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Old Sep 08, 2010, 11:08 PM
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Quote:
Originally Posted by gravityKills View Post
>> I meant people on this thread!
I understand what you meant, but I wasn't posting it for the amusemnt of the regulars.

>> How did you detect it
I saw the 20+ amps on the display and had just enough time to scratch my head, when the wire started to smoke.

>> You'd think the voltage detection circuits would still work to shut the thing down
again, that's what you think but the charger doesn't care too much.

>> shuts off if things aren't 100% perfect.
it doesn't, it's even reproduceable.

>> If FETs totally failed then they'd be on 100% of the time even before the start button was pressed.
wrong, the circuit is apparently more complicated. You assume too much (the well-known equation: assume=***+you+me, in plain English: By assuming things you don't know for certain as facts, you make a donkey out of yourself and maybe others too)
Someone woke up on the wrong side of the bed.

20 amps alone doesn't make wires smoke unless you have really small wires. E.g. I draw 50 amps through my 2100 size battery and nothing smokes. I've also charged up A123's at 20amps and there was no smoke. Something else must be wrong.

Also, I assumed nothing, so your personal attack and editorial is unfounded. If you had of read my last message you would have read that is was mainly questions trying to expose the failure mode of your charger in the hopes that your experience could enlighten us as to what to look out for and how to avoid it. You haven't been very helpful in the regard. But have it your way...
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Old Sep 11, 2010, 12:36 AM
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Is it just me or is this thread detouring from the primary focus of battery safety?
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Old Sep 11, 2010, 02:20 AM
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Rob is the moderator of this thread and can delete the personal attack posts, and might as well get rid of this one too.

Rick.
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Old Sep 11, 2010, 02:46 AM
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>> so your personal attack and editorial is unfounded

take it from someone who has been there, bought the ticket, got the T-Shirt: Chargers do fail and cause LiPo fires. I once had to leave a trade show with several 1000 people in a rather undignified manner, namely running head over heals through an emergency exit with a smoking LiPo in my hand so that it didn't set off the fire alarm. Thanks to an Esky charger that short-circuited.

You can come up with all kinds of clever arguments why this should not happen in your reality. In my reality those are things I take as a fact because I've seen it with my own eyes, and all the arguing about what 'should' happen gets tiring.

About the wire: Yes it's a small charger cable. It's meant for maybe 1 amp. If driven at 20+ amps, it will dissipate more than 20 squared = 400 times the power and starts to smoke within a second or two. Again, it gets tiring, I'm not too keen to discuss the physics behind smoking charging wires when it's obvious.

I'm also not too keen on discuss internals of charger failure. a) it doesn't belong into this thread and b) it is completely irrelevant in our context - take it as a fact that they do fail, and that's all we need to know when it's about LiPos safety.

If you should ever be the target of a personal attack from my side, rest assured, I will leave no doubt to my intentions
Thus far, I simply don't agree with a lot of what you write, and find it annoying to have every second sentence I write challenged, with arguments that fall to pieces on closer inspection.
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Old Sep 11, 2010, 03:16 AM
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More personal attacks... trying putting words in my mouth that I never said.

And I disagree with you. If chargers do fail and cause lipo fires, then surely they are relevant to this thread.
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Old Sep 11, 2010, 03:30 AM
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Quote:
Originally Posted by groundfx View Post
If chargers do fail and cause lipo fires, then surely they are relevant to this thread.
There is no IF, only WHEN for both batteries and chargers. Humans place far too much faith on technology, but that's probably because humans fail even more often than machines.

Rick.
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Old Sep 11, 2010, 03:41 AM
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I agree, but just knowing that something can fail isn't enough. Knowing WHY something fails is critical to improving safety.

Cars would never have improved safety if we all just threw our hands in the air and said cars fail and kill people in simple accidents and never looked at WHY?

Clearly the cell phone industry, for instance, seems to have a much lower failure rate on charging Lipo's than the R/C industry seems to have. Clearly, some charging strategies are safer than others. WHY?

What's the safest R/C lipo on the market today? To answer this we need to understand WHY lipo's fail?

What's the safest charger? To answer this we need to understand WHY chargers fail?

These are all critical questions to advancing safety and making this thread irrelevant.

For instance, if GravityKills could explain how his Hyperion Charger failed, maybe Hyperion could issue a Firmware Revision that will ensure the charger turns off if a FET fails? Wouldn't that be something that people on this thread could benefit from?
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Old Sep 11, 2010, 04:10 AM
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>> More personal attacks...
as far as I'm concerned, this discussion ends here.
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Old Sep 11, 2010, 04:24 AM
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Why are you refusing to share the details of your Hyperion Charger failing so the rest of us can benefit? e.g. maybe a firmware fix could be done to make it safer and prevent an incident
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Old Sep 11, 2010, 04:33 AM
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>>refusing
http://www.gameculture.co.nz/wp-cont...WarriorsGC.jpg
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Old Sep 11, 2010, 04:37 AM
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Quote:
Originally Posted by gravityKills View Post
I ask a serious question and this is what you reply with? Are you 11?

I see that you're not really here to discuss Lipo fires and how to prevent them.
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Old Sep 11, 2010, 01:56 PM
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Quote:
Originally Posted by groundfx View Post
I ask a serious question and this is what you reply with? Are you 11?

I see that you're not really here to discuss Lipo fires and how to prevent them.
fortunately I wouldn't know a personal attack if it hit me over the head with a fence pole.

While I'm here, let me recall another charger failure incident. This one didn't cause any damage, it just reported an error code.
Theoretically it wouldn't have been possible, because the slug that crept into the electronics and left a slime trace all over the PCB would have been chopped to pieces by the fan. Fortunately, the slug was too dumb to comprehend this and did it anyway.

So when you gather data for your teach-Hyperion-how-to-do-chargers project, don't forget to add a chapter on slugs on the circuit board.



As a little service to those who didn't bother to read the last 250+ posts:
I posted a video of a rather spectacular LiPo fire, caused by intentional overcharging.
Regarding the question whether or not this is representative: Yes, it is, because a failing charger may cause exactly the same overcharging, as has happened to me (but I pulled the plug immediately).
And that's it. Sorry, my time to follow all those little side tracks and distractions is limited. I have better things to do with my life.
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Old Sep 11, 2010, 07:00 PM
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And here's my side of the story.

gravityKills comes on here and posts link to a video that shows a pack going up. He claims this is representative, and that any charger can cause this event to happen just as fast as in the video.

With this claim I called foul. To make this unsubstantiated claim, in my view gravityKills has stepped beyond the line and it now participating in sensationalism.

In my view, the video is clearly staged to cause the battery to fail as quickly and violently as possible.
- Clearly in the video they have a large power supply connected to it. It is unknown how many amps they passed through it.
- The pack seems to be pre-charged to cause it to fail as quickly.

Both of these are not representative of typical use and/or charger failures.

gravityKills dislikes my criticism of the video and then goes on to a personal attack as well as violating RCGroups family friendly policy about no swear words.

I have no problem with gravityKills, but I do have problem with the facts as he presents them. He then goes on a to say that he has a charger that would cause this to happen. Here's some things he has claimed:

>I've got one broken hyperion charger that failed this way, insisted of
>driving 20 amps through a little 2Ah pack

>Again, I own one broken Hyperion charger myself that fails to control the
>current and leads to exactly the staged incident once you push the
>"start" button.

>It drives 20+ amps through the pack until night falls because one of the
>FET switches in the power circuit is broken.
>About the wire: Yes it's a small charger cable. It's meant for maybe 1
>amp. If driven at 20+ amps, it will dissipate more than 20 squared = 400
>times the power and starts to smoke within a second or two.

I call foul on these "facts." There are too many inconsistencies.

1. Why is a tiny wire meant for 1 amp is being used to charge a 2100 battery that requires at least 2 amps to charge at 1C? Seems fishy.

2. Small wire (e.g. even 20 awg) will take 20 amps without going up in smoke.

3. I just opened up my Hyperion 720i charger and the output circuit only contains FETs and some (3) current sense resisters. There are no other switching elements on the output side of the circuit so a FET failure on the output side would not fail as described.

Secondly, the current sense resistors would continue to work even if a FET failed, thus it is possible that the MCU of the charger could detect overvoltage/overcurrent and shut down OR beep like crazy. (Whether the software does this or not, I can not confirm, but it could and thus make the charger very safe to any type of FET failure that caused over current.)

4. When asked for more details of how the charger failed to help us all not have the same failure the question was vigorously avoided and there were strong diversions taken to ignore the question. Including stories of slugs???? Why all this cloak and dagger stuff to a simple question?

5. gravityKills seems to have more charger failures than anyone I know.

So, yes, I'm saying the facts just don't add up and at this point I don't believe any of it. Everybody should be putting on the skeptical hat.

Why do I care?

Videos like this do a disservice to the R/C community. While they do create the WOW factor and cause to people to be cautious, they also exaggerate and obfuscate the truth which is less sensational. They also do a disservice because they create a false image that insurance companies, law makers, etc. will prey on in order to raise insurance rates, etc.

What would the world be like if everyone thought their hot water tank was going to blow up like in Mythbusters? Do you think you would have one? Would you live in fear? Could you get insurance? Well... that's the image we're giving about R/C with videos like this on YouTube.

You've read gravityKills side and now you read my side.

Given that, I'll now let this rest if gravityKills does the same.
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Last edited by groundfx; Sep 11, 2010 at 07:18 PM. Reason: typo
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Old Sep 11, 2010, 07:55 PM
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rcalldaylong's Avatar
San Jose, California
Joined Dec 2007
5,863 Posts
OMG - Look what lipos did

http://www.cbc.ca/world/story/2010/0...explosion.html


J/k. I'm poking fun at you guys.

Really, lipos require respect but aren't that nutty as some cook them to be. I've spliced them open, charge till they look like puff daddy, used till they hit 0 and puffed like puff daddy, touch + to - and not even once did I get to experience a nice fire like what people say.

well, maybe I'm just not that lucky.
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Old Sep 12, 2010, 10:52 AM
Space Coast USA
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Space Coast
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21,157 Posts
There are a lot of modelers who wish that they had been as "unlucky" as you.
Like this guy-
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