HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Dec 06, 2012, 08:57 AM
Registered User
United States, MD, Severn
Joined Nov 2012
10 Posts
Discussion
Low batt symptoms??? - mcx2

Last night i was flying and all of a sudden the heli started losing altitude and ignored tx input. I'm guessing that this is because the battery was low (don't know how long i was on it) but the blades kept spinning. I was able to get to the heli and pick it up from the front but had to unplug the battery to get the blades to stop turning. Is this normal, it seems a bad way for the heli to react in a low batt situation if that really is what happened. I put a fresh battery in and it seemed fine. How can I tell when the battery is getting low?

Thanks.
oly_r is offline Find More Posts by oly_r
Reply With Quote
Sign up now
to remove ads between posts
Old Dec 06, 2012, 09:34 AM
Closed Account
Joined Dec 2007
6,549 Posts
Quote:
Originally Posted by oly_r View Post
Last night i was flying and all of a sudden the heli started losing altitude and ignored tx input. I'm guessing that this is because the battery was low (don't know how long i was on it) but the blades kept spinning. I was able to get to the heli and pick it up from the front but had to unplug the battery to get the blades to stop turning. Is this normal, it seems a bad way for the heli to react in a low batt situation if that really is what happened. I put a fresh battery in and it seemed fine. How can I tell when the battery is getting low?

Thanks.
Sounds like you hit the low voltage cutoff (LVC) set into the heli. Typically they will just lose powe and the rotor will slow to the point that the heli falls, but I do remember my old MCX having some strange behaviors sometimes when LVC kicked in.

You don't want to be flying your batts down to that level often, or they will be damaged even more quickly than E Flight batteries do anyway.

Time you flights so you land before hitting the limit.
Xrayted is offline Find More Posts by Xrayted
Reply With Quote
Old Dec 06, 2012, 10:57 AM
Registered User
United States, MD, Severn
Joined Nov 2012
10 Posts
crap, i'm lousy at keeping track of time when i doing something. this doesn't bode well for my batteries. how long is safe then?
oly_r is offline Find More Posts by oly_r
Reply With Quote
Old Dec 06, 2012, 12:01 PM
Closed Account
Joined Dec 2007
6,549 Posts
Quote:
Originally Posted by oly_r View Post
crap, i'm lousy at keeping track of time when i doing something. this doesn't bode well for my batteries. how long is safe then?
There is no way for me to answer that question. It all depends on how robust the current batteries you are using are, and the average flight time you are currently getting with them.

For larger helis and packs we typically do a couple minute test flight on a full pack, then re charge the pack back to full using a charger that tells us how much Mah was put back in. We can then determine how much Mah is being used per minute and calculate how may minutes we can fly using only 80% of the packs capacity (Mah) You always want to leave at least 20% capacity in the pack.

80% is the general rule for lipos if you want them to last, but my assumption is you are using a stock E Flight charger setup and don't have a way to determine capacity being used.

There are two things you can do. Determine how many minutes you can fly before hitting LVC and simply take a minute or so off of that values so you aren't hitting it anymore.

Another option is get yourself a cheap voltmeter and test the batteries voltage after flight. A resting voltage of about 3.7-3.8 after flight typically means you are in the 80% capacity used range......not perfect, but will work in a pinch. Time your flights so that you are not taking the batt down more than this and you should be ok.

Be very careful if testing voltage on those little MCX batts though! It's easy for the tips of the voltmeter to touch each other while testing, and this can cause a short. The lipo can smoke and puff up instantly or possibly catch fire if its shorted out. It's safer to use a female plug with wires on it that will fit the battery, and test using the wire ends.
Xrayted is offline Find More Posts by Xrayted
Reply With Quote
Old Dec 07, 2012, 08:14 AM
Registered User
Philippines, Calabarzon, San Pedro
Joined Jul 2012
4,122 Posts
Quote:
Originally Posted by oly_r View Post
crap, i'm lousy at keeping track of time when i doing something. this doesn't bode well for my batteries. how long is safe then?
Doesn't your TX have a timer?
Hajile is offline Find More Posts by Hajile
RCG Plus Member
Reply With Quote
Old Dec 07, 2012, 10:12 AM
RTF (Ready to Fragment)
Steve_'s Avatar
United States, WI, Beloit
Joined Nov 2012
3,785 Posts
My 250 clone will get a sticky throttle if the pack gets too low.
My Double Horse on the other hand will just drop out of the sky.

For the MCX2, 2 reviewers and 3 people on forums all say
6 to 7 minutes to dump a pack.

If you don't have a timer with an alarm, buy one.
Here is one for under $3 shipped:

http://www.ebay.com/itm/White-Mini-D...item5894d6e0bb

If you don't mind waiting, I found some in Hong Kong for under $2.

I'm pretty good at judging time, so I have gotten by without one,
but I will buy one soon.
Anymore, I try to make my flights 5 minutes or less, just to keep
the motors and electronics cooler. Heat is the #1 reason for failures
with electronics in general. I repair laptops, and I get around one a week
that got so hot inside, it basically de-soldered itself.
Steve_ is offline Find More Posts by Steve_
RCG Plus Member
Last edited by Steve_; Dec 07, 2012 at 02:52 PM.
Reply With Quote
Old Dec 07, 2012, 05:45 PM
Registered User
United States, MD, Severn
Joined Nov 2012
10 Posts
I'll get a timer for sure, i'm lousy at keeping time while involved with something. When i get into something i lose all track of time. My wife hates when i'm reading or doing just about anything that i concentrate on, i don't even realize she is talking to me. hehehe.

Thanks for the general info all, i was hoping for a ballpark answer so that helped.
oly_r is offline Find More Posts by oly_r
Reply With Quote
Old Dec 08, 2012, 09:14 AM
RTF (Ready to Fragment)
Steve_'s Avatar
United States, WI, Beloit
Joined Nov 2012
3,785 Posts
Quote:
Originally Posted by oly_r View Post
I'll get a timer for sure, i'm lousy at keeping time while involved with something. When i get into something i lose all track of time. My wife hates when i'm reading or doing just about anything that i concentrate on, i don't even realize she is talking to me. hehehe.

Thanks for the general info all, i was hoping for a ballpark answer so that helped.
Being able to tune them out is such a life-saver

Marriage saver... not so much.
Steve_ is offline Find More Posts by Steve_
RCG Plus Member
Latest blog entry: HK450GT Lights
Reply With Quote
Old Dec 10, 2012, 02:54 PM
Registered User
Joined Aug 2012
1,472 Posts
Low voltage alarm

Quote:
Originally Posted by oly_r View Post
I'll get a timer for sure, i'm lousy at keeping time while involved with something. When i get into something i lose all track of time. My wife hates when i'm reading or doing just about anything that i concentrate on, i don't even realize she is talking to me. hehehe.

Thanks for the general info all, i was hoping for a ballpark answer so that helped.
On the first page of Banggood.coms' website they have a low voltage alarm for $3.11 and free shipping. You can set the voltage that you want it sound off at. You can attach it to your heli with zip strips. I think they're worth their weight in gold.
Pa flyer is offline Find More Posts by Pa flyer
Reply With Quote
Old Dec 10, 2012, 04:06 PM
Registered User
United States, MD, Severn
Joined Nov 2012
10 Posts
This one: http://www.banggood.com/Wholesale-7_...r-p-25595.html

sounds like a great way to go my only question is How do you connect these? Please say it isn't a soldered connection.
oly_r is offline Find More Posts by oly_r
Reply With Quote
Old Dec 10, 2012, 04:26 PM
RTF (Ready to Fragment)
Steve_'s Avatar
United States, WI, Beloit
Joined Nov 2012
3,785 Posts
Quote:
Originally Posted by oly_r View Post
This one: http://www.banggood.com/Wholesale-7_...r-p-25595.html

sounds like a great way to go my only question is How do you connect these? Please say it isn't a soldered connection.
I think they just plug into the existing balancing / charging plug on the battery.
Steve_ is offline Find More Posts by Steve_
RCG Plus Member
Latest blog entry: HK450GT Lights
Reply With Quote
Old Dec 10, 2012, 07:39 PM
Closed Account
Joined Dec 2007
6,549 Posts
Quote:
Originally Posted by Steve_ View Post
I think they just plug into the existing balancing / charging plug on the battery.
He has a tiny little 1oz MCX with a one cell battery. Those are for larger helis with multiple cell batteries and there is no way to connect it any of the electronics or battery.


Simply time the flights.
Xrayted is offline Find More Posts by Xrayted
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
For Sale Blade MCX2 RTF with 4 TP batts and AC adapter for charger - 85 bucks shipped con US NickBee Aircraft - Electric - Helis (FS/W) 0 Jun 08, 2012 10:55 PM
Discussion mCX2 controller batt change and now trim is off? supermarvin76 Electric Heli Talk 1 Mar 24, 2012 06:31 PM
Discussion mCX2 controller batt change and now trim is off? supermarvin76 Coaxial Helicopters 0 Mar 22, 2012 08:05 PM
Question MSR/ Symptoms of batt. failure tippytoe Micro Helis 8 Jun 17, 2010 01:40 PM
Question Symptoms of 2s lipo reaching low voltage? lammy1000 Batteries and Chargers 3 Dec 04, 2007 08:25 AM