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Suggestion for new battery

Old 03-19-2010, 04:38 PM
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mooseflier
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Default Suggestion for new battery

I have a brand new DX7 radio that came with a 4-cell, 4.8 volt battery for the receiver. Can't remember the amps on it. Long story short, I need to buy a new battery pack. I have two planes... a 40 size sportster using 6 servos and a 120 size biplane that will use 7. I will need to use the current pack for the smoke pump in the biplane, and will need to get another battery pack for the receiver anyhow. Plus, I'm nervous about having so many servos even in the size 40 while using the receiver battery that came with it. I would also like a little extra torque, and from what a guy at the hobby store told me, more voltage will aid with torque.

I've read quite a bit over the last two days, but the more I read about batteries, the more confused I get. There's so many variables to consider... voltage, amps, number of cells, type of battery, etc.

I guess what it comes down to is this... what's a fairly safe battery to use if you had to buy a new one for the receiver of a DX7 when running 7 or 8 servos? And do Ireally want to get a LiPo (the guy at the shop was advocating this for longer battery life... though I doubt I need that since the gas tank is the real limiter).

Thanks for any advice!
Old 03-19-2010, 05:31 PM
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mclina
 
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Default RE: Suggestion for new battery

I would not use a LiPo for a RX battery, simply because I wouldn't want to have to pull it from the plane every time I charged it. I would stick with a 6V NiCd or NiMh pack, at 1100-1500mAh. They can be had pretty reasonably, will give you good battery life, and are safe to charge in the plane.

If you want to be more adventurous, take a look at the A123 or LiFe packs. They are just as safe as NiCds, can be recharged quickly, and will hold onto their charge longer. Unless you like to do a ton of flights in a single day, it may not be worth it.

Good luck
Old 03-19-2010, 05:57 PM
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ChuckW
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Default RE: Suggestion for new battery

I wouldn't bother with a Lipo. You would need a voltage regulator, remove it for charging, etc.

In the past, Spektrum had receiver reset issues when the battery voltage dropped below a certain level. Because of this 5-cell, 6V packs are generally recommended. Even though the problem has supposedly been fixed in newer receivers, I would still play it save and use the 6V packs.

The capacity really depends on how long you like to fly in a day but I'd go at least 1400mAh.

Whether you choose NiCad or NimH is up to you. I generally do NimH these days.

When I had my Spektrum radio, I used a number of these with great success in everything from .40 size to 1.20 size glow/gas airplanes: http://www3.towerhobbies.com/cgi-bin...?&I=LXNHS4&P=0

I haven't tried any of the newer LiFe batteries yet. From what I understand they are safer to charge than Lipos, charge faster and don't require a regulator for receiver use. The downside as I understand is that you can't easily check battery condition throughout the day and youo need a compatible charger. http://www3.towerhobbies.com/cgi-bin...&I=LXYAS9&P=ML

Old 03-19-2010, 11:44 PM
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mooseflier
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Default RE: Suggestion for new battery

Thanks for the replies!

I'm looking at this one: http://www.onlybatterypacks.com/show...ItemID=10315.2

Will that work with a Spektrum? Doesn't have to be Spektrum does it? I can see maybe having to change the coupler, but that's no biggie.

Not bad for $23 bucks.
Old 03-20-2010, 12:30 AM
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jimmyjames213
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Default RE: Suggestion for new battery

http://www.all-battery.com/rcairplanebatteries.aspx
pick your battery, i would personally run life (a123) ,if you could, on the bipe due to the amount of servo's
and a 6v in the other
http://www.all-battery.com/6v2000mah...ctor11106.aspx
or make a pack of life out of these
http://www.all-battery.com/lifepo4battery.aspx

ive had great secuess with both
Old 03-20-2010, 06:10 AM
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Default RE: Suggestion for new battery


ORIGINAL: mooseflier

Thanks for the replies!

I'm looking at this one: http://www.onlybatterypacks.com/show...ItemID=10315.2

Will that work with a Spektrum? Doesn't have to be Spektrum does it? I can see maybe having to change the coupler, but that's no biggie.

Not bad for $23 bucks.
That's actually kinda pricey. Check out the ones that jimmyjames linked from all-battery. $6.99 each vs. $23.99. I thought I got a good deal at $10.99 on sale from Hobby People for a 6V 1600mAh.

I am using a Turnigy Accucell 6 from Hobby City to charge my 6V NiMh packs. I have heard mixed opinions on how well you can charge them with your standard radio charger.

Good luck
Old 03-20-2010, 11:32 AM
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Default RE: Suggestion for new battery


ORIGINAL: ChuckW

I wouldn't bother with a Lipo. You would need a voltage regulator, remove it for charging, etc.

In the past, Spektrum had receiver reset issues when the battery voltage dropped below a certain level. Because of this 5-cell, 6V packs are generally recommended. Even though the problem has supposedly been fixed in newer receivers, I would still play it save and use the 6V packs.

The capacity really depends on how long you like to fly in a day but I'd go at least 1400mAh.

Whether you choose NiCad or NimH is up to you. I generally do NimH these days.

When I had my Spektrum radio, I used a number of these with great success in everything from .40 size to 1.20 size glow/gas airplanes: http://www3.towerhobbies.com/cgi-bin...?&I=LXNHS4&P=0

I haven't tried any of the newer LiFe batteries yet. From what I understand they are safer to charge than Lipos, charge faster and don't require a regulator for receiver use. The downside as I understand is that you can't easily check battery condition throughout the day and youo need a compatible charger. http://www3.towerhobbies.com/cgi-bin...&I=LXYAS9&P=ML

I have been using the 6v 2000 to 2500mah. I have even made up a couple of packs from Eneloops but there only great claim to fame is they don't discharge very much when not in use. The brown out problem was sort of cured, today instead of getting locked out for 4-6 seconds you only get locked out for one second. If your low to the ground and doing something cool that one second can be a life time!! The 6v seems to be the cure to the brown out problem. I run the LIPO in my electric and they really do last a long time but they are a pain in the mule. A regulator would be needed. I have never run the 123s but some of the guys I fly with swear by them. Being a lazy loaf I'm just happy with my plug and charge Nim and Nicad.
Old 03-20-2010, 09:17 PM
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Default RE: Suggestion for new battery

I use 2500 NimH 6 cell in all my planes. I like to keep eveything simple, don't have to worry about which battery is in what plane. They are all the same, and they will fly a plane for hours and hours if charged up.

If you have different batterys, you must know which one it is to charge it properly.

I have charged them up and a week later , they were still up enough fly for the day. I don't go ahead and fly, I charge them for the day.

Thats one thing you will learn about this sport, as you get more planes it gets complicated. I would get with one battery and stay with it. Ni cads are good also, no problem using them.

enjoy, good luck.

sticks
Old 04-26-2010, 08:20 AM
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Default RE: Suggestion for new battery

Using the standard charger that came with my futaba receiver.  Question is simple:  Will this charger that charges my 4.8 battery charger a six volt battery. I would like to convert my planes to 6 V. 

Thanks

divingdave
Old 05-30-2010, 10:08 AM
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dmowery
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Default RE: Suggestion for new battery

Just a correct info - those batts refered to are 7.59 each in lots of 5 each and 9.32 for ship total each at your door 9.46- still a good bargan
I just orderd some thats why I know
Don
Old 05-30-2010, 10:54 AM
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Default RE: Suggestion for new battery

Hi!
Yes! Your Futaba 50-100mAh (Or Hitec,JR ) wall charger will be just fine!
Here is a battery pack I would choose myself, 4,8V, 2000mAh NiMH battery. I use Spektum too.

http://www.all-battery.com/productim...0mAh-11001.jpg
Old 06-01-2010, 02:56 AM
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TimBle
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Default RE: Suggestion for new battery


ORIGINAL: Divingdave

Using the standard charger that came with my futaba receiver. Question is simple: Will this charger that charges my 4.8 battery charger a six volt battery. I would like to convert my planes to 6 V.

Thanks

divingdave
The charger supplied with your Tx is only good for conditioning the NiMH or NiCAD on first charge. thereafter it is useless until you have placed the batteries in storage and you need to "wake" them up again.
NiMH and NiCAD need to be "fast charged" so use a proper fast charger to charge them up in flying season. They like 1C charge rate, i.e. 2500mA.hr battery can be charged at 2.5A irrespective of the voltage.

Also the supplied charger only deliver s 6V max which is not enough to fully charge the NiMH. A 6V NiMH has a max voltage of around 7.6 to 7.8V Your supplied Tx charger will never get it there.

Use the supplied charger for wake up and storage charges, but use a programmable fast charger for all other charging requirements.

Old 06-01-2010, 03:20 PM
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landeck
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Default RE: Suggestion for new battery


ORIGINAL: TimBle


ORIGINAL: Divingdave

Using the standard charger that came with my futaba receiver. Question is simple: Will this charger that charges my 4.8 battery charger a six volt battery. I would like to convert my planes to 6 V.

Thanks

divingdave
The charger supplied with your Tx is only good for conditioning the NiMH or NiCAD on first charge. thereafter it is useless until you have placed the batteries in storage and you need to ''wake'' them up again.
NiMH and NiCAD need to be ''fast charged'' so use a proper fast charger to charge them up in flying season. They like 1C charge rate, i.e. 2500mA.hr battery can be charged at 2.5A irrespective of the voltage.

Also the supplied charger only deliver s 6V max which is not enough to fully charge the NiMH. A 6V NiMH has a max voltage of around 7.6 to 7.8V Your supplied Tx charger will never get it there.

Use the supplied charger for wake up and storage charges, but use a programmable fast charger for all other charging requirements.

I strongly disagree with you. Consistently charging a NiCad or NiMh battery pack at a 1C rate will shorten the life of the battery pack. The best charge rate is a slow rate (C/10) for 15 hours. The charger that came with the radio system should do this just fine assuming it is not a large battery pack. Further you should cycle the batteries three time to "form" them at the slow rate, not just once. The process I use is I put NiCads on a slow charge when I get back from flying. Then I switch to a trickle charge (C/50) rate and leave them there until I next go flying. That way the batteries are ready to go whenever I decide to go fly. I have been doing this for at least 25 years and my packs last 5+ years.

Bruce
Old 06-01-2010, 04:47 PM
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Divingdave
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Default RE: Suggestion for new battery

Thanks for the information on Battery charging. 

It is clear I really need a programable charger to charge various Nicads, Lipos etc.

Does anyone have a suggestion on a reasonably priced unit for multi purpase charging, balancing etc.

Thanks

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