Battery Discharge Questions

[OCsurfer411]

Coming from the R/C car World, I used my charger to do periodic discharges of my batteries and to balance the cells.

For the DJI batteries, I've been told all of the intelligence for balancing and battery health is contained within the battery, and the charger is basically just a power source. I'm going to accept that as true unless somebody says otherwise and offers me an alternative way to test and keep my Mavic batteries balanced.

The manual suggests fully discharging the batteries once every 3 months, and it recommends running it in the Mavic to facilitate this discharge. But here's my question...discharge to WHAT percentage?

Right now I have my threshold set at 30%, so that's when my controller starts yelling at me to land. So it's rare that I let a battery get below 20-25%. How far should I let it go down to once every 3 months in order to maximize battery life?

 

[NYCMAV]

From what I understand they automatically discharge after 10 days as per the stock setting in the DJI app. Theres an option to change this but I'm guessing its fine as is and its not something to be worried about.

 

[OCsurfer411]

Yeah I saw that part, but I'm not talking about long-term storage discharge, I'm talking about discharging the batteries once every few months to keep them conditioned, as recommended in the DJI Battery manual:

https://dl.djicdn.com/downloads/mavic/Mavic+Pro+Intelligent+Flight+Battery+Safety+Guidelines-EN.pdf

What I'm most concerned with is that it recommends discharges every 3 months, and it says how to discharge it, and it says not to over-discharge it, but it doesn't say anywhere what percentage is "discharged enough."

 

[voxelman]

The preferred storage charge level for lithium batteries is about 50%. I'm not sure that this is the value DJI is recommending as a full discharge level. At least from my experience with other lithium battery systems such as those used in phones, a deep or full discharge level would be to something below 10% of total capacity. The primary purpose is to recalibrate the capacity measurement calculations used by the intelligent battery circuitry.

On a related topic, deep discharging is one of the procedures that is recommended to address the issue with iPhones shutting down prematurely when they appear to have remaining charge.

I don't have enough first-hand experience with DJI systems to be sure but I thought that one of the features of DJI's intelligent battery designs was to limit over discharge of the battery. A typical lithium battery discharge limit setting is 3.00 volts. How quickly a specific battery reaches this level depends on several factors the most significant being the rate of discharge.

 

[OCsurfer411]

Thanks Voxelman, that is helpful.

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