Battery Discharge < 10 days

[Chips]

Interesting discussion with some facts and a few opinions. I have had one set of 4 Spark batteries for over a year and the available time does not seem to have changed. To keep the usage balanced, I have numbered each battery and use them in sequence and as I usually fly on weekends, I charge on Friday night and on Sunday evening, I pack them away without recharging. Sometimes one or two batteries may not have been used but I can't help it.

Same for my Mavic Pro batteries which are 7 months old.

 

[WithTheBirds]

I think it’s right to say knowing the IR of the pack would be meaningless for a series connected battery, particularly because we are interested in the weakest cell and variations to give us an indication of pack health.

While we don’t see it in the GO app the BMS SOC does make very frequent measurements of IR for each cell which are logged and contribute to the battery health value. Actually the battery smarts also do a very good job of determining actual and usable capacity. Time to empty fuel gauging is, as you would have seen, very reliable- the algorithm uses temp, IR, instantaneous and average current draw, voltage under load, and probably other factors to determine capacity and remaining flight time. If you are interested have a look at impedance track and gas gauge on the Texas Instriments website.

I have phantom 3 batteries well over two years old I still trust, flight time is down but the flight time remaining is still reported accurately. Another security we have is the DJI firmwares also limit propulsion when the battery struggles, it is difficult to push them to fail in flight.

 

[mnis]

Interesting discussion with some facts and a few opinions. I have had one set of 4 Spark batteries for over a year and the available time does not seem to have changed. To keep the usage balanced, I have numbered each battery and use them in sequence and as I usually fly on weekends, I charge on Friday night and on Sunday evening, I pack them away without recharging. Sometimes one or two batteries may not have been used but I can't help it.

Same for my Mavic Pro batteries which are 7 months old.

YES...
You can certainly do something about it. I guess you just do not have the time to invest a little care in your batteries.

I would recharge empty batteries as soon as possible after cooling down. You can easily bring the batteries back to over 50 percent charge for storage when you connect the battery to recharge and remove it as soon as the third LED flashes for a while. A timer or alarm clock may help.

Full batteries you can discharge also in Quadrocopter. Just leave it in the switched ON state for a while without connection to the remote control. Anyway, that works quite well on the Mavics, for example, and roughly requires 30 to 45 minutes per battery.

 

[W2EJ]

On the Mavic 2 Pro? That setting defaults to 10 days and cannot be changed.

Mike, I wonder if you know. Does the discharge begin after 10 days, so in other words, on day 9 since the last charge, the battery would still be near 100%?

 

[WithTheBirds]

Mike, I wonder if you know. Does the discharge begin after 10 days, so in other words, on day 9 since the last charge, the battery would still be near 100%?

It’s 10 days. It begins after 10 days.

 

[Gregdd]

A great option to knock the top off any lipos you find yourself with is the DJI battery-USB power adapter. Use it to load up your controller and any other devices that need USB charge/power.

Yes that's what I do but it's very slow. Also, it requires me to remember to do it.

 

[DanMan32]

My M2 remote holds its charge. It was at 99% after having charged it over a week ago.

As for hibernation, I'm pretty sure the manual states that after 30 days it hibernates where you must connect it to external power to get it to turn on.

Lots of devices, particularly laptops are shipped this way so that the storage/shipping SoC can remain at 60% without the device power management draining the battery. I even found Asus's utility in the hidden drive partition that electronically disconnects the battery from the laptop's power management. In such a state, the only way to power it on is to connect the AC power supply. Once you do this for a few seconds, you can then use the battery. No need to first charge the battery to a certain level to activate the power management and get it to turn on strictly on battery power.

 

[WithTheBirds]

My M2 remote holds its charge. It was at 99% after having charged it over a week ago.

As for hibernation, I'm pretty sure the manual states that after 30 days it hibernates where you must connect it to external power to get it to turn on.

Lots of devices, particularly laptops are shipped this way so that the storage/shipping SoC can remain at 60% without the device power management draining the battery. I even found Asus's utility in the hidden drive partition that electronically disconnects the battery from the laptop's power management. In such a state, the only way to power it on is to connect the AC power supply. Once you do this for a few seconds, you can then use the battery. No need to first charge the battery to a certain level to activate the power management and get it to turn on strictly on battery power.

The SOC in our batteries does have a shipping mode (the SOC is effectively asleep) however it’s not clear if it is enabled in manufacture if the packs. I have bought dozens of batteries for phantom and Mavic and nine have arrived at the same SOC regardless of how old or fresh (based on manufacture date).

 

[WithTheBirds]

Yes that's what I do but it's very slow. Also, it requires me to remember to do it.

Depends on your definition of slow. The adapter has two 5V 2A outlets so it can pull your 59wh M2 battery down to 50% from full in about an hour an 15 mins (allowing for the losses in the voltage conversion and regulation) if you have a couple of devices hanging off it. The remote is an obvious candidate for one of those charge ports.

 

[Gregdd]

Depends on your definition of slow. The adapter has two 5V 2A outlets so it can pull your 59wh M2 battery down to 50% from full in about an hour an 15 mins (allowing for the losses in the voltage conversion and regulation) if you have a couple of devices hanging off it. The remote is an obvious candidate for one of those charge ports.

I am not sure if your calculations are wrong or not but I did some testings and my results were much different. I plugged in two fast charging devices to the USB ports and after 30 minutes the battery went down by only 12%. Do you have some suggestion on a device that can drain via USB at a faster rate? I also tried some LED lights that I have but that was even slower.

 

[ff22]

I have to admit I'm somewhat confused. Maybe most of my other battery powered devices are just very different or I've never really worried about getting the batteries charged, in Goldilocks' word, just right.

Since these batteries are designed to self-discharge, is it really important for me to sweat it and tweak their residual power after each use or just let the internal mechanics do their job? Clearly, there must be some importance to charge values since DJI did incorporate the self-discharge process.

 

[WithTheBirds]

I am not sure if your calculations are wrong or not but I did some testings and my results were much different. I plugged in two fast charging devices to the USB ports and after 30 minutes the battery went down by only 12%. Do you have some suggestion on a device that can drain via USB at a faster rate? I also tried some LED lights that I have but that was even slower.

I will make a point of timing it. If I have a full pack and plug the IPad Pro and NAS drive into it she is well into the third light flashing on the battery by the time I have transferred my SD card to my home storage and looked at the images and video’s with a bit of editing.

The Ipad has a 36wh battery so just walking off and leaving it alone to charge I know when it’s charged Mavic battery will be at a nice SOC for storage (I charhe the ioad when it’s about 30% remaining).

 

[Gregdd]

I have to admit I'm somewhat confused. Maybe most of my other battery powered devices are just very different or I've never really worried about getting the batteries charged, in Goldilocks' word, just right.

Since these batteries are designed to self-discharge, is it really important for me to sweat it and tweak their residual power after each use or just let the internal mechanics do their job? Clearly, there must be some importance to charge values since DJI did incorporate the self-discharge process.

If you are planning on using the batteries in the near future no sweat at all. However If I know I am not going to fly i don't want to wait 10 days for them to discharge. There is plenty of information on Lipos on the internet and leaving them fully charged for 10 days, when it is not necessary, is not a good idea. Don't believe what DJI says, their batteries are just Lipos like all the rest.

 

[WithTheBirds]

If you are planning on using the batteries in the near future no sweat at all. However If I know I am not going to fly i don't want to wait 10 days for them to discharge. There is plenty of information on Lipos on the internet and leaving them fully charged for 10 days, when it is not necessary, is not a good idea. Don't believe what DJI says, their batteries are just Lipos like all the rest.

Actually the cells in the DJI packs seem to be better than a lot I have used. Yes, the reality is for all LiION chemistries keeping them at full SOC will contribute to accelerated usable capacity loss (increased IR) but it is not the monumental degradation we saw in earlier LiION tech. Would be interesting to see a current study on the effects with current cells. They certainly seem to fair quit well.

 

[Gregdd]

Actually the cells in the DJI packs seem to be better than a lot I have used. Yes, the reality is for all LiION chemistries keeping them at full SOC will contribute to accelerated usable capacity loss (increased IR) but it is not the monumental degradation we saw in earlier LiION tech. Would be interesting to see a current study on the effects with current cells. They certainly seem to fair quit well.

I have read a lot over the years and the general consensus is that Lipos are Lipos. Leaving them fully charged is a bad idea. Until I see something that overrides those years of experience I will default to that. You even said yourself you haven't seen any recent studies so why comment to the contrary? What makes you think DJIs are any better? The only thing DJI has is better monitoring. I completely disregard my own experience (and yours) because the sample size is too small.

 

[WithTheBirds]

I have read a lot over the years and the general consensus is that Lipos are Lipos. Leaving them fully charged is a bad idea. Until I see something that overrides those years of experience I will default to that. You even said yourself you haven't seen any recent studies so why comment to the contrary? What makes you think DJIs are any better? The only thing DJI has is better monitoring. I completely disregard my own experience (and yours) because the sample size is too small.

Keeping LiION calls (all types) at or close to the rated max terminal voltage will accelerate their degeneration, no question. I am quoting my recent (several years) direct experience where I keep a couple of DJI packs charged (rotate among many packs) with no significant negative effects.

 

[Gregdd]

Depends on your definition of slow. The adapter has two 5V 2A outlets so it can pull your 59wh M2 battery down to 50% from full in about an hour an 15 mins (allowing for the losses in the voltage conversion and regulation) if you have a couple of devices hanging off it. The remote is an obvious candidate for one of those charge ports.

I just did some more testing. Your math is correct but actually drawing 20w per hour is not realistic with modern phones and tablets. They don't charge (draw) at a constant rate and are often drawing much less. So in a real world test I used two fast charging devices, each at or below 20% battery level and it took two hours to get the M2 battery to 50%. Also, I have 4 M2 batteries so if I want to go for a flight and they are charged it isnt realistic to use phones to discharge them.

 

[Gregdd]

Keeping LiION calls (all types) at or close to the rated max terminal voltage will accelerate their degeneration, no question. I am quoting my recent (several years) direct experience where I keep a couple of DJI packs charged (rotate among many packs) with no significant negative effects.

Sample size is too small to use your own observations.

 

[WithTheBirds]

Sample size is too small to use your own observations.

Not for me it isn’t.

 

[mnis]

The DJI powerbank adapters are good, I would say too good to be able to quickly bring several flight batteries to storage voltage, the conversion to 5 volts is done with 90% efficiency. I mentioned it already ... There are devices specifically for the purpose of discharging batteries. Such devices generally cost less than a single DJI battery. In addition, only a matching charging cable with XT60 connector is needed, nothing more. Discharging devices such as the ISDT FD-100 or the SkyRC BD-200 are reliable and fast. Of course, both devices can be discharged to a predefined voltage. The automatic discharge of Mavic batteries already ends at 3.89V per single cell (3S-M1P 11.67V / 4S M2x 15.56V). That's 10mV above the recommended storage. Excitement for, probably because it's HV LiPo's. Anyway ... Who does not want to use a discharger, can empty the unused batteries at any time in his Mavic, because the high-tech wonders eat a lot of energy, even without a single flight minute ...