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ignition redundancy

Old 12-12-2010, 07:52 PM
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dustybottles
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Default ignition redundancy

Has anyone considered or implemented ignition battery redundancy?
Old 12-12-2010, 07:54 PM
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speedracerntrixie
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Default RE: ignition redundancy

In 13 years of running gassers, I have never felt the need
Old 12-12-2010, 08:05 PM
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Default RE: ignition redundancy

There isn't any reason it can't be done, but considering the only downfall of an ignition battery failure is a dead stick landing I never felt the need. With a receiver, all control is lost. With an ignition battery failure, you can land dead stick, at worst you can control where the airplane ends up for safety.
Old 12-12-2010, 08:10 PM
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dustybottles
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Default RE: ignition redundancy

I was thinking more of the benefits of low down hovering, as a precaution to maybe protect larger models, IE where the flyer is relying solely on the prop, as opposed to general deadsticks?
Old 12-12-2010, 08:34 PM
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Default RE: ignition redundancy

If you spend most of your time hovering, there could be some minimal merit to the idea. I personally don't know of a single pilot that does, but then again someone had to be the first to run redundant receiver packs, no?
Old 12-12-2010, 09:14 PM
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dustybottles
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Default RE: ignition redundancy

I was thinking along the lines of halving ignition capacity, with two smaller capacity 2s lipos Ie. 2 1300's etc, running through something like this:

[link]http://www.hobbycity.com/hobbyking/store/uh_viewItem.asp?idProduct=14464[/link]

Not sure whether this unit has a single or dual output, it looks as though it may have some form of combined backer/controller.
Old 12-13-2010, 07:50 AM
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Default RE: ignition redundancy

I would worry about that solution being less reliable than a simple dual battery and switches. Batteries rarely just fail in flight. Over the last 10-12 years, using probably hundreds of batteries in various airplanes, I've never had a battery fail. They usually started to degenerate over time and stop holding a charge, etc. The typical failure was a switch gone bad, or a battery that couldn't hold a charge.

With the setup you showed, there are multiple circuit boards in the mix, a dozen or more wire/solder connections that could break, etc. It seems like a lot of complexity to solve a simple problem that dual batteries and dual switches would solve.

If it was a larger airplane that could handle the weight of a second battery and switch, I would go that route before adding electronics to the mix. The dual battery setup can handle a broken solder connection, bad switch, battery that didn't hold the charge, cell dropout/failure, battery short (if a fuse is used in-line between the batts), loose connector or disconnect, etc., which pretty much covers the most common failure modes.

If you did want to go with a backup on the ignition, I would still recommend dual batteries and dual switches. It covers the majority of failure modes, is simple, and there is no single point of failure except the ignition itself. With the controller setup, you have some redundancy, but also two major single points of failure with the controller board, it's wire/solder connections, and a single switch. IMO, you have added complexity yet still retain the single point of failures you would have in a single battery/switch setup. Not really an upgrade in my opinion.

Even as easy as it is to setup a dual battery/switch on the ignition, I never bothered as I never saw it as necessary. Battery failures are rare if you test, log, and maintain them. Even on my airplanes that cost me ~$6K a piece, I didn't see the benefit for the ignition. But I never fly my larger airplanes without redundancy on the receivers.
Old 12-17-2010, 07:12 PM
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dustybottles
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Default RE: ignition redundancy

Would anyone be able to expalin the best way of achieving the dual battery with switches set up. Ie What's the best type of battery to use for larger gassers, and what would be the best way of connecting these?
Old 12-17-2010, 10:19 PM
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Default RE: ignition redundancy

2 standard switches 2 batteries(2000 mah sanyo eneloop) and a custom y harness thats the way a buddy of mine did it.... he says he did it to balance the plane and technically not add dead weight,,,he used sub c packs... dual battery set up is not neccessary and have never even thought about doing it...

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