Drone nube- I have just started practicing with my trainer- a Holy Stone RC MC68R (based on Syma ...

[G+_Jim Koester]

Drone nube- I have just started practicing with my trainer- a Holy Stone RC MC68R (based on Syma X5C?). I purchased two extra batteries , 650 mAh 25C, that are causing trouble. I was able to charge them once, and got some decent flight time from both. But after recharging about 90 min each, using the basic charger that came with the quad, I can't get more than 15 seconds of run time! Results in rapid flashing LEDs, as if low charge. I waited a full day, so temperature can't be an issue. I AM able to fly using the provided 500 mAh cells.

 

I measured 4.4 volts (no load) on these cells after charging. Is this too high? Do I have the incorrect type of Lipo?

[G+_Steve C]

You could have got bad batteries but it sounds like they aren't getting charged up completely.  Are you using the USB powered charger cable that came with the X5C?  Don't try to charge it off a USB port but use a wall mounted charger for a tablet instead since they have more output.   While the batteries are rated at 3.7 volts they generally go up to a little above 4 volts so the voltage is probably OK.

[G+_Eddie Foy]

Plugged in solidly?

[G+_Steve C]

Yes, on the X5C the battery plug doesn't want to go all the way in the first time. You have to press hard until it goes all the way and snaps in.

[G+_Jim Koester]

I agree about the voltage. I just finished charging one of the 500 mAh cells, reads 4.2 volts.

Yes- the charger gave me a "completed" led after being connected for about an hour. If you mean in the quad, yes, I have learned to wait for that click. In fact, had to use needle nose to remove it!

 

I am a bit skeptical about the capacity of the source. It's my understanding that the 25C rating implies that it can be charged quickly -IF I had a large capacity charger.

Do you think it also " Requires" a bigger charger?

 

Perhaps I'll use a USB3 port next...

[G+_Eddie Foy]

25C is the discharge rate (ie: when in use)

 

Can you measure the voltage with the quads tied down and props at full speed?  It shouldn't drop more then 0.1 - 0.2 V  (I'm guessing)

[G+_Jim Koester]

I believe the upper case "C" is the charge rating, while a lower case "c" is discharge rating. ( At least that's what I read over on UltimateRC.com)

 

I can't measure with the motors running, unless I disassemble the quad. Or rig up some extra leads from the battery connector to the quad.

 

I think it would be easier to test the voltage across the battery with a resistor as a dummy load. Maybe I'll try that tonight...

[G+_The Grimm Perspective -]

Not sure what you're referring to when you say upper case "C" and lower case "c"? But your 25C is the battery discharge rate. Most would suggest a charge rate of 1C or in your case 650mAH/1000=.65A

[G+_Jim Koester]

I appreciate the feedback, I'm learning more every day!

The discussion about the meaning of the"c" rating was fueled by an interesting post over on UltimateRc.com

 

forum. https://www.google.com/url?q=http://www.ultimaterc.com/forums/showthread.php%3Ft%3D115264&sa=U&ei=ztsSVeONENi3yAT2poHoAQ&ved=0CAYQFjAA&client=internal-uds-cse&usg=AFQjCNGNurG73QuFx7pYYRmZNxkiboPBDA

 

Part of the problem may be the very basic USB charger that came with the M68R. Did it allow the cell to overcharge? Both show a voltage of 4.4v after charging, and one has puffed up .

[G+_Jim Koester]

Just a quick follow up- KH episodes 117 & 118 had great discussion on Lipos and charging.

Ordering my Lipo charging bag tonight!