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Old Jun 23, 2009, 09:16 AM
firstimeflyr
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Alabama
Joined Feb 2009
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lipo's, Worth the Risk??????

WOW, I just read the sticky thread on lipo's. Makes me not want to ever have lipo's. Very scary stuff. Could burst into flames at any time, burn the house and or car down , i mean wow, is it really worth the risk vs nimh batterys? Tell me that lipo safety has come a lot further since the thread was posted. Its like you got 27 steps to charge the lipos and if you miss one step your house burns down. I mean come on, i have always followed steps and instructions on everything i am doing but this really makes me un easy for some reason. I guess thats why i have not gotten into lipos yet. I want to get into lipos, but i always like to research the hell out of something before i get into it and thats when i came across that thread. So that brings me back to my question. Lipo's is it worth it? Also if you have any advice to somebody just getting into lipos lets hear it.
Thanks,
Scott
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Old Jun 23, 2009, 09:21 AM
Frankenstein recycled packs
rampman's Avatar
USA, AZ, Gilbert
Joined Jan 2006
8,756 Posts
Once you try lipos you won't go back. Nothing packs the punch of a lipo.
The most important thing is to get a GOOD balancing charger. If you plan to fly 4S and smaller, a Cellpro4S is a GREAT choice. This one is one of the safest chargers out there.
http://www.fmadirect.com/products.htm?cat=45&nid=4

Advise? - Never charge unattended, never take something for granted and use common sense.
Rick
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Old Jun 23, 2009, 09:24 AM
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Arendal Norway
Joined May 2008
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If you follow some very simple precautions, LiPo's are safe. Think about it: Gasoline is highly flammable, even explosive given the right conditions. Yet we use it without worries because we have learned how to handle it.
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Old Jun 23, 2009, 09:30 AM
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Bakersfield, CA
Joined Apr 2008
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firstimeflyr - I think most of what is posted about lipos is based on the owner's irresponsibility in handling them. If you follow the manufacturer instructions, lipos will last a long time. Major items - store in a cool environment, use a sack when charging, watch run time and full thottle, and use the correct charge rates. Other than that they are generally very safe. Good luck!!
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Old Jun 23, 2009, 10:46 AM
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United States, AZ, Queen Creek
Joined Aug 2004
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Quote:
Originally Posted by RJD1234
firstimeflyr - Major items - store in a cool environment, use a sack when charging, watch run time and full thottle, and use the correct charge rates. Other than that they are generally very safe. Good luck!!
This and other reasons I wouldn't touch one with a 10 ft. pole.

Check this out:


http://www.rcgroups.com/forums/showp...56&postcount=4
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Last edited by dirtybird; Jun 23, 2009 at 11:32 AM.
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Old Jun 23, 2009, 10:53 AM
firstimeflyr
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Alabama
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Something wrong with the link. says "The page you requested cannot be found"
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Old Jun 23, 2009, 11:21 AM
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Raleigh, NC
Joined Apr 2007
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Quote:
Originally Posted by dirtybird
This and other reasons I wouldn't touch one with a 10 ft. pole.

Check this out:

http://www.rcgroups.com/forums/show...756&postcount=4
Error 404: Page not found...

The link is corrupted... Try again.

Bill
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Old Jun 23, 2009, 11:23 AM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,832 Posts
IMO, they are worth the risk.

They present a minimum risk if handled properly.
To me that means:
Charge with a balancing charger.
Charge in a firesafe container.
Store in a firesafe container.
Transport in a firesafe container.
Do not discharge more than 80%.
Prop the system to draw no more than 70% of the C-rate at full throttle.
Do not store in a hot place.
Do not store fully charged.
Do not use physically damaged packs.
Do not use puffed packs.
Do not discharge below 3.3V/cell under load, 3.7V/cell after resting.

Yes they present a fire hazard. I just try to keep that from happening anywhere but in a firesafe container or outdoors in the unlikely event that happens. Read the fire reports ( http://www.rcgroups.com/forums/showp...56&postcount=4 ) and get an idea of what not to do. The more you know and plan, the less the risk.
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Old Jun 23, 2009, 11:29 AM
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United States, AZ, Queen Creek
Joined Aug 2004
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It works now
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Old Jun 23, 2009, 12:31 PM
How does it work? How did it?
mareklew's Avatar
Karlsruhe, Germany
Joined Mar 2009
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Quote:
Originally Posted by dirtybird
This and other reasons I wouldn't touch one with a 10 ft. pole.

Check this out:


http://www.rcgroups.com/forums/showp...56&postcount=4
You can write half of that list off with any modern charger: they just won't let you charge N cell battery on N+1 cell setting. Not even a discharged N+1.

E.g. Accucell 6 (iMax 6, BAntam BC6) checks pack voltage if it matches setting, if okay starts to charge (at this point a deeply discharged 4 cell can be mistaken for a 3-cell), but then after several minutes (enough for a deep-discharged 4-cell to regain some voltage) checks again. If voltage stopped matching cell count - aborts charging and beeps. This is pretty idiot-proof.

Then, from the rest, you can again throw quite many away, as they can be attributed to strong imbalance in the pack leading to overcharging a cell - again, modern chargers balance the pack while charging and monitor cell voltages individually, rising alarm if one drifts off.

If you remove also the cases, where a pack failed due to abuse (ignored crash damage, deep-discharge etc) you are left with only a few cases where a failure was truly unexpected and hard to avoid (e.g. pack igniting IN a crash), but is it so much more often than fires in crashed nitro powered models?

Marek
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Old Jun 23, 2009, 12:48 PM
firstimeflyr
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Alabama
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55 Posts
Funny you should talk about the Accucell 6, I was looking at this charger as a possible first lipo charger.
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Old Jun 23, 2009, 12:51 PM
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United States, AZ, Queen Creek
Joined Aug 2004
777 Posts
In the fifty+ years I have been in this hobby I have never seen or heard of anyone having a fire from a nitro powered model.
There is an old saying in the engineering design departments:
You can make a system fool proof but you can't make it idiot proof.
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Old Jun 23, 2009, 12:57 PM
How does it work? How did it?
mareklew's Avatar
Karlsruhe, Germany
Joined Mar 2009
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I own it, that's why I mentioned it. I'm satisfied with it, it has some issues as in nice-to-haves-it-doesn't-have, but all implemented functions work fine.

My only complaint is, you:
- can't choose end-of-discharge voltage for a LiPo (not a biggie, as you don't want/need to discharge lipos prior to charging, and NiMH can be discharged to any chosen voltage adjustable down to 0.1V)
- can't choose to charge lipos to 4.15V instead of 4.2V. You can either select 4.1V or 4.2V, my lipos have noticeably less capacity at 4.1V.

Marek
PS: the charger has an undocumented PC-link. Details here: http://www.rcgroups.com/forums/showthread.php?t=1046318
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Old Jun 23, 2009, 01:02 PM
How does it work? How did it?
mareklew's Avatar
Karlsruhe, Germany
Joined Mar 2009
1,155 Posts
Quote:
Originally Posted by dirtybird
In the fifty+ years I have been in this hobby I have never seen or heard of anyone having a fire from a nitro powered model.
There is an old saying in the engineering design departments:
You can make a system fool proof but you can't make it idiot proof.
Well, lipos arent around long enough to have 50 years of experience with them, but none of my flying buddies has ever had a fire from a lipo either. But they are not skimping on a proper charger and handle their packs responsibly, i.e. replace a crash-damaged pack rather than trying to fly it still.

There was a fire from a crashed jet in my region though, nobody I know personally so I don't know any details.

I'm not really trying to compare which is safer, I try to put that huge list of mishaps in a different light: most of it won't happen ever again, not unless one ignores common sense and drives a nail through a pack. Or throws a match in a pool of spilled fuel...

Marek
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Old Jun 23, 2009, 01:49 PM
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United States, AZ, Queen Creek
Joined Aug 2004
777 Posts
A friend of mine did everything right but lost a good lipo battery and the $50 pressure cooker he was charging in the other day.

I use A123's. I pulled a bonehead stunt and hooked a 9s1p pack to the charger backwards and ruined the whole pack. They were dead but they were not even worm.
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