I'm thinking of putting a 1650mh Nimh battery in my futaba 9c, I was wondering how much more flying time would i get with it?( as aposed to the 28 min max i get with the 700mh nicd thats in it now)An will the colored gimbles by airtronics work on my futaba. Your input would be great. Thanks..............

I put a 1450 mAh NiMH in mine, and I can fly all day, and most of the next--heck, call it all weekend on one charge. At full charge, mine reads 11.2V, which fairly quickly will drop to about 10.6V, but after that falls off slowly but gradually. I usually recharge at 9.6-9.7 V. This equates to about 1-1/2 hours total use, I guess, spread out over the entire day or days. I don't think it would last that long if used continuously.

Thats alot better than what i'm getting. One more thing my low voltage alarm don't go off till 8.4 volts, why is that?It was not that way on a past 7caps.....

Bax will be able to confirm this, but I've been told at two hobby shops that if you change out the battery in a Futaba radio to a non-Futaba battery that the warranty is voided. Same on the receiver. Just some food for thought, and possibly something to look into.

Hogflyer

I replaced my battery also. The biggest problem was charging the new hi cap battery. The stock charger, charges at 70 ma to the transmitter and 100 ma to the receiver. That roughly translates to a 700 and 1000 mah battery, You need a charger capable of 200ma to get a battery to full charge in a reasonable time. My first replacement was a 2000 mah Ni-HD battery. I blew out a cell trying to charge it on the accucycle. I cycled it and then after the charger went to standby, I pulled the battery and turned off the charger to reset it. Pluged things back together and hit it again. I'm guessing the charger doesn't detect full charge, and just charges for something like 15 hours. Anyway, it fried my new battery. I ended up with a good four cell for a receiver out of it though.

Don

Hog, i'm going to check into that battery dill, Thanks. Camp i have a triton, it would take three days of chargin to get it up with at 70ma charger. Back to hog..... How can futaba expect anyone to want to fly there radios with the factory batteries... About 28 mins is all i can get... Thats just enough to make you mad. takes longer to get up an tear down, than the time you get to fly..If that is infact true i may have to move over to a 9303

I have upgraded my batttery in my 9C to a 2000 Mah NMH . I can fly all week end plus a couple of night after work. Pretty much charge once a week and not worry about it. I'm not sure about the warranty thing but it would not surprise me, I've hears of similar things with other electronic items. My radio was already out of warranty so that part was not a concern for me. Do it and rnjoy the flying time!
Peter

http://www.hangtimes.com

Get a NO BS Batteries transmitter pack. I have a 1650 pack and I can fly several helis and a airplanes all weekend not get to the transmitter battery alarm.

Hog, thats hogwash, there's all kinds of people using other than Futaba batteries on recievers, as long as you dont blow it up with a battery thats over the rated voltage I doubt they would deny a warranty claim and if you are worried about the transmitter warranty just stick the 700mah factory pack back in before you mail it off, but I doubt they would even care about that, you dont have to undo any screws to change the battery and as long as the battery didnt directly cause the problem I doubt they would care.

Not only that, but how could they prove that you were using a different battery? I've got a 2100 ma pack for my 9CAP, and it lasts and lasts and lasts.

With a 1650maH NiMH pack in a 9C you will get 5.5 hours from fully charged to 8.4volt warning.

I get about four hours with the original factory battery.

Why does the voltage warning come on at 8.4? Your takeing a chance after 9.6.

No you are not correct.
Most NiCads are good and stable at load down to 1.1 to 1.0 volts per cell.
This is 8.8 to 8.0 volts so there is no problem.
The pack is basically depleted at 0.9 volts per cell which is 7.2 volts.
With NiMH, the voltages are the same but the pack will get there a lot faster.

The standard 9Cap has a current drain of about 300ma.
For you to get 4 hours, you must be using a 1200maH pack or something close to it.
Unless something has changed, the standard pack for the 9C is 600maH.
Not sure how you are getting 4 hours from a standard pack.
Not questioning your statement, but could you help me understand?

I went ahead an ordered a 1450 Nimh. Not the 1650. So you are saying the new battery will get to 8.4 volts before the factory 700mh Nicd will. I'm way lost, make me understand

I use the the stock 700mh in my 9C. I can fly 7-8 /10min flights with no problems. If 28 minutes is all your getting maybe the pack is bad. Have you tried to cycle it? I pull mine in the spring and cycle it. It will not cycle through the TX it must be pulled. I am going on 3 years and have only had to field charge the TX twice.Both times were at a Fly In with above normal # of flights.

David

No, What I am saying is that the alarm on my 9C goes off at 8.4 volts.
The typical discharge rate is 300ma.
Divide the capacity of the pack by 300ma and you will find the time the pack should give you.

You can cycle the 9c batteries in the transmitter.

The newer ones you can.
The original ones you could not.
They didn't have the poly-switch installed.

I have a Futaba 9C. I often fly for a full day and can have the radio on for 4+ hours. When I fly slope soaring flights can easily extend over an hour. I have a 2500 MAh pack in mine. I charge it with my Triton peak charger but I also charge it with the stock wall charger. I just leave it on for 20-30 hours on the wall charger. Works fine.

So still flying after you hit 9.6 is okay? Cause thats what takes 28 mins, going from 11.2 to 9.6 then i stop. I have always heard below 9.6 is a major no no

People who try to equate there RX pack to the TX pack will say this.
The TX pack's load stays pretty constant so this can be better understood.
The RX pack voltage will go from a relatively light load 100ma to a heavy load 10,000+ ma peak.
At the load of C/2 for a 600maH pack you can go down to 1.1 volt per cell with NO problems or fears.
Lets not believe me, lets believe SANYO.
http://sanyo.wslogic.com/pdf/pdfs/KR-600AAL.pdf
Look at the C discharge rate. TO drop from 1.2 volt per cell to 1.1 volt per cell. 20 minutes.
This is at twice the discharge rate of the 9C the pack will take 20 minutes to go from 9.6 volts to 8.8 volts
So do you believe the MFG or your flying buddies!
Choice is yours.

Do I fly at 9.6V sure? You can fly a long time from 9.6V to the low battery warning at 8.4v. Typically I don't take it down to 8.4 but I would have no hesitation to take it to 9V and have had the warning come on at 8.4 on occasion. Never had a problem, but at the warning I land immediately. I only need a minute or two to land.

Remember the nominal voltage of that pack, fully charged is 9.6V so you still have lots of capacity left at 9.6. At 8.8 V you are still at 1.1V per cell and probably still have 20% of the useale pack to go. On a 700 MAh pack that is 140 MAh, That is probably good for another 10 minutes till you hit the 8.4V warning which itself probably gives you another 10 minutes before the radio dies, though I have never had the radio shut down.

Your 9C, with standard frequency module uses about 250 MAh per hour so the standard pack should give you a good 2 hours of actual radio time. Try it at home some time. Be mindful of where you live vs the flying field as you don't want this test shooting someone down.

Fully charge it. Now put the antenna up about 20% so the transmitter secton does not oveheat but so that you are not transmitting at full range. Let it run. See how long it runs before you hit the 8.4V warning. I bet you get 2 hours or more.

If you are going to stop flying at 9.6V you better carry multiple packs. I have the 2500 that lives in the radio. I have only drained it once and I think that is because I did not fully charge it. If I am going to go out a second day I charge it overnight on the wall charger to replace what I have used.

I carry the 700 that came with it in my bag as a spare, also charged. Sunday I loaned that spare pack to a friend. After beign at the field for 6 horus and having the transmitter on for probably 4 of that 6 I was still at 10V. I used the standard wall charger to charge the 2500 MAh radio pack. When I took it off the charger is was at 11.2V.

Definately get a second pack if you like to fly all day. Unless you are slope soaring all day, a 1200 or higher primary pack with the stock 700 MAh pack would be fine for almost anyone. 1600 packs are very reasonable, and QUALITY 2500s are easy to find but you pay a premium for them.

This issue comes up here in the beginner's forum quite a bit, and there's a lot of confusion about it every time it comes up. Normally the discussion is about the receiver battery, but it's the same with the transmitter battery too because all batteries have a similar discharge curve. First of all, if you watch the voltage of the battery only and quit when the voltage hits 9.6 v (4.8v for receiver batteries) then you are losing what could be as much as 50% of the batteries capability. Batteries do not have a linear discharge rate, meaning they do not drain constantly. Instead (see attached diagram) they will quickly discharge down to ~9.6v (again, 4.8 for receivers) and then stay at that level for long time, and then after that they will quickly drop off towards being unusable. How long your battery will stay at that 9.6v level is hard to say, this is why batteries need to be cycled. Cycling the battery will let you know how long that battery will last in a usable state. If you don't have a battery cycler you can just turn on your radio with a fully charged battery and observe how long it takes to drop down to 8.8v (1.1v/cell times 8 cells), since radios have a constant power draw you can get a very accurate idea of how long your radio will last. Two very very important notes here, if you do this make sure that you have your antenna fully extended when you do this or you will burn out the RF transmitter portion of the radio, and secondly make sure you are not withing a 3 mile distance from any flying field.

If interested everybody should visit the [link=http://www.rcbatteryclinic.com]RC Battery Clinic[/link] . Anything and everything you ever wanted to know about the batteries we use are covered here. It's definitely a must read for anybody in this hobby.

Hope this helps

Ken

It sounds like you guys have it figured out about the voltage an stuff, why does my volt meter say to recharge at 9.5? I'm kinda weiry about flying below 9.6, but whats been said makes sense. But i'm not sure i want to take a chance like that with a 2500 dollar toy or not. But it sounds like i have been just useing half of it power. Its like filling your truck up an only useing a half a tank an going back to feel up agin, never useing the lower half. In not going below 9.6 volts i hope i have not developed a memory yet in my ni-cd, cause i still want to use it as a back up battery. The input has been great guys thanks..............