Battery got wet.

[MileHighSi]

Yes - until it drops out of the sky.
Fill your boots - go fly.

Point being that it won't drop from the sky as I'm conducting very short test flights in a controlled environment. I'll await a more objective answer.

 

[The Editor]

Point being that it won't drop from the sky as I'm conducting very short test flights in a controlled environment. I'll await a more objective answer.

Until one day one cell goes short circuit and your pack output drops to 7.4v and the esc LVC cuts in and stops the motors.
Enjoy your flights.

 

[MileHighSi]

Sure thing. Which is why I'd like to know how long to test for, before assuming it'll be okay (or assuming it might not be). I'm quite keen on not assuming anything. There is a rough time limit you would expect corrosion to occur by if it is going to at all. Personal opinion is great and I don't want to discourage it, but I've gathered yours. There is no need to rephrase it any other way Right now I'm after something factual regarding corrosion timescales.

 

[Kilrah]

Which is why I'd like to know how long to test for, before assuming it'll be okay (or assuming it might not be). I'm quite keen on not assuming anything.

Contradictory - if you're not keen on assuming anything then don't ask about when to assume something

Anyway, nobody here can answer that question, as simple as that. You do what you feel like. I would trash it too.

I've had "passive" cells (no electronics like in the Spark battery) that were touched by seawater, the salt must have somehow entered the cells themselves and the next day were down to 0V and could not be charged (appeared as a short). If such a thing happened the meter on the Spark battery would not know about that and still show you full even if the cells aren't (assuming there's just enough power for the electronics to actually run of course).

 

[MileHighSi]

Contradictory - if you're not keen on assuming anything then don't ask about when to assume something

Anyway, nobody here can answer that question, as simple as that. You do what you feel like. I would trash it too.

I've had "passive" cells (no electronics like in the Spark battery) that were touched by seawater, the salt must have somehow entered the cells themselves and the next day were down to 0V and could not be charged (appeared as a short). If such a thing happened the meter on the Spark battery would not know about that and still show you full even if the cells aren't (assuming there's just enough power for the electronics to actually run of course).

To be clear, I'm not asking for assumptions. As made clear, I'd like a fact - maximum time before knowing for sure that corrosion won't be an issue. If I tested it for 20 years and it worked flawlessly, I'd be quite right to consider the battery fine and anyone saying otherwise is a worrywart. However, 20 years is laughably long (of course) so perhaps someone who knows about saltwater corrosion could provide some valuable insight. How long/how many test flights/whatever metric you want to use before the worries of corrosion can be categorically dismissed? I'm not asking for assumptions or speculation. I don't know how to make the question any simpler.

 

[The Editor]

To be clear, I'm not asking for assumptions. As made clear, I'd like a fact - maximum time before knowing for sure that corrosion won't be an issue. If I tested it for 20 years and it worked flawlessly, I'd be quite right to consider the battery fine and anyone saying otherwise is a worrywart. However, 20 years is laughably long (of course) so perhaps someone who knows about saltwater corrosion could provide some valuable insight. How long/how many test flights/whatever metric you want to use before the worries of corrosion can be categorically dismissed? I'm not asking for assumptions or speculation. I don't know how to make the question any simpler.

I do not know how to make the answer any easier.
Try this....
Corrosion doesn't stop. It keeps going.
If it is in contact with air it will keep eroding.
Rate of corrosion is impossible to quantify due to too many variables.
If corrosion has started (which it will if it has touched sea water) it will continue.
However, since you appear to have already made up your mind to continue flying the pack, I doubt anyone's comments or statements will change your mind.
Your Spark, your lipo pack, your liability.

 

[MileHighSi]

I haven't made my mind up at all - I'm just interested in gathering more than one or two opinions. That's what a forum is for, after all. Otherwise I'd have just asked my neighbour and accepted his answer as gospel. If I'm honest, I've read a few of your posts throughout this forum and your apparent desire to be the voice of all Spark owners kind of makes me take your opinions with (a-ha) a grain of salt. I don't mean that in a mean way, it's just how I feel, personally. Besides, you've made your opinion clear (several times). Like I've said, I'd like more opinions and, ideally, I'd like some fact (regarding maximum corrosion timescales from a slightly more scientific standpoint). In the interests of clarity I'll break the question down as follows:

If a small dose of saltwater is going damage a Spark battery, how long (maximum) would you expect to wait before seeing any effects during safe testing?

Opinions are valued. Assumptions aren't. Citations are lovely.

 

[Kilrah]

You will find exactly 0 people on this forum who have made a scientific study of evolution of corrosion on a Spark battery that was in a bag of which the lower part was submerged by repeating the process with 20 of them and monitoring the evolution over 6 months.

As mentioned saltwater exposure can already drastically vary in effect between 2 different batteries, so any insight not on that particular one and the matching conditions is moot anyway.

 

[MileHighSi]

You will find exactly 0 people on this forum who have made a scientific study of evolution of corrosion on a Spark battery that was in a bag of which the lower part was submerged by repeating the process with 20 of them and monitoring the evolution over 6 months.

As mentioned saltwater exposure can already drastically vary in effect between 2 different batteries, so any insight not on that particular one and the matching conditions is moot anyway.

Very true, I expect. However, that's perhaps a touch more specific than required. You do raise an important detail, though, which is that it would only have been the bottom half of the unit which was exposed (none of the gold plates or pins at the top), and even then just through the bag. The internals may not have been exposed much, if any at all, to saltwater – depending on how watertight these unit are. Even more reason to want to know how long is long enough to ascertain whether corrosion will occur.

Someone out there with good knowledge of both lithium batteries and salt's corrosive properties on electronics over time knows the answer. I'll ask elsewhere and report back.

 

[clouseau]

how long is long enough to ascertain whether corrosion will occur...

What holds true for corrosion in other electronic components is no different for the Sparks battery! Which doesn't take a science experiment or study to figure out what the outcome will be.

The only way to tell with 100% certainty that saltwater is not going to eventually damage your Sparks battery is to take the battery pack apart and inspect the PCB board, switch, components, and contacts for any corrosion.

Saltwater corrosion usually sets in quickly within a matter of hours to where you should be able to see components inside start to turn green or rust. If you think that you can just keep testing out the battery pack without inspecting it internally, your just rolling the dice and taking a gamble. Over time environmental conditions such as condensation and humidity can eventually aid even the smallest traces of salt and start corrosion inside without you ever seeing any adverse effects until over time it finally has a catastrophic failure from it.

I don't recommend you opening the battery unless you have experience handling or building Lipo's batteries yourself. If by chance you puncture or damage a cell, you will have poisonous smoke and possibly a fire on your hands that you possibly won't be able to extinguish.

The critical thing that must be done almost immediately with any electronics that has been exposed to saltwater is that the power source needs to be disconnected from it, and it needs to be either rinsed with fresh water or cleaned off with a good electronics parts cleaner so that all the salt is completely removed from it. After this the electronics needs to be completely dried before it can be tested or used again.

If you have failed to remove any trace of the salt, it can come back to haunt you later on. Soaking the electronics in rice sometimes works as only a short term solution, however I have repaired many DJI drones that have been in either saltwater or swimming pools chlorinated water and soaked in rice to dry out afterwards. And the critical mistake the owners usually have made that lead to the aircrafts eventual demise even after having it flying and operating again, is them having not cleaned or completely rinsed out the saltwater or chlorine before putting their drones in the rice.

I don't use or even tell others to use the rice method works, I'd personally rather take everything apart and properly clean and dry it. If there is a part I know that has saltwater in it, and I can't take it apart to clean and dry it, it gets trashed and replaced.

Conclusion: Replace the battery, or just keep it for use only on the ground.

 

[MileHighSi]

Yeah I won't be opening the battery haha..

That's good info, thanks. My only doubt now is whether or not salt actually got in to the unit, which is why I was wondering about how long it'd take to be absolutely sure (without deconstructing the unit). Although the battery stopped working initially, it has now started again and as far as I'm aware, corrosion doesn't reverse As stated earlier, my current plan is to purchase another battery but (flying in the face of popular opinion) keep this one as my emergency third, for those rare moments when two isn't quite enough. For me this is literally once or twice a year. I'm resigned to having to charge/test it periodically. Frankly, if it still works after a year I'd probably put my concerns behind me.

 

[Blue Baron]

To the T.O.

If 50$ would mean a lot to me, I‘d use the affected battery at dry weather conditions, and if kept dry all the time. I would still buy a new one though.

Wrt corrosion ... the corrosion has already happened and will continue to happen except if air is extremely dry. Humidity normally is everywhere. But corrosion from humidity in the presence of salt can be slow (or fast if you look at last century cars operated near a coast).

The question isn‘t when the risk is over. But rather than it becomes significant. However, I wouldn‘t expect the cells to fail. Cells are isolated further and didn‘t become wet internally. Nevertheless, esp. in humid weather conditions, the battery electronics will at some point start to mal function and with bad luck, become dead to the craft, then becoming a falling stone.

 

[MileHighSi]

As I've said earlier it's not so much a cost issue as it is waste and environmental concerns. I live in Malaysia and I have serious doubts as to whether I could get it responsibly recycled. I have already sourced a replacement. The question is whether to keep the suspect one for emergencies. I remember draining both batteries whilst travelling around Japan one day and cursing myself for not saving a little juice. The third battery would have definitely (IMO) been worth getting out at an abandoned temple we stumbled across.
The other question which I'm increasingly asking myself is whether or not any salt/water actually got inside unit. In which case it's not a question of when the battery will fail (as has been suggested near enough universally here) but if - hence my questions around when I would be able to tell.. at the longest; i.e. if corrosion has already started (as is popular opinion) then how slow is the very slowest it can possibly take to corrode before I actually notice (i.e. if the battery still works after that timeframe I can assume all is okay).

 

[Blue Baron]

As I said, it can be very slow. 10 years easily.
Malaysia is humid, I‘d sent the battery back to DJI for disposal. At least here in Germany, it is a law dealers must take back used batteries for recycling. So, DJI must be prepared to receive used batteries.

 

[MileHighSi]

10 years?! God ****! But it can also be like.. 2 months? That's annoying. Then again, if I'm still flying Spark 1.0 in 10 years I'll be quite upset haha...
I'm going to give it to a professor in the area who said he can get to the bottom of what damage if any has occurred. After a quick look at the contacts he actually seems less worried than this forum is, which is kind of reassuring.
In any case, I'll look up DJI's policy for here. Thanks for that valuable info!

edit: can't believe that got censored

 

[Povl H. Pedersen]

I would keep using the battery. I assume the 3S output is thick wires inside the battery, so it will continue to deliver power to the quad long time after the internal electronics are dead. But again, I fly safely, and if it drops out of the sky, that is what happens. I also use bad lipo cells on planes/race quads, until I think they perform too bad to be used. Been charging single cell on 3S/4S batteries a few times in an attempt to save it.

 

[The Editor]

I would keep using the battery. I assume the 3S output is thick wires inside the battery, so it will continue to deliver power to the quad long time after the internal electronics are dead. But again, I fly safely, and if it drops out of the sky, that is what happens. I also use bad lipo cells on planes/race quads, until I think they perform too bad to be used. Been charging single cell on 3S/4S batteries a few times in an attempt to save it.

No it will not.
The O/P is switched through a logic circuit internally.
If the 'smart' part of the battery fails then the pack will cease to provide voltage to the terminals.

 

[Povl H. Pedersen]

OK. I am mostly used to plain standard LiPo. And since the current draw can be pretty high (same here), power output is unrelated to the rest. Assume we can discharge the battery in 6 minutes full throttle, then it is 10C. So around 15A. But looking up, you can get pretty small 20A MOSFETs, so I assume it is possible.
So I assume that means that it is impossible to over-discharge the cells.

 

[The Editor]

OK. I am mostly used to plain standard LiPo. And since the current draw can be pretty high (same here), power output is unrelated to the rest. Assume we can discharge the battery in 6 minutes full throttle, then it is 10C. So around 15A. But looking up, you can get pretty small 20A MOSFETs, so I assume it is possible.
So I assume that means that it is impossible to over-discharge the cells.

Correct - there is both over discharge protection as well as LVC monitored per cell, pack temp sensors and charge and balancing is also done internally.
They are in fact a PITA and normal lipos give the user much more control and flexibility but these 'smart' packs were developed with the 'idiot gene' in mind and to try and prevent Darwin Award candidates from setting their houses on fire.