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Old Dec 08, 2010, 03:57 PM
Heli Mania
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Originally Posted by Biggie D View Post
Does the battery lead get hot? Hot enough to melt the connector? I'm guessing there is a reason why I haven't seen this mod on the S107 (mine scheduled to arrive 12/10).
When I got my first S107 two days ago, I fully charged the battery and did the first flight. Immediately after the flight I removed the canopy and felt the battery ... it wasn't even warm. The motors were also not even detectable in a temperature rise. I flew it a good 6 minutes. Then I charged it with the canopy off and felt the battery while charging ... again, it didn't even feel warm at all.

I've seen a couple of videos on YouTube where guys have modified the S107 to swap batteries with a plug ... it's been done. Personally, I get a good 6 minute flight out of my bone stock S107, so that's OK for me anyway. Got a couple more to fly too, so never a lack of flying opportunities.
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Old Dec 08, 2010, 04:00 PM
Heli Mania
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Originally Posted by scorp View Post
Two questions on lipos that may have been discussed here though i cant find it.

1) why is it that s107s with a 150mah lipo take 45-55 min to charge while on my 6010 with a same 150mah lipo it only takes 15-20 min?
Has to do with the charging voltage level. The USB charger with the 6010 may put a little more voltage across the battery during charging. I measured the charging voltage across the battery leads on the circuit board on my S107 during a charge, and it was around 4.3 volts.

The USB charger must have a way to regulate the charging voltage (ie, small circuit board in the cable's plug), and of course sense the voltage so it can turn the red light on indicating full charge.

My S107 always takes 58~60 minutes to charge every time from the USB charger.
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Old Dec 08, 2010, 04:20 PM
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Another delicious nugget of information

Quote:
Originally Posted by jrgroucho View Post
Well, since science demanded it at the bequest of SoloPro...(besides, Newton hardly ever played video games and look at all the science he did).

Syma S107 Motor Temperature Experiment

Room Temp (degrees C/(F))------Flight Time (s)---------Temp (degrees C/(F))

24.5(76.1)------------------------300----------------------40.5 (104.9)

24.1(75.4)------------------------360----------------------40.5 (104.9)

23.8(73.8)------------------------420----------------------44.8 (112.6)

===============================================
I also took the cool-down temp every five minutes for 15 minutes

5 min. Trial-Time After Stop (s)-------------Temp (degrees C/(F))

---------------300-------------------------------30.1(86.2)

---------------600-------------------------------27.5(81.5)

---------------900-------------------------------26.5(79.7)

6 min. Trial-Time After Stop (s)-------------Temp (degrees C/(F))

---------------300-------------------------------28.5(83.3)

---------------600-------------------------------25.5(77.9)

---------------900-------------------------------25.2(77.4)

7 min. Trial-Time After Stop (s)-------------Temp (degrees C/(F))

---------------300-------------------------------30.3(86.5)

---------------600-------------------------------27.6(81.7)

---------------900-------------------------------25.3(77.5)
===============================================

This experiment was done with a Red S107 that has been slightly modded. I replaced the stock battery with a 240 mAh battery. I have also removed the tail boom struts and feathers. The mass of this heli is 38.3g. Also, the front/lower motor, tends to run about .5 degrees higher

I don't know if anyone will find this useful, but here it is. It looks like there isn't a lot of temp difference between my 2-3 minute flights and 5-6. But you can be certain I won't be flying more than five from now on.
As jrgroucho stated in post #2649, his S107 wasn't stock, but it makes for interesting reading nonetheless.

The first table shows that motor temperature remains steady up to 6 minutes (a flight time achievable with the standard battery) and cools back down to room temperature after 10 minutes. Using a bigger battery (like jrgroucho did) could only serve to push the motors to premature failure.

@Hayabusa Heli I want the blue S107 *so* bad... International shipping is $50 though...Takes the total to $79.95 or 60 euros. *sigh*
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Old Dec 08, 2010, 05:01 PM
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Originally Posted by Quagga View Post
The first table shows that motor temperature remains steady up to 6 minutes (a flight time achievable with the standard battery) and cools back down to room temperature after 10 minutes. Using a bigger battery (like jrgroucho did) could only serve to push the motors to premature failure.
yep and bigger battery = more weight which will be the bigger killer of the motors.
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Old Dec 08, 2010, 05:10 PM
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@Quagga - thanks for that tid-bit of test data about the motor temps from jrgroucho. Don't how I missed it in a 308 page thread. LOL.

Anyway, my conclusion is the battery and motors don't even get near hot enough to damage them if the heli is working right. What I mean is if the motors, gears, shafts all are free turning (so the motors don't have to work harder) and the battery is healthy, then a 6 minute flight hardly gets them warm to the touch. 112 deg F (per data above) is nothing to get concerned about IMO. I fly mine until a full up on the remote will not make the heli climb anymore ... that's when I land and shut it down.

Hate to say it ... but I got a blue S107 arriving in the mail tomorrow!
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Old Dec 08, 2010, 05:59 PM
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Quote:
Originally Posted by Hayabusa Heli View Post
@QuaggaAnyway, my conclusion is the battery and motors don't even get near hot enough to damage them if the heli is working right. What I mean is if the motors, gears, shafts all are free turning (so the motors don't have to work harder) and the battery is healthy, then a 6 minute flight hardly gets them warm to the touch. 112 deg F (per data above) is nothing to get concerned about IMO. I fly mine until a full up on the remote will not make the heli climb anymore ... that's when I land and shut it down.

X2

Based on the numbers we've ssen here it seems pretty clear that no significant motor damage will occur with a 6-7 min flight and that makes sense since to me these motors are very well cooled (rotor wash).
I've been playing with LiPo's in my RC truck for a couple of years now and my experience has been that they like being drained down a bit to get a full charge cycle, but they also have no memory so they don't mind partial charges. Either way as long they don't get run down too far LiPo's are by and far the best thing that's happened to battery tech.
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Old Dec 08, 2010, 06:09 PM
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Originally Posted by Chris.S. View Post
X2

Based on the numbers we've ssen here it seems pretty clear that no significant motor damage will occur with a 6-7 min flight and that makes sense since to me these motors are very well cooled (rotor wash).
I've been playing with LiPo's in my RC truck for a couple of years now and my experience has been that they like being drained down a bit to get a full charge cycle, but they also have no memory so they don't mind partial charges. Either way as long they don't get run down too far LiPo's are by and far the best thing that's happened to battery tech.
Here's a couple of my posts that show battery voltage measurements I took on my new S107 the first day I had it. Note that when I fly my S107 to the point where it will not climb anymore, the battery voltage after flight is around 3.3 volts. Does that seem about right for a discharge level? ... doesn't seem to hurt it any - but only have about 8 flights in so far. Battery voltage is 4.25 volts after a full charge.

http://www.rcgroups.com/forums/showp...postcount=4483

http://www.rcgroups.com/forums/showp...postcount=4488
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Old Dec 08, 2010, 07:51 PM
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Great work on post #1
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Old Dec 08, 2010, 08:03 PM
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@Hayabusa Heli Blast you Sir, blast you and your readily-available blue S107! (Presumably for a decent price?)

I agree that the motor temperature numbers seem pretty tame, probably due to them being rotor-cooled (as Chris.S. said). The 10% rise in temp between 6 and 7 minutes does seem to indicate that there isn't a huge margin for increasing flight-time.

Does anybody know what the point of no return for a li-po battery is? Or for the stock S107 li-po in particular?

At first I timed my flights to 5 minutes, but recently I've grown lazy, and simply flies until the heli noticeably looses power
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Old Dec 08, 2010, 08:05 PM
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Quote:
Originally Posted by Hayabusa Heli View Post
Here's a couple of my posts that show battery voltage measurements I took on my new S107 the first day I had it. Note that when I fly my S107 to the point where it will not climb anymore, the battery voltage after flight is around 3.3 volts. Does that seem about right for a discharge level? ... doesn't seem to hurt it any - but only have about 8 flights in so far. Battery voltage is 4.25 volts after a full charge.

http://www.rcgroups.com/forums/showp...postcount=4483

http://www.rcgroups.com/forums/showp...postcount=4488
Lipos should not be discharged below the nominal 3.7V at rest, they can be damaged if remains below the nominal voltage at rest. When purchasing lipo packs for my RC models, I always check the charge when first recieved to insure that each cell are no lower than 3.7V, most manufacturers will ship new lipos at a storage voltage of approx. 3.85V-3.90V. I will reject/ return any pack that has cells that are low, because they are typically already damaged. I've had some that I kept despite they had low cell voltages, and they wouldn't take a full charge and wouldn't balance properly. Fully charged lipo voltage should be 4.20V per cell, I don't hink it harm them to go over that slightly. Most of my hobby grade charger/balancers will sometimes charge an individual cell to 3.23-3.24V, doesn't seem to harm them. Discharging them too low is what harms the cells.
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Old Dec 08, 2010, 08:37 PM
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Quote:
Originally Posted by Doubletap View Post
Lipos should not be discharged below the nominal 3.7V at rest, they can be damaged if remains below the nominal voltage at rest.
So what you appear to be saying is that after your last flight of the day, you should always charge your helicopter up again before storage. Not necessary full charge, but at least somewhat charged. Yes/No?
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Old Dec 08, 2010, 08:53 PM
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Originally Posted by alfa1 View Post
So what you appear to be saying is that after your last flight of the day, you should always charge your helicopter up again before storage. Not necessary full charge, but at least somewhat charged. Yes/No?
A lithium based battery is happiest when charged to between 20% and 80% of capacity, with 40% being the best for longevity in storage. Here is some good data about lithium based batteries.

http://batteryuniversity.com/learn/a...ased_batteries

http://batteryuniversity.com/learn/a..._ideal_battery
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Old Dec 08, 2010, 09:13 PM
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Originally Posted by Doubletap View Post
Most of my hobby grade charger/balancers will sometimes charge an individual cell to 3.23-3.24V, doesn't seem to harm them. Discharging them too low is what harms the cells.
Is there an error in this statement? Did you mean 4.23-4.24 V instead? A 3.7V cell wouldn't charge with 3.24V across it.
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Old Dec 08, 2010, 09:14 PM
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According to this, 3V per cell is the minimum voltage. It appears that is 3V under load though. I'll have to check my phone sometime to see what it reports as the voltage at 0% and 100%. Right now, it is 3.98V at approximately 80%. My wife's reports 3.91V at 76%. Both are LiPo batteries.

http://en.wikipedia.org/wiki/Lithium...olymer_battery
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