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[GARY C]

Please can anybody explain why it states in the Futaba instruction manual for the 2.4Ghz R606FS receiver, that you must NEVER use dry cell batteries?.  ????????????

They state that it would cause a malfunction?????????????????????
I like to carry spare battery packs for the day at the lake, and it is so simple to have a 4 pack of Duracells, plus the advantage of 6 volts.
Ideal for my yacht.

2.4 is a great idea, I like arriving at the lake side, switch on and go.
Also a complant to Futaba, the 606 receiver has now been replaced by the 607 WHY?????? £60 + is getting over the top. Wish I obtained the Spectrum DX5 as I think it suits us "boat boys" better as an extra receiver is only £35.
 

[Colin Bishop]

Probably because of the voltage difference. 4 dry cells=6 volts nominal. 4 NiMH rechargeables= 4.8v nominal. Have you considered using Hybrio/Instant type rechargeables? They don't lose their charge when left in the box for a couple of months like standard ones do. ModelPower sell the Instants: http://store.modelpower.co.uk/aas--aaas-14-c.asp

Colin

[GARY C]

Hi Colin,

This is what I find confusing, the manual says,

Receiver R606FS.
Power requirement 4.8v or 6v (shared with servo)   
Current drain, 80mA (at no signal )

Why not dry cells. ???????????????? ?????????????

Gary.

[FullLeatherJacket]

Colin is right up to a point. If you fully charge a set of four NiMH cells then the voltage will be around 6.2v for a short while, so it ain't that which is the issue. I suspect they are alluding to the fact that dry cells have a lower capacity than rechargeable ones and they wouldn't want your aeroplane to fall out of the sky because you'd flattened them during flight (don't forget that these Japanese guys have never heard of RC model boats). Actually, what they really don't want is you suing them afterwards.............or am I being cynical again? 

To my simple mind volts is volts, whatever type of cells you use.

BTW I'm full square behind you ref VFM of Futaba............sixty quid for a receiver is extracting the Michael, especially when they put ruddy 700mAH NiCads in the Tx. You can buy a DX5 Tx and  Rx for less than that.

FLJ

[GARY C]

You like me, FLJ, volts is volts ?????  ANYBODY FROM FUTABA OUT THERE ?

Also now know why the TX battery does not last 

2 x20 min races and thats about it,  I like your last comment and have to say "I think I wasted my money on this one." 

Gary.

[Mankster]

Dry cells also drop voltage very quickly. The cells could only be half done but may only be supplying 4.5v under load especially if you have lots of large servos or digital servos. Helicopters using full size digtal servos can pull 2A through the RX pack (or BEC) and I doubt if AA Dry cells will stand for that. A 4.8V NIMH pack will always be above 4.8v till is pretty much flat, even when supplying a large number of amps.

[wideawake]

Dry cells also drop voltage very quickly. The cells could only be half done but may only be supplying 4.5v under load especially if you have lots of large servos or digital servos. Helicopters using full size digtal servos can pull 2A through the RX pack (or BEC) and I doubt if AA Dry cells will stand for that. A 4.8V NIMH pack will always be above 4.8v till is pretty much flat, even when supplying a large number of amps.

Yes I would think it's as much to do with the discharge characteristic of an alkaline cell (gradual voltage drop-off) as opposed to that of a NiMH cell (fairly stable after initial drop and then sharp drop at 90% or so discharge.

BTW as a matter of interest Spektrum qote the permissible input voltage range for DSM receivers as 3.5 - 9 volts.   I would interpret that in practice as from a failing 4.8v pack to a freshly charged 7.2v pack.

HTH

Guy

[Sandy Calder]

Gary,I know it is not Futaba but Duracell's note shoud satisfy you that the discharge profile argument is true.
http://www.duracell.com/OEM/comparisons/
In addition "malfunctions" occur when you use non-Futaba gear and a fresh alkaline battery.
The higher voltage causes compatibilty problems on the white signal wire.

http://www.batteryuniversity.com/

[GARY C]

YES,

I see the answer now thanks all.   "CAR BATTERY OR LEISURE BATTERY"  I guess the 2.4 ghz receiver requires a constant level voltage

Thanks Sandy for the Duracell link, they say that their Alkaline batteries have a "SLOPING DISCHARGE CHARACTERISTICS"

I now need to source a 4.8 v NIMH pack but at a very high mAH.

Gary.

[Colin Bishop]

Shouldn't be difficult. ModelPower can do you up to 4300mah. : http://store.modelpower.co.uk/receiver-packs-10-c.asp

[Sandy Calder]

YES,

I see the answer now thanks all.   "CAR BATTERY OR LEISURE BATTERY"  I guess the 2.4 ghz receiver requires a constant level voltage

Thanks Sandy for the Duracell link, they say that their Alkaline batteries have a "SLOPING DISCHARGE CHARACTERISTICS"

I now need to source a 4.8 v NIMH pack but at a very high mAH.

Gary.

I did not mean to imply the sloping characteristic was the reason Futaba not to use alkaline batteries.The voltage is too high and causes malfunction.

The internal resistance is much higher than hydride batteries and that causes problems too.It limits the effective capacity when the discharge rate is above C/5.
The DR30 6-pack has internal resistance is 0.18 ohm http://www.duracell.com/oem/rechargeable/Nickel/impede.asp
An individual MN1500 of the same capacity is 0.12 ohm per cell http://www.duracell.com/oem/Pdf/new/MN1500_US_CT.pdf That is four times the figure for Duracell's hydride product.

You would use a lead acid battery? The same problem occurs with 6volt lead acid batteries or five cell hydride or NiCD receiver packs.
A regulated supply ,say a 6 cell racing pack with a 50 pence bec regulator would have a flat profile but a limit of 1.5 amps unless you were to beef it up.
What would you need all that capacity on a receiver supply for anyway? 2.4 Ah hydride pencells are going for peanuts on Fleabay.

Regards
Sandy Calder

[Mankster]

A switch mode BEC would be even better, 2-3A supply is more common, but you can get upto 5Amp 9though your unlikely to have so many stalled servos to get close this). They dont get hot like ordinary voltage regullators. No need for seperate Rx batteries.

[portside II]

I bought my futaba 2.4 gig set at Blackpool , did a 180 deg turn and bought a 3600ma pack for the tx .sorted  , the 700ma pack is still on the shelf where i left it .
Not looked back and the new battery works great .
daz

[GARY C]

Perfect, many thanks.

A new year upgrade for my 2.4 gear.

If we need to do these battery upgrades for the Futaba 2.4 6ex sets, how does the Spectrum dx5 fair with, I am lead to belive,
only 4 AA pencells battries in the TX ?.

[barriew]

If we need to do these battery upgrades for the Futaba 2.4 6ex sets, how does the Spectrum dx5 fair with, I am lead to belive,
only 4 AA pencells battries in the TX ?.

Don't know yet - but the DX5e is not a computer set. I have the Futaba 6Exa 40Mhz set and the original battery lasted about 30 minutes if you were lucky I think the problem is the 'computer' not the frequency!.

Barrie

[wideawake]

If we need to do these battery upgrades for the Futaba 2.4 6ex sets, how does the Spectrum dx5 fair with, I am lead to belive,
only 4 AA pencells battries in the TX ?.

Don't know yet - but the DX5e is not a computer set. I have the Futaba 6Exa 40Mhz set and the original battery lasted about 30 minutes if you were lucky I think the problem is the 'computer' not the frequency!.

Barrie

The DX6 certainly had issues with battery life.  I bought an upgraded battery pack for mine soon after I acquired it.   It appears from some other forums that the problem may be a power hungry voltage regulator circuit.  There is info out there on swapping it for a more efficient ic.  I've not been tempted to do that as I get sufficient life out of my battery pack for leisure sailing.

Re the DX5e - i think whether it is a "computer" set depends on how you look at it.   It has some user-defined functions it's just that they are very limited and switch rather than menu selectable.   I'd be amazed if internally these aren't supported by some form of programmed chip!  I've got one ATM which I'm trying out for an article.   I think the move to 4 x AA cells is a good one.  High power AA cells are now easily available and carrying spare sets is much more economical than having spare battery packs.   Additionally the battery pack connector on the DX6 is very small and a bit fragile IMHO.

Guy

[Sandy Calder]

Receiver R606FS.
Power requirement 4.8v or 6v (shared with servo)   
Current drain, 80mA (at no signal )

That's the receiver issue sorted.Rechargeable pencells at 2400mAh have the same capacity as Duracell alkaline pencells.

Guy,could you pm me a link to this alteration?
Regards
Sandy Calder

[Sandy Calder]

Ernest H. to Kenny R. .....I've seen it!     Don't bother with a link!

Regards
Sandy Calder

[Sandy Calder]

http://www.datel.com/data/meters/dms-78xxsr.pdf for the tranny mod.

The problem with these regulators (which they share with a 7805) is that ,when used for bec,catastrophic damage occurs if you plug in a receiver pack.

Regards
Sandy Calder

[Max Power]

I am one of these fellows whose other hobby is flying r/c model aeroplanes. I have used futaba gear 35MHz and 40MHz for ages. I also use a 7 channel Futaba 2.4GHz set for boats and planes. All my gear works perfectly well on both 4 and 5 cell nicad or nimh. Experienced model fliers will NEVER use receiver (or transmitter) battery packs where the individual cells are not spot welded or soldered together; individual cells clipped into battery boxes or transmitters are too unreliable for planes. A poor contact between any of the cells and it is curtains for the model!. Since the Futaba sets are basically aeroplane sets this could well be the reason behind the futaba battery recommendations.

[Colin Bishop]

Sounds logical certainly, flyers have to be ultra careful. But not a drawback for scale marine use.

[Stavros]

Got ma Futaba set myself I run it on a 6v nimh set up on a 1 mtr yacht at well over 500 yds and not a problem.I sail for well over 4hrs with no probs at all.Forget all the garbage posted about batts etc even on a 6v gell cell I get over 5hrs with none of this absoloute POO POO about drops in voltage as someone on this forum is saying.Listen,you will only get that kind of voltagae drop if you dont charge your batts before sailing..fact.The fact of the matter is go out there and just sail



Stavros

[Sandy Calder]

....... Since the Futaba sets are basically aeroplane sets this could well be the reason behind the futaba battery recommendations.

It is actually because the voltage of alkaline cells is too high and cauases malfunction of the equipment the receiver feeds.
I've been aware of this for over a decade.