How to prolong the life of your Batteries.

[Robbyg]

Very nice article. You can see why DJI makes certain recommendations. I am now working out a better storage plan based on this articles information.

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Rob

 

[Egika]

I don't. I just use the little toy and enjoy it

 

[Robbyg]

I don't. I just use the little toy and enjoy it

Not when I can do a few small things to go from 500 charges to 1000 or 1500 with my $300 worth of batteries. I think I will follow the articles advice.

 

[Egika]

Sorry. Forget my stupid comment before..
Batteryuniversity has good knowledge and doesn't recommend vodoo stuff.

 

[AlanTheBeast]

Very nice article. You can see why DJI makes certain recommendations. I am now working out a better storage plan based on this articles information.

http://batteryuniversity.com/learn/article/how_to_prolong_lithium_based_batteries

Rob

Good article. Making batteries last beyond a few hundred cycles is not my biggest concern, however. But storage could happen for many weeks at a time - so following that will help.

 

[CyberNate]

You don't have to worry about prolonging the battery life. DJI is already doing it for you.

Here is my post from another thread regarding increasing capacity, but I've also touched on how DJI manages the battery for longer lifespan in charge cycles:

"If you have a spot welder, you can replace the cells with higher capacity Panasonic 18650GA cells. They are rated at 3500 MAh. In a 3s2p pack like the mavic has that is 7000MAh and 80WHr; however I think that's likely what they already have in there or similar. I believe DJI under utilizes the capacity for pack longevity. The 100% you see reported in the app and controller is more like 80% of the cells and likewise, 0% is really 20% left in the cell. The mavic electronics would get wonky if they really tried to use ALL the battery, where voltage drops off quickly under 10%. The pack is rated at 11.4V and 3850MAh. If you only charge to 80% and discharge to 20% the batteries last MUCH longer with more recharge cycles available and more reliability. Electric cars do the same thing, only using a small window of the capacity and gradually using more percentage of the battery over time as the lithium cells deteriorate. As time goes by, the battery producers figure out ways to get more energy density out of the cells to satisfy the electric car industry. We benefit with the new DJI models when they leverage the latest cells in the battery packs."

The one thing you CAN do is to let the cells cool down BEFORE changing again. Heat is the one thing that can decrease cell life.

Edit: Regarding capacity, it looks like DJI is probably using the cheaper 3200MAh cells. So that means the 3s2p back has 6400MAh potential capacity. If you only change to 80% and down to 20% you utilize 60% of the pack. 6400MAh x 60% = 3840MAh which is the precise rating of the battery pack. This means one could replace the cells with Panasonic 18650GA cells rated at 3500MAh and get 7000MAh x 60% = 4200MAh. I could easily see extended packs being offered in the future that are the same dimensions as stock.

 

[ksull72487]

You don't have to worry about prolonging the battery life. DJI is already doing it for you.

Here is my post from another thread regarding increasing capacity, but I've also touched on how DJI manages the battery for longer lifespan in charge cycles:

"If you have a spot welder, you can replace the cells with higher capacity Panasonic 18650GA cells. They are rated at 3500 MAh. In a 3s2p pack like the mavic has that is 7000MAh and 80WHr; however I think that's likely what they already have in there or similar. I believe DJI under utilizes the capacity for pack longevity. The 100% you see reported in the app and controller is more like 80% of the cells and likewise, 0% is really 20% left in the cell. The mavic electronics would get wonky if they really tried to use ALL the battery, where voltage drops off quickly under 10%. The pack is rated at 11.4V and 3850MAh. If you only charge to 80% and discharge to 20% the batteries last MUCH longer with more recharge cycles available and more reliability. Electric cars do the same thing, only using a small window of the capacity and gradually using more percentage of the battery over time as the lithium cells deteriorate. As time goes by, the battery producers figure out ways to get more energy density out of the cells to satisfy the electric car industry. We benefit with the new DJI models when they leverage the latest cells in the battery packs."

The one thing you CAN do is to let the cells cool down BEFORE changing again. Heat is the one thing that can decrease cell life.

Edit: Regarding capacity, it looks like DJI is probably using the cheaper 3200MAh cells. So that means the 3s2p back has 6400MAh potential capacity. If you only change to 80% and down to 20% you utilize 60% of the pack. 6400MAh x 60% = 3840MAh which is the precise rating of the battery pack. This means one could replace the cells with Panasonic 18650GA cells rated at 3500MAh and get 7000MAh x 60% = 4200MAh. I could easily see extended packs being offered in the future that are the same dimensions as stock.

The Mavic got too many sales and too much attention. It's possible DJI introduces a bigger battery with the existing hardware given the popularity.


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[Robbyg]

I find it interesting that DJI rates the batteries at 500 cycles. That matches the 100% charge that the article talks about. Also I think every drone manufacture is interested in offering the longest flight time and selling extra batteries, since accessories are typically a cash cow for companies.

 

[CyberNate]

I find it interesting that DJI rates the batteries at 500 cycles. That matches the 100% charge that the article talks about. Also I think every drone manufacture is interested in offering the longest flight time and selling extra batteries, since accessories are typically a cash cow for companies.

I guarantee you that they are NOT using 100% They are using Panasonic 18650PF cells or similar 3200MAh in a 3s2p configuration. It is standard practice to use 80 to 20 rule. DJI doesn't want to deal with swelled up packs and drones dropping out of the sky when the cells reach 40% and suddenly drop to zero. That is what you get when the cells get damaged.

 

[HumanShield]

Good article and even better comments by you. I try to keep my batteries cool and bring the drone home at 30%.


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[Robbyg]

I guarantee you that they are NOT using 100% They are using Panasonic 18650PF cells or similar 3200MAh in a 3s2p configuration. It is standard practice to use 80 to 20 rule. DJI doesn't want to deal with swelled up packs and drones dropping out of the sky when the cells reach 40% and suddenly drop to zero. That is what you get when the cells get damaged.

Ok if your certain I have no reason to doubt you. I already leave my batteries at about 30%. Basically I do not recharge them until the day I am going to fly. I have not missed a weekend yet but when I do I will just top them off a little if it's needed, so that they don't discharge down too low.

Rob

 

[dewster]

I just don't want my lipos having a sudden death moment when I'm cruising at 400 feet.


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[dangerm0us]

It is true. Been flying mini-quads for a while and I charge my packs to 4.2V per cell, which is the norm for all balance chargers that we use. So a 3s battery (a.k.a 3 cell, like the DJI battery) would be 12.6V, fully charged. But a Mavic battery fully charged is 11.4V, or 3.8V per cell. Which is just above the 'nominal' 3.7V rating of the individual cell (according to DJI website). Now that is really treating the battery like a baby.... I don't have my Mavic here right now so it can't check the DJI Go App which does display the voltage but I'm sure from memory it's 3.8V per cell when fully charged. If someone could chime in on that it would be good.

Normally, again with my mini quad batteries, I fly them down to about 3.2V per cell which is as low as you really want to go. I'm not sure what the 'lower' end is per cell for the Mavic battery, so again it would be good if someone could chime in there if they have a depleted battery and their Mavic in front of them right now. But I'm going to bet it's much higher than 3.2V.

Anyway it's pretty safe to say DJI are not even close to the limits of these batteries, which means you should get the full lifetime they state (500+ cycles) without any issues at all provided you follow the battery care guidelines.

They say you should discharge your batteries to (roughly) 50% when not using them. This is known as 'Storage Voltage'. In fact if memory serves they say 45-65%. They expect you to do this with the Mavic by flying it since the charger they supply does not have a 'storage voltage' charge/discharge function.

The last thing you want to do is leave your battery fully charged or fully drained for prolonged periods. That will DESTROY the lifetime. But did you also know your battery is intelligent? After 10 days (by default, you can change this!) your 'full' battery that you hadn't flown yet will start to bleed its power! This process takes approx 2 days, so by day 12 your battery is automatically at storage voltage! You will notice the battery get hot/warm during this process as it's literally converting energy to heat. So DJI have got your back if you forget to leave your batteries at 50% when not using them for longer periods of time. Personally I think this is awesome.

DJI have done a good job of making battery care as easy as possible here.

EDIT: Well finally go to check my Mavic tonight with a fully charged battery, and they do in fact charge to 4.2V per cell, just like every other LiPO I've used. I shouldn't be surprised. Now just need to figure out what they are at 0%.

 

[Dw911]

I guarantee you that they are NOT using 100% They are using Panasonic 18650PF cells or similar 3200MAh in a 3s2p configuration. It is standard practice to use 80 to 20 rule. DJI doesn't want to deal with swelled up packs and drones dropping out of the sky when the cells reach 40% and suddenly drop to zero. That is what you get when the cells get damaged.

If they are using 18650 cells then unlike the lipo packs, 18650 cells don't swell up.

Are they definitely using 18650 ? Hope so then can just use the batteries without worrying to much and re cell the pack when it starts to under perform

 

[dangerm0us]

They are definitely LiPo's. Says so on the back of the battery, it also lines up with the automatic discharge to 50-60%, which is roughly about 3.8V, just 0.1V over the nominal cell voltage (3.7V), which has been widely accepted as the correct way to store LiPo batteries for some time now.

 

[Kilrah]

Not when I can do a few small things to go from 500 charges to 1000 or 1500 with my $300 worth of batteries. I think I will follow the articles advice.

You're not even going to get 500 even with the best handling.

The article refers to low discharge applications (1C max) which is how most batteries are used EXCEPT in RC.
In RC batteries have to be in shape to deliver at least 10C discharges while keeping sufficient voltage, which means they'll become unusable in this application waaaayyy before they're "worn out" to <1C phone/laptop standards.

DJI batteries are also of the Li-HV type (4.35V charge voltage) which as you can see in the article still further reduces life.
They are designed for performance so they can give the run time people are demanding in a small package, not for longevity. They'll likely be good for the trash after 2 years and/or 200-300 cycles. Which is typically not a problem since most owners will never fly that much nor likely keep using the aircraft beyond that.

Are they definitely using 18650 ?

They are definitely NOT using 18650s.

So that means the 3s2p back has 6400MAh potential capacity. If you only change to 80% and down to 20% you utilize 60% of the pack. 6400MAh x 60% = 3840MAh which is the precise rating of the battery pack.

Complete BS. They are Li-Pos, and documented charge/discharge end voltages confirm every available mAh is used.
You don't waste weight babysitting batteries for aerial applications, you want all the performance you can get and longevity will be what it is. You're buying a $1300 system, $300 every 1-2 years to replace batteries is peanuts.

 

[No1much]

Whatever one's position on the Great Battery Debates, no matter the type of electronics, it seems like everybody brings something to the table that's worth reading. Thank you all from the lurkers on this thread- for contributing to our continued education.

 

[Kate]

I guarantee you that they are NOT using 100% They are using Panasonic 18650PF cells or similar 3200MAh in a 3s2p configuration. It is standard practice to use 80 to 20 rule. DJI doesn't want to deal with swelled up packs and drones dropping out of the sky when the cells reach 40% and suddenly drop to zero. That is what you get when the cells get damaged.

3s, not 2s? wow. I was hoping for an aftermarket 3s to boost mavic down the track

excuse my ignorance, but i was similarly concerned about the %80 rule. Mavichelp, an authority?, told me the same thing, that %0 is either about %20, or the battery is smarter than the average LiPo with circuitry to avoid puffing, voltage drops, etc if run down constantly.
Is this accurate?

 

[J-Dub]

my 2 sense. Your batteries will out live your drone

 

[bootleg.gucci]

So any thoughts on whether the "advanced" charging hub for Mav batteries would sig. shorten the battery life since it's charging faster (esp with P4 power adapter)?

Buy Mavic - Battery Charging Hub (Advanced)


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