Buying a lithium battery – what should you look out for?

In this article, we will show you what you should look out for when buying a lithium battery and explain the main differences between the various lithium batteries on the market. We will also give you a brief insight into the most important features of a good LiFePO4 supply battery.

Lithium batteries are becoming increasingly popular. In the camping sector in particular, there is a real mood of optimism and many motorhome owners are replacing their old AGM or lead batteries with new lithium iron phosphate batteries (LiFePO4). But lithium batteries are also increasingly becoming the gold standard in other areas. For example, as energy storage for photovoltaic systems.

The market for lithium batteries is now quite large. When looking for a suitable lithium battery, most people ask themselves what they should look out for and why the price differences are so great.

In the following article, you will find out why not all lithium batteries are the same and what you should look out for when buying one.

Cell type

One of the most important differences between the many lithium batteries is the type of cell used. A basic distinction is made between LiFePO4 supply batteries between three cell types:

Prism cells

Prismatic cells are rectangular and their design makes them significantly more space-saving than other cell types. In addition, these cells have a higher energy density than round or pouch cells. Another feature is their robustness: prismatic cells are insensitive to vibrations and temperature fluctuations. These characteristics make this cell type the most durable and highest quality in the LiFePO4 battery sector.

Round cells / Cylindrical cells

Cylindrical cells are similar in design to conventional AA batteries. They have a wide range of uses and are easy to replace. Due to their cylindrical design, they are not very space-saving and the energy density also suffers as a result.

Pouch cells

These cells are flat and flexible and are mainly manufactured in pouches made of aluminum or composite material. Pouch cells are perfect for applications in the field of portable electronics. One disadvantage of this type of cell is the relatively high susceptibility to damage due to the unstable outer shell.

Supervolt: At Supervolt , batteries are installed exclusively with prismatic cells. We therefore guarantee a high energy density as well as a durable and robust battery.

Here you will find our first-class lithium batteries:

Cell quality

In addition to the actual cell type, the cell quality is of crucial importance. Lithium batteries are divided into grades A, B and C, with “Grade A” being the highest quality level.

But how exactly do these quality levels differ from one another?

Grade A

Battery cells labeled “Grade A” meet the highest quality standards. During quality control by the battery manufacturer, these cells meet every single specification. These include important parameters such as: Capacity, self-discharge rate, voltage, internal resistance, service life, cycling behavior and more. Grade A cells are used in the automotive industry, among others.

Grade B

Cells that fail one of the battery manufacturer’s many quality checks are rated as “Grade B”. Grade B cells can therefore have a higher self-discharge rate, poorer cycling behavior and a shorter service life than grade A cells.

Grade C

For production reasons, battery cells are stored for longer periods of time. If the cells exhibit high values for the self-discharge rate or a loss of capacity (> 5-10%) after storage, they are downgraded to grade C. Increased internal resistance or bulging also lead to a downgrading.

Assessment of the quality level

The problem with the quality grades is that there is unfortunately no standard for evaluating the cells. It is therefore quite common for battery manufacturers who equip their batteries with grade B or grade C cells to conceal the true grade and advertise a quality level higher.

Supervolt: Only Grade A prismatic cells are used in LiFePO4 batteries from Supervolt.
To ensure greater transparency and counteract the incorrect declaration of battery cells, we have gone one step further and developed the “battery checker” has been introduced.

Our Battery Checker is the first of its kind and a pioneer for more transparency in the field of LiFePO4 batteries.

With our Battery-Checker you can find out the following data about your Supervolt battery:
– Capacity at delivery
– Production date of the battery
– Manufacturer information for each individual cell!
– Serial number & production date of the cells

Battery Management System (BMS)

We often hear about the so-called BMS (Battery Management System) for lithium batteries. But is a BMS absolutely necessary? And what does a BMS do anyway?

The built-in BMS in a lithium battery is a decisive feature for the quality of the battery – because not all BMSs are the same. Although many lithium batteries have an integrated BMS, you should make sure that it also has all the necessary protective functions.

The following protective functions of a BMS are important:

• Overload protection
• Deep discharge protection
• Overvoltage protection
• Active cell balancing
• Protection against short circuits
• Temperature protection (charging process is interrupted at temperatures below 0 °C)

All these protective functions ensure that the lithium battery can be expected to have a significantly longer service life.

The BMS also ensures intelligent charge control of the battery, so that in the vast majority of cases it can be replaced with AGM or lead batteries without changing the charging infrastructure.

In addition to the protective functions, the charge status can also be monitored thanks to a smart BMS, e.g. via Bluetooth.

Supervolt: Every Supervolt battery has a first-class BMS that reliably protects the battery from serious damage. All the above-mentioned protective functions are reliably controlled by the BMS.

Our passive and active cell balancing is also particularly important here. Cell balancing ensures that the installed prismatic cells remain at the same voltage level. Even small voltage deviations between the installed cells can lead to a significantly shorter service life of the lithium battery.

Thanks to our integrated RJ45 interfaces, our BMS data can also be transmitted to external devices such as the Victron GX.

Performance

A decisive difference between the many LiFePO4 batteries on the market is the performance of the battery.

This refers to the maximum discharge and charge of the battery. These values are given in amperes (A) and are particularly important for a battery if you want to connect powerful devices – e.g. a large inverter.

Supervolt: Even our smallest battery (100 Ah) guarantees a constant discharge of 160A (2 KW) – even 250A is possible in the short term.

Our 150Ah batteries even allow a constant discharge of 200A (2.5KW) – up to 300A for short periods.

Even powerful appliances such as coffee machines, kettles or hair dryers in combination with an inverter are no problem for Supervolt batteries

For particularly intensive applications, we have developed our Supervolt Ultra extremely powerful batteries in our range.
Supervolt Ultra batteries have a peak discharge current of up to 1800A! Also perfect as a starter battery for all vehicle makes.

Service life/charging cycles

The expected service life of lithium batteries is given in charging cycles. A charging cycle refers to a complete charge and discharge.

Manufacturers of lithium batteries advertise an immense number of charging cycles. However, when considering the number of charging cycles advertised, the corresponding depth of discharge must also be taken into account. Some manufacturers advertise many possible charging cycles, but only a low depth of discharge.

Example: A battery can complete 2000 charging cycles when fully discharged and recharged (100%). However, if the same battery is only discharged to 50 % and then recharged to 100 % each time, over 6000 charging cycles are possible according to this model. With a discharge of 30 %, even 15,000 cycles would theoretically be possible.

It should be noted that these values are laboratory values. In practice, optimum conditions would have to prevail in order to achieve these peak values.

It is therefore much more important that the battery has a good BMS, which protects the battery from gross misbehavior. E.g. charging at too low a temperature, short circuit, overvoltage and undervoltage. These protective functions make the biggest contribution to the long life of a lithium battery.

Supervolt: We guarantee 3000 charging cycles at a depth of discharge of 90 %. With its protective functions, our smart BMS ensures that our lithium battery is protected against serious damage and therefore provides long-lasting enjoyment.

Heating

Lithium batteries are available with and without built-in heating mats – but why are they needed at all?

This is quite simple: LiFePO4 batteries should not be charged below 0°C, as this would severely damage the cells (discharging below the freezing point is not a problem). To avoid this typical battery problem, there are lithium batteries with built-in heating mats. If the lithium battery is connected to charging current at sub-zero temperatures, charging of the battery cells is blocked thanks to the BMS. Instead, the integrated heating mats are supplied with power. The heating mats bring the battery cells above the critical temperature limit and the BMS then releases the charging of the lithium battery again.

Lithium batteries with heating mats can usually be identified by a suffix such as “Polar”, “Arctic” or “Low Temperature”.

Supervolt: With our series Supervolt Polarseries, we offer lithium batteries with integrated heating mats and a powerful BMS, which makes it possible to charge the battery down to -30C°. Perfect for anyone who wants to use their battery in extreme conditions.

With a Supervolt Polar LiFePO4 battery you really don’t have to worry about using the battery in extreme temperatures. As soon as the battery receives charging current, the heating mats are first heated until the battery reaches plus degrees again. The battery is then released for charging.

We started a practical test and cooled our Polar batteries down to a constant -20C°. How long the batteries need to heat up to +10C° and how much power they consume in the process is shown in the table below

Supervolt battery	Duration (from -20C° to +10C°)	Consumption
Supervolt Ultra 100Ah	40 min	60 W
Supervolt Polar 100Ah	approx. 1 h	85 W
Supervolt Polar 150Ah	approx. 1.5 h	175 W
Supervolt Polar 180Ah	ca 1 h	145 W

Design/housing

LiFePO4 batteries are now available in many shapes and sizes. Depending on the application, there are more or less suitable designs. In addition to the design of the battery, the housing itself is also very important for the intended use.

Many manufacturers offer battery shapes that are specially advertised as“under-seat batteries“. These designs fit perfectly under the most common motorhome seats.

Special “slim” versions for narrow spaces are also available from some suppliers.

In addition to the design, the actual housing of the battery is decisive for the intended use. If you want to use your battery on boats or in off-road vehicles, you should make sure that it is waterproof .

Supervolt: Our lithium batteries all have DIN dimensions. This means that they fit perfectly under the seats of standard panel vans and motorhomes. Our new design also has an IP65 protection rating. This means that Supervolt batteries are waterproof and well suited for use on boats and in off-road vehicles.

Supervolt batteries can also be easily unscrewed. The new screw-on housing makes maintenance much easier in the event of a defect.

If you want to get the most out of your under-seat construction, you should take a look at our 480Ah JUMBO under-seat battery should take a look. This battery is the perfect fit for the under-seat construction of (almost) every panel van.

Guarantee

A long warranty period is automatically a great confidence boost for the battery. Only very few LiFePO4 battery manufacturers offer more than the legally required 2-year warranty.

Supervolt: We offer a 5-year manufacturer’s warranty. If there is a warranty claim within the 5 years, we will ensure that the battery is replaced without any complications.

Bluetooth

Batteries with a BMS can also have a Bluetooth module. With a Bluetooth connection to the BMS, the most important battery data can be read, e.g. via an app.

This means that there is no need for external devices to read the battery data and real-time battery data can be called up.

Supervolt: All our batteries can be easily connected with our self-developed Bluetooth app. The app shows all relevant battery data at a glance. For example, remaining capacity, voltage, current flow, battery temperature and even the voltage status of all installed cells.

Our Supervolt BMS app is available for IOS and Android.

Customer service

As lithium batteries are not exactly cheap, good customer service is worth its weight in gold. When buying a lithium battery, you should pay attention to how the retailer handles returns.

Technical support should also be a matter of course. When installing a battery in an existing or new system, there may be a number of questions that need to be clarified. It is therefore very helpful if a contact person is available to answer such questions.

Supervolt: Our returns process is quick and uncomplicated. The most important thing: if your battery needs to be replaced, we will send you the replacement battery before you have to return the old battery.

Our technical customer support is available Monday to Friday by phone or Whatsapp. We are happy to answer any technical questions you may have.