Noob lipo question.

[Dewster]

Is it possible for a battery to go under voltage per cell during flight and trigger DJI's voltage monitor even though only 30% of the capacity has been used.

I know the battery voltage drops under load, but i haven't touched the 80% capacity of my battery.

 

[Benjamin Kenobi]

Yes, it is. Reduce your cutoff voltage a bit, the default is too high. I have mine to warn me if it gets to 3.4V per cell. Admittedly it never gets that low but that's the point. If your protection activates you know there's something wrong. A timer is more accurate. How much mah you out back in on the charger is a true test of how much your setup is pulling.

 

[TAPPEDOUT]

I turned NAZA voltage monitoring off and use the cheap voltage display with audible alarm set at 3.7 v along with timer.

 

[Dewster]

Thanks! I've adjusted the low voltage settings and will do a test run with a lipo checker. I'm trying to find the sweet spot for keeping it in the air and landing safely when the first level kicks in.

 

[OneStopRC]

Get a higher discharge rated battery also, posting more details of your setup will render you more replies. What are you flying with, batteries? age of batteries? quad or hex? weight?

 

[janoots2]

Agreed, go with a $9 ebay lipo audible alarm for each battery and timer.

 

[Dewster]

I found two very helpful links for lipo batteries. The key is not letting the cells of the battery get low under load (while in flight). The voltage bounces back on the ground. I have a lipo alarm. I will hover test the craft and monitor the voltage and flight time (at hover) to see when DJI's first stage warning kicks in. I will recharge the battery to see how many mah are put back in to the battery and compare that with its capacity to make sure that I'm not going over the 80% threshold.

http://www.instructables.com/id/Lithium-Polymer-Etiquette/?ALLSTEPS

Im using two 6000 mah 3S lipos in parallel for a 7 pound craft. I've been getting on average 6-6.5 minutes of flight time and I'm putting 40% back into the batteries when I recharge. I'm trying to figure out if I'm going below voltage during flight before reaching 80% of the battery threshold.

 

[janoots2]

It's a great exercise. You can also take a voltage read off the alarm while flying every minute. Do that for 5 or 6 batteries and then chart them on excel to see how they discharge.

After doing this I found the dji voltage protection to be inconsistent (most likely due to the inconsistent nature that lipos discharge). Now I just use an alarm for each battery and a timer and it works great.