Lithium batteries are everywhere - why do we need to store ours at ~50%? (and set auto-discharge at X days?)
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Kilrah
Well-Known Member
People have answered your question, but I figured you would like to hear this.
DJI batteries aren't you run of the mill hobby grade batteries, DJI calls them "intelligent flight batteries" and it's not just a marketing ploy. What makes the batteries smart is their power management system. The batteries when charged to full will stay full for an amount of time set by the user. In my case it's 10 days, after this period the battery will slowly discharge to 50 percent then go into a hibernation period. Also you can view the voltage of all of your batteries from the go4 app as well as set the discharge time.
I actually prefer NiCd batteries when not in smart products. They are eager to maintain.
Aren't LiFePO4 batteries supposed to be far more superior to LiPo s when it comes to cycle life and consistency of discharge voltage? They are also far more stable and safe from what little I know about abtteries. I wonder if DJI will switch to these in the future.
I had no idea the batteries were auto discharge after 7 days or so... That explains a lot.. I thought we were dosed to keep them fully charged.. This is good info.. Thanks everyone
Kilrah
Well-Known Member
The energy density is way less so they're typically not used in things that must fly or be small, so since DJI make small flying things they're not the best candidate. Would be good for tools.
jzguitar
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It would be great if DJI would develop an “intelligent charger” that had the option to automatically charge or discharge the batteries to the ideal storage charge. Like the 4 battery charger they have now but maybe with a “maintenance” button that would activate that feature. Just a thought.
It's quite similar to NiMH batteries — there different types with different specs and purposes.
You could buy NiMH batteries of 2 types:
Lithium batteries are much more different in their chemicals and technology.
For regular devices (mobile phones, notebooks) it's more important to have batteries that don't require some special handling. Even if capacity is lower. So, manufactures use lower capacity batteries.
But for drone battery is extremely important to have as much capacity (flight time) as possible. But you should pay price for this capacity — special handling rules.
I believe, DJI may create some kind of optional "low-discharge" batteries that would keep full charge for years. But it would significantly decrease flight time (maybe, 20 minutes in Mavic 2 Pro instead of 30 minutes on standard battery).
For me it's more important to have maximum possible flight time (so, pay price of keep batteries half-discharged and fully charge them only before flight).
You could buy NiMH batteries of 2 types:
- "High Capacity" — high capacity, but also have fast self-discharge (lose their charge in several months). Ideal for RC toys that drain battery in hour and no need to keep charge for month.
- "Low Self Discharge" — lower capacity, but keep charge for years. Good for IR remotes, wall clocks, rare used devices, etc.
Lithium batteries are much more different in their chemicals and technology.
For regular devices (mobile phones, notebooks) it's more important to have batteries that don't require some special handling. Even if capacity is lower. So, manufactures use lower capacity batteries.
But for drone battery is extremely important to have as much capacity (flight time) as possible. But you should pay price for this capacity — special handling rules.
I believe, DJI may create some kind of optional "low-discharge" batteries that would keep full charge for years. But it would significantly decrease flight time (maybe, 20 minutes in Mavic 2 Pro instead of 30 minutes on standard battery).
For me it's more important to have maximum possible flight time (so, pay price of keep batteries half-discharged and fully charge them only before flight).
I would be on the safe side and get lipo bags. The airline might demand that even if it is not in the FAA rule book just as a cop come up to you and tell you that you cannot fly in a certain place.
Some people of self-imposed importance just make the rules up as they go.
Many laptops now tend to sometimes stop charging at 95%
My experience tells me it is more harmful to keep lipos at low charge than full or near full. Very full is worse but intelligent batteries or regular batteries with chargers made for them prevent over-charging.
Heat is another potential killer, especially when the battery is at low charge.
M2 doesn't provide option to change days to discharge. It's fixed at 10 days.
Hibernation occurs after an extended period of non-use, I think 30 days. In hibernate state, the actual batteries are cut off from the internal electronics. It takes power from the charger to power the electronics back up. Some laptops may do this, or at least are set that way from the factory.
My experience tells me it is more harmful to keep lipos at low charge than full or near full. Very full is worse but intelligent batteries or regular batteries with chargers made for them prevent over-charging.
Heat is another potential killer, especially when the battery is at low charge.
M2 doesn't provide option to change days to discharge. It's fixed at 10 days.
Hibernation occurs after an extended period of non-use, I think 30 days. In hibernate state, the actual batteries are cut off from the internal electronics. It takes power from the charger to power the electronics back up. Some laptops may do this, or at least are set that way from the factory.
Lithium Cells used in products such as Phones and tablets are far less stressed than those used for motive power, they never get too close to 100% charge (it might say 100% on your display, but it aint 100% of the cell's capacity) also protected against deep discharge and of course are subject to low current demands
We ask a lot more from the Batteries in our drones so they take a bit of care to get decent life.
We ask a lot more from the Batteries in our drones so they take a bit of care to get decent life.
Lithium-ion cells are not the same!
There are a lot of different material combinations used for anode, cathode, and electrolyte. Also the physical package (insulator, shell) can be designed different. This gives the batteries very different properties!
There is always a compromise between capacity, max current output, ruggedness, safety, self discharge, sensitivity to over/under discharge, lifetime and so on.
DJI drone batteries are of course optimized for high energy density. Hi-voltage LiPo is used. They will swell up (or at least get much reduced lifetime) and if stored at full charge.
For powertools something like a Sony VTC battery (IMR chemistry) is used. They can deliver very high bursts of current, they can be quick charged. They dont swell up just because they are stored full charged, it just reduces the liftime a bit.
So, the answer is not that power tool manufactures don't care, etc. The batteries are different, and carefully selected for each purpose. This brings different pros and cons for each type.
You can read more here (all types not covered): Battery chemistry FINALLY explained
There are a lot of different material combinations used for anode, cathode, and electrolyte. Also the physical package (insulator, shell) can be designed different. This gives the batteries very different properties!
There is always a compromise between capacity, max current output, ruggedness, safety, self discharge, sensitivity to over/under discharge, lifetime and so on.
DJI drone batteries are of course optimized for high energy density. Hi-voltage LiPo is used. They will swell up (or at least get much reduced lifetime) and if stored at full charge.
For powertools something like a Sony VTC battery (IMR chemistry) is used. They can deliver very high bursts of current, they can be quick charged. They dont swell up just because they are stored full charged, it just reduces the liftime a bit.
So, the answer is not that power tool manufactures don't care, etc. The batteries are different, and carefully selected for each purpose. This brings different pros and cons for each type.
You can read more here (all types not covered): Battery chemistry FINALLY explained
oldcelt
Well-Known Member
Just a small clarification:-
Lithium ion batteries use liquid lithium ion as electrolyte whilst lithium polymer use solid or gelatin like polymers as the electrolyte. Comparison:-
Lithium ion batteries use liquid lithium ion as electrolyte whilst lithium polymer use solid or gelatin like polymers as the electrolyte. Comparison:-
Pontoon-pilot
Well-Known Member
Lots of good information here.
From what we know as a consumers is that lithium ion batteries can swell and start on fire _ samsung note 7 phone, other phone batteries swell up cause screen display issues - iphones.
Lithium polimers will swell up as they age. They will also vent gasses with flames! when shorted. I've seen this when my heli crashed and when when my puppy dog decided to to take one and bite into it. I dint know it until there was a strong burnt plastic smell in the air.
The hard shell on our DJI batteries provide protection but can't see easily see when it is starting to swell until it has built enough pressure to bulge out the plastic shell.
Lastly, I found some of my heli batteries, that were left fully charged for a year or more, and still worked...it was dated 2011 as service date; it was not a fancy or expensive battery. Surprised it lasted this long.
From what we know as a consumers is that lithium ion batteries can swell and start on fire _ samsung note 7 phone, other phone batteries swell up cause screen display issues - iphones.
Lithium polimers will swell up as they age. They will also vent gasses with flames! when shorted. I've seen this when my heli crashed and when when my puppy dog decided to to take one and bite into it. I dint know it until there was a strong burnt plastic smell in the air.
The hard shell on our DJI batteries provide protection but can't see easily see when it is starting to swell until it has built enough pressure to bulge out the plastic shell.
Lastly, I found some of my heli batteries, that were left fully charged for a year or more, and still worked...it was dated 2011 as service date; it was not a fancy or expensive battery. Surprised it lasted this long.
Use the USB adapter that snaps on to the Mavic Air battery to drain the batteries down to 50% by charging your cellphone etc. with them.
What does a person do if you get called out for a search and rescue mission and your batteries have discharged. What does, if anyone, do in this case. I don’t have time to charge batteries if I Get called out to look for a suspect or trying to find a lost kid. Any advice helpful. Thanks.
If I was in that situation, I would always keep one battery charged up to 100% for a couple of days and invest in a portable charger. Depending on the type of DJI gear you are flying, there are a few portable battery charging solutions out there. I would invest in one and keep it charged at about 85% for charging batteries on the go.
BayouBill
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In my opinion DJI is doing its customers a disservice by not providing the option of charging their batteries with a quality LIPO charger. Many RC hobbyists have a good balance charger that can deliver a storage charge after a day of flying to maximize the battery life. I do that with my Bebop batteries even though Parrot provides automated charging like DJI. I modified a charging cable to use with my computerized charger and now I can easily monitor the status of each battery. That is not possible with DJI batteries (except possibly with major surgery on each battery). Just now, I charged a MA battery intending to stop it a 50% but forgot and now I will have to hover it in the back yard tomorrow :-( Not willing to wait 10 days.
Last edited:
Hi everyone,
I do normally fly my Mavic and land with 20% remaining battery (battery level warning set up at 30%) most of the times which is 1 steady light. I flight the 3 batteries once a month.
My questions are:
- Is it too low leaving the batteries at 20%?
Could this affect the battery life span or cells?
- If I charge it back to the recommended storage level, would that consume one cycle?
Charging it back to 50%-60%, would be a pain and perhaps consuming a cycle. I do not want to be constantly checking out the batteries and that’s why I do not drain them completely and leave them at an appropriate percentage, or that’s is what I thought until I read this thread... ?
Thanks in advance and safe flights!!
I do normally fly my Mavic and land with 20% remaining battery (battery level warning set up at 30%) most of the times which is 1 steady light. I flight the 3 batteries once a month.
My questions are:
- Is it too low leaving the batteries at 20%?
Could this affect the battery life span or cells?
- If I charge it back to the recommended storage level, would that consume one cycle?
Charging it back to 50%-60%, would be a pain and perhaps consuming a cycle. I do not want to be constantly checking out the batteries and that’s why I do not drain them completely and leave them at an appropriate percentage, or that’s is what I thought until I read this thread... ?
Thanks in advance and safe flights!!
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