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6v or 4.8v reciever battery?

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Old 09-01-2010, 08:29 PM
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LargeScale88
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Default 6v or 4.8v reciever battery?



Hello. I am wondering what would be a better choice for a reciever battery voltage, 4.8 or 6. I'm still running FMon this airplane. Its a top flite P-51 with 10 servos, higher torque on some. I'm wondering, 6v, longer run time? More power out of servos? 4.8, less power? Less running time?

I'vebeen running 4.8v for 5 or so years now, always held up good, but for smaller airplanes, only 4 servos.

Thanks

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Old 09-01-2010, 08:45 PM
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Default RE: 6v or 4.8v reciever battery?

5-cell NiMh (6 volts) for everything from now on. Until you get to large planes (30% and up) then use A123 (2-cell pack) at 6.6 Volts. No regulators.
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Old 09-01-2010, 09:25 PM
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Default RE: 6v or 4.8v reciever battery?

Ok thanks for the help!

Jason
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Old 09-01-2010, 11:25 PM
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Default RE: 6v or 4.8v reciever battery?

6V pulls more amps than 4.8V in the same plane

So you need to up your Mah capacity when you go to 6V?
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Old 09-02-2010, 01:44 AM
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Default RE: 6v or 4.8v reciever battery?

the voltage is not the issue in your plane Laregescale, you need to focus on capacity.
the amount of servo's you are using and if some are high torque means that you will draw large amounts of current in bursts.

So you need capacity to prevent voltage drop to the point where you could suffer a sort brown out.

Higher voltage draws more current and high torque servo's will just draw evenmore current.

a large capacity 4.8V NimH or NiCAD will suffice, hower I wouldrecommend a large capacity LiFePO4 or A123 LiFePO4 battery pack at 6.6V unregulated and 2100mAhr capacity minimum.

Also what is your flying style? Do you balance your plane for a easy relaxing flying attitude i.e. cg further forward in the range, or do you prefer a more edgy scale like flight that requires more work on the sticks? The higher the workrate, the higher the current and capacity draw.
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Old 09-02-2010, 07:33 AM
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Default RE: 6v or 4.8v reciever battery?

Is this the Giant P-51 or the 90 size?
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Old 09-02-2010, 08:54 AM
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Default RE: 6v or 4.8v reciever battery?

5 cells (6 V) is the way to go with NimH. The reason: Safety! The most common failure mode in NimH batteries is internal short circuit. If this happens a 6 V pack will drop to 4.8 V, which is a safe voltage for almost any system. If the same thing happens to a 4.8 V pack the voltage will drop to 3.6 V, which is marginal. As for current draw, yes it will be higher. On the other hand the servos will move faster, spending less time to move from one position to another, which to some extent compensates for the higher current draw. Capacity is not a problem nowadays as batteries can be had in almost any capacity.
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Old 09-02-2010, 09:06 AM
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Default RE: 6v or 4.8v reciever battery?

Actual current draw is increased by about 5% so it's really not dramatic.

I'd definatly run 5 cell, of sufficent capacity, probably in the 2500 mah range.
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Old 09-02-2010, 09:15 AM
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Default RE: 6v or 4.8v reciever battery?

With that many servos, be more concerned with capacity and internal resistance than number of cells. Higher capacity batteries usually have a lower internal impedance (good). Even better is two (either 4 or 5 cell) packs in parallel with suitable switch and charge jack on each pack as that will give you the most reliability and lowest internal impedance.
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Old 09-02-2010, 12:06 PM
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Default RE: 6v or 4.8v reciever battery?

LargeScale88,

Something else to think about would be do you plan on going to 2.4 in the future? If so, 6 volts is the way to go since there are issues with brown outs and low voltage running 2.4. I have been on 2.4 for over a year and run 6 volts on all my onboard equipment.
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Old 09-02-2010, 07:21 PM
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Default RE: 6v or 4.8v reciever battery?


ORIGINAL: Zippi

LargeScale88,

Something else to think about would be do you plan on going to 2.4 in the future? If so, 6 volts is the way to go since there are issues with brown outs and low voltage running 2.4. I have been on 2.4 for over a year and run 6 volts on all my onboard equipment.
Horizon stated this too a couple of years ago when all the brown outs were happening on a regular basis. When buying a new pack these days I head right to the 6volt counter. In my large scale planes I have been running 6volt sub-Cs with 4800 mah. At the time I had no charger for the newer packs but I will now be looking at other types of batteries, I was given a very nice charger!!!
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Old 09-02-2010, 09:03 PM
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Default RE: 6v or 4.8v reciever battery?

I'm not sure about the 2.4, I have so many hardly used FMradios that are in great shape. I've got an JR 8103 with little use, so probably no in the near future for 2.4.

Its the Giant P-51. I'm running higher-torque servos for flaps, ailerons, elevator, and rudder. The gear, throttle, choke, tailgear steering are all standard.

I'm looking at lots of flying time on one charge. At least 3 (maybe 4) everytime I go to the field with it fully charged.

Jason
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Old 09-02-2010, 09:07 PM
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Default RE: 6v or 4.8v reciever battery?

So I was looking at the JR 6v 2700 mAH Ni-Mh 5 cell pack. Its my first 6v ever, so do I have to buy a different charger? I've used all the standard chargers I've gotten with my radios over 6-7 years ago, they work great for my 4.8v, but not sure on the 6v.

Someone brought up about running batteries in parrallel? Advantage? Still running 6v? How is this done?

Thanks
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Old 09-02-2010, 09:32 PM
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Default RE: 6v or 4.8v reciever battery?


ORIGINAL: LargeScale88

So I was looking at the JR 6v 2700 mAH Ni-Mh 5 cell pack. Its my first 6v ever, so do I have to buy a different charger? I've used all the standard chargers I've gotten with my radios over 6-7 years ago, they work great for my 4.8v, but not sure on the 6v.

Someone brought up about running batteries in parrallel? Advantage? Still running 6v? How is this done?

Thanks
Your old wall wart will work on a new 6V pack but it will take longer

Batteries in parallel
I use two switches and plug them into two different places on the receiver where I don't have servos plugged in.

I charge the batteries separately

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Old 09-02-2010, 11:06 PM
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Default RE: 6v or 4.8v reciever battery?

The advantage is redundancy, if one battery or switch goes out for some reason you still have one working. Only way to know you have a problem is with a volt meter if you check voltage after every flight. I have one big Sub-C battery pack that has two wires for separate switches, if a switch goes out it still works, if the battery poops out who cares how many good switches I have. Everyone figures it differently when to go to two batteries. After 60 size I often do it, not always but often.
There is another thread talking about 2.4 VS 72, think it's titled {why haven't the 72s gone down in price} it's worth a read. I'm just now starting to change over slowly as money starts filling my pockets, very slowly. There isn't anything wrong at all with 72 other then watching out for other 72 people. One thing you may want to invest in is a good AC/DC charger and a good loaded volt meter. A good charger/cycler is something everyone should invest in and a meter is used several times a day when at the field. When I'm at the field I may be flying one plane a lot and as soon as the battery is down I plug it into my field charger and fly something else until it's charged back up. During a BS break I plug in my TX, we all check our planes but I tend to forget my TX.
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Old 09-03-2010, 06:36 AM
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Default RE: 6v or 4.8v reciever battery?

ORIGINAL: LargeScale88

I'm not sure about the 2.4, I have so many hardly used FM radios that are in great shape. I've got an JR 8103 with little use, so probably no in the near future for 2.4.

Its the Giant P-51. I'm running higher-torque servos for flaps, ailerons, elevator, and rudder. The gear, throttle, choke, tailgear steering are all standard.

I'm looking at lots of flying time on one charge. At least 3 (maybe 4) everytime I go to the field with it fully charged.

Jason
If you are looking for allot of flying time, like 4-6 flights an outing, light weight, a ton of punch power to the servos, then why not go with lipos, 3000-4000 MA 7.8V regulated. I have been doing this for years now with all my giant scale stuff and never had a single problem. I do however charge my batts in a glass bowl with a lid for safety.

Bob
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Old 09-03-2010, 09:10 PM
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Default RE: 6v or 4.8v reciever battery?

I will consider the lipos, but don't I have to get a regulator to bring the voltage down? Moneys a little bit tight.

Gray Beard: You were talking about plugging your batteries into a quick field charger, and they charge up fast enough to go fly again. What kind of charger are you using? One that plugs into your car battery? Or your field box battery? I would like to purchase a charger where if the battery gets low, I can throw it on the charger at the field, and have it charge up enough to do some more flying.Thanks

So on a 6v, what voltage means the battery is getting low? What voltage means the battery fully charged and ready to go?

I think on my 4.8v batteries, I usually read about 5.5v after they charge.

Thanks.
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Old 09-03-2010, 09:37 PM
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Default RE: 6v or 4.8v reciever battery?

I use this one

http://www3.towerhobbies.com/cgi-bin...&I=LXCTZ5&P=ML

I had an earlier model for many years. I've used the quick field chargers for some 15 years
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Old 09-03-2010, 10:23 PM
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Default RE: 6v or 4.8v reciever battery?


ORIGINAL: w8ye

I use this one

http://www3.towerhobbies.com/cgi-bin...&I=LXCTZ5&P=ML

I had an earlier model for many years. I've used the quick field chargers for some 15 years
Ditto on this charger.
even more so tho, Ditto on the 2 switch/2battery system.
in a 40 size model i'm using 2 6v 600 mah packs that together weigh a mere ounce more than 1 4.8v pack.
i check periodically by switching one switch on, then off and then the other to make sure they are working. one of our beloved and well respected members introduced me to this system and i never felt safer in regards to the power source than i do now.
like Gray said earlier, it adds a lot of insurance for very little effort.
i do disconnect one pack when charging both at the same time though.
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Old 09-03-2010, 11:40 PM
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Default RE: 6v or 4.8v reciever battery?

My 2 cents... love the hobbico field charger...  I bought packs from cheapbatterypacks.com.  I ordered 5cell (6v) hybrid NiMH 2100 mAh packs @ $15 ea.  Work great, low self discharge and high capacity.  I probably could fly every weekend for a month without charging them (although that would be silly).  I top em off at the start of the day and not worry about them.  I got a pack for my Airtronics rds8000 as well, stays at full voltage the entire day.  Supposedly the hybrid NiMHs don't like high loads and can have voltage drop outs (maybe a capacitor can overcome this?).  How much and at what current I don't know.  For my 40 size no worries, but for a large scale high current warbird you may want to get some actual figures on that. 

Have fun with your bird!
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Old 09-04-2010, 01:41 PM
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Default RE: 6v or 4.8v reciever battery?

I have completely abandoned four cell packs for serveral years now and use only five cells in everything big and small. Typically will replace with five cell Nimh packs that are two to three times the capacity of the four cell Nicd packs they are replacing.

The increase in servo speed is noticible in most cases despite what some say and it will tend to improve (smooth out) your flying.

John
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Old 09-04-2010, 05:02 PM
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Default RE: 6v or 4.8v reciever battery?

I have had too many problems with Hobbico and there service so I went to Horizon and have been happy with there products and service. Yes, a fast field charger is what we are using. They operate on most any 12 volt battery. My van has plug ins for computers in several places so I soldered on a plug to my charger that goes right into any of thes ports. You can use a field battery to charge with.
As to the two batteries, I don't bother on my smaller planes. In the last 15 years I have had one battery short out on me and I have had one switch that ended up with so much sand/dirt in it then it started to short out on me, not 100% but I was getting little control glitches. In any plane I have a lot of time or money in I may run two batteries and switches and I always run two on my giant scale planes if I really care about them. It's one of those choice things.
If you decide to get a field charger make sure you get one that charges the batteries you plan on using. Today there are chargers that charge them all. The field charger does not replace your at home charger, kinda sorta. NIMH doesn't like heat and a fast charger pushes in a lot of juice in a hurry. Not that I care too much but what I have found is I get a lot more life out of my batteries if I slow charge them at home then if needed I can fast charge them when out flying.
Today you have several choices on types of battery packs you buy. Just make sure your charger will handle the task and charge them.
I don't feel everyone requires a Tach either but everyone should have a good volt meter. When you are shopping around look at the volt meter/tach combo that Horizon sells. I have compared the tach to my own good TNC tach and so far I haven't found one that was off very much. For the price you get two meters rolled into one. Just something to look into while you are shopping around, there are cheaper ways to go but you should have a good volt meter.
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Old 09-05-2010, 07:50 AM
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Default RE: 6v or 4.8v reciever battery?

Ok thanks guys.

Whats your opinion on smart fly? I'm looking at the Power Expander sport. I'm a little confused on everything about them. Someone at my club basically says I can hook 2 6v batteries into the smart fly, and if one battery fails, I have the other battery. I don't see what else a smart fly is good for. It may just be another piece of electronics that could fail, instead of the battery failing.

Thanks
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Old 09-05-2010, 12:06 PM
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Default RE: 6v or 4.8v reciever battery?

I haven't seen anyone using one and I haven't ever tried one myself. The higher end JR 9ch RXs are already designed for two batteries. Most the people I fly with are already on 2.4 and most of them are also flying very nice giant scale planes so they take no chances. They are also using the A123 batteries. Just do a search and read up on the products that are out there for yourself and give them some thought. Two batteries and two switches have been used for years and today there are new products that do the same thing in a bit different way. I use JR heavy duty switches with the charge jack, they cost under $15.00, I think I have been paying $12.00 for mine. I usually have several on hand. One of my friends just bought the new HD switch, I think it is MPI and it has the little LED lights built in to show you the charge of the battery, sort of like a volt watch. There's a lot of ways to do the same thing, it's up to you to look around and decide how you want to go. In my case it's more about how much money is in my pockets and what plane I'm working on. I'm just putting on the finishing touches on a new plane right now. It's taken me months to build it. It's a very nice 60 size pattern plane, one switch, one battery. Due to the CG problem, it's nose heavy, I may decide to go to the two batteries and switches?? I will decide after the maiden then do some CG testing and see how much closer the double system will help. I like to add useable weight instead of just lead.
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Old 09-05-2010, 02:23 PM
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Default RE: 6v or 4.8v reciever battery?

So for the 2 batteries and 2 switches, how would I switch over to the other battery?

Thanks
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