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Batteries & Chargers Discuss Li-P, Li-Ion, NiMh, Nicad battery technology and the chargers that juice 'em up!

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Old 01-01-2011, 09:14 PM   #1
syd123
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Default I've committed no offense against them, but 3C lipos won't charge. Ugh.

Happy new years! ..And thanks so much for reading.

My brief honeymoon with electrics may be coming to an end (I'm a longtime glow builder/flyer) . Though I've committed no known offenses against them, my two 3-Cell Lipos won't charge after just 7 cycles and it's causing me to wonder if glow-power (in spite of it's many drawbacks) might not be more reliable and affordable. I've followed all charger directions to the letter and have been careful not to run the batteries down too far. In fact, my ESC has yet to cut off power to the motor. I haven't crashed, my flight times are under 7min. and I fly at under 1/2 throttle for all but an occasional loop (plane is a bit overpowered so 1/2 throttle is plenty). When I land the ESC and motor are barely warm!

Yet after just 7 charge cycles, both batteries cause the charger to flash "ERROR". UGH! These batteries cost nearly $100, and the charger $30 (yes, it's an inexpensive, but it's designed for only 3-C lipos of b/w 1500 - 2500 mAh, so in this context, it's kinda not). What went wrong?

Here's my gear:
Motor: Rimfire .10
ESC: Great Planes Electrifly 35A
1st Battery: Electrifly 3S 11.1V 1800mAh 25C
2nd Battery: Super Tigre 3S 11.1V 2500mAh 15C
charger: Great Planes 3S LiPo Balancing Smart Charger (AC/DC)

..I'm reluctant to buy more batteries or another charger without knowing what I did to cause this. ..The obvious guess would be that the charger went bad but I don't really want to buy a $150 charger without first knowing that it's the charger to blame. Any advice?? The simplicity of connecting the battery to ESC then flying has been great. No fuel, mess, vibration, noise, etc.. are great. ..But after reading all the warnings, cautions, and tales of woe about LiPo's, I'm beginning to think it's only for the wealthy and for those with a Phd in Electrical Engineering.

Many thanks.
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Old 01-01-2011, 09:52 PM   #2
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you lost a cell...charger is being safe and not charging...
OR

you left them plugeed in to the esc or charger not pluged in...
OR

cells DEAD..charger doens't see any voltage or too low..wont charge...
OR

charger not working right.....
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Old 01-01-2011, 09:58 PM   #3
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do you have a multimeter?

the small withe balance plug , you can check voltage on each cell. black is neg and each wire is one of the cells.

if no, the how much total power on the pack.

if a lipo drops below 3.2v /cell the charger wont charge...
non balancing..if to low it wont charge because it would over charge the remaing cells trying to reach it high point and thus FIRE....

if a lipo goes to 0 volts, you forget to unplug from esc and it slowly drains the power for a week in the closet...it will not recharge....DEAD

if you for get to unplug from a charger that is not pluged in long enough it will slowly drain it to 0 also...DEAD

once you understand their limitations ..their great , but not as forgiving as nicad/nimh
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Old 01-01-2011, 10:00 PM   #4
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It would help to get a voltage reading on each cell to see if the battery is actually low.

Can you get a voltage reading per cell?

It could be many things, but it will most likely end up being something simple.

Could be something as simple as a broken or bad connection in the charging lead.

Do you have anyone near you good with electrics that can see your setup and help?

Cliff
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Old 01-01-2011, 10:01 PM   #5
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oh please fill in you location..it helps those close to you help out...

and buy zippy or flight max..much cheaper for sport flying
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Old 01-01-2011, 10:18 PM   #6
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Your offense (IMO) > Great Planes electronics.
The charger is, well, pathetic.

The ESC of which the low voltage cut-off is a critical component, is beneath contempt in that ESC.

For lipos an LVC of MINIMUM of 3.0v/cell is CRITICAL. If it falls below that many chargers will reject them.

Read the Manual carefully for that ESC.

From their website:
SS-35 GPMM1830 67%
67% of starting voltage is the LVC.

Now do the math:
12.6v starting voltage x .67 = 8.42v divided by 3 (cells) > 2.8v/cell.
Already too low

If the charger did not charge fully and you started out lower then it's worse.
If you flew a few minutes, landed, unplugged, and went back up expecting the LVC to save you > now it's WAY worse.

Since the cut-off depends on voltage and voltage sags as a function of power draw flying around at very low throttle the 'sag' down to LVC will not be much, so when you hit LCV it's way too late.

You've been likely over discharging your lipos due to poor electronics. It's unfortunate but the Electrifly ESC just are not good units. IMO they should be boycotted until extinct or upgraded.

Get some better ESC (Hobbywing or Turnigy Plush -same thing, plus programming card and use the 3.2v LVC) or Castle Creations T-Bird and the Programming Link and set your own LVC where you want it. This is a VAST improvement.

Get a GOOD charger. I suggest for maximum safety, information, and ease of use a FMA Cellpro 4S. If your batteries are not ruined (merely being rejected) you may be able to recover some use of them with that charger.
You will need proper balance tap adapters for the batteries. Read up.

fly
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Old 01-01-2011, 11:20 PM   #7
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Thank you all for your replies.

I'll borrow a multimeter and measure the cells and will let you know.

As for great planes electronics, I didn't know that there were junk. ..I knew they were a bit overpriced, but I didn't know there were bad. ..That's disappointing. ..The primary reason I went with GP stuff is because one of the area hobby shops carried all the GP stuff and I (as is my preference in general) wanted to give them my business rather than buy over the internet. ..Oh well. That bums me out. ..So now, in addition to buying a new charger, I'm facing having to buy a new ESC. Ugh....
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Old 01-02-2011, 12:27 AM   #8
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No good reason you would without some extensive reading. A lot of folks assume a major brand name like that is fine and your LHS wouldn't do your wrong.....right?

Here's how you measure individual cells at the balance tap:

Measure 1&2, 2&3, 3&4 wires at the balance tap. That will give each individual cell.
DO NOT TOUCH THE PROBES TOGETHER - SHORT! BAD!!!
You should get all cells above 3.0v.
If not you have a lipo problem-bad cell/over discharged or broken tap wire likely
If all cells are OK, the tap is OK, then you have a charger problem.


Tower Hobbies is the general source of GP products. Some of them are fine. This is characteristic of many lines of electronics. You end up needing to learn what to pick. For example another company GWS, also makes lousy ESC (worse than Electrifly), decent planes, very good servos, crappy batteries and so-so RX. That kind of thing is common.

The good part is better ESC can be had cheaper. Too bad a lot of LHS are not up to par when it comes to electrics.

40A Brushless Electric Motor Speed Controller ESC [Volcano Series]

Same as a Hobby Wing . MUCh better speed control.
DO (trust me on this) get the programming card to go with it (bottom of the page)

This is handy to have
Lipo Battery Tester

Here's a bit more expensive alternative to the ESC above but with a bit better thing called a 'switch mode' battery eliminator circuit (BEC) vs. the 'linear' BEC of the above suggestion:
Emax 35 Amp ESC with 3 Amp switchmode BEC
It is also a Hobby Wing that is re-branded. This is an extremely common practice in electronics.
BEC is a whole different discussion. Switch mode is more desirable than linear, costs more, and starts to appear on somewhat higher Amp ESC.
Linear vs. Switching and UBEC ??

Think of a charger as literally the backbone of an electric fleet. You REALLY NEED A DECENT CHARGER! You don't have to bleed money for it but dirt cheap just doesn't cut it.

Addendum: Did a bit of research on your motor-from Tower Hobbies:
Max. Constant Current: 30A
Max. Surge Current: 35A
Suggested Propeller Size: 10x4.5 - 10x7 electric

Batteries need to be sized by mA and C-rating the application and should be within the "80% rule" for longevity (don't push electronics beyond 80% of spec)
This is the formula:
Amps x C-rating > Max amps capability
So.....
Electrifly: 1.8A x 25 = 45A capable (theoretically) x 80% > 36A. It should have been OK. Since it's Electrifly, I think I'd rate it lower than that.
Super Tigre: 2.5 x 15 = 37A x 80% > 29A. Not quite up to snuff for that application.

NOW....What prop ARE you actually using? Exact size brand and style needed. If you were over propped all the above math is messed up.
Prop size for electrics makes a HUGE difference in power draw. That in turn makes a huge difference in the electrics used.

fly
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Old 01-02-2011, 02:20 AM   #9
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I Use the Turnigy Accucell 6, i think its a great charger with plenty of functions, plus its only $23. http://hobbycity.com/hobbyking/store...idproduct=7028

Need More Glue!!!
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Old 01-02-2011, 04:52 AM   #10
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Originally Posted by flydiver View Post
NOW....What prop ARE you actually using? Exact size brand and style needed. If you were over propped all the above math is messed up.
Prop size for electrics makes a HUGE difference in power draw. That in turn makes a huge difference in the electrics used.
Thanks so much flydiver for your thoughtful reply. ..I started out using a 10X4.5 prop, but then cut it down to 9x4.5 (and re-balanced) because the plane was sooo overpowered. ..Perhaps that has contributed??

I'll probably go ahead and order the ESC you recommended. ..While hardly a megabuck scale model (see attached pic), I have spent a considerable amount of time building this plane and would hate to see it crash b/c the ESC failed. ..And it's a shame that the local hobby shops don't carry the brands I see recommended here on Wattflyer as I'd much prefer giving them my business. Had it not been for the old hobby shops I visited as a kid, I wouldn't be in this hobby.


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Old 01-02-2011, 05:45 AM   #11
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Nice looking model.

Cutting the prop down would lower the amp draw. I was making sure you had not over propped with something like a 12x6 slow fly.

What does the LHS carry? Some products may be fine. I certainly understand shop loyalty and wanting to keep the $$ at home-an increasingly daunting task.
Eflite are common in LHS. A bit expensive and stick programmed which I dislike. OK, but a bit expensive for what they are. Castle Creations are expensive but very good. They are my personal favorite. I reserve them for better planes.

FWIW I dont' think the ESC will fail. What it does is fail YOU via the poor LVC. The LVC technology in some products is very old and long outdated-suitable for NiXX batteries. I have no idea why some large brand names are still selling that kind of stuff. Ultimately it will bite them with the ease and rapidity of communication now.

You CAN fly an ESC like that. You just need to have tools to measure your battery and make sure you stop before it gets too low. This is common practice among knowledgeable electric fliers. I practice it myself. I consider LVC an emergency backup for failure to pay attention.

The Accucel-6 mentioned above is fine. I have one. But, I suggest you download the manual [Files tab on that page] and read it before purchase. Some people are fine, others hate the instructions. Watch a couple video off that page also. The Cellpro 4S Gold is easier to use, and likely safer.

The Hobbypartz linked earlier also sells similar clones of it (Thunder, Dynam Supermate). All of them are clones of a charger called Bantam which sells for way more.
You'll see the E-sky chargers on that page also which are probably what your GP charger is. It's a rebrand too. There is a huge amount if it in this sport. Hard to keep track of.

Let us know what your battery voltages turn out to be.

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Old 01-02-2011, 12:03 PM   #12
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Hi Syd123 At First I did not Think i was going to like E Power too, only because I did not know about what parts were Quality and what were Junk, it almost turned me off too to E Power, Now I know better keep asking questions here, there are a lot of Very Sharp People here, listen to them, I Know I have learned a Lot, and I can now return the Favors, you have received a lot of good Advice here, I have flown glow for over 40 years, I converted to E Power and I am never looking back, give yourself a little time to learn E Power, it took me about 1 year to really soak it up, and Learn, your not going to learn it over night, thats for sure, as you did not learn about glow over night too, Now i love E Power Take care and have fun, Chellie

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Old 01-02-2011, 02:58 PM   #13
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Don't feel bad about buying things twice. I went out and bought the GP Trition Jr charger. I quickly found out I did not like it. I went out and bought the Turnigy Accucell 6. I love this thing. It does every thing I want and the price was right as well.
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Originally Posted by HeliScRapYard View Post
I Use the Turnigy Accucell 6, i think its a great charger with plenty of functions, plus its only $23. http://hobbycity.com/hobbyking/store...idproduct=7028

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Old 01-02-2011, 04:10 PM   #14
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Originally Posted by flydiver View Post
Nice looking model.


What does the LHS carry? Some products may be fine. I certainly understand shop loyalty and wanting to keep the $$ at home-an increasingly daunting task.

The Accucel-6 mentioned above is fine. I have one. But, I suggest you download the manual [Files tab on that page] and read it before purchase. Some people are fine, others hate the instructions. Watch a couple video off that page also. The Cellpro 4S Gold is easier to use, and likely safer.

The Hobbypartz linked earlier also sells similar clones of it (Thunder, Dynam Supermate). All of them are clones of a charger called Bantam which sells for way more.

Let us know what your battery voltages turn out to be.
Flydiver:

Thanks again for your help (and to all others as well!).

Is either the Thunder charger or similarly priced Hyperion charger seen in the link adequate? They can be purchased locally.

http://www.hobbyhut.com/Chargers_s/270.htm

..It seems that their prices, compared to Hobbypartz, are a bit high. ..I may be able to negotiate the price down a bit, but I don't mind paying them a reasonable premium over Hobbypartz ($15 more perhaps) if it helps ensure that they stick around. Any harm in purchasing this charger and seeing if it will succeed in charging my two batteries (in otherwords, could it damage the charger)?? I figure that I need a better charger any way, so I might as well make that leap now. ..If it manages to save the batteries, great, if not I'm in now different position anyway.

As for the volt readings, I plan on retrieving the multimeter later in the day.
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Old 01-02-2011, 04:21 PM   #15
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Happy new year syd123,

I would HIGHLY reccomend that hyperion charger, I use one as does my father. We both have had them for years with flawless service.
You can feel confident in putting your batteries on that charger to see if they can be brought back.


Now for something some may not reccomend:

Sometimes, a battery can be brought back using lower cell count charge rates and low amp rates.
I use older 3 cells on my transmitter. I have left it on before, flattening the battery out. I was able to charge at 1 amp, at the 2 cell voltage at first, which brought it back to the point where the charger would see the correct voltage to charge at 3 cell rate. Again, I charged at a lower amp (which takes a bit of time) but it does not 'push' the battery.

I highly reccomend you using a fire safe charge container of some type. Even if you simply set it outside away from everything thats better than you puffing and swelling a battery inside your house. Lipos are dangrous, flat Lipos are still dangerous too. Treat them with respect and caution.

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Old 01-02-2011, 07:39 PM   #16
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Originally Posted by Nitro Blast View Post
Happy new year syd123,

I would HIGHLY reccomend that hyperion charger, I use one as does my father. We both have had them for years with flawless service.
You can feel confident in putting your batteries on that charger to see if they can be brought back.


Now for something some may not reccomend:

Sometimes, a battery can be brought back using lower cell count charge rates and low amp rates.
I use older 3 cells on my transmitter. I have left it on before, flattening the battery out. I was able to charge at 1 amp, at the 2 cell voltage at first, which brought it back to the point where the charger would see the correct voltage to charge at 3 cell rate. Again, I charged at a lower amp (which takes a bit of time) but it does not 'push' the battery.

I highly reccomend you using a fire safe charge container of some type. Even if you simply set it outside away from everything thats better than you puffing and swelling a battery inside your house. Lipos are dangrous, flat Lipos are still dangerous too. Treat them with respect and caution.
Thanks Nitro.. ..I called the HS and was told that they now have just the Hyperion in stock. ..So the Hyperion it is. ..I'll post later about whether or not this charger was able to charge my lipos. ..If not, well... based on all that I've read here, I needed a proper charger anyway.

And I'll buy a Lipo bag in which to charge the batteries. ..I'm pretty careful to NEVER stray more than a few yards from my batteries as they charge. Thanks for the headsup!
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Old 01-03-2011, 12:48 AM   #17
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Well I'm pleased to report that my batteries appear to be fine. ..Acting on the advice I rec'd here, I went to one of the (few) local hobby shops and purchased a better charger (Hyperion) and it charged each pack to completion without throwing out any warnings/errors. The 1800 mAH Great Planes Electrifly 3-cell took 35 minutes and charged to 4.2/4.2/4.21v; the SuperTigre 2100mAH took 67 minutes and charged to 4.18v/4.19/4.19v. So, unless I hear otherwise from someone here about these voltages being sub-par, I'll assume that the batteries are okay and that the culprit was the crummy Electrifly ac/dc charger. And an interesting FYI about that charger... ..I can no longer find it on the Great Planes website. ..It's still available from Tower Hobbies, but it appears that GP has discontinued it. ...Wonder why

Thanks to all for your help.
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Old 01-03-2011, 01:20 AM   #18
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Originally Posted by HeliScRapYard View Post
I Use the Turnigy Accucell 6, i think its a great charger with plenty of functions, plus its only $23. http://hobbycity.com/hobbyking/store...idproduct=7028
That's the one I use... Never an issue, had it over a year now...
Used weekly at least...

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Old 01-03-2011, 05:32 AM   #19
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Your battery voltages look fine. Did you happen to get the voltage before re-charging them?

fly
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Old 01-04-2011, 02:35 AM   #20
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Originally Posted by flydiver View Post
Your battery voltages look fine. Did you happen to get the voltage before re-charging them?
No I didn't, though that would have been a smart thing to do of course. ..This Hyperion charger is pretty neat. ..I should have bought something like this from the get-go.

And I took your advice and ordeed the Emax 35 ESC with 3A switch-mode. I should have asked before ordering, but will this ESC play nicely with my cheapy Futaba S3107 servos?? ..They are not supposed to be used with a 6v BEC or they'll prematurely wear out (or so says the instructions). ..I'm using four of these (one for each aileron).

Oh, and rather than leave well enough alone, when ordering the ESC I took the opportunity to replace the Rimfire .10 motor I'm currently using with something more suitable. ..With the rimfire my RV4 takes off at about 1/8 throttle and I use only the first half of throttle travel throughout the flight. ..It will climb almost vertically at 1/2 throttle.. ..So I figured I'd buy a motor which is more appropriate. The 2830-11 Outrunner Brushless Electric Motor from Head's Up RC produces 30oz of thrust while drawing 17amps. Do you agree that this should fly my 32oz. plane well enough if all I'm looking for is to do a few loops, rolls, and a couple terrifying moments of inverted flight? ..Just a basic sport flyer. I have no interest in making it fly like a helicopter.

Thanks flydiver!
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Old 01-04-2011, 03:09 AM   #21
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The servos will be fine. Most BEC in ESC put out 5V.

This is the Rimfire motor specs:
Max. Constant Current: 30A
Max. Surge Current: 35A
Max. Constant Watts: 333W
Max. Burst Watts: 390W
RPM/V (kV Rating): 1250
Weight: 2.5oz (71g)
Suggested Propeller Size: 10x4.5 - 10x7 electric

A good way to compare motors is watts to watts.
Pay attention to the weight as it's at the far end of the plane and can
upset the CG if you have limited ability to move other stuff around. KV+motor
size and power will define the prop size used.

New Motor (Jeff does his own testing so specs are probably accurate)
Weight = 1.9 ounces (54 grams)
Motor length = 1.2 inch (30 mm)
Shaft = 1/8 inch x 0.5 inch (3.17mm x 13 mm)
Current = maximum of 17 amps or 180 watts for 30 seconds
KV = 1150

You've maybe almost halved the possible power. You'll find out. A cheap solution
would have been a smaller prop with less pitch.
Are you sure you are truly American? All Americans grossly over motor their
planes. I thinks it's a law.
A few points:
Rimfire motor specs tend to be 'generous'. Sterling specs sell product but that does not make it so. The Chinese have learned this. Be advised.
Some Rimfire use an odd 3 point motor mount. I don't think this one did but it's a pain sometimes.

The BEC is where power comes off the battery to feed the RX and servos. As I said, switched is better than linear, and more is better than less. Once you reach 4 servos and 3S some folks consider it important > critical to go minimally with a 3A switched BEC or add and after market stand alone BEC. If the BEC is not up to feeding the servos it can overheat, shut down, and you are out of luck. It happens. If it happens while using Spectrum gear you may suffer a potentially fatal condition known as [Brown Out] where the RX shuts down for awhile. If you care to get more info about that read this:
WHATS a UBEC ? and Who Needs Them ?

fly
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Old 01-04-2011, 04:26 AM   #22
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1/2 the power of the Rimfire would probably be perfect. But if the motor isn't an easy "drop-in" replacement (I believe the mount pattern is identical), I'll keep the rimfire mounted and use the new motor for a future project (possibly a foamy for my son).

I bought the rimfire b/c I thought the Great Planes RV4 Kit was going to finish out considerably heavier than the plans indicated. I was unhappy with the flimsy design (being unused to electrics, the design seemed way too delicate as I began to build it) so I significantly beefed up the structure. ...What I didn't take into account (this being my first electric) was that a brushless motor/ lipo system was MUCH lighter than the geared 400/ nicad system and that the weight saved would offset the weight added b/c of all the structural enhancements.. So I ended up with a grossly over-powered model. ..I (like all true Americans) do like a bit of extra power, but it's frustrating having so little useful range with the throttle stick.

If I were to simply use a smaller prop with the rimfire, wouldn't I be risking damage to the (soon to be Emax) ESC or Motor?? ..I don't believe a 7" prop is among those suggested in the manual.
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Old 01-04-2011, 05:23 AM   #23
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You would benefit from studying this review of Rimfire motors including the one you have by an independent tester. Dr. Kiwi is a gem.
More motor/prop data.

In general you prop a motor to about 3/4 of it's un-propped RPM for best 'effect'. Most efficient is often smaller than that. Then you try to run it to less than 3/4 throttle with WOT only for short bursts near maximum.

You could easily prop that Rimfire down to 9x5 GWS and get it in the same general range you think you are looking for. In electric motors it is important to not over prop them but it's fine to under prop them until it gets ridiculous. At that point you may as well motor down and save weight. As you are learning, electric is often about making it light, not beefy and heavy.

The ESC merely passes through the current demanded by the motor + prop combo. As the props get smaller and pitch gets lower the amp draw goes down and vice versa.
If you prop up too much and the amp draw goes beyond the ESC rating then you risk damaging the ESC (and/or motor). You want a slightly larger capacity ESC than the motor rating. Too big doesn't hurt except in the weight and $$ dept.

Too small is not good. In electrics you cannot limit the voltage that the ESC sees by turning the throttle down. The throttle is managed by switching FULL VOLTAGE ON and OFF very fast (PWM=pulse width modulation).
Full throttle > full voltage
1/2 throttle > full voltage half time on, half time off. So the ESC still sees full voltage as far as it's concerned.

More voltage does not make the ESC 'more powerful' from the BEC point of view. The amps the motor sees do increase. BUT---the BEC portion has to pull that voltage DOWN to 5v to run the servos and RX . The linear BEC does that with resistors and gets hot. More voltage > hotter BEC. That's why as voltage goes up the servo count it can handle come down. Seems backwards until you get that part.
Switching BEC do it with electronics so don't get hot and are more efficient.

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Old 01-04-2011, 12:52 PM   #24
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Thanks for the links flydiver. I've begun reading some of the info. Obviously, it will take a while to get through all of it.

I'm already using a 9x4.5 prop so I'm not sure what you mean by propping down. ..Did you mean 8x4?

Also, which voltage values on the chart most nearly predict what I'm going to experience with my 3-Cell Lipo setup?? I tried searching around Dr. Kiwis website but couldn't find an explanation. A 3-cell lipo has a nominal voltage of 11.1, but I know it's higher when charged. ..But how much higher, I'm not sure. Maybe I'm not reading the chart properly, but I don't see a prop that allows me to use my 3-Cell lipos and stay around 30 oz of thrust. Perhaps I should be looking to use just a 2-cell Lipo?? Sheesh, I feel kinda dumb trying to make sense of all of this (I'm a sales/marketing guy with NO background in engineering ). ..And please accept my apologies for asking questions that have probably been covered a hundred times on this site.
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Old 01-04-2011, 05:38 PM   #25
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On his chart he will indicate the voltage used and the subsequent results. Be aware that there are basically 2 styles of props: slow fly-which tend to have small hubs and a fatter elongated figure-8 blade; and direct drive/thin electric which have a fatter hub and skinnier blade. They are not comparable.

SF is for slow turning motor and planes. The fat hubs 'bite' more air, have good thrust, generally eat more amps, and are not suitable for high RPM operation. They can blow up.

DD/TE are suitable for higher RPM, have less thrust but due to use at higher RPM may be faster even if they have less pitch. They use less amps and may be more efficient-but efficiency is closely related to proper use.

A single cell lipo is 'nominal' 3.7v and 4.2 volts fully charged. So 12.6v for a 3S. But a lipo voltage will always sag (drop) under use so working voltage may be 11'ish volts. Props of different makes and styles even of the same apparent dimensions are not necessarily comparable. From the [flybrushless] chart linked above (sorry the cut and paste skews the numbers) picking 2 same size props from different manufacturers at similar working voltage gives entirely different results.

Propeller Gear Ratio Volts Amps Watts RPM Speed (mph) Thrust (g) Thrust (oz)
APC E 8x4 1 11.7 16.6 194 11580 43.9 905 31.92

GWS HD 8x4 1 10.9 11.9 129 11430 43.3 704 24.83

So try the APCe (thin electric, NOT slow fly). That's about what you think you are after.

You may want to get a wattmeter. That's where some of these critical #'s come from.
Here is one in action. BTW-that guy does a really long test on a high output motor without flying speed to cool things. He's getting away with it because a turbine flow cools the motor aggressively. You can fry stuff if you persist too long with bench tests this way.

2S lipo? Well, kinda possible. You drop voltage almost 30% > drop RPM the same. To make it up you prop WAY back up to get the power back. I think you wouldn't like it for this application. It works well for small planes using a higher KV motor and then you can use a 2S lipo (lighter/cheaper).

If you are settling in for the long haul as you appear to be you may want this reference:
EVERYTHING YOU WANTED TO KNOW ABOUT ELECTRIC POWERED FLIGHT

It includes a section on how to size/power your plane

fly
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