I wasn't referring to Arcing- even a slight increase in contact effective resistance can provide for significant power dissipation in higher current applications.
The circumstances you describe may lead to a premature battery failure in flight however it won't be attributed to a failed connector. How might you propose cell failure could cause increased current flow? Current is demanded by the load- a sick battery can't decide to force feed your phantom no matter what the conditions.
Yes, current would significantly increase with reduced supply voltage however the battery will auto power off in these conditions.
Hence why I said "intermittency" this will vary the effective resistance of the contact involved.
This is what where my concern is. Again looking at the full flight data. Over 2 min of 20amps plus. This is not normal. The contacts should handle the 20+ amps for a short duration which is normal, but not for the extended period as in this flight.
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I am not versed on electronics so I can not tell, but a failure model with a single cause (a bad connection, high winds, etc) would make this kind of event much more frequent, hence I believe is a combination of several factors, probably more than two. For instance bad cycling, take off with a battery which has been self discharging for a while and demanding flying conditions. In fact the only way to know is to create a data base of events like this were all possible factors are compared.
If 5.8Ah does a 27min flight down to 10% remaining capacity that’s 11.6A average current draw. That puts our 20A at less than 100% above average rating. Should not be a problem at all abscent poor system design.
Connector quality, rating (current) and mechanical design (ensuring proper seating with battery installed) are all factors. Battery condition isn’t and can’t be, at least with respect to the factors your suggesting.
@With The Birds ..I am not stating that this is definitive at all. It is something that I have not seen for a prolonged period, as far as the data goes. It is only "suggestive" as to the relationship of the "high winds" and "long duration" very high current draw, that "could" result in the contact issue. @sar104, I usually like to have at least 3 opinions on the data from incidents such as these. What do you think?
We all have the same intent here- to arrive as close as we can to the issue.
20A isn't excessive (even for a prolonged period) having regard to the average current draw of the P4. To the extent it might be DJI failed at the design stage when the connector was specified.
If it could be determined that the P4 can't maintain a 20A load for any operating parameter by design then you would have a good case for suggesting the 20A load was in part attributable to the poor performance of the connector. What we do know is it melted, melting requires heat the source of which in this case must be a poor electrical connection. Gets us back to poor mating (not fully inserted), insufficient current rating for purpose, corrosion or weak pins but more likely the compliance of the female terminals (spring tension).
If the connector was failing during the 20A depicted loading we can be confident at least part of that load would relate to the power being dissipated in the poor connection. We can see the connection failed from the physical damage, the logs don't contribute much here.
As I mentioned in Post#5. The aircraft data may give a bit more. Personally, I have been attempting ( To little avail ), to determine the numerous P4 shut down issues and common instances. None of which have been any where near conclusive. There have been only a few that I know of that had "physical" evidence of said shutdowns. This particular flight as well as the previous image from another were very similar ( The first was a mid air shutdown, this one was not ). Coincidence? Maybe.
The current draw correlates with tilt, as expected, particularly clearly during the high current draw period on the return:
What is unusual is the tilt angle of 34° in RTH. The specs for the P4A indicate a maximum tilt of 25° in P mode. However, it is rated for 42° in sport mode, and so that current draw should not be a problem. I don't see anything obviously amiss with the battery data, and I'd have to suspect a poor connection (high contact resistance), perhaps due to the battery not being fully inserted.
I don't know if you tried this, Right click on the icon and choose "RUN AS ADMINISTATOR" from the drop down list and see if this does it ?
SteveP55
Haven't read all the responses but when i see the burnt terminals like this i can only assume bad connections coupled with high amp draw causes arcing and will do this type of damage
Go to your advanced startup settings and disable 'Driver Signature Enforcement'.
The heat measurements shown in the monitoring data don't come from the terminals. It's battery temperature only.
I have some experience in the field as well and I'll say this response and similar ones are pretty much on the mark.
The fun part is that the failure modes can feed on themselves. One of the things I don't recall seeing mentioned by the way is that the heat can affect the temper of the metal which can affect connection quality and feed the heat related failure mode. Softening the supporting plastic adds to it, etc.
Tangent: Anyone who has put a lot of miles on Honda and older Suzuki motorcycles (and perhaps some others) will see the pics posted and say to themselves "hey that looks familiar!" I could spend days talking about those failure modes. I've replaced lots of charred connectors on my Honda VFRs.
They seem to be burned out? Those connectors are indeed pretty much burned out. It will need to be replaced before you try to fly it again. What does the matching connector in your P4A airframe look like?
I was pretty certain that was the case given it would require much more than 55C to do the type of damage to the terminals seen in the photograph.
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The reported batt. temp. has nothing to do with the temp. at the melted point. It must have been much over 100 deg. If we know the melting temp. of that plastic material then the temp. could be much more exactly estimated. But this is not what I want to say about this issue here.
We do not know if this melting happened at last flight or was happening at several flights before the last one.
So, the question is: How many of you folks check the battery contacts regularly after each flight? I for myself can say that almost never!
We do not know if this melting happened at last flight or was happening at several flights before the last one.
So, the question is: How many of you folks check the battery contacts regularly after each flight? I for myself can say that almost never!
UPDATE: I contacted DJI about my battery. They asked me to return it (even offered shipping, but I had sent it already). UPS called today with a brand new battery. The whole thing, door to door, took about 10 days. No questions asked, just a straight swap; ruined battery for new one. Thank you DJI!
Awesome update!
If you've answered this and I missed it then I apologize but have you checked the condition of the contacts and surrounding area on the bird?
If you've answered this and I missed it then I apologize but have you checked the condition of the contacts and surrounding area on the bird?
