Battery Care - OK to keep on charger?

[paulatkin73]

I am somehow convinced, that I cannot ruin the batteries fast enough even with 10 days discharge time upon a new Mavic in the next 2 - 3 years.

it depends. most new packs these days are better then old ones - like the 100C 1500mah CNHL take an enormous amount of an abuse and do not puff. i also keep some charged for quite a while - no issues so far, rock solid stuff.

those new HV DJI packs seem to be puffing quite often, and, the small HV cells i use with the EMAX tinyhawk - they do puff immediately after 3.0v level discharge and if kept charged up, so, i think this 4.4v level cells do not have a good chemistry figured out for them yet.

 

[globetrotterdrone]

@paulatkin73
Certainly, where there's a will, there's a way. But following the guidelines should provide a good level of quality overall.
I did not mean to maltreat the batteries delibaretly and expect the "intelligent" part of the battery to smooth it out instead of the user thinking about his actions.

 

[paulatkin73]

@paulatkin73
Certainly, where there's a will, there's a way. But following the guidelines should provide a good level of quality overall.
I did not mean to maltreat the batteries delibaretly and expect the "intelligent" part of the battery to smooth it out instead of the user thinking about his actions.

all i am saying is - those 4.35v HV cells are not as robust as old 4.2v cells, from what i am observing so far. i dunno why dji used them and what kind of a real benefit they provide, compared to old cells.
i think it provided a very minor improvement of flight time duration, but, also just made life much more difficult. like i said - i am not keeping them overnight at above 4v per cell level.

 

[JMagnus]

The RCGEEK parallel battery charger has a switch that can be toggled to charge the batteries up to 100% or 65%.

View attachment 75769
View attachment 75770

Msinger, will this work for the Mavic Pro also? Thanks!

 

[m0j0]

Msinger, will this work for the Mavic Pro also? Thanks!

This particular charger will not work with the Mavic Pro. There are other chargers for the Mavic Pro that will charge the batteries simultaneously but I have not found any that will charge to storage capacity.

 

[Randall8686]

the HV Lipo's they have used is just to get a little more capacity to be honest. they offer a better power/duration to weight over the older 4.2v cells but again are not as robust long term and leaving them fully charged for extended periods will see battery deterioration fairly quickly (unless DJI have some magic technology that the rest of the industry do not know about) I work with LiPo and LiIon every day from EV to solar storage and i have seen LiPo's destroyed in 30 cycles of abuse yet follow the technology by the letter and they last a very very long time. The reason Tesla car batteries last as long as they do is all of the conditioning that goes on. to the point the car heats and cools the batteries to keep a constant temp. people moan the car looses range if they have gone on holiday etc but its intentional if the car thinks its not going to be driven again to ensure that the longevity of the packs is retained (they offer 7 year warranty on their cells)

Storing the HV LiPo cells at maximum voltage for 10 days really will shorten their life expectancy. keep doing it and you will be lucky to see 2 years out of a pack. I have personally tested hundreds of LiPo's and working in the industry i see vast amounts of Data on LiPo packs. everyone will have their own opinion and some wont care if they need to buy new batteries every 12/24 months and that's fine but for people that want their batteries to last for years and most importantly retain their capacity for the life of the pack follow the golden rules and they will last you long enough to see 3 years of using your drone without any issue. I have only just picked the MP2 up but will take a look at the batteries in detail and work out what the pin configuration is and what the charger inside is doing. it should be fairly easy to make up a charger that just automatically puts the battery into storage mode by either charging or discharging. I currently have 6 LiPo packs beside me now that are being discharged to storage stage on a home brew charger (not drone related)

It should also be pretty easy to re cell the pack once i find out what actual cells are inside these packs so changing the indavidual cells over to "refurbish" a battery should not be too much hard work as long as your handy with a soldering iron and respect the fact these are unprotected cells so shorting them will result in a nice little firework show.

It would be very handy to have a battery checker that monitors each cell voltage so you know if your in a good storage voltage without having to plug it into the drone. I will see what i can come up with and report back with a nice cheap solution

 

[BigAl07]

All rock solid advice.

It should also be pretty easy to re cell the pack once i find out what actual cells are inside these packs so changing the individual cells over to "refurbish" a battery should not be too much hard work as long as your handy with a soldering iron and respect the fact these are unprotected cells so shorting them will result in a nice little firework show.

That's the one "hurdle". I've known a couple (as in known on the internet) to get away with swapping cells occasionally but the "Smart" board on the battery doesn't appreciate the process and "fries" more often than not. I would LOVE to see someone be able to "RePack" these but to date it's a rarity to get one right.

Keep us posted if you find a way to refurbish them.

 

[Randall8686]

That's the one "hurdle". I've known a couple (as in known on the internet) to get away with swapping cells occasionally but the "Smart" board on the battery doesn't appreciate the process and "fries" more often than not. I would LOVE to see someone be able to "RePack" these but to date it's a rarity to get one right.

Keep us posted if you find a way to refurbish them.

The key is to replace all the cells at a storage voltage. replacing one cell with a wildly different internal resistance would cause issues. cells ideally should be matched for internal resistance. I have "re packed" loads of different batteries over the years. i will try find a cheap used pack or find some one with a dead one to donate to me to re cell it for them. the hardest part is usually getting these things open without damaging the case. I have a spot welder for hard cells and tabs etc so you dont transfer heat into the cells but with a heat shunt you can solder them usually without damaging the cell. I will find one and make a How Too video although I am always cautious of these as some people who have no clue really should not attempt this.

 

[paulatkin73]

The key is to replace all the cells at a storage voltage. replacing one cell with a wildly different internal resistance would cause issues. cells ideally should be matched for internal resistance. I have "re packed" loads of different batteries over the years. i will try find a cheap used pack or find some one with a dead one to donate to me to re cell it for them. the hardest part is usually getting these things open without damaging the case. I have a spot welder for hard cells and tabs etc so you dont transfer heat into the cells but with a heat shunt you can solder them usually without damaging the cell. I will find one and make a How Too video although I am always cautious of these as some people who have no clue really should not attempt this.

DJI cells are most likely built up to their spec and have no direct aftermarket replacements. still, all what you say is exactly correct - i only see a marginal amount of benefits from those 4.35v cells with a major drawback - chemistry is not as reliable as the old one at all. i hope they will not start burning under max load, but, will see. there was already one report here of the crash caused by the exploded pack during normal loiter flight.

do you know, what is the effective C rating of those DJI packs? is anything known at all about those cells they use? i boosted my sport mode setting, so, in some flights if i pusg it around at max speed i see it draws about of 15A top and pack feels quite warm after that. 100C 1500mah CNHL is dead cold after 15A, to warm it up i need to draw 60A-80A from it. so, this DJI pack - is it more like 20C or so?
it really reminded me of this one:

Multistar High Capacity 10000mAh 4S 10C Multi-Rotor Lipo Pack XT90

Multistar High Capacity batteries are the result of extensive testing with one goal in mind. Increasing flight times for multi-rotor without the penalty of added weight. The batteries are able to provide flight times longer than LiPoly batteries

hobbyking.com

i tried to use long time ago on the model that was drawing merely 12A at loiter - so, that pack heated up like no tomorrow and lasted for less time in flight than a 45C 5000mah pack, and sagged under load tremendously. it was a complete waste of money.

 

[msinger]

Msinger, will this work for the Mavic Pro also? Thanks!

No.

 

[Randall8686]

DJI cells are most likely built up to their spec and have no direct aftermarket replacements. still, all what you say is exactly correct - i only see a marginal amount of benefits from those 4.35v cells with a major drawback - chemistry is not as reliable as the old one at all. i hope they will not start burning under max load, but, will see. there was already one report here of the crash caused by the exploded pack during normal loiter flight.

do you know, what is the effective C rating of those DJI packs? is anything known at all about those cells they use? i boosted my sport mode setting, so, in some flights if i pusg it around at max speed i see it draws about of 15A top and pack feels quite warm after that. 100C 1500mah CNHL is dead cold after 15A, to warm it up i need to draw 60A-80A from it. so, this DJI pack - is it more like 20C or so?
it really reminded me of this one:

Multistar High Capacity 10000mAh 4S 10C Multi-Rotor Lipo Pack XT90

Multistar High Capacity batteries are the result of extensive testing with one goal in mind. Increasing flight times for multi-rotor without the penalty of added weight. The batteries are able to provide flight times longer than LiPoly batteries

hobbyking.com

I cant imagine they have a massive C rating as they are charged at around 1C and lets face it at 15amps thats only 4c so a 20c pack would be fine 20c =77amps they have gone for capacity over C rating as its always a trade off. I would guess they are most likely a "made to order" cell as they would likely buy enough to warrant that setup fee. although i would imagine that you could buy a cell of similar spec that would fit. downside of finding replacement cells is they would have to be the HV LiPo as fitting a non HV and the on board charger then assuming it is would be a fire risk and if nothing else destroy the cells very quickly. I cant imagine that programming the charger to work with standard voltage cells would be all that easy either. its definitely been engineered not to be serviced and be thrown away. although there are clone packs about so they are either buying genuine cells or have found a replacement that works. However this is all going a little off topic from the OP question lol

 

[Milo187]

No. And that won't work anyhow since the batteries will stop charging after they have been fully charged.

It would be better to only charge the batteries when you are planning on using them. Check out this guide for additional battery tips:

HOW TO: Maintain and store your DJI Mavic batteries

Mav is correct and DJI recommends this as well to extend the life of your batteries. They are Intelligent batteries and bleeding them down when not in use is healthy for them.
I also have that exact charger and love it!

 

[MagicMike]

Useful information from this discussion. Thank you

 

[John S]

I keep my batteries at 60% unitl I plan to fly. I charge up the thee I have and either fly or run into the inevitable delay and end up with fully charged packs. When that happens I use this wonderful little product I found on this forum called the Phantom Angel discharger. It uses a halogen bulb and electronics that allow me to either discharge to 60% (Store) or take it all the way down (Cycle), as DJI recommends every 20 cycles with the flick of a switch. . I’ve been using it for a few weeks and I love it! Highly recommend.

Phantom Angel

Inspire, Mavic and Phantom batteries discharger. Calibrate your LiPo batteries and extend battery life.

phantomangel.rocks

 

[baddog]

This happens to everyone.


This is an undesired circumstance. Remember that these batteries are only good for so many cycles. You don't want to discharge them without using them in flight.



Here is what I do. I purchased a charger that can charge all the batteries at once. the charger also has a switch that allows you to charge to storage which is 65%. So I fly my batteries down to about 20%. Then as soon as I get home I charge them to storage and leave them there until I know I am going to fly then I top them off prior leaving. Takes about 35 minutes to get them ready to go.

This drastically reduced the number of times I charged the batteries fully and had to let them self-discharge.

What charger is this? I fly a lot for dronebase.com and sometimes the missions come up as same day. I need to be able to accept and get going within an hour usually.

 

[drakkor]

I dont know a great deal about the Mavic 2 pro yet as i have only just purchased it however i have been using and working with LiPo batteries for a long time (since they became commercially viable) and leaving your batteries fully charged damages them as does leaving them fully discharged. General rule of thumb if you want your rather expensive batteries to last the longest is dont discharge them below 20% now i dont know what DJI have programmed the drones software at so 0% in the drone could be 5/10/20% of the Lipo Voltage range i have no clue on this however they have put a safety margin in so i would say try not to go below 10% during a flight. once done allow batteries to cool and then charge them as soon as you can (after any warmth has gone). now if you plan on NOT flying the pack again only charge to 40% or as close as you can. Its hard with these packs to know where 40% is, but 40% capacity is storage voltage or to be exact 3.85v per cell. i have run various tests including 1 very long test. I used some LiPo's for 50 cycles and then put them at storage voltage and chucked them in my loft for....3 years! and then started using them again (i have a lot of LiPo's) they performed perfect and i am still using them in various RC models.

leaving a LiPo that long in charged state and discharged resulted in a knackered pack. discharged ones ended in cells dropping to below recovery voltage. leaving a lipo fully charged for 10 days and waiting for the pack to discharge its self is also too long to maximize battery life. Ideally only leave them fully charged for 2/3 days. a good way to discharge them is use the USB power bank adapter. you can just charge phone's/tablets until they are around the 50% mark. or failing that buy a little USB Load tester for a few quick and put a 2amp load on the fully charged battery via the power bank adapter and it will discharge the pack over a few hours or of course the fun way is to fly the drone!

Sorry for the long reply however i cannot stress enough how leaving these batteries charged for long periods of time will drastically reduce the life of the pack. a well looked after LiPo will happily do 600+ cycles a poorly looked after LiPo can do as little as 50 Cycles. Its also a good idea if you dont use them for 2/3 months to just top them back up from storage voltage and then discharge them to storage voltage again.

I have worked with LiPo's in industry long enough and also in my hobbies too see people Kill LiPo's with poor use and then blame "crappy" batteries when in fact its all their own doing. I know its not ideal having to charge on the day but its best practice but as above if you get a parallel charger you can be fully charged from storage voltage to ready to go with all your batteries in under an hour. will save you Money in the long run.

This is some great information right there. Thanks for sharing !

 

[JimP Florida]

This forum is a great asset, thanks to all !
I have read every post, some 2x.
BUT I am still confused, I have a M2Z 9 months old.
Even the DJI instructions are not clear:
"Discharge the battery to 40-60% if it will not be used for 10 days or more...the battery automatically discharges to below 60% when it is idle for more than 10 days..."
If they auto discharge why do I need to manual discharge?
Here's what I do , after flying I put my 3 batteries on my DJI 3 way charger, with the controller and I pad mini all connected to a power strip. I leave it turned on for 6 - 12 hours and shut off the powers strip. When I am thinking of flying I switch the power strip on a few hours ahead.
What am I doing wrong ??

 

[globetrotterdrone]

If they auto discharge why do I need to manual discharge?

Some say, that 10 days is too long for LiPo HV to rest fully charged and that loss of quality/lifetime is to be expected ... in the older models/days you could set the TTD (time to discharge) to a lower, custom level - 1, 2, 3, 5 ... days to discharge which gave people overall more flexibility on how to treat their batteries.

Here's what I do , after flying I put my 3 batteries on my DJI 3 way charger, with the controller and I pad mini all connected to a power strip. I leave it turned on for 6 - 12 hours and shut off the powers strip. When I am thinking of flying I switch the power strip on a few hours ahead.

I guess that's fine, as long as the batteries are fully charged until you turn off the power strip. Not sure about the "re-loading" prior to flight if you have them charged before the discharge of 10 days though.

Not worrying too much is the thing that DJI anticipated - so theoretically you could just hook on your batteries, let them fully charge and the rest is done by the wizardry of the internal controllers.

While I do think users should have basic knowledge about proper usage by following DJI's guidelines to avoid abusement of these techy things, one might supect that ultimately keeping your LiPos in the storage range give them a higher expectancy of life. There's certainly an overlapping area of comfort/ease of mind/ready to fly nearly anytime to life expectancy which DJI figured out in these batteries. You might care more with reduced cycles and shorter times of 100 % storage, but likely you'll never notice any degredation of quality within your lifetime of the M2Z.

The way I do it now after one month of ownership:

1. after flight hook the batteries on the new 4 way charger and set it to storage mode of 65 %
2. before I go out to fly, charge the remaining 35 % simultaneously into the batteries, which takes about 35 - 45 mins
3. I have 4 batteries and often I only fly 2 - 3 - with the remaining 100 % batteries at home I charge other devices like smartphones, tablets with the USB charger to the point, where the 3rd ring starts flashing. It's then within the range of 50 - 75 %
4. If I am unable or don't have any device to charge in between those 10 days (highly unlikely) I'll confidently trust the auto-discharge to bring it down to 65 %
5. Go out and fly and restart at 1.

Care for your products but don't worry too much!
Use common sense and follow the guidelines!
The quality of DJI's cells is luckily outstanding so far as I have experienced.

Happy and safe flying!

 

[deleted member 877]

I have been storing the batteries (Mavic Pro) at between 30% and 40%. That was the advice I read somewhere. Is that OK or is 65% better?

 

[BigAl07]

I have been storing the batteries (Mavic Pro) at between 30% and 40%. That was the advice I read somewhere. Is that OK or is 65% better?

We've always shoot for around 50% but allowed 40% to 60% (which averages 50%).