Battery help needed
 

I just purchased my first gas airplane, a H9 330 33%. I have been told several different versions of what setup I need for the battery systems. I'm using two match boxes and 9 servos. Do I need Metal Hyd, ni-cad or what. Three switches is a given. Suggestions and inputs---PLEASE
Thanks in advance.

RE: Battery help needed
 

As a minimum:

Two 2200Mah batteries reciever, and one 1200 Mah ignition. Each through a separate switch, as you stated.

NiCads are fine, but a little heavy - 4 cells direct or 5 cells with a regulator. Nimhyd are a little lighter, and Lithiums will be very light.

The sky is the limit from there, but these are the minimum recommendations.

CJ

RE: Battery help needed
 

Agreed with you up to this point. WIth 5-cell packs, either NiMH or Nicad it is NOT necessary to use a regulator. You can plug these packs directly into the RX.

Lithium packs will require the use of a regulator to bring the RX input voltage down to 6 volts or less.

I run 2 5-cell 2700 mAh NiMH packs on my 33% Edge throught 2 switches plugged directly into the RX. I also use a 2700 pack on ignition, also 5 cells (DA ignition). No regulators anywhere.

Bill

RE: Battery help needed
 

I run Futaba. Trust me, you need a regulator........I've tried 5 cells without and the results were not cheap.

CJ

RE: Battery help needed
 

Wow, I have put over 400 flights on futaba servos with 5 cell packs and never had a problem. Never used a regulator. I use hitec servos on 5 cells and never had a problem with them either. What I will say is that for your application, I would recommend Sub "C" cells and my preference is NiCads.

RE: Battery help needed
 

I have no idea what you are talking about. I fly NOTHING but Futaba. I have run NOTHING but 5-cell NiMH and Nicad packs WITHOUT regulators for years. This is in gliders, giant scale aerobatic planes and helicopters.

This is with servos by Futaba, JR, Multiplex, FMA, Hitec, Volz, and Cirrus. Receivers include 148DF, 148DP, 149DP, 309DPS, Hitec 555 and FMA micro on both 72 MHZ and 6-meters.

A regulator is absolutely NOT needed in any set up that I am aware of.

Unless you were usinf servos specifically designated as NOT being able to handle 6-volts, you do NOT need a regulator.

Bill

RE: Battery help needed
 

Sub-C anchors are NOT needed for normal reciver/servo use. I have used 1100 and 2700 NiMH (5-cell packs) in large scale aerobats with up to 12 digital servos without a single probelm.

RE: Battery help needed
 

I never said they were needed.
I said I would recommend them.

RE: Battery help needed
 

OK, here goes. Most of the Futaba gear is designed for 4.8 volts. SOME of their equipment is designed for 6 volts. A fully charged 5 cell pack puts out a little more than 7.2 volts.......that's 50% more than the design voltage. The servos I was using were 9151s. They fried consistently on the 7.2 volts.....and they were $109 a pop. These were the top of the line Futaba digitals 4 years ago.

Now, every electronic device is rated for a nominal , or average, design voltage. When you exceed this, some components will take it, and some identical ones will not. That is exactly what I saw in my planes. I had some 9151's that lasted a thousand flights.......while others fried in one.......yes, I said ONE flight.

I talked to Hobby Services for hours about this very topic......you know.......the guys in charge of warranty work on Futaba. 217-398-8970. In very simple terms, they said not to run even 6volts on these servos. In fact, they have a list of components they do not recommend putting on 6 volts.

I know for a fact that all JR servos will take unregulated 5 cells, but they will twitch and glitch for a flight or two until the voltage reduces below 7 volts. I spend a lot of money for very precise digitals, and the idea of twitching and glitching just doesn't quite do it for me - I think the servo is trying to tell me something. A regulator is 20$. The servos on my last plane were 105$ apiece for 18. For me it's a no brainer. My last plane has a set of JR8411's with 1000 flights, and not one of the 18 servos have ever been back to the shop, not even for gears. You take care of your equipment and it will take care of you.

Also, a regulator actually adds another flight per charge by reducing the power consumption.

Bullard asked for a simple answer. It kills me when guys are proud of the abuse they put on their equipment and give the same advice to the new guys. I can tighten my prop nut with vice grips, but it is nothing I would be proud of, and I sure wouldn't recommend it to anyone!

Bring it on......

CJ

RE: Battery help needed
 

OK. You win. I was wrong. 5-cell unregulated packs are big trouble.

RE: Battery help needed
 

OK. Here goes. Futaba currently lists 31 servos in the active product line.

http://www.futaba-rc.com/servos/futm0029.html

Of those 31, exactly 5 are shown as not rated for 6 volt packs (3104, 3107, 3108, 9205, 9206).

So don't use an unregulated 5-cell pack with these specific Futaba servos.

The jittering JR servo situation is old news. Early on some would do it for the first few seconds that they saw a fresh 5-cell pack. Never for the first 2 flights. It did not do anything to the servos, but it was annoying. They do not do it any longer. In fact, according to my i4c C-Volt my 9 JR 8611 servos and single Multiplex (throttle) see a continuous 6.2 volts after my regulators (lithium packs). No jitter at all.

And finally, regulators DO NOT give you more flights. This is nonsense, sorry. All of the current regulators are nothing more than power resistors that burn off the "excess" voltage that you are keeping from driving your servos. That is why they get warm. Your servos are seeing a lower voltage than if the regulator was not there, but your packs see the increased resistance caused by the regulator.

The only reason for a regulator is if you think that you are good enough to feel the difference between a full charge and a lower charge. I can't, but maybe others can.

The original question was how to set up his new 33% plane. Based on the above facts, the simplest and most effective set up is simply two 5-cell NiMH (or NiCad) packs with 2 switches plugged directly into the RX.

Everything else is simply unnecessary. But do what you feel is necessary, jut don't try to convince others that it is required.

RE: Battery help needed
 

Hi Bullard, hope you make your choice. I have a question about Nihm. I have a cermark 2700 mahr nihm that I will use on my new 2.3 extra. I have always thought that nihm is charged at 1 C. I have read on the expert battery literature that their 2700 nihm should be charged at 2A max. Is this the rule or are they suggesting that to be on the safe side. I have the FMA super nova and can create a charge profile of whatever it take for the battery. I apologize for the off topic.

Joe

RE: Battery help needed
 

For anyone interested, regulators do give more flying time. Here's how it works:

A regulator is just a resistor, as Bill points out. But, it is a highly efficient variable resistor. The MPI regulator has the equivalent circuit of 8 transistors, 2 Op-Amps, and over 20 resistors. It rapidly adjusts the circuit resistance, and also has overload protection.

When you place a resistor in your battery circuit, it restricts current flow. This applies to any resistance, not just a regulator. Less current flow means less power usage, and that means longer battery life. The amount of increased life depends on how much you are dropping the voltage. For example, if you have a 4 cell nicad pack that charges to 5.76 volts, and you are dropping the voltage to 4.8, you won't see much of a flight time increase (in the order of 5-10%). If you are using 3 cell Lithiums at 12.25 volts and drop it to the same 4.8 volts, then you will see a considerable increase in flight time (like 100%). Both examples assume you are using the same milliamphour ratings. For those of you thinking that the servos can't use 12.25 volts......I am currently using a Seiko that can take 12 volts right off the battery. There is a lot of equipment out there we are just starting to tap into.

Let's keep open minds and keep learning from each other!

CJ

PS - Joe, the electric guys could probably answer your question best. They are really up on how fast a particular battery can be fast charged. Usually the manufacturers are conservative in their instructions.