Tx, Rx Battery advice
|Vince Findlay||24/04/2019 21:46:17|
|2 forum posts|
Hi all, I have just bought this combo after a few years away from the hobby and any advice would be much appreciated. The Tx comes with a 4 cell 4.8v 1200 mah battery, could this be upgraded to a higher voltage and capacity? For the 3008SB rx I was planning on using 2 Sanyo enloope 6v 2000 mah packs through 2 switches into different ports for redundancy. Would the rx handle that?
|Frank Skilbeck||25/04/2019 13:37:50|
4422 forum posts
From the manual you could put in a 2s Life battery, but you would need a charger that can handle LiFe batteries. Note a club member has got a 6K and the Tx batteries last for ages, bear in mind these 2.4 sets don't draw much current (unless they have a fancy colour screen), so you would probably get 10 hours out of a set of 1200 mah batteries, but the easy upgrade would be to get a set of 2000 mah Nimh 4 cell pack.
You receiver will have no issues with that set up, just make sure the servos are OK with 6 volts, the only downside with this set up is that if one battery fails it might draw current from the other, so some people who do this put diodes in each feed to stop this from happening. Must admit I don't use 2 battery setups myself, just a good quality battery LiFe or sub C Nimh and an electronic type switch, but my biggest model is only a 1/3rd scale vintage glider.
|Jon - Laser Engines||25/04/2019 16:54:45|
|4723 forum posts|
I use the 8j and run it using the 1200mah nimh as it works just fine, is easy to charge, and requires zero faffing about. On the rx side, power it how you like but personally I use 1200mah 4.8v bomb packs for smaller models, 2000mah 6v packs for medium models, and 3000 ish mah subc 6v packs for big models. It's a system that has served me very well and is very simple to maintain
|Percy Verance||25/04/2019 17:04:29|
8109 forum posts
You don't need two batteries in your model Vince ( your transmitter only has one!) By using two packs in the model, you're actually doublng the chance of problems. Just use one good battery such as a LiFe pack through an electronic switch such as the Powerbox or Multiplex versions. Just be sure to check it when you charge, and again prior to committing aviation.
The nimh pack in the transmitter is where Futaba are just a shade behind the present trend Vince. Some other brands now fit a lithium pack from new, and these tend to give much more operating time, as well as being free from the old nimh self discharge issue. The nimh pack will be fine as long as you look after it Vince.
Edited By Percy Verance on 25/04/2019 17:17:07
|Pete Collins||25/04/2019 18:56:25|
96 forum posts
I'm using a 10C, admittedly a lot older than the 10J, and the only upgrade I have done was to change the original NiMh's for Eneloops. This has made a huge difference. I don't need to charge religiously every time I fly and I usually get 2 or 3 flying sessions from a charge. I just need to keep an eye on the battery voltage - anything over 10v is OK.
|Stephen Smith 14||25/04/2019 19:58:17|
|148 forum posts||
LOL there speaks the voice of misunderstandings and misinformation
|Percy Verance||25/04/2019 20:34:32|
8109 forum posts
There speaks the voice of someone whom has been building and flying model aeroplanes for almost 50 years, has flown/participated in national flying events, spent 25 years as both a BMFA Examiner and Registered Instructor, taught a good many people to fly their model and helped and encouraged them to to pass their "A", "B" and "C" tests. Oh, and I've also been a founder member of two model clubs, negotiated the use of both sites and helped others to do the same at their sites along the way.
But never mind. Maybe it was all a misunderstanding?
Don't simply stop at derogatory comments Stephen, give us your take on it, and the benefit of your wisdom. Oh and when you've a moment, take a look at the MIck Reeves site. Pay particular attention to Mick's comments and advice and read his thoughts on using two receiver batteries. Still, what does he know? He's only a former World Champion. And I had the pleasure of witnessing Mr Reeves win the World Championship in 1978.......
And where exactly was the misinformation in my post Stephen?
Edited By Percy Verance on 25/04/2019 20:55:54
|Allan Bennett||25/04/2019 21:18:58|
|1523 forum posts|
Hmmm . . . . there's twice as much to go wrong, so the risk of it happening is doubled. But statistically, what's the chance of both batteries going belly-up in the same flight? With proper electronic circuitry (basically a couple of diodes) the chance of the bad one affecting the good one should be eliminated. But then one has to add the chances of the electronic circuitry going bad . . . . .
I believe in KISS, which leads me to generally use a single power source for my receiver and servos -- usually a BEC these days because I fly all-electric. I do however use a separate power source for retracts, in case they jam and stall their motors.
|Peter Christy||25/04/2019 21:40:01|
|1483 forum posts|
Oh, dear! Where to start? I'm with Percy on this one. I've known more problems caused by "doubling up" batteries, using regulators and battery backers than all other radio issues put together!
Keep it simple! There is less to go wrong! Even the full-size aviation industry is doing this, with most trans-atlantic flights now done by twins instead of four-engined aircraft. Why? Because there is less to go wrong!
A couple of examples: A few years back, I supplied a radio to a well known scale modeller. I knew it was going in a big twin, so I checked and double checked that radio. It was perfect. The day after he collected it, he called back complaining of short range. Sure enough, it was short of range! He was using two battery packs through an electronic switch. Replacing that with a single battery pack and a good quality mechanical switch, and all the problems went away!
A 3D heli pilot, who had been flying happily for some time suddenly started experiencing intermittent glitching. He had replaced his 4-cell battery pack with a LiPo and regulator. Going back to the 4-cell pack restored normal operation.
It is not just a question of voltage. The internal resistance of the supply is also significant, and even silicon diodes have a significant impact on this.
Basically, if you don't trust a battery pack, you shouldn't be using it at all, either singly or via a backer.
Run your equipment at the manufacturers recommended voltage from a good quality pack of adequate capacity, via a high quality mechanical switch, and you will have no problems - period!
Like Percy, I've been doing this for over 50 years now and never had a problem with this approach.
|Percy Verance||25/04/2019 21:42:40|
8109 forum posts
Any problems needn't necessarily stem from battery issues Allan, there are twice as many connections/switches/leads etc.
Like you, I'm a keep it as simple as possible devotee. If it aint there, it can't go wrong........
It's a single quality (regularly checked) battery pack and a good electronic switch - which defaults to the ON position if it packs up - for me. Never failed me yet.
P.S. Peter. I've not had any issues with the electronic switches I use, but I've never used twin battery packs with them. I notice Multiplex (my radio brand) are now using electronic switches on all their transmitters. It looks as though Jeti do the same?
Oh and Stephen, don't try telling Peter Christy he doesn't know what he's about. He's been designing and building radio control equipment for decades..........
Edited By Percy Verance on 25/04/2019 22:20:38
|Frank Skilbeck||25/04/2019 22:34:09|
4422 forum posts
Not really, for a long time twin engined planes were not permitted on long over water passenger flights, until the manufacturers could demonstrate that they were as safe as 3/4 engined aircraft. The main reason for twins is that they are cheaper to buy and run.
|Martin Harris||25/04/2019 22:41:05|
8669 forum posts
I think Percy's (and for that matter, Pete's) voice is one of experience and personal preference.
I can't claim 50 years of continuous experience but I do go nearly that far back. I totally agree that electronic switching and regulated solutions are a complication and do increase fault potential but I do feel that a simple dual battery supply reduces the possibility of a total power failure and is therefore a wise precaution for a larger model where space and weight considerations combined with increased legal and moral responsibility mean it's both viable and in my opinion wise.
Transmitter batteries operate in a much less hostile environment (very low vibration and G loads for example with lower and steadier power demands) with almost universal warning of dropping voltage so a single battery is a lesser risk factor.
I don't use diodes (except as simple voltage droppers for LiFe packs) as my reasoning is that the typical failure involves either a break in the wiring/cell welding or a switch failure. Neither of these is likely to introduce a short circuit although I have experienced internal cell failure on a NiCd which effectively short circuited the cell internally, reducing the pack voltage significantly. Telemetry was my friend then...and with a dual battery system energy transfer is not of great significance which I've confirmed by practical experimentation.
Should that be repeated with a dual battery system, the supply voltage should remain high enough to maintain control while telemetry should alert me to the problem. A dual battery system must be monitored scrupulously by pre-flight checks (again telemetry enhances these) and I remain to be convinced that if monitored correctly, it can only improve safe operation.
As far as full size practice is concerned, I've yet to hear about any critical electrical systems or electronics not being duplicated - or triplicated in many cases. My recollection is that twin engined transatlantic operation was driven by economic considerations rather than safety.
Edited By Martin Harris on 25/04/2019 22:42:33
|Percy Verance||26/04/2019 06:40:26|
8109 forum posts
I'd agree transmitters do generally have an easier life. Like you though I have had several cell failures over the years, both with nicads and newer nimh cells. Fortunately most of my transmitters have a battery management facility, and using this has meant that it's been easier to see any gradual loss of performance and fit a new pack before it's too late. And I'd happily agree again that twin battery systems in models ought to be checked thoroughly on a regular basis if they're to operate as intended.
Edited By Percy Verance on 26/04/2019 06:47:13
|Peter Christy||26/04/2019 09:37:14|
|1483 forum posts|
My own personal preference is for a good quality 4-cell NiMH pack of adequate capacity through a good quality switch. For the batteries, I usually use Eneloops for small to mid-size models and C or sub-Cs for the larger ones with a lot of high power servos. For switches, I use the JR heavy duty ones - the ones with a separate charging lead, NOT the ones with a socket built in to the switch casing. I believe Futaba make a similar switch. I also have an ever-diminishing stock of Japanese "Noble" switches - still regarded as the "gold standard", even today!
The above set up has served me well for years, even in the hostile environment of IC powered helicopters - well known for their ability to destroy anything through vibration!
On one vintage heli I am now using a 2-cell Life, again through a JR heavy duty switch, but the Rx and servos are designed for high voltage operation and don't need a regulator.
I avoid regulators like the plague! There are two types - analogue and switching. Analogue ones dissipate the excess power as heat - very wasteful - and are rare these days. Switching ones can generate large quantities of RF interference - I once demonstrated a 35MHz PPM set having its "aerial out" ground range reduced from about 8 feet down to four inches by one! Although modern switching regulators are better in this respect, cheaper ones can still be problematic.
And just because modern radio gear can disguise the effects of this kind of interference, it is just that : disguising - not eliminating - it.
As regards twin engined trans-oceanic flights, yes economy was a factor in their introduction, but they also had to demonstrate that their reliability was *at least* as good as the four-engined craft they were replacing. They exceeded this target by a comfortable margin, largely because of the added simplicity - er, if you get my drift!
Remember the old adage: "Simplicate and add more lightness"!
|Percy Verance||26/04/2019 13:52:18|
8109 forum posts
So Stephen. Thoughts? Comments? Or are you still laughing?
I'll offer some friendly advice if I may. You have made 124 posts so far on this forum. It may be rather foolish to assume someone may or may not know what they are talking about after so few posts...........but you may realise that by now.
Ours is a wonderful hobby, and it's one in which you never actually stop learning. Even after nearly 50 years of modelling there are still things I'd like to learn about and understand.
Edited By Percy Verance on 26/04/2019 14:05:10
|Doc Marten||26/04/2019 14:03:37|
|353 forum posts|
You've made your point Percy, why not leave it at that?
|Percy Verance||26/04/2019 14:05:41|
8109 forum posts
I have. That's it from me here........
|Doc Marten||26/04/2019 14:58:07|
|353 forum posts|
In fairness, post count is be no means an indication of experience nor qualification.
Edited By Doc Marten on 26/04/2019 14:58:35
|Denis Watkins||26/04/2019 15:26:41|
|3736 forum posts|
Just a heads up on product design and reasoning, Futaba decided that 4.8v 1200ma pack was enough
The common denominator in choosing another power option is the size, AA
Now, to fit 6v 2000ma inside the same space, AA, as the 4.8v 1200ma
The rolled up electrolyte is Half as thick ! ! !
In theory, this electrolyte will not last as long but is not linear
On a flying day, perhaps 300ma would be used, barely flexing the muscles of the 2000ma cells
The lads will recall using 600 - 900ma nicads to fly all day, and just how many years those packs lasted
|Peter Christy||26/04/2019 16:46:28|
|1483 forum posts||
Ain't that the truth!
And back then, you needed to put about 1 watt in to get 100mW erp out! Nowadays, on 2.4 GHz, the transmitters put out about 60mW, using the gain of the aerial to bring it up to 100mW erp.
The biggest current draw on a modern transmitter is the backlight for the colour LCD.....!
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