An article by Alex de Boer, Owner, The Electric Motor Vehicle Company
October 2025
This information is for the EMVC Lithium Iron Phosphate 9.6 kWh LiFePO4 battery.
It is important to know how to handle the battery, which is the single most expensive component of an electric vehicle, to assist in prolonging the battery’s life.
The energy transfer is a chemical process shown as follows:
Charged: LiC6 (-post) + FePO4 + Li++ e– (+post)
↔ C6 Li+ + e– (-post) + LiFePO4 (+post) :Discharged
The lithium ion ( + ) charged moves from the positive post to the negative post when electrons are moved from the same positive post to the negative battery post during charging. Discharging is using electricity from the battery.
Charging slows down (trickle charge) when the battery is nearly fully charged (above 80%) to stop electrons (e–) being plucked from the cathode(+) with no matching ions on the anode(-) to match. This could damage the terminals.
If running the vehicle aggressively (demanding a lot of current) electrons can get stripped from the anode material (graphene C6). Therefore the space reduces and the graphene can no longer store as many Lithium ions. This reduces the State of Health (SOH) and cannot be recovered.
The above “charging” is a chemical process that is not voluntary. Electrons + Lithium ions must be “pushed” from the positive post to the negative post which uses energy. This comes from two sources:
- electricity supply (mains power) via the charger
- regeneration during deceleration of the electric motor
NB
- Regeneration is only about 20% of the energy used up. Therefore it is important to try not to use the brakes and let the regeneration force do the braking.
- The EV battery will also degrade faster at high temperatures. 20oC is the optimum temperature.
- Heat can also delaminate the Carbon (C) in the anode (-). The detached carbon does not contribute to the battery capacity therefore lowering the SOH.
- Also a very cold battery does not “want” to charge or discharge – that is why EMVC adds a blanket to hold the battery temperature between 0oC and 5oC during cold weather.
- Voltage Curve
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Fast acceleration of the vehicle or expecting the electric motor to work hard (by say pulling heavy loads in a high gear or going up hills in a high gear) pulls a lot of amps from the battery which builds up heat. Driving by using 300amps or more should be minimised / avoided as over time this would reduce the battery SOH more quickly.
EMVC Battery Composition
The Electric Motor Vehicle Company (EMVC) Lithium Iron Phosphate LiFePO4 9.6 kWh battery is made up of 32 individual battery cells and a battery management system all housed in a purpose built stainless steel case to form one large battery. This is a sealed unit and should not be opened.
A phone app is available which connects by WiFi to interrogate the battery if faults occur or to set battery parameters.
Each battery cell has copper M8 stud terminals with bus bar connectors in series and/or parallel to form one large battery.
The cells are prismatic aluminium with terminal covers to prevent short circuits. Each cell also has a safety valve outlet. Each cell is separated by a space for better air circulation.
Each cell has a nominal voltage of 3.2V and is assembled into a pack to operate at 48V.
A fully charged cell is 3.65V and at the end of the discharge it is 2.2V. This measures the amount of usable energy capacity. Each cell has a capacity of 102Ah. The full battery can deliver 9.6 kWh of energy capacity.
The battery should only be discharged to 20% of its capacity. The vehicle will still operate below this capacity but may enter a “limp mode” to conserve energy.
Charging
A There are 2 steps to fully charge the battery:
- Constant current (CC) to reach 60% of State of Charge (SOC)
- When the charge voltage reaches 3.65V (the upper limit of effective charge voltage) the charging changes to constant voltage (CV). At this point the charge current is limited by what the cell will accept at that voltage, so the charging current steps down.
B When the weather conditions are cold ( freezing or below ) do not store the Hisun with a low charge. At -20oC an empty battery may freeze. Keep it on charge during this time as this produces heat. Using the Hisun in cold weather is never an issue as the battery produces heat when in use. However you may notice a reduction in the usable range.
Also when not using the Hisun for long periods ( a month or more ) store it charged to 90% or more. This prevents the possibility of freezing . Also batteries lose a small amount of charge over time so topping up the charge occasionally is good for the battery.
An over voltage can be applied to LiFePO4 without decomposing the electrolyte. It can be charged by CC to reach 95% SOC and by CC + CV to reach 100% SOC.
Self Balancing
LiFePO4 cells in a battery pack in series cannot balance each other during charging.
This is because the charger current stops flowing when the cell is full.
Therefore EMVC have added a “self balancing” control board to the battery management. This allows the battery to use 1 amp of its own power (even when the key is off) to balance individual cells until they all reach the same charge – about 3.65V.
If the battery is used each day with all the cells starting at the same voltage the range available will be greater and the battery life will be longer.
When the battery is in use some cells can be more “lazy” and they won’t all discharge at the same rate. The battery can be charged whenever not in use (smokos, miking etc.) as this will increase the range available and LiFePO4 cells are not adversely affected by this. However these “short” charges will not rebalance the cells. Eventually (in days or weeks depending on the amount of use) the voltage difference between any 2 cells could exceed 0.5V and to protect itself the battery will switch off until this issue is rectified.
Therefore it is important that when possible (usually at night) the battery gets a full charge to SOC 100%. This can be seen when the charger LED displays a constant green light. This also allows the self balancer to equalise the cell voltages again.
Interesting facts:
- the gravimetric energy density of Lithium is 130 Wh/kg compared to lead-acid’s 35 Wh/kg (4 x greater)
- LiFePO4 runs better at elevated temperatures due to higher Lithium ionic conductivity.