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Catastrophe!

Model Air Crash Investigation Experts Sought...

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Don Fry01/02/2019 13:00:16
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4054 forum posts
47 photos

I've never been a fan of NiMh cells. I preferred NiCads, but Eneloops are good as a NiMh gets.

Nowadays I use 6.6 v, (nominal) LiFe cells. Most, inc Futaba , servos are good at this voltage. Not dear, tough, supplies amps until it melts, fast charge, usually fitted with a standard servo plug, and higher amp plug, what's not to like.

The Entronix switch mentioned above are also frequently supplied with the heavy amp plugs.

I am also wary of fancy high torque digital servos, they can eat power. I am wary of all slide switches, and have started to migrate to expensive electronic or throw switches, fed up with throwing slide switches away, because I don't trust, so I change, repeat "ad nausium".

Big fan of data transfer from the plane to transmitter. Receiver volts, fades, bad data packages, etc. Tells you, in precise terms what the machine is coping with. Cheap alternative to crashing.

Thanks for the switch vibration advise.

But this game is a game of blood. If you ever work out the things that have to go right, to get a "that was a nice landing" personal recommendation, you would not open the throttle in the first place.

Tim Flyer01/02/2019 14:33:57
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1075 forum posts
208 photos

Agreed. There are “switches” and switches and quality can vastly differ. I prefer higher voltage for above reason but also how a model is stored is very very important. Many modellers store models in damp and/or unheated conditions where condensation can occur. That’s certainly not good . Also the two stroke petrol engines often in use present an extra installation challenge with their excessive vibration. I’m also currently assembling an Acrowot XL and have opted for twin LIFe battery set up with two switches.

Tim Cheal01/02/2019 15:00:20
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214 forum posts
54 photos

Jon

Sorry to hear about the loss of the Acrowot. I lost confidence in my DX8 a while ago and sent it to Spectrum for a check, they replaced the RF board free of charge. I have had no problems since. It was when they still had a UK HQ though.

You are kinder to Spectrum bashers than me Nigel R!

The switch video is brilliant, and although I don't have any 'big' models with high servo loads I shall be using the eTronix switches in the future - they do one without the fuel dot and a recharging plug I note.

Tim

GrahamWh01/02/2019 16:59:07
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356 forum posts
53 photos

The slide switches look big but inside the plastic case the actual metal switch is small. Open that and the contacts are tiny! I wonder what current they are actually rated at. Good high current toggle switches are easy to get and may be more reliable. Thanks for the video Peter.

Jonathan M01/02/2019 17:35:24
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670 forum posts
275 photos
Posted by Tim Cheal on 01/02/2019 15:00:20:

Jon

Sorry to hear about the loss of the Acrowot. I lost confidence in my DX8 a while ago and sent it to Spectrum for a check, they replaced the RF board free of charge. I have had no problems since. It was when they still had a UK HQ though.

You are kinder to Spectrum bashers than me Nigel R!

The switch video is brilliant, and although I don't have any 'big' models with high servo loads I shall be using the eTronix switches in the future - they do one without the fuel dot and a recharging plug I note.

Tim

Thanks for the commiserations Tim.

Despite my hard luck, I don't feel sufficiently knowledgable about Spektrum to bash them (as I only ever had this DX7 black and the old DX6i and no experience of other makes to compare), but your anecdote about the RF board does beg certain questions about quality-control and robustness/longevity! If Spektrum still had actual premises in the UK I could send the TX to, I would - if only to establish beyond any measure of doubt that it was my TX that caused both fatal losses of control.

I've found the slightly cheaper version of the eTronix switch without the fuel dot - why risk having fuel potentially splashing around the area of the switch!? I do like integrated charging-ports, which allow models to be charged and stored hung-up fully assembled without having to unscrew wing-bolts each time - but if my future IC models are going to have LiFe batteries, then I'll need access to the balancing plug anyway... maybe a custom hatch-cover?

The only model that I'm going leave with its brick 4.8v NiMh and heavy-duty sliding-switch/charger-port is the Middle Phase - I don't want to start messing with it, and with no vibrations from any engine I don't think that's at huge risk.

I store all models in the office area of my workshop - heated with an oil-filled rad on a timer.

Kim Taylor01/02/2019 18:14:32
285 forum posts
53 photos

Logic RC are apparently the 'official service centre' for Spektrum in the UK, although their website makes no reference to it. Also during the chaos that followed the closure of Spektrum in the UK, Al's Hobbies were taking on service / repair.

You could, of course, send it to Horizon Hobby in Germany for their service / repair / comments, but that would probably take at least a couple of weeks and you would have to stump up for carriage to them. I sent a receiver back to them some time ago (during the chaos) and did eventually receive (sorry) embarrasseda replacement f.o.c.

I've decided that IF my DX8g2 gives trouble, I'm going to go to Taranis - not because I necessarily think they're any more reliable, but they do at least have a good technical back up in the UK. The lack of respect shown to UK users by Horizon Hobby has left a bitter taste in my mouth, anyway.

Kim

p.s.

Btw NOT knocking the product - I've always been happy with mine and the Rx I sent back had had more than one 'arrival' caused by my own ineptitude

Edited By Kim Taylor on 01/02/2019 18:15:26

PETER BRUCE - Eastchurch Gap01/02/2019 19:13:44
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856 forum posts
112 photos

Related to the slide switch video - this is shot...

Nigel R01/02/2019 19:51:16
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3104 forum posts
479 photos
The condensation thing can be a proper nightmare. Nothing about our toys gets on with the damp.

Mine are shed stored and I've taken to making socks for the airframes. From the radiator insulation stuff. Cheap and effective.

Don if I could remember where I saw the switch setup I'd give credit - not my idea. It's interesting to see the commercial offerings doubt the same things (and more).

You're probably right about the life packs. We're awash with chargers that can do lipos now.
Jonathan M01/02/2019 19:57:41
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670 forum posts
275 photos

Thanks for the heads-up on Al's Hobbies and Logic. I'll call them Monday to get an estimate for inspection and repair ... that is if the DX7 is indeed faulty!

Still moving to Taranis and FrSky receivers with telemetry for RX voltage , just that I'd feel uncomfortable with selling a potentially faulty TX - or maybe better for selling something with a clean bill of health!

laugh

Edited By Jonathan M on 01/02/2019 20:00:49

Gordon Tarling02/02/2019 18:01:14
234 forum posts
4 photos
Posted by Nigel R on 01/02/2019 12:21:56:

" It's been well proven that Eneloop cells have a high internal resistance"

From memory, manufacturer data on internal resistance suggests they do not. Do you have a link to any testing done on Eneloops that disproves the manufacture information?

The original nimh cells were quite high internal resistance but the newer low discharge cells are much improved.

Nigel - there's some discussion on the subject here - link I have to admit that I've not done any testing, what I say is just based on personal experience.

JonathanM - A123 cells are my preferred choice when a model requires a receiver pack, the 2300/2500mAh cells can easily supply 60 Amps, though they might be a bit large for many models, but you only require two for a receiver pack. There are also 1100mAh (I think) cells which are obviously smaller. There are many 18650 sized cells on the market, which are suitable, too, but you need to ensure you use the big name types with lower capacity, i.e. Panasonic, Sanyo etc.

Edited By Gordon Tarling on 02/02/2019 18:28:08

Jonathan M02/02/2019 18:53:42
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670 forum posts
275 photos

Thanks for that Gordon. What is the difference between a 3s LiFe and an A123?

For the RX on my replacement Wot4, I was looking at this sort of 1600mAh 3s LiFe **LINK** which weighs 71g compared to 108g for a 4.8v Eneloop. Weight is relevant as I'm already carrying the weight of big 4s LiPos up front. For the replacement to my IC Acrowot I could conceivably carry a slightly heavier, bigger capacity version.

Will this do?

Frank Skilbeck02/02/2019 18:58:10
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4489 forum posts
101 photos

Jonathan a 2s Life Rx pack is fine, you don't need a 3s.

A123 cells are Life chemistry, but they are packaged like Nimh cells in a metal casing, very robust.

Stephen Smith 1402/02/2019 19:23:44
153 forum posts
Posted by Nigel R on 31/01/2019 21:13:16:

"Hate to say told you so, but told you so. See my post sixth down on first page. Wonder how long it will be before people realise"

You on Hitecs payroll? Plenty folk use Spektrum with zero problems attributable to it.

Not on anyone's payroll used spekrum when we first got 2.4 with the original DX7 was faultless but built by JR using spectrum software, never missed a beat. When JR and spektrum split I bought a DX8, worst modelling purchase ever, went back 5 times in 3 months including 3 new ones always told nothing wrong but here's a new one anyway. Finally hit with a hammer and dropped in it the wheely bin.

Then bought a hitec never missed a beat and have both the 9 and the 9X, don't use either much now as I have another make as I needed more channels and am buying receivers for this system as I convert my fleet, my son currently uses the 9 and he has never experienced a problem.

I know of at least half a dozon spektrum users at our club all have had some kind of issue with them their are 5 hitec users and not one has had a problem neither, there are 25 members (caped) and I know every one and not one user of other systems others then spektrum has experienced a problem.

Have google about and its common knowledge that there are problems with spektrum but for some strange reason they are defended on this forum, about time people woke up and admitted they are poorly made cheap and nasty tat.

Jonathan M02/02/2019 19:24:28
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670 forum posts
275 photos

Thanks Frank. My mistake, as I read 3C but wrote 3s!  Of course 6.6v is two cells.  A123 doesn't really seem a necessary flack-jacket in this application, but a lite-ply box to hold this receiver battery would be a good idea - once I know where the best CG is on the new Wot4.

Edited By Jonathan M on 02/02/2019 19:29:42

Don Fry02/02/2019 20:44:48
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4054 forum posts
47 photos
Posted by Stephen Smith 14 on 02/02/2019 19:23:44:
Posted by Nigel R on 31/01/2019 21:13:16:

"Hate to say told you so, but told you so. See my post sixth down on first page. Wonder how long it will be before people realise"

You on Hitecs payroll? Plenty folk use Spektrum with zero problems attributable to it.

Not on anyone's payroll used spekrum when we first got 2.4 with the original DX7 was faultless but built by JR using spectrum software, never missed a beat. When JR and spektrum split I bought a DX8, worst modelling purchase ever, went back 5 times in 3 months including 3 new ones always told nothing wrong but here's a new one anyway. Finally hit with a hammer and dropped in it the wheely bin.

Then bought a hitec never missed a beat and have both the 9 and the 9X, don't use either much now as I have another make as I needed more channels and am buying receivers for this system as I convert my fleet, my son currently uses the 9 and he has never experienced a problem.

I know of at least half a dozon spektrum users at our club all have had some kind of issue with them their are 5 hitec users and not one has had a problem neither, there are 25 members (caped) and I know every one and not one user of other systems others then spektrum has experienced a problem.

Have google about and its common knowledge that there are problems with spektrum but for some strange reason they are defended on this forum, about time people woke up and admitted they are poorly made cheap and nasty tat.

Thank you. You might be surprised, that about a third of the users of this site use Spektrum. A fair proportion of the non Spectrum users don't give a monkeys toss. And then there is a rump.

Former Member02/02/2019 21:20:49
724 forum posts

[This posting has been removed]

SONNY MONKS03/02/2019 09:03:33
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269 forum posts

Hi Everyone,I have to totally agree here with supertigrefan,when i flew with spekky i encounted nothing but problems,main board going,six weeks before i got it back(repaired under warranty)it went half way around the world,talk about a poor service,i reckon a lot of people would be leaving the hobby if other brands had the same amount of faults,but dont get me wrong,some have been lucky,and not had issues,so they are fortunate,since i now fly with the horus x10,i think the quality is hard to beat,on a £345 radio.

SONNY MONKS03/02/2019 09:06:39
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269 forum posts

sorry,stephen smiths comments i mean

Nigel R04/02/2019 09:56:25
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3104 forum posts
479 photos
Posted by Gordon Tarling on 02/02/2019 18:01:14:

Nigel - there's some discussion on the subject here - link I have to admit that I've not done any testing, what I say is just based on personal experience.

Thanks Gordon

I've previously seen this thread on candlepower forum **LINK**

There is a nice graph produced and shown there, which shows the cell voltage at various discharge rates.

I did a quick check (fancy chargers are handy!) this weekend on an Eneloop AA pack, at 2A, and my result tallied almost exactly with the result shown in that graph for 2A (i.e. 54minutes before terminal voltage dropped to 1.0V, and about 1800mAh total discharge).

It is always worth considering your worst case scenario (ie "all servos binding" type situation) and for any kind of sport model analogue servo setup the eneloops are all good - in my opinion, backed up by the linked graph - to cover this and still keep the RX alive.

A couple of setups...

4 x standard size standard power analogues, total max current about 3A

4 x standard size digital analogues, max current about 5A

4 x hitec micros, max current about 5A (!)

4 x hi torque digitals, max current 10A

providing you don't try and push beyond a 5A (ish) total, the eneloops are perfectly OK (again, my opinion, other opinions are available).

Or to sum up, the average sport model with standard types of servos, is well served by an eneloop pack. They fast charge quite happily at 1C. Although they do benefit from a periodic trickle charge to keep the cells balanced.

Horses for courses, etc.

Nigel R04/02/2019 10:08:42
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3104 forum posts
479 photos

Posted by supertigrefan on 02/02/2019 21:20:49:

wait for hard evidence rather than condemn a particular brand based on hearsay and anecdotal 'evidence',

Very much that. I've never personally seen anything to show Spektrum has a high failure rate compared to any other brand. I'm obviously more than willing to be proven wrong, if anyone has any credible stats.

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