing here is that every piece of electronic equipment in that plane can fail at any moment including the rx.
The only guarantee is to use reputable products. However, these new chemistry are not as stable as the old and trusty NiCads and that is a fact. My personal opinion is that I will rather risk the use of additional electronics then to run it paralleled and unprotected.

Some smart or intelligent switches can do the same thing, but in the end these are only battery backers in disguise :shock: :shock: :roll:

That is what I do, I don't say u have to do it too, but no one can argue away the fact that Li based batteries are a very different animal and one has to take special care when it comes to maintaining them, charging them, using the right charger and buying the best option packs.
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Re: Redundency Batteries

Unread post by extra300s » Fri Sep 26, 2014 12:44 pm

Hi guys

Just a question. Do you leave your life rx batteries in the plane to avoid wearing the tiny connectors out, and then how do you balance charge them? Extensions on balance leads? And charge via them?

Thanks
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Re: Redundency Batteries

Unread post by Klaas » Wed Oct 08, 2014 9:59 pm

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