Harvick

Just got my first heli ever(CX2) getting ready to try it out today, and the manual warns that if the battery is discharged too far, it may not charge, and may need to be replaced.

How can I avoid over disscharging the battery, never had a lipo before, I run nitro trucks. Am I suppose to discharge it like I do with nicads or nimh? My super brain has a discharge feature and is suppose to handle lipo's.

Can over discharge happen while flying it? How do I know when to stop flying? When it has no more power, or before that.


Thanks in advance

Harvick

Mike Ledbetter

Do NOT fully discharge this battery every time you use it, or ever at all. STOP FLYING when the copter will no longer hover out of ground effect. Good luck.

prometheus

Whatever you do, don't discharge like ni-mh or ni-cads down to zero voltage. When the battery is discharged to about 3 volts/cell, damage occurs. I don't know what a superbrain is, so i don't know what it can do.
While it is possible to overdischarge while flying, it is really hard to do. Just make sure that when you notice a drop in power, bring it down to charge. When you notice that it is taking even more throttle to hover, that is a good time to charge. thanks bzyguy

Harvick

OK, thank you very much. I thought I heard something about that just wanted to make sure before I have my first test flight tonight!

bzyguy01

When the chopper starts to require more throttle to stay in the air the battery is near charging stage. You should be able to get close to 7-9 minutes of normal flight on a fully charged battery.
Always store your lipo charged to avoid it dropping below 3 volts per cell. Any lower than this you risk unrepairable damage and could swell the battery and bossibly destroy it for good.

Prometheus,
I think you accidentally got your #'s mixed up....
The voltage cutoff should be at 3 volts per cell, Not 1.2 volts per cell.

here are a few examples:

Min Voltage for a 2 cell is 6 volts
3 cell is 9 volts
4 cell is 12 volts
5 cell is 15 volts and so on.

bzinfinity

There has got to be a way to wire a voltmeter or something in series on these helis, I'm getting very nervous about over D/Cing my LiPo's for all three of my Blade helis.

Does anyone know of a small meter that will give a reading on the fly, via a small LCD or something of the sort? It has to exist, and it probably wouldn't take much effort to solder it on if the weight wasn't a problem.

Harvick

I got my first flight it, went ok, no crashes, But I was a little dissappointed in the flight time, if I was to purchase extra batteries can I fly say 3 packs in a row without the heli overheating? I got maybe 7-8 minutes while the 1 LHS said 15 was normal, while another said they were getting close to 25-30min. Was flight time (battery charge) less because of all the landing and takeoffs I did (not all by my choice on my first flight?

bzinfinity

LiPo's, in my experience, build charge duration over their life cycles.

Your flight capacity will grow as you continue to charge the battery. My first CX2 flight was 6 minutes until loss of power. 6 minutes on second flight, etc, etc, fifth flight I got 8 minutes, my last flight, which was charge #13 was 11 minutes.

bzyguy01

The flight time is all relevent to the MAH of a battery......A 800mah lipo only holds 800 mah of usefull power. The CX and CX2 use roughly 82-100 mah of that batteries power in 1 minute. If you were to fly the chopper from the ground to the air alot you would be using the maximum amount of power as it requires more throttle to elevate....thus lowering your flight times. If you are keeping the bird in a hover constantly it will use slightly less mah (power) to do so thus giving you slightly longer flight times.

I don't care what others say when they claim 15 or more minutes of flight time because it is a fact as I did the test with my mah meter to measure the amount of mah draw it required to hover the craft and it was 89-95 mah per minute....FACT! A 800 mah battery is only good for 7-8 minutes in a CX or CX2 ....Period.
Claims over 12 minutes are bogus unless some of that time was at idle on the ground.....I am talking about straight flight time here.

Harvick, Don't be disapointed ....you got all of your time in.....Be glad you did so well and kept the bird on its feet! Congrats!

bzinfinity

Just because the battery says 800mah does not mean:

1.) It ACTUALLY contains 800mah once "charged." A number of things can affect how much is actually in the pack. (Peak detection circuitry can be faulty even when functioning properly)

2.) It ONLY contains 800mah when fully charged. My Triton is still showing 220mah at full charge OVER the label on the pack for my CP pro.

But, generally, Bzy is right, the LHS is blowing smoke with 15+ minute flight time claims.

Also, Bzy. I have the heatsinks, and I have greased the shafts and the gear mesh. It is quite possible that your heli is comsuming more power per flight than mine due to drag in the system or simple production tolerance differences, etc, etc. Not trying to flame your post, just saying that there are a lot of factors to consider.

bzyguy01

The only way to really know what is truly in a battery for true mah capacity is to do a bench test and take a battery off the charger that claims a full charge and do a draw test with a meter and discharge it until the battery nears no lower than 3 volts per cell. Then the meter will show you how mah was used during discharge till drained at 3 volts per cell and then you will know the true mah capacity of that battery and some batteries are slightly higher and some lower than the claimed batteries mah rating.

Good point BZinfinity!

bzyguy01

Harvic,
Go to this thread and you can see my test results for my CX2! Good info.

http://www.rcuniverse.com/forum/m_50...tm.htm#5062267

bzinfinity

Bzy, do you know of a way to rig a volt meter or such into a heli to see the remaining voltage of the battery and / or current draw on the pack?

That would be SO helpful.

bzyguy01

I don't know of a small enough mater that would allow the chopper to fly the same due to the added weight. There might be a remote real time gadget somewhere but I don't know and if you come across one let me know as I too would like one for my larger electric planes.

choppersrule

Hi guys,

Most of the inexpensive chargers only charge the batteries to 85% potential. You could spend alot of money on a great charger to boost the charge rate. Or opt to get a spare battery. I opt for extra batteries. More batteries, more flight time in one outting. Stay with the stock set up.

The CX2 is designed for a lot of fun, you can never make it a CP or a Trex.

Dave / Choppersrule

Harvick

Thanks for the link! I haven't been a newbie in anything RC since I was 14, until now it has only been cars and trucks. But this is alot of fun so far.

Harvick

Ok on just my 3rd charge and it took 2 hours plus. Is this normal? How long does it take you to charge your bat with the supplied charger?

bzyguy01

I'm not sure as to what rate the stock supplied charger is charging at but it takes roughly 20-30 minutes at .8 charge on my Astro lithium charger or my Great Planes Electrifly 4 charger.
I don't agree to the standard chargers only charging 85% of the lipo's capacity as I have tested the batteries mah after a full charge on one before and it did hold the stated mah rating. The stock charger most likely is only charging at a lower rate like possibly .4 or.5 rate? Never tested the chargers output tho.. Just my assumption. It's ok to charge a lipo at a lower rate than 1A per 1000mah but not to charge over that. I know I've seen people challenge this and say they charge over the suggested rate but we'll see his/her home burnt to the ground some day I bet. Charging over the suggested rate on a nicad or nimh (Fast Charging) is probabbly done on a daily basis but it does eventually take life out of that battery. But those batteries are not nearly as dangerous.

So Harvick, Its probabbly just charging at a lower rate thus taking longer to peak out at max voltage. But thats safer than over charging a battery's suggested rate. If you do upgrade to a nice charger someday as you expand into more models that use lipo's it will be reccomended to get a good charger like the astro or etc.... this way you can charge a battery at the correct rate that you can dial in.

DaveG55

I don't understand, I thought that if you charge an 800 mah battery at .8A (800ma) that it should take roughly 1 hour to acheave a full charge. Two hours at .4A, etc. How are you getting a full charge in 30 minutes or less?

choppersrule

DaveG55,

The lipo for my CX2 takes about 1 1/2 hours, the stock charger that comes with the CX2 is rated at .65 mAh. So that's about right.
It's a long wait I know. Only thing is to get a better charge or more lipos. I like lots of batteries myself.

Dave / Choppersrule

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they should give you like an owners manual or something[X(]