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Running ignition from receiver pack.

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John Smith 5006/12/2016 18:38:55
89 forum posts
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Is there any reason why I can't / Shouldn't get rid of the ignition battery for my DLE 30CC and run it from the receiver pack. I am using a CC bec not the pro and its set to 6v.

My ignition pack only last 3-4 flights atm so its either getting replaced with a newer one, but I'd rather run it from the bec. I also use an opti power backup guard as well just in case.

Rich too06/12/2016 18:53:40
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3033 forum posts
1070 photos

John, I run mine from the receiver, but I use two batteries. Although that makes no difference. I use a tech aero ibec, what one is yours?

I run two LiFe batteries directly into the receiver.

 

Edited By Rich2 on 06/12/2016 18:55:12

stu knowles06/12/2016 18:53:52
568 forum posts
44 photos

Personally, wouldn't dream of doing so but there probably no reason why it can't be done

John Smith 5006/12/2016 19:02:35
89 forum posts
19 photos

I use this http://www.fast-lad.co.uk/store/castle_switching_regulator_castlebec-p-7355.html for powering everything from a 3s lipos. Does the ignition need a seperate bec then?

Rich too06/12/2016 19:14:07
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Yes, I believe so, how are you getting power from the battery to the ign? My ibec allows me to cut the ignition via the trans.

Google tech aero ibec, the website explains better than I can!

Edited By Rich2 on 06/12/2016 19:21:35

John Smith 5006/12/2016 19:22:21
89 forum posts
19 photos

Its got an ignition kill switch which runs from the receiver.

Bugger i was hoping to do it with everything I already have.

Gary Manuel06/12/2016 19:45:51
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Here's my tu'pence worth.

Ignition power supplies are "noisy". The ignition units job is to supply a very high voltage spike to the spark plug, discharging all of its stored energy in the process. The ignition unit must then re-coup this energy from the battery before the next spark is due. Regardless of how well the ignition unit is designed, some of these energy surges (or their harmonics) will find their way back to the battery.

A receiver requires a "clean" power supply. The last thing your receiver needs is to be supplied by a battery with a noisy output, which could affect it's operation. My advice would always be to have a separate battery for the ignition and receiver. It is also important for the same reason, to keep ignition components and wiring as physically separate from the receiver / servo wiring as possible.

Some receivers will have better noise immunity than others, and some ignition units will have better noise suppression than others, but in general, it's best to keep them completely separate.

The two power supplies deliberately come together where a kill switch is provided because the receiver needs to switch the supply to the [edit] ignition receiver ON/OFF. This should be via an opto-isolated (e.g. RcExl Mk2 ) kill switch. It's job is to ensure that there is no electrical connection between the two supplies.

Edited By Gary Manuel on 06/12/2016 19:56:20

iqon06/12/2016 20:38:11
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1456 forum posts
239 photos

Plus one for keeping them separate......wink

Dave Wilshere06/12/2016 20:50:30
56 forum posts

Powerbox also say Never! I have people wanting to share ignition and radio on some of the PB dual switches and PB say its potentially very dangerous. Their Spark switch is isolated, radio operated and failsafe.

chris larkins06/12/2016 21:41:05
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193 forum posts
124 photos

I personally have never used a single battery for the RX & the Ignition and so far have always used a separate 4 cell NiMh pack for the Ignition..........................  HOWEVER   ................I recently watched the following video from Redwing RC who sell a battery with two outputs and actually recommend using a single battery as long as you are using 2.4ghz.............watch the video and make your own mind up.

Edited By chris larkins on 06/12/2016 21:41:31

Edited By chris larkins on 06/12/2016 21:42:07

Gary Manuel06/12/2016 22:03:07
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1898 forum posts
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Watched it and made my mind up.

One other thing to bear in mind is that your servos are also powered from the same source as your receiver. Any ignition noise reaching your receiver battery is also reaching your servos.

2.4Ghz receivers may well be less prone to interference than 35Mhz (or 72MHz) BUT what about the servos?

I'll stick with one "dirty" supply for the ignition and one "clean" supply for the receiver / servos and recommend this to anyone that asks.

Rich too06/12/2016 23:00:38
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3033 forum posts
1070 photos

All you doom and gloom merchants, check out the tech aero ibec and show me the negatives posts on the net.

Redundancy with twin batteries, what's not to like. Much simpler than the powerbox systems.

Rich too07/12/2016 07:16:43
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3033 forum posts
1070 photos
Posted by Gary Manuel on 06/12/2016 22:03:07:

Watched it and made my mind up.

One other thing to bear in mind is that your servos are also powered from the same source as your receiver. Any ignition noise reaching your receiver battery is also reaching your servos.

2.4Ghz receivers may well be less prone to interference than 35Mhz (or 72MHz) BUT what about the servos?

I'll stick with one "dirty" supply for the ignition and one "clean" supply for the receiver / servos and recommend this to anyone that asks.

The tech aero ibec has a 4 stage filter.

Rich too07/12/2016 07:36:12
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3033 forum posts
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Some useful debate here:

http://www.flyinggiants.com/forums/showthread.php?t=205930

 

 

Edited By Rich2 on 07/12/2016 07:36:26

Gary Manuel07/12/2016 09:01:35
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1898 forum posts
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Rich,

Not doom and gloom, just reasoned preference.

  1. The OP is not using a Tech Aero ibec, which is designed for this application. He is using a Castle Creations bec, which is not. He is also talking about running the ignition from the same bec as the receiver. This would be exactly the same as running them both from the same battery.
  2. There is more to go wrong with a bec than a battery.
  3. A bec costs a lot more than a battery - although the TE ibec saves on the cost of a kill switch.
  4. The OP is modding an existing setup. The power required by the ignition would reduce the running time of the receiver battery unless he replaced it with a larger capacity one.

As I say, just my tu'pence worth based on my reasoned preference. The OP is looking for a solution to his problem and I have expressed my preference with my reasoning.

I'm sure there is nothing wrong with your setup - in fact, I quite like the look of it, but it's not answering the OPs question about altering his existing setup.

P.S. absolutely nothing wrong with using a second battery for redundancy, but this is a different issue.

Rich too07/12/2016 09:35:50
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3033 forum posts
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Fair enough Gary, I admit I was focussed on his first sentence in the opening post. It is personal preference, there are guys flying 60cc machines with one battery..surprise For me redundancy is very important.

Edited By Rich2 on 07/12/2016 09:36:39

Peter Christy07/12/2016 09:55:39
1555 forum posts
Posted by John Smith 50 on 06/12/2016 18:38:55:My ignition pack only last 3-4 flights atm ......

That alone would tell me not to use the Rx battery for the ignition!

Its one thing to lose an engine in flight, but to lose the whole radio system - well, I leave it to your imagination!

I wouldn't even run electric retracts off the same pack as the receiver, unless there were no alternative (ie: small model). A stalled retract servo can drain a battery very quickly! Ask me how I know!

The receiver supply in any model should be sacrosanct, for all the excellent reasons given above. And a model powered by a large spark ignition engine should have no problem handling the weight of an extra pack.

I'm surprised that the OP is only getting such a short duration off his ignition pack, however. I have a large petrol powered helicopter, and the ignition pack on that (originally a 1900 NiCAD, now a 3200 NiMH - same physical size) will outlast the receiver pack. Its certainly enough for a whole day - possibly whole week-end - of flying. Sounds like something else is amiss. Possibly the ignition pack is on its way out?

--

Pete

 

Edited By Peter Christy on 07/12/2016 09:56:38

John Smith 5007/12/2016 11:44:44
89 forum posts
19 photos
Yes it is on its way out which is why i'm replacing it with either another ni mh pack or use the reciever pack. I am also using an opti backup battery in case the reciver pack fails.
Rich too07/12/2016 12:45:39
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3033 forum posts
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What size battery are you using on the receiver?

John Smith 5007/12/2016 13:25:16
89 forum posts
19 photos
3s 3000, I usually do about 10 12min flights on it before i swap it for another one and it has about 50% left

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