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-   -   Using a higher mAh Pack (http://www.Wattflyer.com/forums/showthread.php?t=73790)

Madman1701 05-25-2014 09:59 PM

Using a higher mAh Pack
 
Hi everyone. I'm new to the forums and new to flying larger model planes. Been flying micros for years now.

I have a question. I just bought the Flyzone Sensei. It comes with a 11.1V 2100mAh 20C LiPo battery.

Can I buy a larger pack that is say 5000mAh and 30C still keeping the 11.1V?

I know that weight and dimensions will have an affect on the fit/performance of the plane, just trying to get an idea of what I can do to get longer flight times. I'm away from home until Wednesday so I'm itching to get home and put it together.

Thanks!

Wildflyer 05-25-2014 10:22 PM

Yes you can buy a 11.1 v, 5000 mah or bigger Lipo.

It is not the mah capacity of a bettery that determines the voltage, it is the number of cells connected in series.

BUT, your Sensei is designed to fly well with the battery it comes with. A larger battery as you are thinking of, you will get a much harder to fly airplane, because of the weight.

You may be able to find a slightly larger battery, but try to keep the weight as close as possible. A heavier battery will require the plane to fly faster to carry the extra baggage. You may not get much more time in the air, definitely not over twice as you are hoping.

Some batteries may have a higher C rating which means the internal resistance of the battery is lower than a battery with a lower C rating. I have had a startling difference in performance in a plane when I bought a higher end battery with a much higher C rating. My plane went from 170 watts to 260 watts just changing the battery. The lower C rated battery was not worn out, but I was almost at it's limit.

Instead of a large expensive battery, I would recommend buying 2 or 3 more batteries, then you can have almost endless fun.

Madman1701 05-25-2014 10:45 PM

Excellent. Thanks for the tips. I ordered one extra battery so far. From the reviews I have got it seems to be that I should be able to get 8-10 minutes out of the battery.

So if I were to find a 2100mAh battery with 35C rather than a 20C discharge it would last longer? As well as going from a 3 cell to a 4 cell would make more of a difference than a higher mAh rating.

I understand the effects it may have on the airplane. I may keep it as is and fiddle with batteries when I have more experience with it.

Wrongway-Feldman 05-25-2014 10:48 PM

Another thing to keep in mind is that longer flight times sound great in theory but aren't always so in practice.
If this is your first plane you may have fallen into a trap many new flyers fall into, that of thinking that 10 minutes flight times are too short.
In reality 10 minutes is plenty and you'll find yourself landing in much less time than that.
Unless you're flying a glider you won't need more than 10 minutes per flight. When you are just learning your nerves will thank you for the shorter flight times.
It takes a great deal of concentration to fly well in the beginning and keeping that level of concentration for longer than 10 minutes can wear you out, leading to mistakes that could signal the very sudden end of your aircraft.

Madman1701 05-25-2014 11:01 PM

That is true as well. I really enjoyed flying my Voodoo, which was a flying wing....think it's around a 12 inch wingspan. It does take quite a bit of concentration. Perhaps 2 batteries will be plenty before I'm ready to pack it in for a few hours. I was going to jump straight into a gas plane but thought better of it haha.

I like the thought of only having to refuel the plane if I want to fly again in an hour, whereas most batteries take 4+ hours to charge.

Madman1701 05-25-2014 11:13 PM

Quote:

Originally Posted by Wildflyer (Post 949033)
Yes you can buy a 11.1 v, 5000 mah or bigger Lipo.

It is not the mah capacity of a bettery that determines the voltage, it is the number of cells connected in series.

I re-read this a couple times and I see why you said that as my question made it seem like I thought that mah correlated to the voltage. I understand that you can have a variety of mah's in the same voltage range.

I wanted to make sure that using a higher mah pack or a higher C pack would last longer without damaging the motor.

Sorry for the bad wording in my question :)

JetPlaneFlyer 05-25-2014 11:37 PM

Quote:

Originally Posted by Madman1701 (Post 949034)
So if I were to find a 2100mAh battery with 35C rather than a 20C discharge it would last longer? As well as going from a 3 cell to a 4 cell would make more of a difference than a higher mAh rating.

No, going to a 35c battery wont increase flight time. C is a multiplier used to calculate maximum safe battery amps (you multiply C by capacity to get Amps). If the plane flies ok on a 20c battery there is really nothing to be gained by going to a higher c rating.

Going from 3 cell, to 4 cell would certainly make a huge difference, that difference is that you would probably burn out your ESC and/or your motor due to the increase in current and power.

Madman1701 05-25-2014 11:44 PM

Right and my response was caused by the initial bad wording in my question. So the bottom line is stay with the same number of cells and voltage. A higher mah will increase flight time. What I have noticed is that with the higher the mah, the C goes up with it. Thanks for clarifying that.

JetPlaneFlyer 05-25-2014 11:57 PM

Quote:

Originally Posted by Madman1701 (Post 949042)
What I have noticed is that with the higher the mah, the C goes up with it.

No, c rate is independent of mAh capacity. In fact if you fit a larger capacity battery you could select a lower C rate and still safely deliver the same Amps. However, these days 20c is as low as C rating goes, so it's somewhat a moot point.

Regarding increasing capacity leading to increased flight time.. This is true to a point but taken to extremes you will just make the model overweight and the battery may not physically fit into the plane, and is also likely to upset the balance.
Increasing capacity is a game of diminishing returns. Due to the added weight you need more power to fly so the battery is depleted at a higher rate, this means flight time gains aren't as great as you might expect.
Generally IMHO the plane manufacturers usually have it about right with their recommended battery size. You might be able to go up by say 10-20% or so in size without any significant adverse effect but much more than that you are likely to start noticing an impact on performance.

Longer flight time is something beginners who have never flown before often get very concerned about. Once they actually fly they usually discover that the 8-10 minutes or so that a normal battery will give is really plenty of flight time, you are generally ready to land by then anyway.

Madman1701 05-26-2014 12:20 AM

Great advice. Thanks. Sorry for all the noob questions haha. I've read all the stickies and was still a bit unsure. I appreciate all the help.

thepiper92 05-26-2014 01:02 AM

Most rtf planes can't fit larger batteries without modification. My mini switch fits a max of 1300mah 3s, and for good reason, as the battery is behind cg. If you plan to get more run time, it has to be a battery at or ahead of the cg, for if behind you'll need a good amount of nose weight. This itself, plus the heavier battery will make the motor have to work at higher stress, need higher throttle for level flight, or a bigger motor completely. These scenarios will not increase flight time, although sometimes heavier can be better for wind. If your battery is at or past cg, a bigger battery could give a couple extra minutes. The best way to increase flight time is to have a glider, or a very light plane, with a non-demanding power setup/ a plane that flies level on lower throttle. Believe me, under ten minute flight times were hard to adjust too, considering I came from rc cars getting 30 minute run times. You'll find 5-10 minutes the norm for planes, and if you have multiple packs you'll have fun

kyleservicetech 05-26-2014 01:21 AM

Quote:

Originally Posted by Madman1701 (Post 949031)
Hi everyone. I'm new to the forums and new to flying larger model planes. Been flying micros for years now.

I have a question. I just bought the Flyzone Sensei. It comes with a 11.1V 2100mAh 20C LiPo battery.

Can I buy a larger pack that is say 5000mAh and 30C still keeping the 11.1V?

I know that weight and dimensions will have an affect on the fit/performance of the plane, just trying to get an idea of what I can do to get longer flight times. I'm away from home until Wednesday so I'm itching to get home and put it together.

Thanks!

Yeah
Just think of your 12 volt Lead Acid batteries. They are all 12 Volts DC for automotive and lawnmower use. The amount of power, or more correctly, the amount of current (Amperes) you can pull out of them depends on the quality of the battery, and on the mfg's "C" rating.

FYI, some of those mfg "C" ratings are a bit unrealistic, and actually pulling the maximum out of those batteries might result in short battery life.

As for putting in a 5000 Mah LiPo battery as your example, think of putting in a 12 Volt Lead Acid battery in your model. It will spin the prop very nicely, for a very long time, but the model might not be able to get off the ground. In worst case, a 5000 Mah battery is a concentrated brick of weight, and doing something like a loop could over stress the model, and the model's wings might start flapping. :censor:

The "C" term is used very often in our electric models. This thread describes it in great detail. If it's been awhile since school days, check with your "Fifth Grader" ! :oops: :D

http://www.wattflyer.com/forums/showthread.php?t=65869


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