Frequently asked questions
Categories
Below you will find the most frequently asked questions and corresponding answers on the subject of LiFePO4 lithium batteries, charge boosters, installation, BMS, as well as storage, charging and discharging.
BMS (Battery Management System)
BMS stands for Battery Management System. All Supervolt batteries have a BMS installed in the battery itself.
The BMS is the “smart” unit in our batteries. Thanks to the BMS, the battery is protected against overvoltage, e.g. minor short circuits, excessive charging and discharging current and temperature.
Temperature protection is necessary because lithium iron phosphate batteries should not be charged below 0° to avoid damaging the cells. To prevent this, the BMS reliably switches off the charging process at below 0° Celsius thanks to the integrated temperature sensor.
However, the battery can still be discharged down to -30°.
Another function of our BMS system is to transmit current battery parameters such as voltage per cell, current consumption in amperes or current charging quantity via Bluetooth to the iPhone or Android app and display them clearly.
Another task of the BMS is to increase the service life through integrated protection and balancing functions. Our batteries contain four 3.2V 100Ah prismatic cells. To ensure that these are charged and discharged evenly, our BMS balances the cell voltage evenly between all cells. This prevents discharges and increases battery life and reliability.
The BMS requires very little energy for the Bluetooth module and for monitoring the battery parameters. Nevertheless, we recommend checking the battery after more than 6 months of storage and recharging it if necessary.
The official Supervolt Bluetooth app will be available for Android and IOS in the Appstore from January 2021. It can be downloaded here.
Charging booster
The charging booster is required to ensure that the alternator fully charges the on-board battery as well as the starter battery.
Newer vehicles (especially Euro 6) only charge the starter battery and on-board battery via the alternator until the starter battery is full. To avoid this and to ensure that the alternator also charges the on-board battery until it is fully charged, a charging booster is installed.
The above-mentioned problem does not (usually) exist with older vehicle types, as these continue to generate energy even when the starter battery is full. The on-board battery will therefore normally continue to be charged. However, it is still worth installing a charging booster.
The installation of a charge booster can optimize charging by the alternator. This is because the charging voltage of the alternator can vary greatly. The built-in charge booster ensures that the body battery is always charged with the correct voltage.
This not only shortens the charging time, but also has a positive effect on the service life of the body battery.
The maximum permissible charging current varies depending on the size of the battery. For example, the maximum charging current of our 100Ah LiFePO4 battery is 160A; for our 150Ah LiFePO4 battery 200A and for our 480Ah LiFePO4 battery 300A.
Nevertheless, we recommend a charging current of ≤ 50A to ensure the longest possible battery life.
We have a 30A charging booster and a 60A charging booster in our range.
The amperage here indicates the current strength, i.e. how “quickly” the battery is charged. The higher the amperage, the more the battery charges.
In other words, at 0% battery capacity, a 20A charge booster requires 5h, a 30A charge booster 3h, a 50Ah charge booster 2h, etc.
The D+ or dynamo cable generates 12V direct current as soon as the alternator is turning.
The charge booster requires the D+ signal to determine when the cabin battery can be charged by the alternator and when it cannot.
Loading & unloading
The Supervolt lithium LiFePO4 battery can be fully discharged. This does not mean that the batteries can be deeply discharged, but rather that the BMS reliably switches the battery off above a certain voltage level to protect it from further discharge.
The BMS interrupts the charging process as soon as the battery is full
LiFePO4 batteries should be charged with a charger with CCCV charging characteristics. But don’t worry, these are the normal chargers for wet lead-acid batteries, without any special characteristics, but a simple IU characteristic.
Important: The lead-GEL charging curve must be set in the E-block (14.4V). If a lithium charging curve is available, use this of course.
In our range we carry a 30A AC/DC 12V lithium charger.
A brief explanation of why charging with a lead charger is possible:
Each of our 12.8V LiFePO batteries consists of 4 Prisma cells, which have a fully charged voltage of 3.65V. 4 cells multiplied by 3.65V results in 14.6V, which is only slightly higher than the charging voltage of lead-acid batteries.
Ideally, the charging rate should be a maximum of 0.5C. C stands for coulomb and means amperes/second. In simple terms, you can say that C is x times the battery’s own capacity as the charging/discharging rate.
Example: Charging a 100Ah battery with 0.5C corresponds to charging with 50A.
Depending on how you use your battery, “manual” equalization may be necessary from time to time.
The cells then equalize when the battery is full and the charger is still connected.
Set your charger to 14.6V or 14.7V (AGM) and leave it connected until the cells have equalized. Even if the battery already indicates overvoltage protection.
Depending on how unbalanced the cells are, balancing can take a few days.
Even if our batteries are protected against deep discharge during use by the BMS, there is a risk that the battery will discharge itself if it is not used for a longer period of time.
Although the discharge rate is only 3%, if the battery is not used for 6 months in a low state of charge, it is possible that the battery will discharge itself to a critical point.
The battery should therefore be stored at over 50% and checked and recharged every 6 months if possible.
Of course, most charge controllers are designed for lead batteries and can therefore be used directly.
In our store we offer highly efficient MPPT solar controllers with Bluetooth app.
Yes, this is possible with a charging booster. (see charging booster section)
Don’t worry, this is common with LiFePO4 and unavoidable due to the special voltage curve.
The battery is approx. 99% full at a cell voltage of 3.35V. From then on, the cell voltage rises rapidly and the BMS has difficulty distributing such a low residual capacity evenly.
As soon as a cell reaches 3.7V, the BMS switches to overvoltage protection while the other cells are still at 3.35V-3.45V.
This can be seen from a graph. The X-axis is the capacity in % and the Y-axis is the voltage:
This is because the BMS is in undervoltage protection. This triggers when the battery is empty.
In order for the BMS to release the battery again, currents must be applied to the battery terminals.
The best way to do this is via the alternator by starting the engine briefly.
This is often not possible with many smart chargers using shore power, as they only charge when they detect the voltage from the battery.
However, as the battery is in protection mode, it does not emit any voltage.
Solution therefore:
- Connect normal 12V charger until BMS releases again
- Start the engine and enable the BMS via the alternator
Winter & storage
The battery can no longer be charged below 0°. Our BMS prevents this, as the battery would otherwise be damaged. However, discharging is possible down to -30°.
With our new POLAR batteries you can now also charge in winter, down to – 30°C.
If the temperature remains above -20°C for storage of less than one month and above -5°C for storage of less than 6 months, this is not necessary.
As devices in standby mode or small consumers can slowly drain the battery, we recommend using our on/off switch to switch off the Supervolt battery when the vehicle is not in use for a longer period of time. This effectively prevents the battery from being discharged over a longer period of time.
We recommend only sending LiFePO4 batteries with a state of charge of 50 % (SOC) or more into the winter break and checking and recharging them every 6 months.
Recommended storage temperature:
Storage up to 1 month: -20 to +50°C
Storage up to 6 months: -5 to +40°C
It is recommended to store lithium batteries indoors during the off-season.
It is also recommended to store LiFePO4 batteries at a state of charge of 50 % (SOC) or more.
If the batteries are stored for a longer period of time, you should check the charge status of the batteries regularly. You can do this using our app.
If the voltage is below 13 volts, the battery should be charged.
Do not store batteries that are discharged.
Due to the BMS and the Bluetooth module, the battery discharges at 3% of the original capacity per month.
Devices in standby mode or small consumers can also slowly drain the battery. For this reason, the Supervolt battery should be switched off using our on/off switch when the vehicle is not used for a longer period of time.
The LiFePO4 lithium battery can still be used normally at temperatures below 0°. However, it cannot be charged as the lithium ions crystallize at the cathodes and capacity is lost. But don’t worry, our BMS reliably switches off the charging process automatically at below 0° thanks to the temperature sensor.
As soon as a temperature above 0° is reached again, charging is possible again. To do this, simply check the temperature status in the app.
No, this is not possible as the battery would otherwise lose its service life. Our BMS prevents charging at temperatures below 0°.
Our new Polar batteries now allow charging down to -30°C.
After a long winter break, the BMS must be recalibrated.
In motorhomes, there are
often small consumers that are not detected by the shunt, but which nevertheless discharge the
battery over time. It is therefore possible that the battery is in undervoltage protection
but displays 80%. In this case, please fully charge the battery.
Full does not just mean until the app displays 100%, but until the individual cell voltage has reached 3.6V. Depending on the charger, this may take several hours. Only after a full charge is the BMS calibrated and displays the correct values.
POLAR batteries
No, the heater is never operated via the battery. Only via the applied charging current.
The heater switches on as soon as charging current is applied and the temperature is below 0°C.
If there is no power, the heating will not switch on.
The 100Ah battery contains 2x 1.7A radiators, the 150Ah battery 3x 1.7A.
As soon as the heaters have warmed the battery to above 0°C, the BMS allows charging again.
According to our manufacturer, the heaters are sufficiently strong down to -30°C. We have successfully tested the battery down to -30°C.
As soon as the heater has warmed the battery to 10C°, the BMS switches the heating modules off again.
Installation
This is what our lithium battery is designed for. Thanks to the DIN80 standard dimensions of 318x175x187mm, our battery is the same size as 100Ah lead batteries. This makes our LiFePO4 battery perfect as an under-seat battery for Fiat Ducato, Citroen Jumper or Peugeot Boxer.
Only batteries of the same type may be connected in series or parallel.
As lithium iron phosphate batteries have an almost identical charging curve to lead batteries, they can usually be charged with the current configuration without any problems.
The ideal setting is lead-gel at 14.4V.
However, it must be ensured that the charger does not have a sulphation function. This would damage the BMS.
Our batteries can be connected in series up to 4 times. This depends on the BMS installed. Not every lithium battery can be connected in series.
Yes, our batteries can be connected in parallel indefinitely.
Simply put: Connecting in parallel means connecting 2 batteries in such a way that the capacity is doubled.
When connected in parallel, the possible load capacity is increased. This means that instead of 160A, 320 can now be discharged.
Connecting in series means connecting the battery in such a way that the voltage doubles.
This does not matter, as lithium cells are solid and not liquid. You just have to make sure that the poles are protected.
Larger fuses on the solar regulator, charging booster or shore power charger are not necessary.
Guarantee
The batteries can continue to be used as normal. The service life usually exceeds 10 years.
Shipping
To all of Europe. See shipping.
Shipping is free of charge within Germany.
For other countries please contact us.
Usually 1-3 working days.
Yes, you will automatically receive the tracking link by e-mail.
Return
You have 14 days right of return.
Up to 14 days. After the 14 days only on the basis of the warranty, up to 5 years after purchase.
You return the battery to us and we will send you a new one after checking the cause of the damage.
We will cover the return costs in the event of a defect.
Payment
PayPal, Klarna, installment purchase, purchase on account, instant bank transfer, Visa, Mastercard.
See under the payment methods.
Other
Bluetooth & App
The SOC percentage value and the capacity display are calculated values that are initially inaccurate. Jumping % values are normal at the beginning, as the BMS must first calibrate itself.
With an uncalibrated BMS, the app can display 100%
while the battery is almost empty.
Unfortunately, this is not as accurate for LiFePO4 as it is for cell phone batteries. The voltage curve of LiFePO4 is very flat, which is why the BMS cannot derive the capacity solely from the voltage.
A measuring shunt in the BMS calculates the capacity based on the measured current flow. In order for this to calculate and display accurate values, the battery must be calibrated, i.e. completely discharged and fully charged again.
The calibration can be started manually with the following procedure:
- Discharge completely until the battery is empty and “Low voltage protection” is displayed,
- then fully charge until the charger stops charging and the app displays “Overvoltage protection”.
Due to the long transport route, the Bluetooth switches to energy-saving mode and power has to be drawn from it so that the Bluetooth wakes up again.
We are working with a new Bluetooth module that goes into standby mode if it has not been used for a long time. The aim is to prevent the battery from discharging when the motorhome is stored in winter.
In order for the Bluetooth to “wake up” again, the battery must be used / power must be drawn from it.
The starting current of 12V devices is sufficient for the Bluetooth to be active again in a few minutes.
The current that flows into the inverter when it is switched on activates the “sleeping” Bluetooth module within a few minutes.
The built-in shunt is set to 0.6A.
In the first three cycles, the SOC is actually only calculated using the actual current integral.
If the current is less than 0.6A, the battery is classified as being in standby mode and the SOC slowly decreases based on self-consumption.
After three cycles (≥ 3 cycles), the SOC is simultaneously calibrated to the OCV. This means that the standby SOC changes even if no current is switched on or off, but it is calibrated according to its voltage and standby current. I have provided the test data for this in the link below.
After prolonged transportation or storage, we recommend that our customers perform a complete cycle (full discharge to undervoltage protection and full charge to overvoltage protection) to calibrate the SOC and capacity.
Photovoltaics - balcony power plant
Yes, our energy storage systems can be used universally.
Thanks to a powerful BMS and possible series connection up to 48V, they are ideally suited for home solar.
If you meet the requirements, simply fill out the form at the following link:
If you have any further questions, simply send us an e-mail and we will reply as quickly as possible.