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Batteries & more... I'm not getting it.
707 16 2018-1-12
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Kevin_d
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Flight distance : 4219 ft
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I have a portable Amateur Radio setup. I use a rather larger LiFePO4 battery and keep it on a charger 7x24 to be ready when I decide at the last moment to do some camping or backyard hamming. I've rarely had problems with the variety of lithium batteries I've used in the past few years except on an old toy drone and a wifi hotspot. Both of these swelled. One was real cheap and the other was real old. That's two out of the many.

This morning I went to update my two drones. I've got 4 batteries on the charger that comes with the fly more combo. I understand only one battery charges at a time but I've not been flying for a couple of weeks now and I expected all four batteries to be at 100% or whatever the maintenance charge should be for these batteries. Instead I found that three of the batteries were down below 50% (one solid/one flashing) and one at 100% (4 lights). What's up with that?

I know some people like to create this great mystery around batteries but it really is a pretty mature technology. Some vendors pushed the limit (hey there Samsung) but mostly, if treated properly and used with a charger made for the specific battery technology the user doesn't have to worry. Plug them into the charger and they'll be ready for the next time you need them. At least that's what I expect - particularly when these batteries are intelligent batteries.

I have each of my batteries numbered and use them in order just to share the load. I've kept each on the charger 7x24 assuming they would always be ready. Bad assumption apparently. How do you handle battery management? Do you really think through a process or do you just plug them in when you're done for the day? Have you ever pulled your batteries off the charger only to find out they are not fully charged - or worse, nearly discharged?

This is just one in a list of items that seems to interfere with the concept of just getting out and having fun. It's supposed to be fun, right? Read the manual twice and avoid wind, water, snow, cold, heat, dark, people, too much distance, to much height, rfi, emi, trees, downward vision systems, loose change burried in the ground, and that's all that's requried, right?

Do the developers of the Mavic and its software actually get out of the coding room and play around with these drones? I don't mean perform some sort of lab tests with criteria and checklists but actually get out with them to see if they are enjoying the experience? Maybe the manager at the development center should take the crew out on a week long off-site meeting. Hand each of them a recent model MPP at the beginning and tell them to go out and have a blast. Then, on return, take a look at what survived and what nagging issues were found. Then get the heck back to work.


2018-1-12
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theothernt
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This thread might be helpful...

https://forum.dji.com/thread-85595-1-1.html
2018-1-12
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Bekaru Tree
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maintaining mavic batteries properly might not be the same as with yr other batteries. You mention they (mavic batteries) are plugged in 24/7 - if this is sometimes over extended periods of time (more than 10 days) then perhaps this continuos fully charged situation has degraded some aspect of the battery. i sometimes wonder if the people at mavic actually fly mavics regularly or at all - really should be a prerequisite for the job
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FatherXmas
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These are smart batteries and will discharge themselves down to 50% if  not used for 10 days. I'd bet being connected to the charger wouldn't change that.
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DroneFlying
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FatherXmas Posted at 2018-1-12 13:56
These are smart batteries and will discharge themselves down to 50% if  not used for 10 days. I'd bet being connected to the charger wouldn't change that.

Yes, that's most likely the cause and though I've never tried it myself, I suspect you're right about the batteries being on the charger not having an effect. Given that the whole point of self-discharging is to protect battery life, I can't think of a reason why DJI would have it behave any differently when the battery's connected to a charger.
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FatherXmas
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DroneFlying Posted at 2018-1-12 14:16
Yes, that's most likely the cause and though I've never tried it myself, I suspect you're right about the batteries being on the charger not having an effect. Given that the whole point of self-discharging is to protect battery life, I can't think of a reason why DJI would have it behave any differently when the battery's connected to a charger.

I'd try it except after the Note 7 fiasco, I'd rather not take a chance on becoming homeless.
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Jyunte
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The batteries on the charger will charge to 100%, and then switch off. Once switched off, the logic in the smart battery will begin to discharge the battery to its storage level after 10 days (unless you've changed this value in the battery section of the DJI Go 4 app). They will not automatically start charging again once discharged, and the charger does not trickle charger batteries which were left on the charger. LiPo batteries can be permanently damaged by keeping them fully charged, or fully discharged for long periods (days), hence the logic boards included in them to avoid exactly those situations. Damaged LiPos can, and do catch fire..
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Kevin_d
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OK, weatherwise I'm not able to fly very often lately. But as the weather starts to improve I'd like to be ready to head out for at least 30 minutes - hopefully an hour. With four batteries I thought that wouldn't be an issue. Flying starting at 50% seems out of the question. So spontaneity is out. I have to plan when I'm heading out and then, tap the button on the top of the battery the evening before to start it charging back up again? If I read correctly, I cannot tap the button to check the charge because that resets the timer, it won't discharge, and I could negatively affect the batteries. Right?

A $90 battery that is smart but can't maintain a charge or automatic charge/discharge cycle and can't indicate how much battery % is left without resetting the discharge timer.

I kind of wonder, what is it inside the battery and the charger that is smart? What functions are being provided? The obvious are remaining battery capacity, discharge timing. Any more battery smarts? Or is it like additional flight smarts? There's got to be something cool going on in there I think.
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Bekaru Tree
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DroneFlying Posted at 2018-1-12 14:16
Yes, that's most likely the cause and though I've never tried it myself, I suspect you're right about the batteries being on the charger not having an effect. Given that the whole point of self-discharging is to protect battery life, I can't think of a reason why DJI would have it behave any differently when the battery's connected to a charger.

the value of keeping it plugged in 24/7 is that you will always have a full battery when you need it, right?
yet if it discharges (whilst still plugged in) then it follows that if you wish to grab yr battery at a moments notice, it may be discharged or partially discharged which obviates the practice of leaving it plugged in 25/7.
However you guys may be right  - with yr reasoning that a charged battery will discharge anyway even if still plugged in could be the reason why kevin_d had 3 empty batteries and only one fully charged.
His batteries charge up  one by one and then each discharges again and then each charges up again, one for one, over and over again.
Unless you were constantly monitoring their up and down progress, you could not know at a moments notice for sure weather they are in fact all full charged or all empty or some or one charged and the others empty.

Either way - it appears that leaving on charge 24/7 is not something i would recommend.
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Kevin_d
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Jyunte Posted at 2018-1-12 14:49
The batteries on the charger will charge to 100%, and then switch off. Once switched off, the logic in the smart battery will begin to discharge the battery to its storage level after 10 days (unless you've changed this value in the battery section of the DJI Go 4 app). They will not automatically start charging again once discharged, and the charger does not trickle charger batteries which were left on the charger. LiPo batteries can be permanently damaged by keeping them fully charged, or fully discharged for long periods (days), hence the logic boards included in them to avoid exactly those situations. Damaged LiPos can, and do catch fire..

But wouldn't you expect the "smarts" to be able to cycle the batteries? My Bioenno LiFePO4 batteries are on a purpose-built charger from the same company. They suggest leaving them plugged in forever. And for two years and sometimes months between use they are always ready to rock a whole weekend on the radio.
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Sim-Y
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Kevin_d Posted at 2018-1-12 14:59
But wouldn't you expect the "smarts" to be able to cycle the batteries? My Bioenno LiFePO4 batteries are on a purpose-built charger from the same company. They suggest leaving them plugged in forever. And for two years and sometimes months between use they are always ready to rock a whole weekend on the radio.

I believe lifepo batteries are more tolerant to longer charge/discharge cycles than lipo's which the mavic batteries are.
You need to compare like for like, lipo's don't like being left fully charged, apart from being dangerous they will degrade over time when left fully charged which will reduce performance & flight time, that's the nature of the beast i'm afraid.
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Jyunte
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Kevin_d Posted at 2018-1-12 14:59
But wouldn't you expect the "smarts" to be able to cycle the batteries? My Bioenno LiFePO4 batteries are on a purpose-built charger from the same company. They suggest leaving them plugged in forever. And for two years and sometimes months between use they are always ready to rock a whole weekend on the radio.

LiPo batteries, like all batteries, have limited charging cycles, so having a charger/battery combination that constantly goes through charge/discharge cycles would kill you battery very quickly. I had 235+ miles on my first Mavic, spread over 3 batteries, each having something like 45 charge cycles. That's from August, when it was new, through November when it crashed. Had I left the batteries in the charger throughout August, September, October and November, each battery would likely have been charged and discharged many hundreds of times... and, as someone else pointed out, at any point in time, I could not rely on any individual battery being charged (or discharged, for that matter). That makes flying difficult.

At least now, if I put the batteries on the charger when I go to bed, I know that when my automated electrical outlet switches on at 5am, all my batteries will be charged by the time I wake up! :-)

BTW, if you got the Fly More Combo, you got a car charger. That charges batteries a bit quicker than the regular A/C charger, so you could always use that to charge a battery while driving.
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BigBird2
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Jyunte Posted at 2018-1-12 16:26
LiPo batteries, like all batteries, have limited charging cycles, so having a charger/battery combination that constantly goes through charge/discharge cycles would kill you battery very quickly. I had 235+ miles on my first Mavic, spread over 3 batteries, each having something like 45 charge cycles. That's from August, when it was new, through November when it crashed. Had I left the batteries in the charger throughout August, September, October and November, each battery would likely have been charged and discharged many hundreds of times... and, as someone else pointed out, at any point in time, I could not rely on any individual battery being charged (or discharged, for that matter). That makes flying difficult.

At least now, if I put the batteries on the charger when I go to bed, I know that when my automated electrical outlet switches on at 5am, all my batteries will be charged by the time I wake up! :-)

Interesting about the car dc charging faster. Going to have to research that, tnx.
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AG0N-Gary
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I assume you know that LiFePO4 is not the same as LiPO.  Chemistry is different, voltage is different, charging is different.
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Woe
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AG0N-Gary Posted at 2018-1-12 22:41
I assume you know that LiFePO4 is not the same as LiPO.  Chemistry is different, voltage is different, charging is different.

Wow you read my mind.
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luciens
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That's just "life" (no pun intended) with LiPo batteries - the ready-at-a-moments-notice thing just isn't a part of the equation . However, the way we deal with that normally is by throwing money at chargers, getting the biggest ones we can afford with parallel harnesses and balance boards that can charge all our batts at at least 2C or more simultaneously.

So it'd be nice if DJI or other 3rd parties started making a quality high-power charger that can do multiple intelligent batts at once at 2C charging rates or more. It's kind of silly for a LiPo to take over an hour to charge - even cheap/cruddy LiPos can handle 2C or 3C charging rates and you can get your entire bank charged up and balanced in 15-20 minutes with parallel charging..... That way, you could at least be somewhat spontaneous..
there are a couple chargers out there for the Mavic batts, but their quality seems questionable and they're not particularly high power....
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Hexacopter
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Jyunte Posted at 2018-1-12 16:26
LiPo batteries, like all batteries, have limited charging cycles, so having a charger/battery combination that constantly goes through charge/discharge cycles would kill you battery very quickly. I had 235+ miles on my first Mavic, spread over 3 batteries, each having something like 45 charge cycles. That's from August, when it was new, through November when it crashed. Had I left the batteries in the charger throughout August, September, October and November, each battery would likely have been charged and discharged many hundreds of times... and, as someone else pointed out, at any point in time, I could not rely on any individual battery being charged (or discharged, for that matter). That makes flying difficult.

At least now, if I put the batteries on the charger when I go to bed, I know that when my automated electrical outlet switches on at 5am, all my batteries will be charged by the time I wake up! :-)

I have always wondered why the vehicle charger is quicker than the a/c version?

As already stated, LiPo batteries are a bit different to LiFePo4 (higher energy density/gm discharge current etc) and for long life taking them to storage voltage after discharge is important. dji know this so that's why they implemented  automatic discharge to storage voltage.

I keep my spare batteries in the fridge if they are not going to be used for a few weeks - just let them warm to room temperature for a few hours before re-charging them.

Your LiFePo4 batteries are probably quite adequate for a ham radio but would fail in a Mavic once the ESC's kick in and ask for some decent current from a low esr source to spin the rotors into life.

* hex *  



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