HOW TO: Monitor battery voltage to watch for signs of failure

[Gabriel Lehto Gomes]

Hi,
I notice that during the flight my battery when reached about 60% the voltage get yellow (actually I didn't remember what voltage per cell was shown in the screen) and I noticed that one time get red... but I leave the Phantom 3 Pro in the air for a while without any movement and the battery get green again... The battery has 20 charges... and I follow the DJI indication to discharge by 8% sometimes in other to preserve the battery life, is that wrong?
Can my battery is already damage?
I'm a little bit afraid to have a problem with this battery in the air and crash my P3P because of that, is that a real worry?
Or is it normal?

Thank you so much in advance for your help!

 

[bobmyers]

If you're talking about resting voltage, then 3.3v would be 0%. In fact, you've probably entered the batteries tiny amount of reserve capacity, which should not be done without expecting damage to the capacity/lifespan of the LiPo. A good rule of thumb is to consider 3.85v as 50% capacity remaining and around 3.65v to be 0%. The cell voltage under load will be even lower when flying, probably closer to 3.4v/cell. I'm still in the break in process for my batteries, so I have yet to test this.

One thing to note is that these batteries use the newest LiPo tech call LiPoHV which uses a chemistry that's capable of a slightly higher voltage when fully charged. Considering that this is still a relatively new LiPo chemistry, I'm not sure if the same rules apply from the older LiPo chemistry or not. Perhaps someone from DJI could chime in on this. I'm also curious if the "80% rule" should will be followed.. Which basically just means that you should never consume more than 80% of a LiPo in order to preserve its health. If this is still the case with the LiPoHV chemistry, I would like to know if the battery percentage estimation on the Pilot App takes this into account. If it does, then 0% should still be leaving around 20% to preserve the health of the battery. If anyone can clarify this for me, I would much appreciate it.

This new chemistry may well be different, but until there are some concrete results, I am going to chose not to go beyond the old Lipo rules to prove a theory. These aren't cheap lipos that we use everyday on our airplanes and aren't concerned if we go accidently go 90%---- if we destroy one cell on one of those cheap lipos, it is a cheap fix-- if we destroy a cell on a P3 battery, it is expensive fix and a major issue because you cant replace it tomorrow. The jury is still out on these P 3 batteries as far as low voltage, best maintenance practices and overall longevity. A couple of months and we will know. Until then IMHO, stray on the safe side.

 

[MattyDread]

Mods or whoever can you make this thread a sticky as it's very important imo

Thanks

 

[MattyDread]

Hi,
I notice that during the flight my battery when reached about 60% the voltage get yellow (actually I didn't remember what voltage per cell was shown in the screen) and I noticed that one time get red... but I leave the Phantom 3 Pro in the air for a while without any movement and the battery get green again... The battery has 20 charges... and I follow the DJI indication to discharge by 8% sometimes in other to preserve the battery life, is that wrong?
Can my battery is already damage?
I'm a little bit afraid to have a problem with this battery in the air and crash my P3P because of that, is that a real worry?
Or is it normal?

Thank you so much in advance for your help!

This happened to me on my last flight - any responses please.

 

[Baron LaCat]

Is this battery starting to go? The lowest cell is showing a .03-.05 voltage difference from the others. When is it time to toss the battery? When it's < 90% Battery Life? Please note that the 23 charges shown are not full charges. Sometimes I top it off before I use it if it has been a few days. Is that bad?

How is it that the OP Msingle displays 6 green battery cells, yet NoOne displays only 4 green battery cells.
WHY the Difference ???

 

[N017RW]

It would appear the graphic used is actually for an Inspire-1 which has a 6S battery.

 

[elie kattar]

It's important to monitor the battery voltage in each cell of the DJI smart battery. Be aware of the following:

1) Monitor the battery to ensure all cells maintain a similar voltage.
2) Do not allow any of the battery cells to drop below 3.3V.
3) Consider landing your Phantom when (or before) the first battery cell reaches 3.4V.

You can display the voltage of the lowest battery cell on the main screen of the DJI Pilot application. To do so, enable the "Show Voltage On Main Screen" setting in the "Aircraft Battery" section of the DJI Pilot settings.

View attachment 20220


Once enabled, the lowest battery cell voltage will appear at the top, right of the DJI Pilot application -- like this:

View attachment 20218


In the "RC Settings" --> "RC Control Settings" section of the DJI Pilot settings, you can set either C1 or C2 to "Battery Info" to quickly open/close the battery settings.

View attachment 20219


Below is an example that shows a battery that has a consistent voltage in each battery cell.

View attachment 20221


And, here's an example that shows a damaged battery:

View attachment 20217


It's important to ensure your battery is in good health prior to takeoff. Flying with a battery that has one or more bad cells could cause the battery to discharge very quickly and/or your Phantom to shut off and drop from the sky.

can you please tell me is this battery is in good condition to fly with? i am a bit worried as it has only 12
Cycles (total capacity was higher) but not all fully charged always, 7 of them are more a top up before flight. thx

 

[RoyVa]

Better to bring it down in a couple of days if it's setting.
Msinger, you killed it, those picture were worth a thousand words. Good job!

 

[msinger]

It would appear the graphic used is actually for an Inspire-1 which has a 6S battery.

Correct. It's the concept that's important though -- not the number of battery cells

 

[msinger]

can you please tell me is this battery is in good condition to fly with?

It should be fine. Just keep an eye on the voltage as I suggested via the thread I linked to above.

 

[elie kattar]

It should be fine. Just keep an eye on the voltage as I suggested via the thread I linked to above.

well it turned out badly, the battery have been checked by DJI and called DOA, i got a new battery replacement instead, the old batt turned off mid air but i was 10feet high, so i grabbed the phantom with my hands before it hit the floor... i got my new battery now and going to test it with the break in method and will post it here.

 

[silverstoned83]

That's great to hear that you got it replaced. Good luck with your new one!

This goes to show just how hard it can be to spot an unhealthy LiPo and identify the problem.

 

[elie kattar]

That's great to hear that you got it replaced. Good luck with your new one!

This goes to show just how hard it can be to spot an unhealthy LiPo and identify the problem.

well after the Hype about the Breaking process good or bad posts, i have found my self qualified to try this method with my new battery as for the old one i did not, and possibly could have maintained it in better health if i did the break in lipo suggested by some very respectful RC experts, so now i am in the process on my 4th cycle using my new battery and i can tell you that i am really feeling the difference, i am now about to post the full comparaison to help others understand if this methods work or not with Smart Lipo battery's, so far in my own experience i cant affirm it totally i am waiting on my 12 cycles to confirm as the old one failed at that ratio following DJI recommendations

 

[BigAl07]

Any updates on this thread? Lots of potentially GREAT information and theories in the above posts. It's been almost 3 months so surely many of you have had to time form solid opinions from trial and error on your batteries. I have a couple of questions:

I was under the impression (aka assumption) that the "Smart" aspect of the charging system was able to balance the cells when needed. If the system can't balance charge it should have a means to where the user can balance the cells manually. Thoughts?

What is the general census on the "80% rule" from older LiPo technology on these?

What is the general thoughts on the "Down to 8%" suggestion by DJI?

Lastly:

elie kattar what was your final thoughts when comparing the "Break-in" process vs the NON break-in flying?

 

[EPT160]

it has only 12
Cycles (total capacity was higher) but not all fully charged always, 7 of them are more a top up before flight. thx View attachment 24594

I know that you got a replacement battery from dji.
However it is generally a very bad idea to just 'top' up lipo (or any) batteries. You can do it once or twice and for some types this causes no issues, but in general they do need to have a more complete cycle (never completely flatted) to have a long, long life.

 

[elie kattar]

Any updates on this thread? Lots of potentially GREAT information and theories in the above posts. It's been almost 3 months so surely many of you have had to time form solid opinions from trial and error on your batteries. I have a couple of questions:

I was under the impression (aka assumption) that the "Smart" aspect of the charging system was able to balance the cells when needed. If the system can't balance charge it should have a means to where the user can balance the cells manually. Thoughts?

What is the general census on the "80% rule" from older LiPo technology on these?

What is the general thoughts on the "Down to 8%" suggestion by DJI?

Lastly:

elie kattar what was your final thoughts when comparing the "Break-in" process vs the NON break-in flying?

Hello and thanks for your reminder, its true we have all been testing for long time and yes i have to say that i am able to provide you with some results from my own point of view as follows:

1-Break in process is not recommended by DJI nor by any professional RC manufacturer its just a method of self care that some use from old rc enthusiasts, i have tried it on DJI's smart ( so called) battery and the results seemed to me promising so far 40+ flights 0.01~ maximum difference between cells, the last battery i had failed from 14 charges ( didn't know about the break in process yet).

2- 8% deep discharge also is a good advice, i have performed it so far 2 times and if it wasn't all that good for the battery i expected some consequences by now, but none so far the battery holds great, so yes i recommend the deep discharge also from my own experience, NB: always reach 25% and land then discharge it to 8% holding ground with props off.

3- 25 % landing rule applied all the time

4- 15min+ rest after flight for the battery to cool down

5- 80%rule didnt apply it honestly do i cant help summarise a good answer on that.

6- 2 days discharge time for me working great.

7- charge before flight only never left a battery charged for more then 2 days in case i couldn't fly right away for some reason

8- storing them away of sun light

9- yes they need pampering and good care but this the best way to take advantage of your investment as long as possible

Hope i heped answer your call,
Cheers
Elie

 

[N017RW]

I know that you got a replacement battery from dji.
However it is generally a very bad idea to just 'top' up lipo (or any) batteries. You can do it once or twice and for some types this causes no issues, but in general they do need to have a more complete cycle (never completely flatted) to have a long, long life.

There are a lot of opinions on this.

I prefer to reference this page which is by a non-biased or manufacturer affiliated independent testing house.
How to Prolong Lithium-based Batteries - Battery University

At the link provided above you can find this:

"The shorter the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine. There is no memory and the battery does not need periodic full discharge cycles to prolong life. The exception may be a periodic calibration of the fuel gauge on a smart battery or intelligent device."

It seems to contradict what you've said.

 

[elie kattar]

You can also check my P3P review and conclusions after 100 flights here: After 100 flights, 127km, 13hours, P3P conclusion | DJI Phantom Forum

I have set some great points there
Elie

 

[msinger]

What is the general thoughts on the "Down to 8%" suggestion by DJI?

This also usually rebalances the battery cells.

 

[N017RW]

Balancing is only done during charge.

This is to re-cal the 'intelligent' portion of the battery hardware as found in the last sentence of the quote from 'The Battery University' in post#37 above.