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

I just reviewed this thread and noticed that no one mentioned using HealthyDrones.com as a battery health resource. This is a free site and has been invaluable to me for monitoring battery health.
 
Balancing can be done discharging or charging. DJI "very intelligent" battery theorically can do that becouse it does monitor single cell behavior during use, so it could rule single cell load to maintain balance.
You can smell that battery is going bad, in near future, just running motors idle for a while with porpellers on: if you hear sound of slowing and regaining speed on the motors.. then be carefull and check single cell value (or use HealthDrones.com).
HealthDrones just check reading log from voltage ADC inside the battery ... I don't trust too much the logged readings by DJI, although HealthDrones is an invaluable monitor.
 
Balancing can be done discharging or charging. DJI "very intelligent" battery theorically can do that becouse it does monitor single cell behavior during use, so it could rule single cell load to maintain balance.
You can smell that battery is going bad, in near future, just running motors idle for a while with porpellers on: if you hear sound of slowing and regaining speed on the motors.. then be carefull and check single cell value (or use HealthDrones.com).
HealthDrones just check reading log from voltage ADC inside the battery ... I don't trust too much the logged readings by DJI, although HealthDrones is an invaluable monitor.


Please link to info regarding balancing while discharging.

Never heard of it or understand how it could be done given the current demands during discharge.

Never have such details of the 'intelligent' hardware been discussed or documented here.

I'm all ears. ;)
 
Oh sure, it can be done using a dummy load of variable resistance attached to each cell and a MOSFet circuit driven by a small microprocessor.
In the case of DJI battery it is not possible (or better very difficult) during flight due to high current sucking, but the autodischarge feature may do that without any issue.
 
Without a link I can't give it any credence.

As far as imagining ways to do it, sure you've got one.

There's no literature I could find where anyone employs LiPo balancing during usage or the discharge phase.
 
Sorry no evidence and seems no pub docs, but I have in my docs a circuit schematic for that matter. Anyway it has not much interest in RC world if nobody take in consideration.
 
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.
Do you have any basis to back this up, as it relates to our P3P batteries? I have always understood that topping off is never a problem. I do it before every flight, as I need to start with 100%. 15-17 minute flight times are already too short on a fully charged battery. Starting out at 94% is asking for trouble. Better to top off and not need it, than to have to run them down to 10% because you didn't! :cool:
 
No break in or special handling techniques here and all my batteries, some with 100 plus flights are at 96% - 98% or thereabouts. Always fly 15+ minutes per battery. i never charge warm batteries is all. Other than that, nothing else.
 
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There are some great tips and info here, if anyone is interested in reading further about our RC battery care.
The Ultimate LiPo Drone Battery Care Guide

Enjoy. ;-)

RedHotPoker
The author seems to have compiled and adopted all the myths and misinformation in an attempt to sell an overpriced battery charging hub. Says to never top off a battery, and yet LiPo's can and should be topped off before use, to get the most out of them, and to make sure that your aircraft has sufficient juice to get home, and isn't overly stressed. Always better to start at 100%, especially when warm up to take off and preflight checks will drop that to 95% before she's airborne!
 
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@GadgetGuy,
Interestingly enough, that sounds much like my own batt. practice. ;-)

Even though I do like that smart charger that can do multi functional procedures, I opted for a second 100w DJI charger. Makes it easy to charge two batteries at once, or a battery and radio controller together. ;-)

RedHotPoker
 
The author seems to have compiled and adopted all the myths and misinformation in an attempt to sell an overpriced battery charging hub. Says to never top off a battery, and yet LiPo's can and should be topped off before use, to get the most out of them, and to make sure that your aircraft has sufficient juice to get home, and isn't overly stressed. Always better to start at 100%, especially when warm up to take off and preflight checks will drop that to 95% before she's airborne!

I agree... there is a lot of disinformation on that site. Great for selling products though.

don't top off??? seriously?

Those battery bags are funny.... and a great money grab from those people who just don't know.
 
@GadgetGuy,
Interestingly enough, that sounds much like my own batt. practice. ;-)

Even though I do like that smart charger that can do multi functional procedures, I opted for a second 100w DJI charger. Makes it easy to charge two batteries at once, or a battery and radio controller together. ;-)

RedHotPoker
I instead opted for the DJI Battery Charger Hub, which is supposed to charge the highest charged battery first, and then the rest in that same sequence. However, it appears to suffer from the same limitation of the included charger. If the battery is already 90% charged, it is ignored, and won't top off, unless you first turn it on. So, to get it to charge four 90% charged batteries unattended, all four must be simultaneously turned on and left on, waiting for their turn to be topped off to 100%, while needlessly depleting their original charge, so that they each then take that much longer to charge fully! It's only $90 and uses the original charger, but it still needs serial babysitting, if you don't want to waste battery power while topping off. Otherwise, it's handy for continuous charging of four depleted batteries. You could also easily fly all day with 4 full batteries at 15 minutes each, and an AC source, pulling a full battery off every 15 minutes, and putting a depleted one on to replace it, which then has time to cool before it gets charged.
 
@GadgetGuy,
Can you charge an intelligent flight battery and your radio controller at the same time? ;-)

I saw that hub, but figured for the difference in price, this option of dual chargers, was a better value for me.

RedHotPoker
 
@GadgetGuy,
Can you charge an intelligent flight battery and your radio controller at the same time? ;-)

I saw that hub, but figured for the difference in price, this option of dual chargers, was a better value for me.

RedHotPoker
No, since the hub still uses the original charger, you can't do anything you can't do with the original charger, but it avoids checking every few minutes to see when the battery is fully charged, before you can put the next one on, especially, if they are all at different charges. It will charge 4 batteries in the shortest time possible, unmonitored, and deliver the first one to you the fastest, by determining the highest charged one at all times, and charging it first. I like that. My transmitter battery lasts through 20+ battery depletions, so its not a big deal to dedicate the charger to topping it off once a week, after charging the batteries. The single charger with the hub is very compact and only needs one AC outlet. Only complaint is needing to turn on all 4 batteries to top them all off, if they are all around 90%. It's really only for 20 minutes. No biggie, in retrospect.
 
Hey guys any insight on what you think this might be? Believe it or not oldest battery on right.
ImageUploadedByPhantomPilots - DJI Phantom Forum1444600467.869781.jpg
ImageUploadedByPhantomPilots - DJI Phantom Forum1444600485.045351.jpg
 
Also to keep these smart batteries in good condition, the smart chips need to be calibrated, so discharge to 7-8% every 20 cycles as DJI says in the battery care manual.

Your batteries will last longer doing this as the chips need calibrating else will give false voltage readings over time.
 
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.

Question: You've stated not to let any of the cells drop below 3.3V. What about when we're dropping the battery to 8% (as recommended by DJI). Won't that take it below 3.3V?
 

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