Battery Warranty | Charging | Charging Times | Fault Detection | Maintenance | Safety Features |

Additional Battery
E-PAC uses 1x 30Ah pack in its main body unit. This will give 25~30 minutes flying depending on circumstances. An additional 30Ah pack can be added to the bottom of the body frame (total then 60Ah). It is connected to the main power grid by a single universal plug in the bottom of the E-PAC body unit.

Alarms
Battery Capacity – at 3 minutes, 2 minutes and then 1 minute the handle controller vibrates warning the pilot to check the data screen voltage and warning him of pending ‘Auto Cut’. Each warning has a different vibration with the last warning being the most noticeable.

Battery Care
LiPo batteries should never be allowed to fall below 2.95V per cell. After this the cells can become damaged so it is important to keep the batteries topped up. E-PAC special charger will advise the voltages to the cells and so it is mandatory to balance charge the E-PAC batteries before they are disconnected, removed and left for any length of time.

Battery Packs
E-PAC latest development uses a single large Lithium Polymer (or LiPo) battery pack. This 30Ah pack, each contains 54 cells with a total pack Voltage of 66.6v. So the basic E-PAC operates at 66.6V with 30Ah of capacity.

The battery packs fits inside the main body in compartment within a string ridgid chassis. The pack has a power socket into which a special patented plug is fitted which is connected to the main power grid which controls the E-PAC.

A further ‘optional’ battery pack (giving 60Ah total) can be added to the bottom of the main frame using a special ‘optional’ battery holder. This then plugs into a separate socket in the bottom of the main body.

Battery packs can be purchased individually.

Battery Life
E-PAC uses the highest quality Lithium battery cells. Not only that the individual cells in each pack are matched for maximum performance which also means they operate more evenly as a pack.  Battery life is dependent on the way the batteries are used, both in charging and discharging. Quick charge rates and high discharge rates shorten the life of a battery.

For charging E-PAC uses possibly one of the most sophisticated chargers currently available. This means that the batteries are charged is the best way possible, limiting the possibility of damage and maintaining long life.

In actual use the E-PAC discharge rates are low compared to other types of product like for instance model aircraft, and so good life cycles are expected from the E-PAC batteries.

In general use with the pilot not pushing the batteries hard i.e. aerobatics every height, it is expected that battery pack will handle 600~800 cycles. In hard use that cycle life, can drop to 500 or below. 500 cycles is 250hours of flying and even then the batteries are still operational/usable it only means that they will start to lose power more quickly than before.

Battery Protection
Each E-PAC battery pack has an internal circuit board. This measures the voltage and temperature of the pack and should the pack exceed set current output or a temperature in excess of 80C the pack will shut down.

Battery Safety
There is much discussion about the instability and safety of batteries. Before discussing this further please consider that if there were no cars and today someone came forward and said let’s put 70 liters (20 gallons) of highly flammable liquid in a box with wheels and 4 people inside it, everyone would say you were mad. And as to having open pumps on the street where that highly flammable liquid is poured under pressure into those tanks – well what would your comment be?

So with this is mind the first thing to understand is that batteries are far more stable than fuel but like fuel they must be operated properly and treated with respect. Proper operation includes both charging and in. If operated correctly the Yuneec battery pack will give both long life and constant service.

In use - unless batteries are abused or damaged (shorted out) or discharged too quickly, they are very safe. We use millions of them worldwide every day and Lithium Polymer batteries are no different. So when it comes to powering the E-PAC, withal the additional protection features included it’s LiPo batteries are very safe.

Battery Type - Lithium Polymer
Lithium Polymer (LiPO) currently offers the most commercially affordable, high density, power source available today.

With a power density of 170 (this is 170W per Kilo) no other battery offers such affordable power output. Yes, there are other batteries in development which claim higher output densities and no doubt new technologies are under development but these will take time – after all it has taken over 10 years for LiPo to get to be commercial and even now they are still expensive. And commercial is a key factor unless of course you are the military!

It is predicted that the LiPo power density will increase over time by maybe some 10~20% but it will take a completely new technology to develop the type of power density we need - 300~400W/Kilo – to make electric a really viable day to day power source.

The positive point is that whatever electric powered product is purchased now it is still electric and so it will still be able to run on whatever new electric power sources are devised on the future.

Battery Warranty
Yuneec has yet to decide on the battery warranty relating to cycle life. Obviously any direct manufacturing fault is covered but battery life depends on many factors most importantly charge and discharge rates.

It is expected that Yuneec will offer a guarantee for a number of battery cycles (cycle = 1x charge/discharge) providing that the pack is only used with a Yuneec charger and has not been abused in use, opened, damaged etc.

An internal processor will monitor the charge and output history of the pack to ensure that no abuse has taken place. The pack will also have an internal fuse system so that is case of damage or severe discharge the fuse will blow. This fuse will only be service replaceable.

Charging
For all batteries charging is the most critical time and more so for LiPo. The reason for this is that most chargers do not monitor each cell in a battery pack, they look at the average voltage of the pack. This means that when charging, if one cell is much lower than all the others the overall average voltage appears lower and so, even though many of the cells are already fully charged, the charger keeps on charging trying to bring the overall voltage up to its preset maximum level. In this case the overcharged cells can be severely damaged.

The only way is to control all the cells and make sure that any lower cells are brought up to their top voltage without the higher cells being overcharged.

The E-PAC balancing charger monitors all 54 cells in 3 battery packs all at the same time. This charger was specially designed at Yuneec and it is the only charger of its type in the world at present, capable of handing this number and capacity of cells. During charging it monitors all the cells holding back high charged cells whilst bringing up any lower cells. In the balancing charge cycle each cell is charged within 0.03Mv of each other. No other commercially available charger can do this and it represents a huge breakthrough for battery powered systems.

It is this charger that makes E-PAC battery charging so safe and in turn ensures that each pack is at its maximum charge for use. It also maintains the batteries in a better state and so ensures the life cycle of the batteries is maximised.

Charging Times
Following an increase in specification E-PAC now has two charging systems. One is a full balancing charger which operates as described in the charger section above. A full charge with the balancing charger takes approximately 3 hours.

The other is a standard charger. This charger can be used for quick charging and takes approximately 1.5 hours.

Yuneec’s LiPo battery packs require balance charging approximately every 5~10 charges charge’s and so the quick charger is used for normal charging in-between balance charges. Both chargers are required.

Fault Detection
The E-PAC controller and motor are fitted with sensors, these control the motor and regulate the operation but also give feedback and act as alarms. In case of high motor temperature the control handle vibrates allowing the pilot to view the data screen and adjuster the power setting to reduce temperature. If this is not done then the software automatically adjusts the power output to reduce the motor temperature.

Maintenance
E-PAC needs general maintenance. There is nothing in the speed controller or motor that can be user maintained so maintenance revolves around general checking of the unit – Screws tight, Propeller not chipped, Frame fixings/joints, Power connectors, Arm hinge bolts, tight Harness, Shackles locked etc. etc.

The most important maintenance is checking the battery pack voltage and keeping the pack charged and in balance.

Safety Features
Yuneec International constantly evaluates product safety and E-PAC has many unique safety features for both fault detection and also general flight safety.

These safety features include:

Main Body
Main Master Switch:
Ultra Bright Red LED:
Audible Sounds:
'Power ON' Switch:
Ultra Bright Red LED:

Hand controller
Data Screen:
Vibrating Alert:
Auto Temp Adjustment:
Software:

Total shut off of the main power
Activated when main power switch is on
On main power switch activation & hand controller power on
Situated on the control handle this activates the motor controller and data feed back
Flashes when motor controller power on switch is activated

Shows all key parameters including temperature for controller and motor
Control handle vibrates 5°C before maximum temperature has been reached
The power output is automatically regulated to reduce power to lower motor temperature
Auto adjusts motor power/rpm at maximum motor temperature