Tom, Craig, Speedbird.

Many thanks for your valuable inputs, they are VERY much appreciated, and what I believe RCU is intended to do.

Firstly, Tom, please substitute 767 for 747, I have never flown the jumbo. However the 767 being the first of the big twins to be cleared for ETOPS had an interesting electrical system, full of backups to ensure total electrical failure was virtually impossible......................until a European 767 lost almost everything, that certainly got Boeing's full and undivided attention.

I had no idea that the rx lands could handle 30 amps, I thought perhaps 10 or 15 but it was not just the current draw that concerned me but the likely voltage drop if large currents were being drawn. It also concerned me that these receivers were designed before the introduction of powerful digital servos and multiple use of such servos but I do wish manufacturers would give us some guidance on these issues.

I see there being two basic issues, one being the security of electrical power, the second being possible Rf pickup and voltage drop in long cables. I am not technically competent to make decisions on a purely technical basis so I have read the opinions of many experts in this matter, my only firm conclusion is there is NO consensus !

On point one, I no longer use a single battery except on a couple of smaller models, but even these use regulators which are dual channel (Mini Hobby) so if one channel should fail then all power is not lost. I do use Duralite 4 cell packs which are series/parallel wired so if a cell should fail only capacity not voltage is decreased so normal operation will continue allowing a safe landing. Never had a problem with RF noise from regulators using JR receivers.

On larger models with several powerful digitals, I use twin Duralites and switches with regulators. Of course there is double the chance of failure but the chance of a simultaneous failure and total loss of power is extremely unlikely. I need larger battery capacity so splitting them makes good sense, to me at least. In flight voltage is monitored by a MAS volt logger and rarley shows a drop of more than one green LED. All batteries get a voltage check before EVERY flight. Both batteries, actually the regulator outputs, are connected directly to the receiver exactly as recommended by the battery expert over on the RCU battery clinic, again never a problem.

For larger models with lots of servos such as my FC Mig 29 (13 8411s on long leads plus many other servos) I use the Power box having read a great deal about it and picked the brains of many other fliers. It offers twin battery redundancy, failsafe switching, signal amplification, opto isolation etc. etc but still keeps a small load on the receiver to retain tuning. Well thats what it says in the manual and I have no reason not to believe it as so many are in very sucessful use. The acid test is that in my Mig 29 range, with everything off (except receiver etc), is the same with both engines running and the hydraulic system running, over 300 feet aerial off. I am using twin batteries and Powerbox Champions on my new AirWorld Hawks which have powerful servos at the end of long leads.

I agree with you wholeheartedly on many of the other points you raised:
I use ONLY heavy duty top quality, extension cables, been using vertical whips, only, since 1999, seperate pumps etc from aerials and power leads. Never found the need to use torroids so RF pickup in long leads seems not to be an issue. Just bought the superb Orbit charger for NiCd, LiPo and NiMh charging and I check and minimise the current drawn in my entire installations by use of the Hangar 9 meter, a VITAL instrument if using ganged servos. (see next RCJI !)


I might also add that I have moved over to JR's new synthesised Tx modules and receivers. The Tx module seems to have greater output power and gives excellent range and has proven to have a completely solid RF link according to my JetCat ECUs and the volt logger which records glitches.

Well thats my approach to electrical power and the proof is it works beautifully AND the use of dual power supplies gives me a comfortabe feeling and THATS important too for my peace of mind.

Regards (and thanks to you all for your valuable input in this excellent debate)

David Gladwin.

PS Just measured the cables to the 4 stab. servos on my Mig 29, almost 2 metres long, but voltage drop even under load is negligible