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Old Feb 22, 2012, 08:38 PM
If it spins, wear it.
whirlcap's Avatar
Northern Nevada
Joined Jan 2011
2,255 Posts
I should mention I only have five flights now on mine and I'm not done getting used to the plane and tweaking things.
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Old Feb 23, 2012, 11:31 AM
Live to Fly, Fly to Live
tonyd075's Avatar
United States, PA, Pittsburgh
Joined Feb 2012
37 Posts
Got my 2nd flight in today and it went better then the 1st. One question I do have is when flying the motor quit on me several time both on take off and during flight. Does the ESC cut out when the battery gets low or am I completely off base. When the motor cuts out the servos still worked.
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Old Feb 23, 2012, 12:45 PM
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North West UK
Joined Nov 2010
349 Posts
I would try running it on the ground to see if the motor cuts and try and determine the cause that way. Try another battery which can be larger for testing purposes on the ground. It could be the battery, ESC or motor or even a bad connector.
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Old Feb 23, 2012, 09:10 PM
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tonyd075's Avatar
United States, PA, Pittsburgh
Joined Feb 2012
37 Posts
LiPo for stock motor?

I am looking into getting a few LiPo's for my MM. First of all can I even use a LiPo on the stock 400 brushed motor?

If so then what size battery should I get? 2s or 3s? 20c,25c or 30c? 7.4v or 11.1v? Also what mAh 1600, 2200, 2650, 3000?
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Old Feb 23, 2012, 10:16 PM
If it spins, wear it.
whirlcap's Avatar
Northern Nevada
Joined Jan 2011
2,255 Posts
Quote:
Originally Posted by tonyd075 View Post
I am looking into getting a few LiPo's for my MM. First of all can I even use a LiPo on the stock 400 brushed motor?

If so then what size battery should I get? 2s or 3s? 20c,25c or 30c? 7.4v or 11.1v? Also what mAh 1600, 2200, 2650, 3000?
Under "specifications" in the manual it says 2 cell with 16amp continuos draw. I don't know how that translates into what xxc rating that is but I bet you can find it in the battery sections here on regroups. The brushed motor is 6 volt, lipo 2 cell is 7.4 and won't cook the motor but 11.1 will. mah is up to how long you want to fly verses how heavy you want it to be. I'm using a 1200 mah on a brushless setup and getting good flight times but that's a different situation.
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Old Feb 23, 2012, 10:46 PM
If it spins, wear it.
whirlcap's Avatar
Northern Nevada
Joined Jan 2011
2,255 Posts
Found more battery information. To find the continuous current draw rating for a battery, you need to know its maximum charge rate. It is that number times the "c" rating. For example: my 3 cell 1200 mah 20c battery has a maximum charge of 1.2 amps. Being a 20c discharge rate that = 1.2x20=24 amps continuous amps can be drawn from it. If it was a 30c it would be 36 amps. Very likely any 2 cell 20c battery that is at least a 1200 mah size should work.
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Old Feb 23, 2012, 11:07 PM
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tonyd075's Avatar
United States, PA, Pittsburgh
Joined Feb 2012
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whirlcap thanks for the info
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Old Feb 23, 2012, 11:36 PM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
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Quote:
Originally Posted by whirlcap View Post
Found more battery information. To find the continuous current draw rating for a battery, you need to know its maximum charge rate. It is that number times the "c" rating. For example: my 3 cell 1200 mah 20c battery has a maximum charge of 1.2 amps. Being a 20c discharge rate that = 1.2x20=24 amps continuous amps can be drawn from it. If it was a 30c it would be 36 amps. Very likely any 2 cell 20c battery that is at least a 1200 mah size should work.
C does not stand for "Charge Rate", but for the battery's Capacity.

Your battery has a capacity of 1200mAh or 1.2Ah, i.e. C = 1.2A

Usually, all LiPo batteries can be safely charged at 1C, or 1.2A for your battery. You also have types nowaydays, which can be charged at much higher rates, but that does not change the value of C. Only the charge rate may now be 4C to 6C.

Jürgen
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Old Feb 23, 2012, 11:38 PM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
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Quote:
Originally Posted by tonyd075 View Post
I am looking into getting a few LiPo's for my MM. First of all can I even use a LiPo on the stock 400 brushed motor?

If so then what size battery should I get? 2s or 3s? 20c,25c or 30c? 7.4v or 11.1v? Also what mAh 1600, 2200, 2650, 3000?
A 2s2000mAh to 2s2200mAh LiPo should be fine. 2S = 7.4V nominal voltage.

Jürgen
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Old Feb 23, 2012, 11:57 PM
If it spins, wear it.
whirlcap's Avatar
Northern Nevada
Joined Jan 2011
2,255 Posts
Jurgen,
Thank you for clarifying that. The "c" can be confusing. The maximum charge rate is referred to as a "c" in much of the information I have been reading, it's used again with a double digit number to rate its discharge but often without giving the maximum charge number. However, your explanation of the capacity clears that up. I should not have recommended a capacity without more understanding.
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Old Feb 24, 2012, 07:44 AM
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tonyd075's Avatar
United States, PA, Pittsburgh
Joined Feb 2012
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Jurgen,
Thanks for the info. I understand now about the 2s and 3s. I have also read up on lipo batteries last night and I am still wondering about mAh and 20c rating. My understanding is the higher the mAh the longer the flight? I was looking at a 2650 or a 3000. Would this be ok? Also the "c" rating is the rate of discharge? Things that I have read say this rating is over rated.

All I am doing right now is slow flying and learning to fly. The more I am able to keep the MM in the air without a battery change the better, since landing in the field where I am flying is a problem for me!!!!
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Old Feb 24, 2012, 10:35 AM
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Jurgen Heilig's Avatar
53859 Niederkassel, Germany
Joined Sep 2000
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Quote:
Originally Posted by tonyd075 View Post
Jurgen,
Thanks for the info. I understand now about the 2s and 3s. I have also read up on lipo batteries last night and I am still wondering about mAh and 20c rating. My understanding is the higher the mAh the longer the flight? I was looking at a 2650 or a 3000. Would this be ok? Also the "c" rating is the rate of discharge? Things that I have read say this rating is over rated.

All I am doing right now is slow flying and learning to fly. The more I am able to keep the MM in the air without a battery change the better, since landing in the field where I am flying is a problem for me!!!!
A battery rated "20C continuous discharge" can be discharged at 20 times its nominal capacity, i.e. a 2200mAh (= 2.2Ah or 2.2C) can be discharged at up to 44A - provided the battery is cooled as required. Discharging a battery at 20C also means, that the battery is completely drained in less than 3 minutes.

As mentioned before, a 2s2000mAh or 2s/2200mAh battery is more than adequate for a MiniMag. A bigger battery may provide slightly longer flights, but may not fit into the battery bay and makes the model heavier and more "sluggish". If you have problems landing the model with a light battery in your field, you will have even more problems with a heavier battery.

Better to look for a descent flying field.

Jürgen
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Old Feb 24, 2012, 02:42 PM
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tonyd075's Avatar
United States, PA, Pittsburgh
Joined Feb 2012
37 Posts
Jurgen,
Thanks again for the valuable information. I wound up ordering 3- 2650mAh 2s 20C LiPos and Thunder AC6 charger.

I looked at the different weights on the LiPos and tried to match up the largest 2s battery that had the same weight as my current NiMh batteries.

Thanks again

P.S. no flying today winds expected to get upwards to 60 MPH (96.5 km/hr) and snow later
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Old Feb 24, 2012, 10:53 PM
If it spins, wear it.
whirlcap's Avatar
Northern Nevada
Joined Jan 2011
2,255 Posts
I have settled on my prop, motor battery combo now. Getting 20 minutes flight with my BL Alpha 370 1080 kv motor with a 8x4sf prop and a 1200 mah 20c battery (charge rated at 1.2 amps) Performs well and my MM has ailerons added and will ROG off grass in about ten feet. (3 meters) Climb is strong and loops from level flight with WOT. Battery, motor and ESC are only warm to the touch on landing. I don't have a WATT meter but everything seems to be well within operating envelope. The plane also flys well in 10 MPH wind. I was able to get out twice today and fly in both calm conditions and the 10 MPH wind later in the day.
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Old Feb 26, 2012, 06:26 PM
Build, fly, crash. Repeat.
Goeland86's Avatar
Switzerland, Canton of Neuchâtel, Neuchâtel
Joined Feb 2007
652 Posts
Quote:
Originally Posted by whirlcap View Post
I've read 3 degrees down and 3 right as well but not sure I would go that much on this plane. I use that much on my micros though. I'm using the stock mount for my brushless motor on my MiniMag and the stock angle, whatever it is. Looks pretty straight.

I'm running stock recommended throws on mine too and have the differential set on the ailerons as recommended. I did bump the travel on the ailerons a bit but roll rate is still pretty low. I think I allowed just a hair more "up" on the elevator. Heading for the ground is a bad time to say, " I wish I had more up travel".

EDIT: I looked closely at the stock motor mount and it looks to have three degrees of both down and right factory built. Since my motor swap is using the factory mount, I still have these angles in place. I guess I notice it more on my smaller planes. It's not as obvious on the MM at a glance.

Gotcha, thanks for the info! Sorry for being late replying - but time has a habit of running away from you when your thesis is afoot!

I'm thinking I might get some washers to angle the plate downwards even more, and I'll switch to the 8x6 prop (webOcalc seemed to recommend it more than the 7x5). The 7x5 hardly had any torque effect at all, so I'm not worried about the side-thrust. I may just mix some elevator with the throttle though, and fix the range of throws available.
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