"Lithium Polymer batteries are volatile. Failure to read and follow the below instructions may result in fire, personal injury and damage to property if charged or used improperly."
This excerpt from Thunder Power's Lipo Safety Warnings pretty much says it all – Lipos are a great power source with high density storage – but they do require careful handling. Now if you think this is a bit of an over-reaction, look at this picture:
There were a number of laptops and cell-phones that were catching on fire – guess what kind of batteries were involved?
What's The Problem?
When a lipo is shipped from the factory, the cells are most likely "balanced" – that means if you measured each cell's voltage, they would be substantially the same – let's say 4.0 volts.
There is no such thing as 2, 3, 4 or more perfectly balanced cells for the life of the battery. Gradually one or more cells can vary in voltage from the others and as the difference increases, the probability of damage increases. If the lipo charger you have does not have a built-in balancer, then each cell will get the same charge. If one cell is higher than the others, this cell will be overcharged, and THAT'S the problem.
When you CHARGE a lipo, it's done at 1 "C" – this means that you have to set the charger to deliver only as many amps into the battery as its rated; eg, a 2200 mah lipo is 2.2 Amps (all you're doing is moving the decimal 3 places to the left – milli = 1/1000), so you can charge this lipo at a rate of 2.2 amps. If you're not in a hurry, then charge it at less than 1C – just takes longer.
Lipos take a charge to 4.2 volts – NO MORE! Overcharging a Lipo can result in a fire with acrid smoke – no fun in the house. So charging a Lipo with anything BUT a charger designed for it is playing with fire – literally. Charging it at a higher rate will damage the lipo and it can result in a fire.
Lipo Balancer
To avoid this problem and increase your lipo's life (lipos can take as much as 500 charging cycles; unbalanced lipos last much less), equalizing the voltage among the cells – balancing – is required. If you have a charger that incorporates a balancer, then you're fine; if not, you need a separate Lipo Balancer.
A Lipo Balancer (I reviewed the Thunder Power's Cell Balancer #TP-205v HERE.) does exactly what it says – it balances the cells by discharging a higher voltage cell to the lowest cell level – hence the term "Balancer" – all cells are of equal voltage.
Using one is drop-dead simple – lipos now come with a separate balance plug. Plug it into the balancer and it will start to do its thing – it may take 10 minutes or maybe an hour depending on how out of balance the lipo is; if it's in balance, it will tell you – the Thunder Power uses a system of colored LEDs.
However, as of yet there is no standard lipo balance plug, so you may have a Thunder Power Balancer and a lipo with a different balance plug – that's why God made adapters; this is something you'll have to live with.
Recognizing Lipo Damage
A damaged lipo is not shy – you will know VERY QUICKLY if a lipo is damaged:
If one or more cells is "puffed" – ie acting like a balloon – it's toast; discard it.
If you crash and the lipo is punctured, odds are that it's toast. Remove it from the plane, place it in a fire-safe location and watch it for about an hour. If it's still hot or it's puffing, it's toast.
If you charge a lipo and it only takes 80% of its charge, it's toast.
If you charge a lipo and it gets hot – it's toast.
Check with your lhs or local waste disposal facility for proper disposal.
CONCLUSIONS
A lipo is NOT a ticking time bomb. However, it DOES require some care in its use. Proper charging and balancing are two pre-requisites for trouble free flying.
Balancing Lipos
"Lithium Polymer batteries are volatile. Failure to read and follow the below instructions may result in fire, personal injury and damage to property if charged or used improperly."
This excerpt from Thunder Power's Lipo Safety Warnings pretty much says it all – Lipos are a great power source with high density storage – but they do require careful handling. Now if you think this is a bit of an over-reaction, look at this picture:
There were a number of laptops and cell-phones that were catching on fire – guess what kind of batteries were involved?
When a lipo is shipped from the factory, the cells are most likely "balanced" – that means if you measured each cell's voltage, they would be substantially the same – let's say 4.0 volts.
There is no such thing as 2, 3, 4 or more perfectly balanced cells for the life of the battery. Gradually one or more cells can vary in voltage from the others and as the difference increases, the probability of damage increases. If the lipo charger you have does not have a built-in balancer, then each cell will get the same charge. If one cell is higher than the others, this cell will be overcharged, and THAT'S the problem.
When you CHARGE a lipo, it's done at 1 "C" – this means that you have to set the charger to deliver only as many amps into the battery as its rated; eg, a 2200 mah lipo is 2.2 Amps (all you're doing is moving the decimal 3 places to the left – milli = 1/1000), so you can charge this lipo at a rate of 2.2 amps. If you're not in a hurry, then charge it at less than 1C – just takes longer.
Lipos take a charge to 4.2 volts – NO MORE! Overcharging a Lipo can result in a fire with acrid smoke – no fun in the house. So charging a Lipo with anything BUT a charger designed for it is playing with fire – literally. Charging it at a higher rate will damage the lipo and it can result in a fire.
To avoid this problem and increase your lipo's life (lipos can take as much as 500 charging cycles; unbalanced lipos last much less), equalizing the voltage among the cells – balancing – is required. If you have a charger that incorporates a balancer, then you're fine; if not, you need a separate Lipo Balancer.
A Lipo Balancer (I reviewed the Thunder Power's Cell Balancer #TP-205v HERE.) does exactly what it says – it balances the cells by discharging a higher voltage cell to the lowest cell level – hence the term "Balancer" – all cells are of equal voltage.
Using one is drop-dead simple – lipos now come with a separate balance plug. Plug it into the balancer and it will start to do its thing – it may take 10 minutes or maybe an hour depending on how out of balance the lipo is; if it's in balance, it will tell you – the Thunder Power uses a system of colored LEDs.
However, as of yet there is no standard lipo balance plug, so you may have a Thunder Power Balancer and a lipo with a different balance plug – that's why God made adapters; this is something you'll have to live with.
A damaged lipo is not shy – you will know VERY QUICKLY if a lipo is damaged:
Check with your lhs or local waste disposal facility for proper disposal.
A lipo is NOT a ticking time bomb. However, it DOES require some care in its use. Proper charging and balancing are two pre-requisites for trouble free flying.