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Rx battery questions

Old 09-10-2009, 02:51 PM
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brett65
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Default Rx battery questions

Was looking at this for my Focke Wulf, http://www3.towerhobbies.com/cgi-bin...?&I=LXNRH6&P=0 anybody use one? I want a high capacity because it will have so many servos, but was also thinking about using 6V this time. Any other recomendations are welcome. I've heard nimh don't have the same strength to the servo the nicad has, is this true?
Old 09-10-2009, 02:57 PM
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RCKen
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Default RE: Rx battery questions



Brett,
 How many servos are you talking about?? You have to be carefull when going to a higher voltage pack. Higher voltage does not equal longer capacities. Usually higher voltage will give you more power in the servo as well as faster response times. But most times higher voltage will drain the battery faster. If you want more capacity you want to get a battery with a higher MaH (milliamp hour) rating. This will give you more run time with your system.

Ken

Old 09-10-2009, 03:40 PM
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ChuckW
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Default RE: Rx battery questions

I have 4 of these packs (5-cell version) currently in service and a couple more waiting for a home and they work great.

Some older and/or less expensive NiMh batteries do supposedly have higher internal impedance which can restrict current flowand cause a voltage drop in high demand situations but I haven't found that to be the case with the Hobbico packs. They seem to work really well for what I've used them for.

I'm running a single pack in my TF P-47 and my Cap-580 and dual packs in parallel on my Yak-54. I've been very happy with the performance in each plane. If you are really concerned though, running the two packs will not only increase capacity, it will lower the overall resistance along with providing a little redundancy.

A high capacity 4-cell pack will also work just fine as RCKen pointed out. Either way you'll be fine.

On your FW, how many servos are you talking? Typically on a smaller warbird you have 2 aileron, 2 flaps, 1 elevator, 1 rudder, 1 throttle and 1 retract. The flaps and retracts servos really only operate twice during a flight (up once and down once) so the power demand is slightly higher but not dramatically more than a typical sport plane. Where you really run into problems with servo drain is the monster digital servos on large aerobatic planes.

What FW do you have?
Old 09-10-2009, 04:59 PM
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orangehat44
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Default RE: Rx battery questions

I have it in my escapade, though i havent put more than 4 flights on it yet it seems to work great.
Old 09-10-2009, 05:30 PM
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Default RE: Rx battery questions

As the guys pointed out above, with the extra servos you want more capacity..

Also, for the warbird, you may also be looking at having to add extra nose weight. So, it might as well be battery..

I run 8 servos on my Skyraider; 4 digital on the flight surfaces and for standard BB servos for the "other" stuff (throttle, retracts, flaps and bombs)..

I just upgraded to a JR 2400 Extra pack.. I went with good old NiCd batteries because I believe (I - Just I - not trying to start a debate) they are more durable (multiple charges) and will last longer (better shelf life) than the similar NiMH batteries..

With the bigger battery, I took 3 oz of lead off the front and have more capacity..

Now, the JR pack is about twice as much money as the one you are looking at.. Maybe for a reason... But it also comes in a 6-volt pack...

Just my thoughts...

Just
Old 09-10-2009, 05:50 PM
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Default RE: Rx battery questions

These work well:
http://cgi.ebay.com/Two-RC-4-8V-2500...4.c0.m14.l1262


http://cgi.ebay.com/2-RC-6V-2500mAh-...4.c0.m14.l1262

2500 MaH and the price is for two.
Old 09-10-2009, 11:18 PM
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brett65
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Default RE: Rx battery questions


ORIGINAL: RCKen



Brett,
How many servos are you talking about?? You have to be carefull when going to a higher voltage pack. Higher voltage does not equal longer capacities. Usually higher voltage will give you more power in the servo as well as faster response times. But most times higher voltage will drain the battery faster. If you want more capacity you want to get a battery with a higher MaH (milliamp hour) rating. This will give you more run time with your system.

Ken


Yeah, thats why I was looking at the 2000mah pack. Biggest I got now is 1100. It has 7 servos total, 2 being flaps and rudder. I thought I would use 6V for a little more umph on the control surfaces. I plan on using a micro servo for the throttle to save weight and power. Gonna go to the Realm tomorrow and see what they got on the shelf.

I am a little leary about using ebay packs without a known brand name, I've invested a lot more money and time than usual in this plane and want a name brand pack for my own personal peace of mind.
Old 09-11-2009, 12:38 AM
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Default RE: Rx battery questions

I use a 1100 mah 4.8 volt Ni Cad pack in mine. There is no great drain with the required number of servos assuming you set it up properly. 1100 mah pack will give you about 70 to 80 useable minutes with 6 standard servo's and 1 retract servo.
Old 09-11-2009, 05:28 AM
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Missileman
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Default RE: Rx battery questions

Those hydromax packs are great. You won't have any trouble with them.
I can fly 7 servo planes all on a single charge.
Keep in mind when figuring how much battery will be used that flap and gear servos are not used through most of the flight so won't draw a whole lot provided you have your end points set up good.
Old 09-11-2009, 10:04 AM
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brett65
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Default RE: Rx battery questions


ORIGINAL: Missileman

Those hydromax packs are great. You won't have any trouble with them.
I can fly 7 servo planes all on a single charge.
Keep in mind when figuring how much battery will be used that flap and gear servos are not used through most of the flight so won't draw a whole lot provided you have your end points set up good.

I have a standard servo on the flaps, is that normal or am I supposed to use one like I did for the retracts? This is my first flap and retract setup.
Old 09-11-2009, 10:07 AM
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Missileman
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Default RE: Rx battery questions

Standard on the flaps is fine, just make sure the end points are set correctly so it doesn't want to keep trying to move once it is where it needs to go. ie... it will hum if it bottoms out.
Old 09-11-2009, 12:32 PM
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Default RE: Rx battery questions

I have used the HM packs quite a bit and find them very good batteries. I also use a fast field charger at the field if the batteries get too low. The one thing I have noticed over the years is the NIMs don't like the added heat from being charged too fast and wear out faster over time.
I haven't noticed any faster drain using the 6 volt battery pack but according to the experts it is something that happens. I check my batteries before each flight and if they are down I just stick them on the charger for a while.
If you happen to need some extra weight to CG then you could give the two battery pack set up a thought too, I have done that a number of times.
I still have some old chargers at home and they will only charge up to a limited mAh so it's something else to keep in mind, will your charger give them a full charge? I use SUB-Cs in my big planes and they are 4500mAh and my home chargers don't go up that high. I charge them at home and leave them on trickle then plug in my fast charger on the way out to the field. Not the correct way to do things but I haven't gotten a better charger yet so it works.
Old 09-11-2009, 09:09 PM
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Default RE: Rx battery questions

get these http://www.all-battery.com/6v2300mah...kingrobot.aspx
i use all battery.com for everything havnt had a bad battery out of the 100 or so i have

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