Well, Dave, I started using it when I started with my Excelleron 90, which is a pattern design type plane. It seemed that the larger aircraft had bigger control surfaces, stronger servo's, and required more battery energy to maintail more than what standard RX batteries could provide.

The 'club pro', who is a Master level pattern flyer, has used dual 800 mah's in his pattern planes and we talked about that. His thoughts were to keep it as simple as possible because more stuff only adds to that point of failure issue that pops up when starting to add redundancy. So, he suggested, that if I wanted to go to dual battery setup, that I keep it simple with two batteries, two switches, into two separate RX channels and that's it. And, he always talks about how things fail, vibration is the usual culpret, and vibration is always with us, and what we would lose if a single battery failed during flight.

The simplicity and ease of care for a dual battery setup, one battery, one switch, one channel, then the second independent battery, on a separate switch, and to a separate channel, is the simplest way and the best way to provide this redundancy.

So, to answer your question, when you feel that your investment would be enhanced by such a setup, if you have any doubt about a single setup, then you must decide if this is what you want.

I paid over 300 bucks for the Excelleron 90, over 250 for the OS 1.20 AX, and each servo was $73,00 (four of them) and one standard servo for the throttle, and 99 bucks for the DX7 receiver, plus time and effort building and setting up, so I figured the cost of an additional battery and switch was worth it for the investment I had in that particular aircraft, so I went with it.

Again, it all comes down to a choice you have to make with regard to certain factors. Larger control surfaces, stronger servos, higher speeds (more pressure on control surfaces therefore more torque from the servo thus more battery drain), all adds up.

Dual battery setup is not always the best solution, it just happens to be one that I take with my larger models. The smaller ones, well, single setup is just fine. Trainers, smaller size aircraft.. my Tiger 60 has one battery... don't need all that redundancy. If all is well, and if you check your battery frequently, then you will get 3 or 4 flights out of a standard battery. The key here is to check it with an ESV before starting out that day, and after each flight. You can't go wrong.


One of the main thing that most people, even the nay-sayers here, is that some sort of voltage monitor is a good thing. I chose Voltwatch (see Tower Hobbies for that). Sure, you cannot see it in the iar, but you CAN see it before and after flights and it will warn you of potential problems, or a battery discharge situation in either case. You can then take the necessary action to correct it. Remember my post a bit back.. my Venus II that I did not have the voltwatch setup on at the time... flew it a few times, checked the batteries individual and found one that was dead.... flying on what that second 1200 mah was providing.. well, I now have voltwatch installed on that plane and I can see trends immediately as they develop.. not in the air, but before and after each flight. If all is in the far left green, then all is well with the world because it checks under load.

If you stick with single battery, then at least spend that little additional amount to put something on there to monitor battery condition to warn you of any potential probems before they develop.

Good luck, and no matter what you do, it will be the right choice, so don't worry about it. What I have been saying is strictly advice and how I would handle it. You decide. Take all the plusses and minuses you have read here on RCU and judge for yourself and you can't go wrong.

DS.