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Power panel fire

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Nigel R25/06/2018 15:51:34
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1286 forum posts
284 photos

Wise words. There's definitely no overdriving a plug with the nicad/nimh glowsticks. Simple is often best.

"From now on I take the model(s), transmitter and a handfull of batteries."

Tis great for small models, but, a stack of 6S 5000mAh is getting quite heavy. And expensive. And you don't get many in a handful!

Obviously, YMMV smiley

In a previous incarnation, the "small model" kit box was a quarter gallon container with a hand pump, a valvespout bottle to drain tank at end of session, and a 2V battey with long lead. And a slot for the TX.

Solly25/06/2018 15:56:06
213 forum posts
1 photos

Can't understand the anti power panel comments. It's like saying I bought a faulty TV so all TV's are rubbish. I've had two, the first one lasted many years until the integral fuel pump began to leak. The second one is four years old so far trouble free. And the power panel blowing plugs? That's something I've never experienced.

Martin Harris25/06/2018 16:46:31
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7627 forum posts
189 photos

Count yourself lucky then, Solly. I suspect all the negative comments are born from experience.

Bob Cotsford25/06/2018 17:07:31
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7268 forum posts
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Posted by Nigel R on 25/06/2018 15:51:34:

Wise words. There's definitely no overdriving a plug with the nicad/nimh glowsticks. Simple is often best.

"From now on I take the model(s), transmitter and a handfull of batteries."

Tis great for small models, but, a stack of 6S 5000mAh is getting quite heavy. And expensive. And you don't get many in a handful!

Obviously, YMMV smiley

In a previous incarnation, the "small model" kit box was a quarter gallon container with a hand pump, a valvespout bottle to drain tank at end of session, and a 2V battey with long lead. And a slot for the TX.

Nope, 3 or 4 6S5000 plus a few 4S3700 packs in an ammo box are still lighter and easier to manage than the gallon of glow fuel, flight box with it's built-in power panel, model stand, starter, cleaning gunk, rags,...... If it wasn't the case then I'd still be flying mostly large glow models. I AM doing this for my health this time!

Your previous incarnation flight box was something like my kit in the 1970s, before discovering the labour saving delight of an electric starter and an electric fuel pump. I never did find a hand-pump (glow or petrol) that didn't leak near as much as it pumped. You missed the washing up liquid and rags to clean the Merco 35 powered models before fitting them on the back seat of a Vauxhall Viva wink

Horses for courses. I'm still with Solly on this one re power panels.

Solly25/06/2018 17:20:49
213 forum posts
1 photos
Posted by Martin Harris on 25/06/2018 16:46:31:

Count yourself lucky then, Solly. I suspect all the negative comments are born from experience.

I fully accept that. And so is mine.

supertigrefan25/06/2018 20:40:16
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180 forum posts
1 photos

Are MOSFET panels better?

Percy Verance25/06/2018 21:05:59
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6622 forum posts
111 photos

Yes, far better if you don't have one.

My list of field kit was simple and uncomplicated. I used a 12v leisure battery for my starter. A manual hand cranked fuel pump (no battery to let you down) An RCATS lithium powered glow driver, supplied as standard with a Dubro (quality) plug connector. I also had a chicken stick for if the 12v failed. No messing about, it all just worked. I'd much rather fly than fiddle.

Edited By Percy Verance on 25/06/2018 21:06:18

fly boy325/06/2018 21:22:05
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3200 forum posts
11 photos

Hi Peter, thanks for explanation, well written, but are you saying plugs can be blown with power panel just because we have adjusted the amps to a high level, and with a single cell the volts and amps are fixed ? Cheers

will -026/06/2018 09:15:58
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456 forum posts

Of course in this weather, a glow stick, fuel pump and a stick of wood is all you need.........

Nigel R26/06/2018 09:35:28
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1286 forum posts
284 photos

"plugs can be blown with power panel just because we have adjusted the amps to a high level"

Quite so.

"You missed the washing up liquid and rags to clean the Merco 35 powered models before fitting them on the back seat of a Vauxhall Viva"

You got me there! smiley

Don Fry26/06/2018 10:27:02
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2496 forum posts
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Posted by fly boy3 on 25/06/2018 21:22:05:

Hi Peter, thanks for explanation, well written, but are you saying plugs can be blown with power panel just because we have adjusted the amps to a high level, and with a single cell the volts and amps are fixed ? Cheers

I am out of my comfort zone, but I believe a panel supplies 12 volts to the plug, but in very short bursts, think high speed switch. There is a school of thought that this is not good for plugs. Might be right, might be wrong.

Cuban826/06/2018 10:51:41
1991 forum posts
3 photos

My Turnigy power panel doesn't have an adjustment for current, but automatically drives about 2 to 3A to the plug depending on whether the plug's a bit wet or whatever. Has a useful glowstick charger as well - I do tend to use the glowstick rather than the panel's driver, but I'm rarely left without 'heat' with the choice of two sources. Dumped the old (20 years according to the date I'd written on it) 12V gel battery in my flight box for a 2200 lipo. More than enough.

Nigel R26/06/2018 11:01:01
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1286 forum posts
284 photos

"I am out of my comfort zone, but I believe a panel supplies 12 volts to the plug, but in very short bursts, think high speed switch. There is a school of thought that this is not good for plugs. Might be right, might be wrong."

 

Yes, panels operate a cheap & simple chopper circuit (much like a brushed motor ESC). Key words are normall cheap, cheap, and, er, cheap.

They can fail "on", i.e. 12V constant to the plug. Obvious end result.

They may or may not enjoy driving a shorted plug, or having the clip attached in such a way as to create a short.

If they are in working order, it's not bad for the plug in the slightest, providing the overall energy delivered to the plug is correct.

The major problem they seem to suffer is the glow goes south when the starter motor is used. Again, easily compensated with some extra circuitry, but AFAIK most panels simply do the bare minimum necessary to get a variable drive. 

Edited By Nigel R on 26/06/2018 11:02:12

Don Fry26/06/2018 11:01:42
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2496 forum posts
30 photos

I would suspect Cuban8 has an answer with the lipo. Because, while I think panels are overcomlicated, my main criticism is the lack of power to drive it all with a small lead acid. A lipo would work.

Nigel R26/06/2018 11:11:11
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1286 forum posts
284 photos

Gel cell about 4 or 5lbs, vs the lipo at about 1/2lb, no contest.

Gel cells are mainly useful to stop your workbench moving when test running a 20cc+ motor.

J D 826/06/2018 11:43:26
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849 forum posts
53 photos

I use a 3s 1300 for my power panel and a 3s 2200 for the starter. Both are old batts but do their new job fine.

Peter Christy26/06/2018 12:01:59
954 forum posts
Posted by Cuban8 on 26/06/2018 10:51:41:

My Turnigy power panel doesn't have an adjustment for current, but automatically drives about 2 to 3A to the plug depending on whether the plug's a bit wet or whatever.

And this is - potentially - another problem! Different plugs glow at different current levels, depending on the thickness of the wire! An OS 8 or Enya 5 will typically draw around 3 amps when lit correctly. However, some of my older engines use long-reach plugs, which are glowing quite happily at 1.5 amps! Pushing 2 or 3 amps into them will definitely not do them much good!

What is important is the VOLTAGE at the plug itself - not the current or the voltage at the power panel! At these sort of currents, a long glow lead will significantly drop the voltage by the time it reached the plug.

An ammeter is only useful as an indicator of whether the plug is wet or dry (or blown!) once you have learned how much current your particular plug draws. There is no "one size fits all" current that is suitable for all plugs.

A single cell NiMh (or NiCad) and short leads (or a glow stick) will allow the plug to draw whatever current it needs without human intervention and without any risk of over-driving it.

Most power panels are pretty crude, with just a big variable resistor in series with the plug. High current rating variable resistors are not noted for their reliability! More sophisticated ones use a variable resistor to drive a transistor, which eliminates the need for a heavy duty variable resistor. The most sophisticated ones use a variable mark-space ratio to deliver 12V to the plugs in short bursts, producing the equivalent of 1.5 or 2 volts *on average*. However, as the peaks are 12V, I can't help but wonder what the ensuing vibration (thermal, if not mechanical) will do to the thin platinum coating.

In short, you can't beat a single NiMh cell of adequate capacity as a glow igniter. Its self-regulating regarding current, and makes it almost impossible to overdrive.

--

Pete

supertigrefan26/06/2018 12:06:20
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180 forum posts
1 photos

Not being an electric guy I'm under the impression that a LiPo needs a LiPo charger so what is the cost of a reliable 12v and charger compared to a gell cell where I already have a charger?

What sort of wiring change needs to be made to a panel to make it more 'acceptable' and plug friendly?

Nigel R26/06/2018 14:17:31
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1286 forum posts
284 photos

Maybe my experience is a bit limited, but, I've not ever seen a power panel with a large variable resistor. It'd have to be capable of wasting about ~30W of heat and would be pretty large and expensive. A power panel with a transistor wasting that heat would need the transistor to be bolted to a significant chunk of metal to sink the power. Metal cases and heatsinks tend to be a bit expensive compared to a plastic box. A 555 chopper circuit and mosfet transistor on the other hand, costs pennies, and wastes no heat, and can be stuck in a cheap plastic box.

The Turnigy panel regulates to 1.5V, according to the Hobbyking web page. Presumably using some voltage sensing arrangement to control a chopper circuit.

Bob Cotsford26/06/2018 15:46:11
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7268 forum posts
415 photos

In 50+ years messing with models driven by glow motors I think I'm right in saying that the only time I've had a power panel blow a plug was the time I plugged the glow lead into the 12v starter socket by mistake. That cost me 2 * OS-Fs. I've run glowplugs off cyclon cells, 2v lead acid, NiCad, all manner of on-board glows and the worst, least practical, most dangerous and most likely to let you down were the clip-on glow sticks.

I'm sure Pete is correct on the theory side but in practise my plugs last for years and were more likely to be swapped because they'd become gunged from running castor than any other reason.

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