Post by wolfwood on Jan 17, 2013 21:46:38 GMT -7
A personal collection of things and advice found here and on the net about using and charging lipo's. I take no responsibility about this being 100% correct. All is not "my truth" but what I understood from reading post of other people.
Terminology:
Lipo: Lithium polymer battery Pack: total battery you "see", each battery is made up out of cells (one can compare a pack with different small battery's put together). Cell: part of a battery. each cell is the basic element of a battery pack and delivers normally 4.20 volt when fully charged. The number of Cell's is normally indicated with a "S" ( 1S , 2S , 3S ..) and the rated voltage of the battery is always the number of cell's * 3.7 volt (not 4.20). For example a "7.4 volt 2S 1250 mAh" battery is a "2 cell" battery, an 11.1 volt battery is a 3 cell battery etc.. Balanced charging: charging method that tries to make sure each cell in the battery has the same end voltage (normally 4.20 volt). Balance leads: each battery pack has 2 "main" wires (that you use to connect the battery to the air plain/car/... speed controller) and extra set of (normally) thinner wires , coming together in one connector, those thinner wires are the "balance leads". Those are needed to allow "balanced charging" and are used to monitor the voltage of individual cells (even when not using balance charging but normal charging). C : one time the charge or "Capacity" of the battery in expressed commonly for R/C usage in mA (miliAmp's). For example: an "2200 mA" battery has a "C of 2200 mA" . This is however more correctly expressed as mAh (h = Hour), an "2200 mA" battery should be in fact be described as an "2200 mAh" battery For example: an 2200 mAh battery can deliver (in theory) a contiguous current of 2200 mA for one hour, after one hour it is flat. If the same battery needs to deliver a contiguous current of 4400 mA then it will be flat after 1/2 hour. Charge C: the amount of current used to charge the battery, expressed in C . For example: charging an 1300 mAh battery with 2 C means charging it with a current set to 2 * 1300mA = 2600 mA, this battery should then in theory be charged in 30 minutes ( actual time will be around 10 to 20% more ). Discharge C (also called "C-rate" ) : the amount of current, expressed in C, you can get from a battery without destroying it. For example: a "25 C discharge" 1500 mAh battery is made to handle a maximum discharge current of 25 * 1500mA = 37500 mA ( 37,5 A). If this 1500 mAh battery is discharged with "25 C" (37500 mA) then it will be flat in 2.4 minutes ( one hour (60 minutes) / discharge C (25) ). A battery with 2 ratings like a "25 - 50 C discharge" battery means normally that you can use 25 C of current all the time (continuous) and it will survive delivering "bursts" (this are seconds not minutes...) of power up to 50 C . Cycle: one time going from fully charged to empty. If you for example discharge/charge 2 times only 50% of the battery then this might be roughly considered "one cycle" Normal battery life : the amount of cycles a battery can have until it is broken. If a battery has at least one cell that cannot charge anymore up to 4.20 (or charges to a higher voltage) , it is broken. Thermal runaway event: A Lipo that goes up in flames is not like "normal" fire. Once it is starts burning/ignited it goes and will go until all material is consumed. You will not like that. Plenty of examples on the Internet, have a look.
Safe Way to charge LiPo's:
General things to avoid burning down your house:
Do not charge unattended and use your LiPo bag if you charge the battery in a closed space (room). You did get a Lipo bag did you (or a cash box)? Connect the balance leads always to allow monitoring of per-cell voltages by the charger. It's safer that way. Really. If a LiPo becomes "bulged" (bubbled / part(s) swell up) or has physical damage (it has holes or is dented after a crash or fall ) - do not use it anymore and dispose of it. You risk a "thermal runaway event". Do you really want to risk setting your house on fire trying to save 30 $ ? Do NOT punch a hole in LiPo's and putting them in salt water is not the good way to "dispose" them. Before throwing a bad LiPo away discharge the bad LiPo very slowly (discharge with 1 / 20 C or lower -use a small flash light bulb or so) and then throw them away (they are supposedly "landfill safe"). Otherwise bring it in for recycling at a local drop off point. Using the temperature sensor of the charger (if available) is not a bad idea for extra safety but not really a necessity - connecting the balance leads is. Start the charging only with the battery pack at room temp or mildly warm (if you cannot keep it in your hand comfortably let it cool down before charging) Do NOT charge the battery when it's below 5° Celsius (battery or ambient temperature) unless the manufacturer says its ok. Otherwise, dendrite formation can occur and cause an internal short creating a "thermal runaway event". If the ambient temperature is 35° Celsius or more do not charge with more than 1 C to avoid the pack heating up above 50 °Celsius . For safety do not charge packs in the car but use a decent thick cable from the 12 volt socket and charge them outside the car. If anything goes wrong you then still can drive home.
Voltage stuff:
Make sure your charger is set to no more than 4.20 volt / cell as max voltage. Use the "balanced" charging setting in your charger whenever possible (or use an external balancer). Charging a battery in "balanced" mode will take (some) more time to charge the battery compared to not using the balancer in your charger as the balancing is an extra step after the battery is (almost) fully charged. Use unbalanced if you need to charge the battery faster (out on the field for example) but do not overdue it (aka after like 3 - 5 charges use a "balanced" charge cycle). Even when using "Unbalanced" charging always connect the balance leads . After using a new charger a few times compare the voltage of the battery reported by the charger with a *decent* volt meter. If you have only a 10 $ multimeter then also do not trust that 10 $ multimeter to be accurate. Borrow or get a decent one (or better, get 2 voltmeters and compare both). Do the same check again after a few months. The voltage of cells should not differ more than 0.01 up or down the target charging voltage when using "balanced" charging.
For example a 3 cell LiPo after "balanced" charging to 4.20 volt/cell should not differ more than: 4.21 volt / first cell 4.20 volt / second cell 4.19 volt / third cell if one cell in this example would read 4.17 or 4.23 volt then * or your charger is going bad (assuming the charger say's all are 4.20 volt but the extra voltmeter/multimeter say not and that meter is actually correct - this means your charger is not correctly reading the volts of the battery) * or your battery is going bad (assuming the voltage measured is correct).
Current stuff:
Many packs can be now safely charged at 2C or 3C so long as the balance lead is connected and a decent charger is used. Some are even rated up to 10C charging. When in doubt if the battery can handle more than 1 C charging (it is NOT written clearly in the battery specifications you can use 3 C for example), use max 1 C charging current. When in doubt if if your 15 $ LiPo charger is any good (hint: no) , use max 1 C charging current.
Settings:
If available use preference settings you can save and recall in your charger and define each battery type you have. If your charger has no memory/presets then double check the battery type detected (number of cells 1s , 2s etc) and the defined amount of charging current before pressing ok.
Discharging using a Lipo charger.
Most LiPo chargers offer "discharging" functionality. Check the default "cut off discharge" voltage set in your charger. In many the default is 3.00 volt, this is to low, use 3.30 v. If your charger cannot discharge your battery with 5 C or more then raise this even to 3.40 volt. The reason behind this is that when LiPo are discharged with a relatively small current (compared to the C value of the battery) you can go "deeper" - take out more mA - before you hit 3.30 volt than when you are discharging the battery with a high current ( = use it in your R/C).
The Sensible Way to treat your LiPo's (to keep them working fine/alive a decent time - most packs should reach 200 ~ 300 cycles):
Packs should not be below 3.7V/cell within 5 minutes of sitting idle after use. This is more an Art than Science. in general it's good practice to set a cut off of the speed controller to 3.3v or use a LiPo battery watcher that warns at 3.3v when the battery is in use and a high discharge current is used from the battery. Simply try not to squeeze the last drop out of the pack, stop at around 80% discharge. LiPo's don't like to be squeezed out totally. If your pack mentions 1 discharge C value then do not discharge faster than the mentioned "discharge C " , you might even want to stay a bit under this. For example: you have a "20 C discharge" battery and a car that uses 22 C when full throttle and 17 C when at 70% throttle and you like to drive the car hard or it is used on heavy terrain you should be using a "25 C discharge" battery as minimum. Most battery's allow a bit more than the rated "discharge C" for a very short time (10 seconds or so - not for minutes). If your pack mentions 2 discharge C values then do not discharge them for most of the time faster than the lowest discharge C mentioned. For example: you have a "20 - 25 C discharge" battery and an air plain that uses 23-24 C when full throttle and 19 C when at 70% throttle. If you run a airplane almost always at 50 to 70 throttle and only go a few times full throttle during a flight it will be most likely fine, if you run it often at full throttle then you're pushing the battery and you should use an "25 - 30 C discharge" battery. Don't "top off" LiPo's (use like 5 or 10% of the battery and then charge them again)..chemically they "don't like it". Use them 40 up to 80% and then recharge them. LiPo's like temperatures between 10 to 35 ° Celsius. They really really don"t like temperatures below 0 ° Celsius or above 60 ~ 70 ° Celsius at all . If your pack is fully charged then do not expose it to cold ( below 5 ~ 10 ° Celsius ) temperatures. Keep it warm in a beer-cooler (without ice of course) or some gloves... If the ambient temperature is below 5 ° Celsius when using the pack in a R/C car/air plain/... charge the pack not fully but only op to 4.10 volt. If a fully charged pack get really cold it might break down and loose most of it's capacity. This is irreversible if it happens . Do not expose your pack to direct sunlight in the summer. Keep it in the shade or in a beer-cooler (again, without ice...)
The Sensitive Way to treat your LiPo's (to keep them working fine/alive a much longer time)
note: you have to ask your self if this makes economical sense, with LiPo battery getting quite cheap, you might simply not care if it survives 50 or even 100 cycles more...
Charging with with a lower charge current than 1 C , like 0.5C or 0.8 C will extent the battery life. Charging always to a lower voltage than 4.20 volt /cell like 4.10 volt will extent the battery life dramatically (500-800 charges for 4.10v instead of 200-300). Note that the lower you go the less charge the battery will contain ( 4.10volt = about 85% of C). Keep the maximum continuous discharge to the (lower) C discharge rating minus 30 to 25%% - ex: for a 25 - 30 C discharge battery never discharge with more than 18 C , for a 20C discharge pack keep it under 15 C.
Storing LiPo's if you don't use them for a while.
If you have to store LiPo's for an extended period charge the battery up to 3.75 ~ 3.85 volt (the exact "best" voltage for storage differs depending on who you ask) and then keep at 10 to 25 ° Celsius (put them in a dry basement if you have one - do not put them in a freezer) and dry (don't put them in your fridge , that is a rather humid) environment. Storing LiPo's fully charged or discharged is a Bad Idea. Storing them on a hot attic is a Bad Idea. Both will reduce the amount of charge a LiPo can store. By storing is meant not using them for several weeks or months. A good trick is when done with using them for the day and you do not plan to fly/drive/hoover the next day(s) do not charge up to 4.20 but only charge them (unbalanced) up to 3.80 v , store them like that and then the day before or the day itself you want to use them charge them up to 4.20 using balanced charging.
Other Things To Know:
4.30 volt is the actual maximum safe voltage to charge a cell. Note that is different from the 4.20 which is the maximum voltage for normal operation. If you charge to more than 4.20 volt you are going over the intended limit but the battery should be able to handle it. Note the "should". This is like blowing tires up to more PSI than advised. You have the recommended psi value for a safe and economic drive and then you have the max psi before tire burst. 4.30 is the "tire bust" limit. No-one wants to have a tire burst in his living room. 3.00 is the absolute minimum discharge voltage, same story as with 4.20 vs 4.30. if you go to 3.00 volt then the battery should survive it. Note the "should". It does not mean the battery will be happy with it or not loose charge. Use 3.30 volt as minimum discharge voltage when the battery is in use and a high discharge current is used from the battery, not 3.00 volt. A battery will, over time, hold less and less "capacity". An battery that you could charge up to 2200 mAh when new will for example only "hold" 1950 mAh after a few 100 cycles and it cannot be charged to hold the same capacity (mAh) anymore as in the beginning. Note that it is mandatory to use the same cell voltages and charge/discharge C when comparing - it's comparing a good state with a bad state, not comparing with what is written on the battery (BIG difference !). Normally a battery that has 80% (some say 75%, some go even lower, it depends who you ask) of the initial usable capacity left should be disposed of or at least watched more carefully and a replacement should be considered, the chance of a malfunction enlarges with the capacity dropping. Incorrect (to fast) charging, discharging (to much) or storing Lipo battery's fully charged during a winter will reduce the capacity and so the number of times you can use the battery. There seams to be a strong consensus that no LiPo can be regularly discharged beyond about 80% of it's capacity ( see the "Packs should not be below 3.7V/cell within 5 minutes of sitting idle after use") without damaging it. This 80% means that if you discharge a 4000 mAh battery ( a battery with 4000 written on it ) you will only manage to get out 4000 - ( 4000 / 5) = 3200 mA out of it before it risks to gets damaged. This also means that if you charge it up after beeing discharged for 80%, your charger will mention it has "put" only 3200 mA "in" the battery. So 3200 mAh is then the "real" (useful) capacity of this battery. You can get more than 80% out of the pack but that will reduce the lifespan of the battery and might be only possible when using a low discharge current . Something that seams to be more controversial is "breaking in" or "conditioning" a new LiPo battery . You seam to have LiPo manufacturers who suggest to do this, you have other who don't speak about it. You have people who never did this and claim their battery's are just fine without doing it. So you seam to have believers and non believers. The actual figures on how to do the "breaking in" or "conditioning" differ but the ballpark figures seam to be to use for the first 4 or 5 charge / discharge cycles only a balanced charge with 1/2 C ~ 1 C and to not discharge the battery with more than 1/4 to 1/2 of the C rate of the battery. Some people claim that after "breaking in" a new LiPo the "netto" (actual) capacity going up after a few cycles like this. Other haven't. All this might be simply depending on the brand of the battery and/or the way they are manufactured. Not all LiPo battery's are exactly the same, there are differences in production between different suppliers of the cell's. Bottom line is that, while it might not prove magic, it might indeed be a good idea to "take it easy" the few first charge/discharge cycles. Use a (dis)charger to do a few 'gentle" discharge / charge cycles or simply use new battery in your car/airplane but take it easy with new battery's, do not go full throttle, stop after no more than 80% is used and charge it then at 1C or lower.
Terminology:
Lipo: Lithium polymer battery Pack: total battery you "see", each battery is made up out of cells (one can compare a pack with different small battery's put together). Cell: part of a battery. each cell is the basic element of a battery pack and delivers normally 4.20 volt when fully charged. The number of Cell's is normally indicated with a "S" ( 1S , 2S , 3S ..) and the rated voltage of the battery is always the number of cell's * 3.7 volt (not 4.20). For example a "7.4 volt 2S 1250 mAh" battery is a "2 cell" battery, an 11.1 volt battery is a 3 cell battery etc.. Balanced charging: charging method that tries to make sure each cell in the battery has the same end voltage (normally 4.20 volt). Balance leads: each battery pack has 2 "main" wires (that you use to connect the battery to the air plain/car/... speed controller) and extra set of (normally) thinner wires , coming together in one connector, those thinner wires are the "balance leads". Those are needed to allow "balanced charging" and are used to monitor the voltage of individual cells (even when not using balance charging but normal charging). C : one time the charge or "Capacity" of the battery in expressed commonly for R/C usage in mA (miliAmp's). For example: an "2200 mA" battery has a "C of 2200 mA" . This is however more correctly expressed as mAh (h = Hour), an "2200 mA" battery should be in fact be described as an "2200 mAh" battery For example: an 2200 mAh battery can deliver (in theory) a contiguous current of 2200 mA for one hour, after one hour it is flat. If the same battery needs to deliver a contiguous current of 4400 mA then it will be flat after 1/2 hour. Charge C: the amount of current used to charge the battery, expressed in C . For example: charging an 1300 mAh battery with 2 C means charging it with a current set to 2 * 1300mA = 2600 mA, this battery should then in theory be charged in 30 minutes ( actual time will be around 10 to 20% more ). Discharge C (also called "C-rate" ) : the amount of current, expressed in C, you can get from a battery without destroying it. For example: a "25 C discharge" 1500 mAh battery is made to handle a maximum discharge current of 25 * 1500mA = 37500 mA ( 37,5 A). If this 1500 mAh battery is discharged with "25 C" (37500 mA) then it will be flat in 2.4 minutes ( one hour (60 minutes) / discharge C (25) ). A battery with 2 ratings like a "25 - 50 C discharge" battery means normally that you can use 25 C of current all the time (continuous) and it will survive delivering "bursts" (this are seconds not minutes...) of power up to 50 C . Cycle: one time going from fully charged to empty. If you for example discharge/charge 2 times only 50% of the battery then this might be roughly considered "one cycle" Normal battery life : the amount of cycles a battery can have until it is broken. If a battery has at least one cell that cannot charge anymore up to 4.20 (or charges to a higher voltage) , it is broken. Thermal runaway event: A Lipo that goes up in flames is not like "normal" fire. Once it is starts burning/ignited it goes and will go until all material is consumed. You will not like that. Plenty of examples on the Internet, have a look.
Safe Way to charge LiPo's:
General things to avoid burning down your house:
Do not charge unattended and use your LiPo bag if you charge the battery in a closed space (room). You did get a Lipo bag did you (or a cash box)? Connect the balance leads always to allow monitoring of per-cell voltages by the charger. It's safer that way. Really. If a LiPo becomes "bulged" (bubbled / part(s) swell up) or has physical damage (it has holes or is dented after a crash or fall ) - do not use it anymore and dispose of it. You risk a "thermal runaway event". Do you really want to risk setting your house on fire trying to save 30 $ ? Do NOT punch a hole in LiPo's and putting them in salt water is not the good way to "dispose" them. Before throwing a bad LiPo away discharge the bad LiPo very slowly (discharge with 1 / 20 C or lower -use a small flash light bulb or so) and then throw them away (they are supposedly "landfill safe"). Otherwise bring it in for recycling at a local drop off point. Using the temperature sensor of the charger (if available) is not a bad idea for extra safety but not really a necessity - connecting the balance leads is. Start the charging only with the battery pack at room temp or mildly warm (if you cannot keep it in your hand comfortably let it cool down before charging) Do NOT charge the battery when it's below 5° Celsius (battery or ambient temperature) unless the manufacturer says its ok. Otherwise, dendrite formation can occur and cause an internal short creating a "thermal runaway event". If the ambient temperature is 35° Celsius or more do not charge with more than 1 C to avoid the pack heating up above 50 °Celsius . For safety do not charge packs in the car but use a decent thick cable from the 12 volt socket and charge them outside the car. If anything goes wrong you then still can drive home.
Voltage stuff:
Make sure your charger is set to no more than 4.20 volt / cell as max voltage. Use the "balanced" charging setting in your charger whenever possible (or use an external balancer). Charging a battery in "balanced" mode will take (some) more time to charge the battery compared to not using the balancer in your charger as the balancing is an extra step after the battery is (almost) fully charged. Use unbalanced if you need to charge the battery faster (out on the field for example) but do not overdue it (aka after like 3 - 5 charges use a "balanced" charge cycle). Even when using "Unbalanced" charging always connect the balance leads . After using a new charger a few times compare the voltage of the battery reported by the charger with a *decent* volt meter. If you have only a 10 $ multimeter then also do not trust that 10 $ multimeter to be accurate. Borrow or get a decent one (or better, get 2 voltmeters and compare both). Do the same check again after a few months. The voltage of cells should not differ more than 0.01 up or down the target charging voltage when using "balanced" charging.
For example a 3 cell LiPo after "balanced" charging to 4.20 volt/cell should not differ more than: 4.21 volt / first cell 4.20 volt / second cell 4.19 volt / third cell if one cell in this example would read 4.17 or 4.23 volt then * or your charger is going bad (assuming the charger say's all are 4.20 volt but the extra voltmeter/multimeter say not and that meter is actually correct - this means your charger is not correctly reading the volts of the battery) * or your battery is going bad (assuming the voltage measured is correct).
Current stuff:
Many packs can be now safely charged at 2C or 3C so long as the balance lead is connected and a decent charger is used. Some are even rated up to 10C charging. When in doubt if the battery can handle more than 1 C charging (it is NOT written clearly in the battery specifications you can use 3 C for example), use max 1 C charging current. When in doubt if if your 15 $ LiPo charger is any good (hint: no) , use max 1 C charging current.
Settings:
If available use preference settings you can save and recall in your charger and define each battery type you have. If your charger has no memory/presets then double check the battery type detected (number of cells 1s , 2s etc) and the defined amount of charging current before pressing ok.
Discharging using a Lipo charger.
Most LiPo chargers offer "discharging" functionality. Check the default "cut off discharge" voltage set in your charger. In many the default is 3.00 volt, this is to low, use 3.30 v. If your charger cannot discharge your battery with 5 C or more then raise this even to 3.40 volt. The reason behind this is that when LiPo are discharged with a relatively small current (compared to the C value of the battery) you can go "deeper" - take out more mA - before you hit 3.30 volt than when you are discharging the battery with a high current ( = use it in your R/C).
The Sensible Way to treat your LiPo's (to keep them working fine/alive a decent time - most packs should reach 200 ~ 300 cycles):
Packs should not be below 3.7V/cell within 5 minutes of sitting idle after use. This is more an Art than Science. in general it's good practice to set a cut off of the speed controller to 3.3v or use a LiPo battery watcher that warns at 3.3v when the battery is in use and a high discharge current is used from the battery. Simply try not to squeeze the last drop out of the pack, stop at around 80% discharge. LiPo's don't like to be squeezed out totally. If your pack mentions 1 discharge C value then do not discharge faster than the mentioned "discharge C " , you might even want to stay a bit under this. For example: you have a "20 C discharge" battery and a car that uses 22 C when full throttle and 17 C when at 70% throttle and you like to drive the car hard or it is used on heavy terrain you should be using a "25 C discharge" battery as minimum. Most battery's allow a bit more than the rated "discharge C" for a very short time (10 seconds or so - not for minutes). If your pack mentions 2 discharge C values then do not discharge them for most of the time faster than the lowest discharge C mentioned. For example: you have a "20 - 25 C discharge" battery and an air plain that uses 23-24 C when full throttle and 19 C when at 70% throttle. If you run a airplane almost always at 50 to 70 throttle and only go a few times full throttle during a flight it will be most likely fine, if you run it often at full throttle then you're pushing the battery and you should use an "25 - 30 C discharge" battery. Don't "top off" LiPo's (use like 5 or 10% of the battery and then charge them again)..chemically they "don't like it". Use them 40 up to 80% and then recharge them. LiPo's like temperatures between 10 to 35 ° Celsius. They really really don"t like temperatures below 0 ° Celsius or above 60 ~ 70 ° Celsius at all . If your pack is fully charged then do not expose it to cold ( below 5 ~ 10 ° Celsius ) temperatures. Keep it warm in a beer-cooler (without ice of course) or some gloves... If the ambient temperature is below 5 ° Celsius when using the pack in a R/C car/air plain/... charge the pack not fully but only op to 4.10 volt. If a fully charged pack get really cold it might break down and loose most of it's capacity. This is irreversible if it happens . Do not expose your pack to direct sunlight in the summer. Keep it in the shade or in a beer-cooler (again, without ice...)
The Sensitive Way to treat your LiPo's (to keep them working fine/alive a much longer time)
note: you have to ask your self if this makes economical sense, with LiPo battery getting quite cheap, you might simply not care if it survives 50 or even 100 cycles more...
Charging with with a lower charge current than 1 C , like 0.5C or 0.8 C will extent the battery life. Charging always to a lower voltage than 4.20 volt /cell like 4.10 volt will extent the battery life dramatically (500-800 charges for 4.10v instead of 200-300). Note that the lower you go the less charge the battery will contain ( 4.10volt = about 85% of C). Keep the maximum continuous discharge to the (lower) C discharge rating minus 30 to 25%% - ex: for a 25 - 30 C discharge battery never discharge with more than 18 C , for a 20C discharge pack keep it under 15 C.
Storing LiPo's if you don't use them for a while.
If you have to store LiPo's for an extended period charge the battery up to 3.75 ~ 3.85 volt (the exact "best" voltage for storage differs depending on who you ask) and then keep at 10 to 25 ° Celsius (put them in a dry basement if you have one - do not put them in a freezer) and dry (don't put them in your fridge , that is a rather humid) environment. Storing LiPo's fully charged or discharged is a Bad Idea. Storing them on a hot attic is a Bad Idea. Both will reduce the amount of charge a LiPo can store. By storing is meant not using them for several weeks or months. A good trick is when done with using them for the day and you do not plan to fly/drive/hoover the next day(s) do not charge up to 4.20 but only charge them (unbalanced) up to 3.80 v , store them like that and then the day before or the day itself you want to use them charge them up to 4.20 using balanced charging.
Other Things To Know:
4.30 volt is the actual maximum safe voltage to charge a cell. Note that is different from the 4.20 which is the maximum voltage for normal operation. If you charge to more than 4.20 volt you are going over the intended limit but the battery should be able to handle it. Note the "should". This is like blowing tires up to more PSI than advised. You have the recommended psi value for a safe and economic drive and then you have the max psi before tire burst. 4.30 is the "tire bust" limit. No-one wants to have a tire burst in his living room. 3.00 is the absolute minimum discharge voltage, same story as with 4.20 vs 4.30. if you go to 3.00 volt then the battery should survive it. Note the "should". It does not mean the battery will be happy with it or not loose charge. Use 3.30 volt as minimum discharge voltage when the battery is in use and a high discharge current is used from the battery, not 3.00 volt. A battery will, over time, hold less and less "capacity". An battery that you could charge up to 2200 mAh when new will for example only "hold" 1950 mAh after a few 100 cycles and it cannot be charged to hold the same capacity (mAh) anymore as in the beginning. Note that it is mandatory to use the same cell voltages and charge/discharge C when comparing - it's comparing a good state with a bad state, not comparing with what is written on the battery (BIG difference !). Normally a battery that has 80% (some say 75%, some go even lower, it depends who you ask) of the initial usable capacity left should be disposed of or at least watched more carefully and a replacement should be considered, the chance of a malfunction enlarges with the capacity dropping. Incorrect (to fast) charging, discharging (to much) or storing Lipo battery's fully charged during a winter will reduce the capacity and so the number of times you can use the battery. There seams to be a strong consensus that no LiPo can be regularly discharged beyond about 80% of it's capacity ( see the "Packs should not be below 3.7V/cell within 5 minutes of sitting idle after use") without damaging it. This 80% means that if you discharge a 4000 mAh battery ( a battery with 4000 written on it ) you will only manage to get out 4000 - ( 4000 / 5) = 3200 mA out of it before it risks to gets damaged. This also means that if you charge it up after beeing discharged for 80%, your charger will mention it has "put" only 3200 mA "in" the battery. So 3200 mAh is then the "real" (useful) capacity of this battery. You can get more than 80% out of the pack but that will reduce the lifespan of the battery and might be only possible when using a low discharge current . Something that seams to be more controversial is "breaking in" or "conditioning" a new LiPo battery . You seam to have LiPo manufacturers who suggest to do this, you have other who don't speak about it. You have people who never did this and claim their battery's are just fine without doing it. So you seam to have believers and non believers. The actual figures on how to do the "breaking in" or "conditioning" differ but the ballpark figures seam to be to use for the first 4 or 5 charge / discharge cycles only a balanced charge with 1/2 C ~ 1 C and to not discharge the battery with more than 1/4 to 1/2 of the C rate of the battery. Some people claim that after "breaking in" a new LiPo the "netto" (actual) capacity going up after a few cycles like this. Other haven't. All this might be simply depending on the brand of the battery and/or the way they are manufactured. Not all LiPo battery's are exactly the same, there are differences in production between different suppliers of the cell's. Bottom line is that, while it might not prove magic, it might indeed be a good idea to "take it easy" the few first charge/discharge cycles. Use a (dis)charger to do a few 'gentle" discharge / charge cycles or simply use new battery in your car/airplane but take it easy with new battery's, do not go full throttle, stop after no more than 80% is used and charge it then at 1C or lower.
