Blogs

Taken from the page:

http://www.rcgroups.com/forums/showthread.php?t=209187

After seeing the many many posts on LiPoly's and answering similar questions time after time I've decided to put up a guide for using LiPoly batteries. 

Lithium batteries are the preferred power sources for most electric modelers today. They offer high discharge rates and a high energy storage/weight ratio. However, using them properly and charging them correctly is no trivial task. There are many things to consider before using lithium cells for e-flight. But none is more important than safety.

1. Charging/Saftey IMPORTANT!
Until you are willing to follow all saftey precautions, DO NOT use lithium batteries. If your a type of person that prefers to push the limits of products, or be haphazard about following saftey requirements. Lithium technology is not for you. Read on to find out why.

Lithium cells must be charged very differently than NiCad or NiMH. They require a special charger specifically designed to charge lithium cells. In general any charger that can charge lithium ion can charge lithium polymer, assuming that the cell count is correct. You must NEVER charge lithium cells with a NiCad or NiMH only battery charger. This is dangerous. Charging cells is the most hazardous part of using lithium batteries. EXTREME care must be taken when charging them. It is important to set your charger to the correct voltage or cell count. Failure to do this can cause the battery to spew violent flames. There have been many fires directly caused by lithium batteries. PLEASE BE RESPONSIBLE when charging lithium batteries.

Here are a few MANDATORY guidelines for charging/using LiPos (Lithium Polymer Batteries).


1. Use only a charger approved for lithium batteries. The charger may be designed for Li-Ion or Li-Poly. Both batteries are charged in exactly the same. Some older cell phone chargers may charge the batteries .1 volt to low (4.1 vs 4.2), but that will not harm the battery. However, inexpensive lithium chargers are widely available and the use of cellphone chargers is highly discouraged. 
2. Make certain that the correct cell count is set on your charger. Watch the charger very closely for the first few minutes to ensure that the correct cell count continues to be displayed. If you don't know how to do that, get a charger that you do know how or don't charge the batteries.
3. Use the Taps. Before you charge a new Lithium pack, check the voltage of each cell individually. Then do this after every tenth cycle there after. This is absolutely critical in that an unbalanced pack can explode while charging even if the correct cell count is chosen. If the cells are not within 0.1 volts of each other then charge each cell individually to 4.2 volts so that they are all equal. If after every discharge the pack is unbalanced you have a faulty cell and that pack must be replaced.
Taps are provided on most new lithium packs. Taps give you the ability to check individual cell voltages and charge one cell at a time. Make sure and get the appropriate connector to go into your taps. Don't try to stick you volt meter probes in the taps to measure voltage. They could slip and short your cells. Don't try to charge more than one cell at a time from the taps. Unless you have an isolated ground charging system, you'll short your batteries out. Refer to your individual cell maker for tap pin-outs. 
4. NEVER charge the batteries unattended. This is the number one reason for houses and cars being burned to a crisp by lithium fires.
5. Use a safe surface to charge your batteries on so that if they burst into flame no damage will occur. Vented fire safes, pyrex dishes with sand in the bottom, fireplaces, plant pots, are all good options.
6. DO NOT CHARGE AT MORE THAN 1C unless specifically authorized by the pack vendor. I have personally had a fire in my home because of violating this rule. Todays highest discharge batteries can supposedly be safely charged at greater than 1C, however so far in all cases doing so shortens the life of the pack. Better to buy 3 packs than to try to charge 1 pack 3 times quickly. This may change in the future but as of Winter 2005 1C is still the recommended charge rate. 
7. DO NOT puncture the cell, ever. If a cell balloons quickly place it in a fire safe place, especially if you were charging it when it ballooned. After you have let the cell sit in the fire safe place for at least 2 hours. Discharge the cell/pack slowly. This can be done by wiring a flashlight bulb of appropriate voltage (higher is voltage is ok, lower voltage is no) up to your batteries connector type and attaching the bulb to the battery. Wait until the light is completely off, then throw the battery away.
8. If you crash with your lithium cells they may be damaged such that they are shorted inside. The cells may look just fine. If you crash in ANY way carefully remove the battery pack from the aircraft and watch it carefully for at least the next 20 min. Several fires have been caused by damaged cells being thrown in the car and then the cells catch fire later and destroys the car completely. 
9. Charge your batteries in a open ventilated area. If a battery does rupture or explode hazardous fumes and material will spew from the battery. 
10. Keep a bucket of sand nearby when you are flying or charging batteries. This is a cost effective way to extinguish fires. This is very cheap and absolutly necessary.
11. It can happen to you, do not think to yourself that “it won't happen to me” as soon as you do that it you'll be trying to rescue your kids from your burning house or car. I'm very serious about this.

Now that we have covered that important topic let's move on to lighter matters:

2. Lithium What?
Lithium Polymer batteries are used in many electronic devices. Cell Phone, Laptops, PDA's, Hearing Aids just to name a few. Most, if not all, lithium polymer batteries are not designed for RC use, we use them in different applications than they were designed for. They are similar to Lithium Ion batteries in that they each have a nominal voltage of 3.6 volts, but dissimilar in that they do not have a hard metal casing but rather a flexible material encloses the chemicals inside. The "normal" lithium polymer batteries are thin rectangle shapes with two tabs on the top one positive one negative. The reason we use Lithium cells is that they are significantly lighter than comparable NiCad or NiMH batteries, which makes our planes fly longer and better.

3. Voltage and Cell Count:
LiPolys act differently than NiCad or NiMH batteries do when charging and discharging. Lithium batteries are fully charged when each cell has a voltage of 4.2 volts. They are fully discharged when each cell has a voltage of 3.0 volts. It is important not to exceed both the high voltage of 4.2 volts and the low voltage of 3.0 volts. Exceeding these limits can harm the battery.
The way to ensure that you do not go below 3.0 volts while flying is to set the low voltage cutoff (LVC) of your electronic speed control (ESC). It important to use a programmable ESC since the correct voltage cutoff is critical to the life of your batteries. Use the ESC's programming mode to set the LVC to 3.0 volts per cell with a hard cutoff, or 3.3 volts per cell with a soft cutoff. If your ESC does not have hard or soft cutoff, use 3.0 volts per cell. You will know when flying that it is time to land when you experience a sudden drop in power caused by the LVC. 
If your ESC has an automatic lithium mode. Use it, it will correctly sense the number of cells and set the auto cutoff appropriately. 
If you have previously been flying with NiCad or NiMH batteries, switching over to lithium polymer will result in a different number of cells being used. If you had 6 to 7 round cells then 2 lithium polymer cells will correctly duplicate the voltage of those cells. If you had 10-11 cells then 3 lithium polymer cells would be right for you. There are a lot of 8 cell flyer's out there that are stuck between 2 and 3 cells. In my experience the best option is to determine how many watts you were using before and duplicate that with your LiPos, Motor, and Prop. For example. If you were running 8 cells (9.6volts) at 10 amps on a speed 400 airplane, then you have 9.6 x10, 96 watts. So if you went with 2 lithium polymer cells (7.2 volts nominal) then you'd need to change your prop such that you used 13 amps. If you went to 3 LiPoly's (10.8 volts nominal) then you'd need to reduce the amperage to 8.9 amps. These estimates are approximate, and some experimentation is required for best results but conserving Watts is a good way to start.

4.10C from 3S4P? Naming conventions explained.
How fast a battery can discharge is it's maximum current capacity. Current is generally rated in C's for the battery. C is how long it takes to discharge the battery in fractions of an hour. For instance 1 C discharges the battery in 1/1 hours or 1 hour. 2 C discharges the battery in ½ or half an hour. All RC batteries are rated in milli Amp hours. If a battery is rated at 2000 mAh and you discharge it at 2000mA (or 2 amps, 1 amp = 1000mA) it will be completely discharged in one hour. The C rating of the battery is thus based on its capacity. A 2000mAh cell discharged a 2 amps is being discharged at 1C (2000mA x 1), a 2000mAh cell discharged at 6 amps is being discharged at 3C( 2000mA x 3).
All batteries have limitations on how fast they can discharge. Because of this many LiPoly batteries are put in parallel to increase the current capacity of the battery pack. When 2 batteries are wired positive to positive and negative to negative they become like one battery with double the capacity. If you have 2 2000mAh cells and you wire them in parallel then the result is the same as 1 4000mAh cell. This 4000mAh cell has the same C rating as the original 2000mAh cells did. Thus if the 2000mAh cells could discharge at a maximum of 5C, or 10 amps then the new 4000mAh cell can also discharge at 5C or (4000mA x 5) 20 amps. This method of battery pack building allows us to use LiPoly batteries at higher currents than single cells could produce. 
The naming convention that allows you to decipher how many cells are in parallel and how many are in series is the XSXP method. The number in front of the S represents the number of series cells in the pack so 3S means it's a 3 cell pack. The number in front of P means the number of cells in parallel. So a 3S4P pack of 2100mAh cells has a total of 12 cells inside. It will have the voltage of any other 3S pack since the number of cells in series determines the voltage. It will have the current handling of 4 times the maximum C rating of the 12 individual cells. So say our 3S4P pack had a maximum discharge of 6C. That means that it has a nominal voltage of 10.8 volts (3x3.6) and a maximum discharge rate of 50.4 amps (2100mAh x 6Cx4P ). 

5. Which battery should you buy?
With so many choices out there it is difficult to decipher what is marketing hype, what is brand
loyalty, and what is outright lies. Battery manufacturers are constantly trying to one up one another. While capitalism can drive prices down, it also can give cause to false claims about products. 
One great way to find out what the best battery is, is to look at graphs of the batteries performance. Looking at how low the voltage of the cell drops at various amperages will give you a metric to compare that battery to similar size/weight batteries. 
If graphs aren't your thing then simply look at what other people are using in successful setups that are similar to your application. If a lot of people are reporting long flight times and lots of power from airplane X, with power system Y, and battery Z and you do the same, then if your setup is similar the same battery will probably work well for you. 
It pays to learn something about Watts, Volts, and Amps. Understanding these concepts is beyond the scope of this document, but can serve you well in not only figuring out what battery is best but also in your electric aircraft hobby.
I'm not convinced that a 30C battery is really any better than a 10 or 20C battery. Sure a higher C rating means it can discharge faster. But at the same time a battery discharged at 20C continuously will be empty in 3 minutes. Do you really only want to use the battery for 3 minutes? I love having burst power in helicopters and boats, but in almost all other applications actually running a battery at or above 20C is useless to me. I prefer to run batteries at 8-10 C and have a little headroom if I need it.
A final note on choosing a battery. Don't cheap out. Confirm that your batteries are capable of running that the amperage level you plan to use them at. Running a cell at a higher C rating than the battery can handle can not only damage your batteries, but it can also damage your speed control. Castle Creations has an excellent article on how using a weak battery can destroy a perfectly good speed control of any brand. Better to buy a bit better battery than you need than to destroy your electronics.

6. Dealing with temperature.
Lithium batteries like heat, but not too much. In the winter time, try to keep your batteries from the cold as much as possible. Leave them in the car while your flying, or keep them in your cargo pants... etc. At the same time don't let them heat up too much. Try to keep your batteries from reaching 160F after use. This will prolong the life of the cells. A good way to measure temperature is a handheld IR meter, they can be found for around $50.00 at most hobby shops. 

If you have any suggestions for future sections or additions to the current document let me know and I'll add the information requested...if I know the answer!

Posts that have referenced a lipo cell catching fire have been categorized as to failure cause. This list most certainly does not contain all the incidents and a statistical analysis would be meaningless. It does however show that the warnings presented for lipo cells are not just legaleeze but warnings that should be heeded to prevent possible personal harm and/or property damage.

These first two posts will be updated as data is collected. 
Information was gathered from the posts referenced. Please PM me if you see any discrepancies. The listing does not include any of the many 'ballooning only' reports.

FIRE DURING CHARGING:
Operator Error-
9s pack catches fire while being charged at 10s setting. (9)
2s pack catches fire being charged as 3s (10)
2s pack catches fire when charged at 3s setting (13)
2s pack catches fire in plane while charging at 3s setting. (22)
3s pack charged at 4s voltage ignites (27)
2s pack catches fire charged at 3s (30)
2s pack ignites when charged at 10.2V (31)
Overcharged battery (34)
2s pack charged at 11.1V catches fire. (36)
2s pack charged at 3s setting (40)
2s pack charges at 11.1V burns – (44)
2s charged at 11.2V goes off in garage – (47)
2s charged at 3s voltage ignites in garage – (49)
2s charged at 3s ignites in workshop – (52)
Another count problem – Heli burns (57)
Cell count error caused fire – (61, 62)
Pack charged on NiCd setting - (66)
Run Down pack catches fire during charge – (71)
LiPo Burns during charge on 109 charger after mode mis-set (82)
Charging slightly swelled pack causes fire (86)
Li-Ion cells catch fire from charger setting error (88)
Cell catches fire during attempt to repeak - (91)
Charging puffed cell causes it to ignite – (93)
Lipo burns during attempt to restore overdischarged cell with CC/CV PS (94)
Pack ignites during charging – smoke corrodes shed and contents (98)
Possible damaged pack burns like rocket in can – (100)
Attempt to recharge dead lipo causes plane fire (103)
Charging probably fully charged 3s pack with Astro 109 result in pack ignition. (104)
2s charged as 3s ignites in safe (109)
Restart of charger resulted in wrong charge mode – (113)
Wrong charger settings burns 2 packs – (112)
LiPo burns in modelers hand after charging - (115)
Charging slightly puffed cell causes fire, plane burns (117)
Using NiCd setting causes LiPo fire. Owner forgot to switch over to LiPo setting during charge cycle (118)
Charger set on 4 cells with 3 cell pack (126)
Garage fire during charging (127)
Modeler reports 2 lipo fires from wrong cell count (129)
Lipo charged on NiCd setting ignites (130)
Auto cell count charger fire – (131)
5s2p4000 packs ignites on first charge (133)
Overvoltage charge ignition – (135)
Lipo ignites during charge causing house fire – possible charger setting error. (139).
Too high charge rate burns battery (142)
3s charged as 4s 109 with pictures of burn: (144)
3s charged as 4s burns SUV (Schulze 6-330d) (146)
Garage Burns – balancer used - (162)
Garage Burns during charging – complete loss - (163)

Undetermined Cause While Charging 
Fire damages garage while charging pack. (7)
1500 3s pack catches fire during 1A , 11.1V initial charge. (1)
2 cell pack ignites while being charged with 2 cell charger. (11)
Car burns when pack being charged in car catches fire. (24)
2s2p pack catches fire in helicopter – possible that charger misread # of cells. (25)
2s pack ignites while on charger set for 2s. (28)
$30,000 damage to house when pack ignites during charging. (no details) (43)
3s pack burns in garage – (35)
3s pack burns at correct settings- (41)
3s pack burns at correct charger settings – (46)
3s 8000mah pack catches fire after 15min – correct settings – (53)
Helicopter and pack burns after 15min charge – (54)
Automatic cell count charger – pack catches fire (55)
Automatic cell count charger – pack catches fire (56)
Lipo rockets across room (58)
Automatic cell count charger – Lipos burn in garage (59)
Battery ignites in car seat during charging (63)
Damaged battery ignites during charge (67)
Pack balloons during charge, burns while under water (68)
11s3p pack burns during charging at correct parameters (70)
Another charging fire – (72)
Helicopter burns when LiPo ignites during charge (73)
Undetermined cause to LiPo fire during charge – (74)
Chopper burns from charging LiPo fire (76)
House fire (81)
3s Pack Ignites burning front of car during charge at correct settings. (83)
Helicopter in garage burns while charging (106)
Well used Lipo ignites under correct charging parameters (107)
SUV Vehicle burns (114)
Garage burns during charging – (119) Extensive pictures
2 fiires in 2 weeks (120)
Charging battery in plane fire with 109 – posts 97&99 (121)
Charging 3000mah with Triton catches fire in garage- (122)
Pack in plane ignites while being charged under hood of truck (123)
Fire in Basement – (136)
Lipo catches fire during charging and continues to burn in salt water (138)
Lipo charging in Helicopter ignites burning carpet, drapes and Heli (141)
Lipo charging on hood catches fire - (147)
Lipo charged on correct settings ignites (148)
Lipo fire during charging burns house. (150)
A123 pack burns(?) (152)
Possible charger failure causes lipo fire – (157)
House Fire – Cause not determined yet – (158)
Lipo in back of SUV ignites while charging – (159)
5 packs burn during charging – (165)
Battery on charger with balancer ignites (166)
Another battery on a balancing charger ignites (167)
Pack on charger causes workshop fire (169)
Very new pack with GWS CP -LP charger ignites (170)
Pack puffs on charger – taken outside where it ignites (171)
Pack gets hot on charger, ignites outside (172)

FIRE FROM PACK DAMAGE:
Cell poked with exacto knife catches fire- (2)
Dog bites pack, pack catches fire (4)
Lexus burns after pack from crashed plane put in car. (8)
Ballooned pack ignites when punctured. (20)
Repaired pack catches fire when connected to plane. (29)
Pack catches fire after plane crashes. (37)
Pack cut while shrink wrapping (39)
Pack punctured during crash burns. (64)
Plane crashes, pack removed and 10 minutes later burns (65)
Battery pack at 1V ignites while charging (71)
Puffed pack ignites during charging – (77)
Puffed Pack smokes when punctured (79)
Nicked pack catches fire (87)
Plane crashes, battery catches fire (89)
Damaged pack catches fire – (90)
Dog chews pack, chars pillow and smokes house - (95)
Battery compartment screw penetrates pack causing loss of plane (102)
Pack balloons dring mischarge, ignites when punchured (108)
Pack ignites 20 min after Heli crash – (111)\
Nicked pack “explodes in modelers hand” (116)
Intentionally punctured LiPo burns (124)
Dented Heli pack burns i min after disconnecting- (137)
Poked Lipo burst into flame (140)
Lipo Shorted for 4 sec. 3 min later it burns (143)
Lipo catches fire after crash damage. (149)
Punctured lipo catches fire – (151)
Crash causes fire – (154)
Damaged pack catches fire in flight – (156)
Dog bite shorts pack – (161)
Lid of charging container pinches battery leads and ignites (168)
Dropped pack catches fire minutes later (173)

BATTERY SHORTED FIRES:
Shorted pack catches fire (26)
Pack burns after shorting (15)
Possible Short (38)
Shorted when moved on table – (42)
Pack Shorted putting connector on and burns – (45)
Shorted pack burns hole in BMW seat – (48)
Crash causes 3s pack to short and burn – (50)
Pack ignites sometime after connector shorted for a short time (85)
Lipo Shorted for 4 sec. 3 min later it burns (143)


CAUSE UNDETERMINED:
Multi cell pack catches fire in flight (5)
Possible over discharge (33)
Lipo pack catches fire in car (60)
2s pack starts house fire (84)
In flight F3A fire reported (92)
New pack partially burns sitting on desk (96)
Pack ignites with no known cause (97)
Pack ignites after soldering wires on (101)
Pack catches fire in pick up truck (105)
In Air ignition – (125)
Pack ignites in pocket (132)
Pack ignites in car at 3AM (134)
Undamaged pack starts to burn in car – (145)
Unconnected Pack sitting on bench burns over night – (153)
In Flight Fire – (155)
Pack ignites 2 hrs after charging – not connected to anything. (160)
Unused, uncharged pack without connectors catches fire – (164)
Lipo catches fire for no apparent reason (174)
Plane lands after short flight, battery disconnected, battery ignites shortly after (175)


OTHER
2s pack connected in series with 3s pack ignites in fireball (78)
Lipo burns garage (99)
Packs used in parallel catch fire in flight (110)
Too high current draw causes fire (128)

References
1. http://www.rcgroups.com/forums/showt...93#post1625193
2. http://www.rcgroups.com/forums/showt...&pagenumber=18
3. http://www.rcgroups.com/forums/showt...37#post1531337
4. http://www.rcgroups.com/forums/showt...99#post1531599
5. http://www.bayrc.com/boards/viewtopic.php?t=226
6. http://www.rcgroups.com/forums/attac...postid=1478616
7. http://www.rcgroups.com/forums/showt...fire+explosion
8. http://www.rcgroups.com/forums/showt...ght=lexus+fire
9. http://www.rcgroups.com/forums/showt...t=funtana+fire
10. http://www.rcgroups.com/forums/showt...ghlight=rocket
11. http://www.ikarus-modellbau.de/ubbth...b=5&o=&fpart=1
12. http://www.rcgroups.com/forums/showt...ight=lipo+fire
13. http://www.rcgroups.com/forums/showt...hreadid=160086
14. http://www.rcgroups.com/forums/showt...hreadid=160079
15. http://www.rcgroups.com/forums/showt...hreadid=160551
16. http://www.rcgroups.com/forums/showt...ight=lipo+fire
17. http://www.rcgroups.com/forums/showt...ight=lipo+fire
18. http://www.rcgroups.com/forums/showt...ight=lipo+fire
19. http://www.rcgroups.com/forums/showt...ight=lipo+fire
20. http://www.rcgroups.com/forums/showt...ight=lipo+fire
21. http://www.rcgroups.com/forums/showt...ight=lipo+fire
22. http://www.rcgroups.com/forums/showt...ight=lipo+fire
23. http://www.rcgroups.com/forums/showt...402#post806402
http://www.rcgroups.com/forums/showt...ight=lipo+fire
http://www.rcgroups.com/forums/showt...ight=lipo+fire
24. http://www.hornet-heli.com/ubb/Forum3/HTML/003428.html
25. http://www.rcgroups.com/forums/showt...ight=explosion
26. http://www.rcgroups.com/forums/showt...95#post1243595
27. http://www.rcgroups.com/forums/showt...90#post1571890
28. http://www.rcgroups.com/forums/showt...30#post1581630
29. http://www.rcuniverse.com/forum/fb.a...325&tostyle=tm
30. http://www.rcgroups.com/forums/showt...129#post844129
31. http://www.rcgroups.com/forums/showt...29#post1553429
32. http://www.rcgroups.com/forums/showt...65#post1658165
http://www.rcgroups.com/forums/showt...hreadid=185530
33. http://www.rcgroups.com/forums/showt...34#post1699734
34. http://www.rcgroups.com/forums/showt...91#post1731091
http://www.rcgroups.com/forums/showt...15#post1731915
35. http://www.rcuniverse.com/forum/fb.a...352&tostyle=tm
36. http://members.jcom.home.ne.jp/42232...%20trouble.htm
http://www.rcgroups.com/forums/showt...31#post1761331
Charging crashed pack caused pack unbalance problems - http://www.rcgroups.com/forums/showt...03#post1767503
37. Pack catches on fire after crash - http://www.rcgroups.com/forums/showt...34#post1779434
38. Possible short – undamaged pack catches fire -http://www.rcgroups.com/forums/showthread.php?postid=1810304#post1810304
39. Battery shorts and burns during shrink wrapping - http://www.rcgroups.com/forums/showt...08#post1399608
Lipo Fire Video’s
http://www.rcgroups.com/forums/showt...15#post1394715
http://www.rcstuff.us/battery/lipo/lipo_DNA.html
http://www.helihobby.com/videos/LithiumBattery.wmv
http://www.utahflyers.org/movies/Lipofires.wmv
(40) Battery catches fire, wrong charging voltage - http://www.rcgroups.com/forums/showt...22#post1898922
(41) First charge of pack - http://www.rcgroups.com/forums/showt...hreadid=180434
(42) Pack shorted on bench - http://www.rcgroups.com/forums/showt...hreadid=206095
(43) $30,000 house damage – charger error - http://www.rcgroups.com/forums/showt...90#post1816790
(44) 2s charged at 11.1V burns - http://www.rcgroups.com/forums/showt...47#post1844047
(45) Pack Shorted putting connector on and burns - http://www.rcgroups.com/forums/showt...hreadid=209532
(46) 3s Pack burns at correct charger settings - http://www.rcgroups.com/forums/showt...hreadid=209767
Picture of burned bench – German site - http://www.modellflugjugend.de/archiv/user/lipo2.jpg
(47) 2s charged at 3s goes boom in garage - http://www.rcgroups.com/forums/showt...hreadid=100803
(48) Shorted pack burns hole in BMW seat - http://www.rcgroups.com/forums/showt...86#post1199486
(49) 2s charged as 3s ignites in house - http://www.rcgroups.com/forums/showt...ghlight=rocket
(50) Crash causes 3s to short and burn 
http://www.rcgroups.com/forums/showt...82#post1863182
(52) 2s charging at 3s causes fire in garage - 
http://www.runryder.com/helicopter/...light=fire+lipo
(53) 8000 3s pack catches fire at correct settings - 
http://www.runryder.com/helicopter/...light=fire+lipo
(54) Pack catches fire after charging for 15 min - 
http://www.rotory.com/ubbthreads/sh...o=&fpart=1&vc=1
(55) Pack catches fire using automatic charger - http://www.rcgroups.com/forums/showp...6&postcount=15
(56) Pack catches fire using automatic charger - 
http://www.rcgroups.com/forums/showp...46&postcount=1
(57) Helicopter fire - http://runryder.com/helicopter/t82226/?goto=newpost
(58) LiIon pack rockets across room: http://www.rcgroups.com/forums/showp...6&postcount=11
(59) Dented Pack Catches fire - http://www.rcgroups.com/forums/showp...56&postcount=3
(60) Lipo in closed car catches fire - http://www.rcgroups.com/forums/showthread.php?t=241627
(61) Wrong cell count fire - http://www.rcgroups.com/forums/showp...97&postcount=3
(62) Wrong cell count fire – http://www.rcgroups.com/forums/showp...26&postcount=1
(63) Battery catches fire in car seat while charging - http://www.rcgroups.com/forums/showthread.php?t=248194
(64) Battery catches fire when plane crashes - http://www.rcgroups.com/forums/showthread.php?t=256098
(65) Battery catches fire after crash: http://www.rcgroups.com/forums/showp...7&postcount=12
(66) Battery ignites in under 10min on charger - http://www.rcgroups.com/forums/showp...59&postcount=1
(67) Damaged battery catches fire during charging - http://www.rcgroups.com/forums/showp...34&postcount=5
(68) LiPo Pack catches fire even tho immersed in salt water - http://www.rcgroups.com/forums/showthread.php?t=261922
(69) Lipo ignition causes house fire - http://www.rcgroups.com/forums/showp...50&postcount=4
(70) Pack catches fire for no apparent reason during charge -http://www.rcgroups.com/forums/showp...1&postcount=34
(71) Pack at 1V charged and catches fire - http://www.rcgroups.com/forums/showthread.php?t=263600
(72) Battery catches fire during charging - http://www.rcgroups.com/forums/showp...21&postcount=1
(73) Helicopter burns - http://www.rcgroups.com/forums/showthread.php?t=266337
(74) 3s Pack ignites during charge - http://www.rcgroups.com/forums/showthread.php?t=266875
(75) House fire reported in Belgium - http://www.rcgroups.com/forums/showp...1&postcount=24 CHECK OUT
(76) Plane burns during charge - http://www.rcgroups.com/forums/showp...5&postcount=47
(77) Puffed pack ignites during charging - http://www.rcgroups.com/forums/showt...64#post2560964
(78) 2s pack connected in parallel to 3s pack ignites - http://www.rcgroups.com/forums/showthread.php?t=274028
(79) Ballooned Pack Burns when punchured - http://www.rcgroups.com/forums/showthread.php?t=274557
(80) 7s pack catches fire during flight - http://www.rcgroups.com/forums/showthread.php?t=296507
(81) House fire – 3rd story burns - http://runryder.com/helicopter/t145397p1/
(82) Lipo catchs fire during charge on 109 charger. http://www.rcgroups.com/forums/showthread.php?t=307806
(83) 3s Lipo catches fire at correct settings. http://rcgroups.com/gallery/showphot...cat=500&page=1
(84) 2s pack starts house fire- reason unknown - http://www.rcgroups.com/forums/showthread.php?t=311323
(85) Pack catches fire after a short short - http://www.rcgroups.com/forums/showt...13#post3044752
(86) Charging slightly swelled pack causes fire - http://www.rcgroups.com/forums/showp...77&postcount=4
(87) Nicked cell catches fire - http://www.rcuniverse.com/forum/LiPo...tm.htm#2366986
(88) Li Ion cells ignite from charging mistake - 
http://www.rcuniverse.com/forum/LiPo...tm.htm#2427714
(89) Battery ejected from crashed plane burns - http://www.rcgroups.com/forums/showthread.php?t=289255
(90) Battery involved in crash ignites several weeks later - 
http://www.rcgroups.com/forums/showthread.php?t=273490
(91) Charging abuse causes fire - http://www.rcgroups.com/forums/showp...35&postcount=7
(92) Pack fire during F3A contest - http://www.rcgroups.com/forums/showp...8&postcount=11
(93) Slightly puffed cell catches fire during charging. http:// http://www.rcgroups.com/forums/showp...d.php?t=268523
(94) Lipo burns during attempt to restore overdischarged cell with CC/CV PS -http://www.rcgroups.com/forums/showthread.php?t=323693
(95) http://www.rcgroups.com/forums/showp...4&postcount=15
(96) New pack partially burns sitting on desk - http://www.rcgroups.com/forums/showthread.php?t=329744
(97) Pack ignites with no known cause - http://www.rcgroups.com/forums/showp...3&postcount=31
(98) Pack ignites during charging – equipment in shed corrodes -http://www.rcgroups.com/forums/showp...&postcount=177 andhttp://www.rcgroups.com/forums/showp...&postcount=187
(99) Lipo burns garage - http://www.rcgroups.com/forums/showp...6&postcount=14
(100) Lipo burns like rocket in a can during charging - http://www.rcgroups.com/forums/showthread.php?t=356474
(101) Cell ignites while soldering- http://www.rcgroups.com/forums/showthread.php?t=357380
(102) Screw penetrates pack igniting it - http://www.rcgroups.com/forums/showthread.php?t=360222
(103) Attempt to recharge “dead pack” causes plane fire - http://www.rcgroups.com/forums/showp...37&postcount=9
(104) Charged 3s (?) ignites while recharging with Astro 109 - http://www.rcgroups.com/forums/showthread.php?t=362011

(105) Packs in truck catch fire, burn truck – unexplained - http://www.rcgroups.com/forums/showthread.php?t=368758
(106) Battery charging inside of helicopter catches fire in garage. No cause determined.http://www.runryder.com/helicopter/t177482p1/ 
(107) Well used Lipo ignites during charging under correct conditions -http://www.rcgroups.com/forums/showthread.php?t=373643
(108) Lipo charged as NiCd burns when the ballooned pouch is punchured -http://www.rcgroups.com/forums/showt...10#post3794339
(109) Charging 2s1500 with possible wrong cell count ignites in safe -http://www.rcgroups.com/forums/showt...20#post3829205
(110) Packs used in parallel catch fire in flight - http://www.rcgroups.com/forums/showthread.php?t=378566
(111) Helicopter crashes – 20 minutes later, lipos burn - http://www.rcgroups.com/forums/showthread.php?t=384490
(112) 2 packs at wrong charger settings burn - http://www.rcgroups.com/forums/showthread.php?t=384585
(113) Charger unplugged, on restart it went into different mode – lipo burns-http://www.rcgroups.com/forums/showp...45&postcount=1
(114) Battery charged in SUV burns vehicle - http://www.wattflyer.com/forums/show...09&postcount=1
(115) Battery ignites after charging in modelers hand http://www.rcgroups.com/forums/showp...83&postcount=1
(116) Nicked pack “explodes in hand” http://www.rcgroups.com/forums/showp...&postcount=155
(117) Charging slightly puffed lipo causes it to ignite in plane. http://www.rcgroups.com/forums/showthread.php?t=434713\
(118) Using NiCd setting causes LiPo to burn in garage - http://www.rcgroups.com/forums/showthread.php?t=435043
(119) Garage Burns – Cause undetermined - http://www.laureanno.com/RC/fire-pics.htm
(120) 2 fires in 2 weeks – 109 charger - http://www.rcgroups.com/forums/showthread.php?t=446313
(121) Charging battery in plane fire with 109 – posts 97&99 http://www.rcgroups.com/forums/showthread.php?t=443646
(122) Charging 3000mah with Triton catches fire in garage- http://www.one18th.com/forums/showthread.php?t=18104
(123) Pack in plane ignites while being charged under hood of truck - http://www.wattflyer.com/forums/showthread.php?t=2770
(124) Intentionally punctured LiPo burns - http://www.rcgroups.com/forums/showp...35&postcount=9
(125) In Flight LiPo Fire - http://www.rcgroups.com/forums/showthread.php?t=460823
(126) Fire under hood while charging - http://www.rcgroups.com/forums/showthread.php?t=463204
(127) Garage burns during charging – possible operator cell count error -http://www.rcgroups.com/forums/showthread.php?t=463115
(128) Lipo ignites after flying with too large prop after landing - http://www.wattflyer.com/forums/show...2&postcount=14
(129) 2 fires from wrong cell count - http://www.rcgroups.com/forums/showp...97&postcount=5
(130) Lipo charged on NiCd settings catches fire - http://www.rcgroups.com/forums/showp...8&postcount=14
(131) 3 cases of charger caused (?) fires reported - http://www.rcgroups.com/forums/showthread.php?t=473376
(132) Pack goes thermal in pamts pocket - http://www.rcgroups.com/forums/showp...6&postcount=20
(133) 5s2p 4000 ignites on first charge - http://www.rcgroups.com/forums/showthread.php?t=489495
(134) Pack ignites in car – No reason seen. http://www.rcgroups.com/forums/showt...65#post5371633
(135) Pack ignites – high charge voltage - http://www.rcgroups.com/forums/showp...6&postcount=25
(136) Lipo ignites in basement during charge - http://www.rcgroups.com/forums/showthread.php?t=519443
(137) Lipo ignites after landing - http://www.rcuniverse.com/forum/m_40...tm.htm#4118760
(138) Lipo ignites during charge, continues to burn after thrown in water -http://www.rcgroups.com/forums/showthread.php?t=261922
(139) lipo ignites during charge causing house fire. - http://www.rcgroups.com/forums/showp...50&postcount=4
(140) Poked Lipo burst into flame - http://www.rcgroups.com/forums/showp...38&postcount=4
(141) Lipo charging in Helicopter ignites burning carpet, drapes and Heli -http://www.rcgroups.com/forums/showthread.php?t=552619
(142) Too high charge rate burns battery - http://www.rcgroups.com/forums/showthread.php?t=556456
(143) Lipo Shorted for 4 sec. 3 min later it burns: http://www.rcgroups.com/forums/showp...08&postcount=1
(144) 3s charged as 4s 109 with pictures of burn: http://www.rcuniverse.com/forum/m_36...tm.htm#3694610
(145) Undamaged pack burns http://www.rcgroups.com/forums/showp...13&postcount=2
(146) 3s charged as 4s burns SUV (Schulze 6-330d) - http://www.rcgroups.com/forums/showp...8&postcount=13
(147) Lipo charging on hood catches fire, cause undetermnined - http://www.rcgroups.com/forums/showthread.php?t=614885
(148) Lipo charged on correct settings ignites - http://www.rcgroups.com/forums/showthread.php?t=654348
(149) Lipo catches fire after crash damage. - http://www.rcgroups.com/forums/showthread.php?t=662396
(150) Lipo fire during charging burns house. http://www.rcgroups.com/forums/showp...43&postcount=1
(151) Punctured lipo ignites - http://www.rcgroups.com/forums/showp...9&postcount=64
(152) A123 fire during charging – cause unknown - http://www.rcgroups.com/forums/showt...99#post8554156
(153) Cause unknown – Battery on benchtop burns http://www.rcgroups.com/forums/showthread.php?t=779431
(154) Battery ignites after crash - http://www.rcgroups.com/forums/showthread.php?t=800629
(155) Battery ignites during flight - http://www.rcgroups.com/forums/showp...&postcount=127
(156) Damaged lipo pack catches fire in flight - http://www.rcgroups.com/forums/showp...1&postcount=14
(157) Battery ignites during charge - http://www.rcgroups.com/forums/showp...&postcount=154
(158) House Burns – Lipo charging in garage. http://www.rcgroups.com/forums/showp...&postcount=191
(159) Lipo charging in back of SUV catches fire - http://www.rcgroups.com/forums/showp...&postcount=199
(160) Lipo catches fire 2 hrs after charging and off charger - http://myhobbycity.com/showthread.php?t=2883
(161) Dog bites lipo – lipo heats up but is dunked before igniting. -http://www.rcgroups.com/forums/showp...35&postcount=4
(162) Garage Burns, charging with balancer http://www.3drc.info/forum/showthread.php?t=1137
(163) Another Garage fire - complete loss - fire during charging - http://www.3drc.info/forum/showthread.php?t=888
(164) New battery catches fire – didn't have connectors on it yet.http://www.rcgroups.com/forums/showt...0#post10463160
(165) 5 packs being charged burn - http://www.rcgroups.com/forums/showp...&postcount=228
(166) Pack on charger with balancer ignites - http://www.rcgroups.com/forums/showthread.php?t=945715
(167) Pack on balancing charger ignites - http://www.rcgroups.com/forums/showthread.php?t=947656
(168) Pack catches fire when lid closed on leads. http://www.runryder.com/helicopter/t473552p1/
(169) Pack on charger causes workshop fire. http://www.rcgroups.com/forums/showthread.php?t=978810
(170) Very new pack with GWS CP -LP charger ignites - http://www.rcgroups.com/forums/showt...8#post11861155
(171) Pack puffs on charger – taken outside where it ignites - http://www.rcgroups.com/forums/showp...5&postcount=64
(172) Pack gets hot on charger, ignites outside - http://www.rcgroups.com/forums/showp...&postcount=363
(173) Dropped pack catches fire minutes later - http://www.wattflyer.com/forums/show...3&postcount=28
(174) Lipo catches fire for no apparent reason - http://www.rcgroups.com/forums/showp...11&postcount=3
(175) Plane lands after short flight, battery disconnected, battery ignites shortly after -http://www.rcgroups.com/forums/showp...&postcount=373
(176) Battery ignites in plane during charging - http://www.rcgroups.com/forums/showp...&postcount=393
(177) Pack on Display in Hobby Shop catches fire - http://www.rcgroups.com/forums/showp...98&postcount=4

I tested two different MKII chargers and the results were the same, 80% capacity of a 4.20v per cell charge.
If you fly to a higher cutoff voltage and use less of the total pack capacity, percentage of charge for the MKII would be less not more.

The MKII is a nice safe charger for Lipo, but unless there was a revision change(?) it can’t charge a 3-cell pack to 12.4v because it terminates the charge at a lithium-ion safe 4.1v per cell or 12.3v. 

This is a test I did for capacity vs. Resting voltage.

72 degree pack and room temp.
The (999mAh) pack was discharged each time at 1C, to a 3v per cell cutoff.
Then I added a fixed percentage of charge, and measured the resting voltage after 12 hours.
Next I discharged the pack and verified the percentage of capacity.
At the end of all testing I charged the pack fully and did a accuracy / repeatability test.
The repeatability of the test was over 98%.

4.20v = 100%
4.03v = 76%
3.86v = 52%
3.83v = 42%
3.79v = 30%
3.70v = 11%
3.6?v = 0%

Capacity below 3.7v "resting" is not usable for flying, it's where the battery voltage dump begins.