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reciever/battery quest. voltage???

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reciever/battery quest. voltage???

Old 04-06-2006, 07:21 PM
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ir8prim8
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Default reciever/battery quest. voltage???

ok so im almost done building my bud nossen cessna 310. and as I mount the various electronics i have been pondering some differnet battery questions. basically i want to have a proper amount of juice avalible (and be confident in getting more then 2 tanks of gas out of a battery before changing it). I was wondering if instead of using normal 5cell nicads to run my servos. Can i use a speed controller from an electric plane and use a 3-cell li-po. My thought is that using the speed controller would act as a voltage regulator so that my servos dont get sent too high a voltage. but at the same time the 3-cell li-po with only servos drawing jucie at 6v would give me lots of run time. has anyone done this before? is there any fear of overloading the servos. or can someone suggest what works well in there giant scale birds???

Old 04-06-2006, 09:02 PM
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AllTheGoodNamesAreTaken
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Default RE: reciever/battery quest. voltage???

I can't answer the Li-po /ESC question, but for my planes I've switched to Ni/Mh batter packs. You can charge them with your standard trickle charger that came with your radio (special fast chargers are needed). They hold 2-4X the capacity for the same size Ni/Cad. The cost is the same (and in some cases lower!) than Ni/Cads and you can toss them in the trash when they're spent.
My 1/4 Scale CAP-232 with 4 high torque and 1 standard servo has a 2000 mAh Ni/Mh and I get 5 10-15 min flights before a re-charge.
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Old 04-07-2006, 11:04 AM
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Rodney
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Default RE: reciever/battery quest. voltage???

I doubt that you would be able to get by using an ESC to power your servos. Most of the ESC have a limited amount of current they can supply to the servos (usually limited to 3 standard size servos). As to receiver battery, you will get twice the lifetime from NiCads at a slight (about 20%) increase in weight over NiMh. NiCads are also better at delivering high current peaks (most servos, especially digitals, require very high momentary current bursts with abrupt control inputs. NiCads are also much more tolerant of abuse such as overcharge. From a reliability standpoint, NiCads win at slight increase in weight per MAH required.
Old 04-07-2006, 12:30 PM
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Default RE: reciever/battery quest. voltage???

You can use a 2 cell lipo plugged right into your receiver. Still gives you a lot of capacity for not much weight.
Old 04-07-2006, 12:41 PM
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Default RE: reciever/battery quest. voltage???

Hi!
Sorry but a 2-cell Lipo won't work in our radios...7,4V or slightly more will destroy our receivers.

Regards!
Jan K
Old 04-07-2006, 01:43 PM
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Default RE: reciever/battery quest. voltage???

Jan,

Not sure what receivers you guys are running over there....... US receivers (and servos) fron JR, Futaba and Hitec will handle 7.4 V, no problem. One of the guys at our field is a JR rep and he runs 2 cell lipos on a bunch of his planes.

Rich
Old 04-07-2006, 02:27 PM
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ir8prim8
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Default RE: reciever/battery quest. voltage???

ok, i understand the esc not being able to deliver the proper amount of juice. lol sucks that all my lipos are 3cells. does anyone know of a voltage regulator that could be used instead of a normal esc?? i dont have any electric planes that i would want a 2cell in and id rather not pour money into li-po's for the sole purpose of powering servos.

Most of my battery packs are NI-MH usually around the 2000 mark. I wont be doing any major stick movments with this plane (at least i pray i wont have too). its sole purpose is to drop r/c skydivers which basically means pattern flying up to drop altitude. however at the time of the drop i will need enough juice to run anywhere from 4-8 servos at once. (each jumper has a dedicated servo for the release mech) and also all high torque flight controls. granted at the time of release i cant imagine i will be doing anything but level flight and using the 2 throttle servos to idle down. Im just trying to dot all the I's and cross all the T's.

FYI im using all futaba gear except for the high torque control surfaces (elev x 2, alieron x 2 rudder/nose wheel x2)which are traxx.
Old 04-07-2006, 03:53 PM
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Default RE: reciever/battery quest. voltage???

Hi!
Yeah! but I'm sure he runs a voltage regulator too...never heard of any radio receivers that could take 7,2-7,4V (I have seen some K&O servos made for 7,2V though).

Regards!
Jan K
Sweden
Old 04-08-2006, 01:33 PM
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Default RE: reciever/battery quest. voltage???

I believe most of the FMA receivers will take up to 15 volts without damage. If I remember correctly, that was in one of the adds for the M5 miniature receiver. Many years back, anything over 6 volts could damage most of them as they used 6 volt tantalum capacitors.
Old 04-09-2006, 02:46 PM
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Default RE: reciever/battery quest. voltage???

Hi!
I contacted one of the Swedish repair shops for JR radios and the owner said that all JR receivers are constructed to run just on 4,8V, they could however be run on max 6 volts but not more.
He also said that many JR receivers that they had serviced had been run on too high voltage.

Regards!
Jan K
Sweden
Old 04-09-2006, 04:26 PM
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Default RE: reciever/battery quest. voltage???


ORIGINAL: ir8prim8
ok so im almost done building my bud nossen cessna 310. and as I mount the various electronics i have been pondering some differnet battery questions. basically i want to have a proper amount of juice avalible (and be confident in getting more then 2 tanks of gas out of a battery before changing it).
This statement has me wondering what you are talking about... Just how long does a tank of fuel last you?
Next question; How many flights do you do in a day?

Point in fact I like to consider myself an active flier, I go out on weekends about 08:00 and fly until noon, this gives me 4-5 flights each lasting 10 -15 minutes. Average total flight time for the day is 50 minutes with plenty of ground setup time...

I have a Digipace battery cycler that counts the number of minutes of charge in my batteries - 93 - 110 minutes is average.

Just how much time do you think that you need?

The average Nicad battery will do the average guy all day, if you need extra power for your paradrop -OK - but I still don't think that you will exceed the normal battery pack ... perhaps I'm wrong... have you ever cycled your batteries to see how long they can last?

Have you ever checked to see how much power the extra servos take?

OR;

Are you just changing the battery packs on Speculation?? []
Old 04-09-2006, 07:38 PM
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ir8prim8
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Default RE: reciever/battery quest. voltage???

my statments and observations are based on the need to run many servos. i too can get your aproxx 50 flight time. however this is based of a 40 sized plane with 4 or 5 standard servos. for each drop run a make i will be using 12 servo 6 of which will be high torque. if i were to use all at once the amperage draw would stress the battery. i dont plan to use them all at once but having just enough battery power is not a secnerio i want to test. im trying to find the best choice. at this point i plan to run 2 or 3 5-cell NIMH 2000 mah in parrallel. Since i have alot of li-po 3-cell batterys i wanted to know if there was any way i could parlay them into my needs.

having more ampers to be able to provide jucie for all servos plus looking for a redundant avalibility is my goal. just recently a pro at our local field lost one of his big birds due to battery issues. if it can happen to him it can happen to anyone.
Old 04-10-2006, 01:56 AM
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jeffk464
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Default RE: reciever/battery quest. voltage???

Hey, why your at it toss the old 12v battery out of your car and put in a nice 24v.
Old 04-10-2006, 05:49 AM
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ir8prim8
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Default RE: reciever/battery quest. voltage???

lol well as a matter of fact... i have 2 deep cycle batterys in my car. ill be installing the colapseable wings next week

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