Battery Question

R

rwilabee

Member
Well I posted something similiar before but now I have more info.

I am using a Thunder Power Battery rated 3S 6600 45C and I'm getting a solid 10 minutes of flying time with my HEX with 20% in reserve. I see that I can get a a 4S battery rated at 6600 but 25C. I wonder if it would give me longer than the 10 minutes that my 3S is giving me.

Rich
 


Tomstoy2

Tomstoy2

Member
Here's the deal, Rich. When you up the voltage you reduce the amp draw. Just keep in mind it's not linear when considering flight time.
Example; 10 minutes with 3s, linear thought would be 20 minutes with 6s. But the problem is you also increase weight. More weight equates to more draw.
So, yes, you will get more flight time, but it's expotential with weight.

What you need to determine is if you get the best flight time by going with one 4s battery or 2 3s in parallel?
2 3s in parallel should weigh more than 1 4s of the same mah. However, you double the mah's by going in parallel.

Myself, on my X/A Hexa, I'm running 2 each 4s 5000mah's in parallel now and getting 14 minutes in flight time using 10" props to counter the weight increase. With this combination, I'm extremely satisfied with the results. She still flys like the weight hasn't changed at all, until I reduce the throttle. Throttling back up after power reduction is when I really notice that she weighs a hell of a lot more. Takes a lot more throttle and more time to recover.
Other than that, no difference in flight at all.

In the interest of experimenting. I tried 2 each 3s of larger mah's in parallel, keeping the weight of 2 3s vs. 2 4s as equal as possible. The results were not what I expected.
I only gained 1 1/2 minutes of flight time, but the flight characteristics changes radically. She was sluggish with 2 3s. She felt heavy as hell for the entire flight and temps were a lot higher afterward on the system.

So, with this in mind, with a single battery, going from 3s to 4s, keeping the mah's the same, you will get more flight time but the real difference will be in performance of the system.

It's all about efficiency.
 

R

rwilabee

Member
So the C rating doesn't have that much to do with it? When going from 3S to 4S?

Tomstoy2 said:
Here's the deal, Rich. When you up the voltage you reduce the amp draw. Just keep in mind it's not linear when considering flight time.
Example; 10 minutes with 3s, linear thought would be 20 minutes with 6s. But the problem is you also increase weight. More weight equates to more draw.
So, yes, you will get more flight time, but it's expotential with weight.

What you need to determine is if you get the best flight time by going with one 4s battery or 2 3s in parallel?
2 3s in parallel should weigh more than 1 4s of the same mah. However, you double the mah's by going in parallel.

Myself, on my X/A Hexa, I'm running 2 each 4s 5000mah's in parallel now and getting 14 minutes in flight time using 10" props to counter the weight increase. With this combination, I'm extremely satisfied with the results. She still flys like the weight hasn't changed at all, until I reduce the throttle. Throttling back up after power reduction is when I really notice that she weighs a hell of a lot more. Takes a lot more throttle and more time to recover.
Other than that, no difference in flight at all.

In the interest of experimenting. I tried 2 each 3s of larger mah's in parallel, keeping the weight of 2 3s vs. 2 4s as equal as possible. The results were not what I expected.
I only gained 1 1/2 minutes of flight time, but the flight characteristics changes radically. She was sluggish with 2 3s. She felt heavy as hell for the entire flight and temps were a lot higher afterward on the system.

So, with this in mind, with a single battery, going from 3s to 4s, keeping the mah's the same, you will get more flight time but the real difference will be in performance of the system.

It's all about efficiency.
Click to expand...
 

Tomstoy2

Tomstoy2

Member
I'm running 30c. Batterys come down nice and cool. Think of c rating like throwing on a larger carburator. Unless everything else in the engine is set up to make use of more fuel it's just a waist of money.

The great thing of these multi motors is that they don't have much in the way of demand on them as opposed to srh's.

With a srh, 30c may work just fine in a stock configuration, but throw on a Scorpion and you can puff the same battery.

The more motors, the less demand on them. 4 is better than 1, 6 better than 4, and 8 better than 6. That is why when you go with more motors you go with less kv's, demand.

With my personal experimentation, I've found no need to go larger than 30c.
 

R

rwilabee

Member
I am running 6 Tiger MT2216 KV900. They show 20 amp max draw so I should be in good shape for a 25 to 30 C I would think. What you said makes sense. I used to run the Avroto 2814 motors but they seemed a bit heavy. In face I need to change the info on the bottom of my posts. I am getting a solid 10 minutes from a Thunder Power 6600 3S 45 C pack with 20% left in the pack. I might experiment with a 6600 4S 25 C pack and see what happens. In fact my Hex pulls 513.39 mah per minute from the battery. I have a 4S battery at about 5000 mah I could test with that and see what my mah draw per minute is.

Thanks
Rich
 

Tomstoy2

Tomstoy2

Member
Yours and mine are about the same set up. With a single 4s 5000mah I was setting the timer at 7 minutes, but could actually stretch out to about 8 minutes and still maintain 20%. With 2 4s 5000 I have the timer set at 14 minutes and still have a minute extra before dipping below 20%.
The big difference is my altitude. I'm at a mile up here so the air is a lot thinner. Down there you should expect a little better.

For props, running parallel batterys, I've found APC 10x3.5's the best. She's really a heavy pig now. Been thinking of trying some Graup's but really don't like the price tag.

How's your fpv working out for you? I'm running 5.8 myself.
 

R

rwilabee

Member
I am running the Graupner 9 x 5 props and they are giving me about 10 minutes with my 3S 6600 45C Battery. I might try one of the Thunder Power 25C 7800 mah 3S which I think would take it up to 12. Thunder Power makes a 45 C 7800 3S but it weighs more than the 25C. I think that would be enough fly time for me and the 7800 3S 25C only weighs 542 grams. I'm trying to find out if 4S would be a problem for my FPV camera which is only rated to 15 volts. I run the transmitter on a separate battery but the FPV camera is working thru the flight battery.

My 1.3 FPV is working out fine. I have the iOSD and I can switch between my Gopro Camera and my FPV Camera which looks out to the horizon. I just have to get used to everything on the OSD being in meters. Which they had a feet toggle.
 

kloner

kloner

Aerial DP
c ratings are a mesaurement of a brand new lipos internal resistance. While to some it might sound like extra money being wasted.... others look at it like a lower internal resistance gives better performance as it is used,,, like 100 cycles in it's not showing it's age, it likes to charge and discharge more cycles and is more dependable.

i buy alot of packs and look at ir alot. the last 20c packs i bought came out with 40 resistance. the last 60c packs i bought had a 24 resistance, no matter what the c, i throw away my packs when 4s packs hit mid 40's or more than 9 a cell....... I won't even consider anything under 30c, to me that's a kids pack on a model that doesn't matter. i'll even use 30c on ground equipment that sits there at a 2 amp draw for the life i'll get from the packs.

The one major thing i've learned to avoid is them thunder packs. nobody buys em and they sit around a long time to sell. a lipo has a life span of about 2 years, if you buy that thing a year old, it's half used up and it's IR will show it. A mojority of modelers use turnigy packs therefore they have a huge turnover rate and are almost always fresh, and a 1/4 the price. i'd especially avoid TP packs that are on sale cause garunteed there old.
 

kloner

kloner

Aerial DP
something else worth mentioning

c ratings are a measurement that tells the user how many available amps a new pack has. That is dictated through the quality of the cells, the the matched of those cells to make packs and the parts used inside like how thick of wire, etc. a 1000mah 30c pack has 30 amp service, a 2000 mah 30c pack has 60 amp service and so on. a 1000 mah 60c is 60 amps, 2000 mah 60c is 120 amps. but that's new and like a new car smell, wears off quickly and the pack falls into whatever quality it can give for the care the user gives it. the better the parts, the longer that will last
 

R

rwilabee

Member
That is interesting about the Thunder Power packs. My 6600 mah is a work horse. In fact for my 6600 and the 7800 packs my hobby dealer has to work directly with Thunder Power. They have to make them up as no one carries them off the shelf that I could find. Do you know of another manufacturer that carries the 7800 packs that I could check out. My 6600 mah pack is 2 3300 packs in parallel that TP makes up into one battery.
 

kloner

kloner

Aerial DP
yea, if there fresh then there ya go, your in. i fly 8000 mah and 10.600 mah in pairs of packs. I've bought 3 TP packs and every one of em was junk when it got here. I;ve bought well over a hundred, would say closer to two hundred packs in the last few years and them turnigy have never let me down, gens ace are usually spot on and the sky lipo are killer. I'd never give more than i had to in lipos, if were talking cars, there brands of gasoline and all do the same thing. turnigy day in and day out prove it. In litteraly 10's of thousands of cycles, i've never had one take off on fire for no reason, none of em have ever morphed into a devil on my shoulder, none of that. They just work and are cheap
 






Tomstoy2

Tomstoy2

Member
Kloner is right, of course, c is a measurement of ir. A perfectionist, like our dear friend Kloner, expects the best. If you run high output motors that take a high demand, then I would follow this example myself, and do with my srh fleet, which are all hopped up to the max.

My point being, these are not that type of application. These is even less demanding than an electric plane motor.
Myself, I had some high c motors I used in the beginning. When I replaced them I never noticed a difference at all in performance.
In fact, the only time I had a battery problem it was with a 65c battery.
Now, if I had an expensive CarbonCore or such, an $800 gimbal throwing up a $$$ camera, then deffinately, I would use the best high c rated battery I could.
That's not what I have though. Not saying that what I have doesn't deserve the best, just there is a line out there somewhere.

The biggest concern, for me at least, is what Kloner stated about age of batterys. I've turned into a Nano-Tec believer. Great batterys, great price, great quality. Don't feel bad when one gets taco'd.

Guess if I was to fly miles out over the ocean, like somebody I know, miles out over a river bouncing off sand bars or a desert, I would want to ensure everything it spot on, too.

All great advise and info! Consider all and judge for yourself.

Kloner, hope the leg is doing better, buddy!
 

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