Agree with
@The Editor ,
@johnmeyer and other comments. One advantage of the DJI smart batteries is their "smart" circuit... that works 98% time... until battery lipo chemistry begins to alter; which can be caused by temp, rough handling, improper charging, and simply lipo chemistry breaking down... to list a few.
Standard LiPo's (non-smart) require care when charging in current rate, measuring IR, and cell balance. They also require an adopted routine to discharge, balance or cycle ... or as needed. Determining these needs requires more attentive knowledge and attention to the LiPo. They also require additional hardware beyound simply plugging in a charge pak and sliding a set of batteries on rack.
The majority of this LiPo maintenance interaction has been removed, blocked, prevented, hidden from the DJI Owner... and given a nice name... "smart battery" so you simply use & forget... until one of the above causes of failure... or simply life cycle.
To deviate for a short bit...
You CAN prevent "premature" failure, but you CAN NOT actually "extend" or prevent life cycle failure... the LiPo gel chemical has a specific lifetime. The act of "charge" & "discharge" behavior of the chemical will deteriorate, fade and cease to provide a useable storage battery... regardless of your attempts to extend, it began decay the day the chemical was mixed... and if low grade chemicals or poor mix ratios, it effects quality, life span or both. Those non-OEM batteries selling much lower in price; part of lower price is "Brand", but a lot of the cost savings is chemicals or mix.
In a very rough comparison, compare it to the old "Playdough" we all enjoyed as a kid (at least the Old Farts)... once the can was opened: 1 method of decay began: "Drying", but even if you never opened that 1 special can, placed it in frig, cool dark closet, etc... the other decay already started: "chemical breakdown", it's ability to bond, adhere, etc was less even if newly opened a few years later. As a rough comparison, LiPo is behaving similar... chemical instability... aka: decay. If decay is rapid, or poor, cheap chemicals or shielding foils... results in rapid instability that can produce undesired burn, explosion, spray, etc.
Back on Smart Battery...
The DJI Smart battery prevents (most of the time) the extreme low voltage, over saturation (over charge), imbalance of cells, etc. The circuitry prevents low
voltage, over charge, attempts to balance cells, and will provide a trickle discharge circuit that turns on after specified time.
Taking a "smart battery" down to App indicated zero is probably in the range of 20-25% based on voltage at near Smart zero. LiPo minimal volt is often debated, but 3.0v to 3.2v per cell is considered bottom value, and 3.5v commonly stated as base. The Smart circuit's LVC is normally 3.4 which is not near a damage point... statically( no discharge). Nominal voltage is usually 3.7, thus just above at 3.8 is considered safe storage and where the Smart circuit is targeted.
I mention "statically" above... in simple terms; if flying the discharge rate can pull surface saturation faster than cell can replenish... so it is possibly to draw a "cell" down below 3.0v if other cells are higher; and/or dip the voltage below the ECM circuit rating, effecting craft stabilty & reliability. Thus the logic in designed lower limits to land within safety margins. Watch your App's voltage indicator after shutdown of motors but still on... voltage quickly climbs.
Some of the smart lipo killers... 1) high amperage draw consistently discharging rapidly, 2) high heat, storing battery case in trunk in Summer, 3) hard drops causes possible gel to shift altering density of material, and 4) Recharging a spent battery prior to cooling down... keep in mind if feels warm externally, the gel is HOT internally. Observing these points will help prevent premature failure... often referred to extending battery life.
All these points are why SAR teams have minimum of 3 sets, if not 5 or 6 sets. Many Surveyors or SAR teams take a cooler along for assisting in cooling batteries... and refreshments.
As indicated earlier, not a major concern compared to standard LiPo maintenance. Until the smart battery fails, the "smart" will help you maintain the battery. Just use it as designed, be glad you don't have to charge it as a standard lipo needing to connect balance leads, charge leads, set C rate, number of cells, etc.
My personal routine, fly to 25-28% and if time allows I'll hover until 18-20%, land and restart motors to 12-14%. If more rushed, fly to 35% and recharge when cooled.
