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Old Nov 10, 2003, 03:32 AM
TeamTP,Minicopter,Spartan
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Mississippi 31 years , Now Kotzebue , Alaska 12
Joined Apr 2001
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hey , Ben , Good work man , I bet you are tickle pick with the big helis and the new found HV setup , And the suprise faces you will get from the nitro guys , so are you going to go with the 12s2p tanics ? I sure hope those cells can withstand a long term life pushing them at the max , and it sure looks like you have the right motor too, cant wait to see a video of it .
man I sure wish we still had warm weather ,


Tony ;~)
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Old Nov 10, 2003, 03:40 AM
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San Francisco, CA, USA
Joined Jun 2001
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disaster strikes

moments after my last post, the LiPos which were charging in the adjacent room exploded. they were in the heli at the time, being charged by my astro 109. there was a massive fireball. thank god i had a fire extingusher sitting right next to my workbench. it saved the house from burning down. the heli however, is roasted. i'd say about a 50% loss. what a mess. more details tomorrow.
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Old Nov 10, 2003, 03:40 AM
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my workbench where the heli was sitting
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Old Nov 10, 2003, 03:49 AM
TeamTP,Minicopter,Spartan
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Mississippi 31 years , Now Kotzebue , Alaska 12
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Damn ! MAN! Ben ! the tanics ???? man !!! ,


Sorry Bud ? wonder why ?

Tony
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Old Nov 10, 2003, 03:56 AM
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Mississippi 31 years , Now Kotzebue , Alaska 12
Joined Apr 2001
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Dang ! what a let down on my side , and I do bet yourside too just wrote on what a fine job and happy that its working out great and few minutes later , you post this , man that just sucks , glad you was able to put the fire out , was the chargers set right ? , huh????


Tony
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Old Nov 10, 2003, 04:11 AM
17 years on RCG!
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Im just happy to see your house is safe and most importantly that YOU are safe!!!

I cant explain how my heart just dropped to see these pics.

Again, Im glad youre ok Ben!

Jason
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Old Nov 10, 2003, 04:33 AM
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thanks guys.

i'm pretty sure i know what happened. it was the 7s2p pack that was charging, and that's the one that exploded, although the explosion set one of the other 5s1p packs on fire too. i initially set the 109 to charge at 2.2A, but after 45 min, i realized that it was a 4400mah pack, and that i could charge at 4.4A. so i increased the current to 4.4A. however, the 109 apparently has a 60 minute time limit, so it timed out when the pack was maybe 75% charged. i simply unplugged the pack, then plugged it back in again. i did look over the screen to check on current and voltage, but i probably did not notice that the 109 had incorrectly detected 8s instead of 7s. it was about 15 minutes later that the pack exploded due to overcharging.

the fire was almost certainly the charger's fault, but i feel pretty stupid about leaving the packs in the heli while they were charging. they were zip tied in place as a temporary measure, and it would have been a pain to take them out. sure wish i had learned a lesson from gary wright's funtana incident.

oh well, it's only money. the heli can be repaired. not sure if i want to mess with lithiums again though. i guess if i had taken better precautions this could have been much less of a disaster. i thought i had resolved myself to be super careful with these lithiums, but i obviously wasn't careful enough. it will take a major shift in thinking in this hobby to avoid incidents like this in the future. we're either going to have to start treating LiPos like TNT, or we'll have to find something less dangerous to power our models.

damn, there's fire extingusher dust all over my keyboard. i wonder if that awful smell will ever leave the house.
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Old Nov 10, 2003, 04:36 AM
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South Orange County, CA
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That's just it, I don't think these packs are being pushed at all. I was watching the video from the onboard camera while it was being transfered into the computer and through most of the manuevers, it rarely gets above 40A. Only on the "rocket launches" did it get to the max, which was 63-67A and those only lasted for one screen update on the Whattmeter (about 1/2 second...).

Actually, I think the TPs could easily handle this as well. If the packs aren't getting hot , at all, how could they be stressed? I think the problem is that we are just used to running them at such low voltages that we've lived with the heat. They just aren't getting hot anymore. In all three LiPo-powered helis that were flown today, the Predator, the Logo 10 and the Eolo, the packs were right around 100 degrees. In the Eolo I used a 5s1p pack and it worked great. With the Aveox 27/39/1.5 and the 5s1p pack it weighs a full 7 ounces less than a Hacker C40-8L and a 3s3p TP pack. That's a HUGE difference on a heli that weighs about as much as Ben's flybar on the Predator! Even using just a 1p config, the pack didn't any hotter than the 7s2p pack on the Logo or the 12s2p arrangement on the big boy.

I'm jsut about done with the editing but they still hae to be rendered and then uploaded to a server. I'll have to finish them up in the morning.

-- Gary
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Old Nov 10, 2003, 05:05 AM
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Oh my god, how awful!!!

I definitely agree it looks lioks the software in the 109 is the culprit. It is well known that it has a problem determining the proper cell count when the pack is near empty. It looks like the much more dangerous case where it has problems on the high end as well. This is just terrible.

It may just be time for the extra protection circuitry on the packs. The phones and the computer packs use them and so should we, I think. Relying on the charger manufacturers to make smarter chargers is not the answer.

Man, what a bummer...

So glad you are safe. I'm definitely going to re-think my recharging procedures.

-- Gary
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Old Nov 10, 2003, 05:32 AM
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Mississippi 31 years , Now Kotzebue , Alaska 12
Joined Apr 2001
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Man , Im sure glade I have the 636 , but it is kinda easy to make a misstake , I wasted a 5s4p 3 weeks ago just being in a hurry to fly and ended up plugging the 2 packs into each other , didnt want to take the canopy off my F1-60 heli , cold and one thing on my mine , fly , Im suprised my lipo pack didnt catch a fire , it blew a tab as soon as I plugged it up , and welded my powerpoles together , so I will force myself to take the time to make sure Im doing it right , with the charger and connecting the batteries ,

Man , dang .


Tony
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Old Nov 10, 2003, 01:01 PM
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Wow, glad to hear you are OK Ben. I hate it when you reaad all this good news, then get the blast of bad at the end.

I've been leery of the Astro109 from the start and am glad I got the 6-330. Still, I never feel comfortable charging the LiPos and always keep checking them. Now I may pull them out of the heli for charging and put them in a small metal container.

I hope everyone has a fire extinguisher around when charging/using these batteries. This stuff is just as dangerous to have around as glow fuel, no reason not to treat it that way. I'm going to go out and get another one tonight, after seeing that, I'm thinking one may not be enough!

Wow.....
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Old Nov 10, 2003, 02:04 PM
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uk
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Sorry to read about your trouble Ben, having just bought a 109 after reading various posts about them i am now a little concerned i was under the impression that the cell count program in the 109 would switch to a lower cell count if it was not sure .
Was it because it was nearly charged before that the charger misread the cell count ?I think that we should not take safety to casually with this new tech.

Graham
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Old Nov 10, 2003, 02:49 PM
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Russellton, PA
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WOW, sorry Ben to hear and see the pics.

I was soo enjoying both your and Gary G's latest post in your break through flights! MAN!!!

I have a 109 coming to do an article comparing the 636 and ORBIT PRO. I see I need to STRESS double and triple checks when we are charging.

I'm happy to hear no life or bigger home loss occurred.

WE ALL NEED TO BE SAFE WITH THESE GREAT BATTERIES!
__________
Best regards,

Ron Osinski
aka - GMRO
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Old Nov 10, 2003, 03:36 PM
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South Orange County, CA
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The problem with the 109 is in the algorithm used to determine series cell count. If you have a cell/pack that is pretty well spent its voltage level is actually below the "peak" value for a pack with one less in series. Until last night, this hasn't been a real problem because usually you could just plug it back in a couple of times and it would finally trip over to the next level and take off. What happened to Ben was it was close to the peak value when he plugged it back in after it timed out when he had the current set too low. The algorithm then trip to the next level and Ben didn't notice. 15 minutes later, the fireball happened.

I think an immediate mod needs to be made to these chargers that at a minimum adds a manual control for cell count with some sort of alarm if the charger thinks the pack is lower in series. This should have to be overidden to continue.

All we need is for some kid to get hurt with a LiPo explosion and the government will be in "helping" us to fix the problem. We need to be smart and we need to be safe. Nobody feels worse for Ben than I do but we need to use this as a wakeup call. I know I am.

-- Gary
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Old Nov 10, 2003, 04:51 PM
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Kansas
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Ben glad you and your are fine
call me
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