low battery warning

[wings]

Got a red screen that said low battery but the battery stilled showed good voltage? Can someone take a look at the telemetry for me. On the voltage page you can see where the battery took a big dip and I also got a CCW, compass calibration warning. On the very next flight, about 5 minutes later, new battery, everything was back to normal? Thank you!

 

[Steve Carr]

I think it's just a case where the battery got too low during the return flight. Looks like maybe some wind as well.

 

[wings]

Strange thing was that the voltage on the St16 was showing 15V at the time of the warning. Way to early. Or is the voltage indicator not that accurate?

 

[Steve Carr]

The display should read the same as the telemetry. The battery warning occurred when the heading was into the wind. So 11 mph speed + 13 mph wind = about 24 mph air speed.

 

[wings]

I flew a different battery just after this one, same conditions, similar flight profile and went 12:00 with no warning. Batt volts start was 16.6 End was 14.9. I attached the Volt graph from the warning flight. Does that dip look normal to you? Also, what program do you use that allows you to see the wind speed? Is it something I can get access to or buy?

 

[Steve Carr]

The battery on your first flight rebounded to 15 volts after the motors were off and it sat a couple of minutes. Perhaps it just can't deliver power at the same rate as your second battery. I have a couple of batts that work fine on conservative flights but drop quickly in wind or faster flying. I can still get 14-15 min of slow flying. At some point they will get tossed.

The wind speed came from the airport: Weather History for New Smyrna Beach, FL | Weather Underground

 

[wings]

Thanks very much Steve: Now if someone could invent a light weight battery that gave 30 minutes of flying time and cost $50 they could get very rich quick!

 

[CraigCam]

Have you compared the two batteries different resistance readings? Chances are good one of the cells on the suspect battery is at a high value. It seems any numbers over 20 ohms on a cell is a suspect battery. A good test is to hover long enough to get below half power and then in rabbit mode punch the throttle and ascend for a second. If you have a “sagging” cell, you’ll get the LVC warning that will go off during the punch but stop when you go back to center stick.

When Yuneec ventured into 3 cell lipos with the Chroma, those batteries were super fussy and really weren’t powerful enough for 3rd party camera gimbals and GoPros. That’s why they quickly added the first gen CGO2 camera and the whole ball centered design. The Chroma would descend in a power wash and bounce down. It was this forum where I learned that you can’t stay in a straight line down and getting out of your own downdraft zone was necessary. That’s a practice I use on my Q500 now as it’s descent is not stable like the 480.

With the 480, the battery is quite heavy and it’s pushing the ratio of weight to power for safe flight. Cold weather only adds to battery inefficiency and an already high ohm cell will perform more poorly. Chroma s flew away on these conditions or just power dropped within first minute of flight. I’ve got ammo cans full of batteries I’ve taken too many times into first warning and really hate getting into second as that’s were you can increase resistance. Depending on age of battery, it can improve with a good slow charge but it’s not the same as it was when new and in its early cycles. I loathe the LVC warning because that means I’m late to shut off and I’m damaging my cells. My battery logs back this up as does 100s of hours flying.

 

[wings]

I charged the suspect battery up. It indicated 4.2 per cell. Fully charged. Then I put it int he H and within 2 hours of charging went out and flew it. Wind was light but I put the H into a couple of tasks like POI and CCC. In other words I did not just let it hover. Well *** if it didn't perform great. Got 13:24 out of it. Went from 16.6 and landed at 14.5. Video was running all the time. Perhaps I did not have it charged up fully the day I had that low batt warning. Don' know. However I will always be a little leery of this battery and watch its performance carefully. I log all my battery usage and time. BTW, the voltage graph looked normal after this flight.

 

[CraigCam]

Does your charger measure internal resistance? That’s what I check now after every charge or storage cycle. The GiFi batteries seem to be the best right now. Venoms I don’t trust. Tattuu (?) have given up prematurely but it’s on two batteries that may have been left in my car on our one below freezing night. OEM Yuneec batteries usually fall within 8-12 Ohms per cell. GiFi batteries have 2-5 ohm readings. Once I see a cell get out of line with the others, I watch that battery closely. I currently own 26 batteries and of those I have 8 I don’t trust. I’m slowly heading towards all GiFi as I loose a Yuneec. “New” batteries from Best Buy have been NOS in old boxes and I’ve had them already out of spec immediately pre charge so I don’t trust any Yuneec battery sold in the white box but if I find one in the brown cardboard box I’ll jump on it. Obviously Best Buy is pulling from old internal inventory and no one knows what extremes they have been through hence the high ohms already.

Bottom line - LiPo batteries are always a crap shoot and you basically lease your power. I apply the renting beer philosophy to batteries and it helps ease the pain when I look at all my puffed up inventory I’ve accumulated over the years from my path to get here.

 

[wings]

Thanks for the info Craig. Do you have a link to the GiFi batteries? Not familiar. My Mopilot charger does not measure internal resistance. Wish it did. thanks again.

 

[rdonson]

FWIW I've had good luck with Powerextra batts - I've had them less than a year and I don't have extensive logs for the batts though.

https://smile.amazon.com/Upgrade-Po...typhoon+h+battery&refinements=p_85:2470955011

 

[CraigCam]

I bought them from Carolina Dronz
GIFI YUNEEC TYPHOON H, 7000MAH, 4S, 14.8V LIPO BATTERY

 

[wings]

Thanks Craig. I ordered one and will give it a try. In the mean time you could possibly invent a light weight battery that will give 30 minutes of flt time and cost $50? I think you could make a lot of money! lol

 

[CraigCam]

That would be amazing. I’m turning my old batteries into temporary power supplies for guitar pedals.

 

[wings]

Now that's good resource management!