Lithium Batteries FAQ

What is a Lithium battery?

Just like standard lead acid batteries, Lithium batteries consist of positive plates (cathodes) and negative plates (anodes) as well as insulating separators to avoid short circuits between the positive and negative plates, and finally electrolyte, which is the conductive liquid although unlike flooded lead acid batteries, there is no free liquid in LiFePO4 batteries.

A lithium battery differs in the materials used for the above mentioned components, especially the cathode and also the process undertaken during charge and re-charge. A lead acid battery undertakes chemical reactions, which change their components. Lithium just transfers ions during the charge and discharge process leaving everything else the same.

Are all Lithium batteries the same?

The term “Lithium” or “Lithium Ion” refers to a family of batteries in which ions move from the negative electrode (anode) to the positive electrode (cathode) during discharge and back again when being charged. The point to note in this definition is that it refers to a “family of batteries”. Just like Lead Acid family which contains Absorbent Glass Mat (AGM) and Gel types, there are a number of different “Lithium Ion” technologies within the Lithium Ion family. They each utilize different materials for their cathode and (to a lesser degree) anode and as a result exhibit different characteristics, which makes some more suitable than others for different applications.

What are the different types of Lithium Ion batteries?

According to Battery University, the most well-known types of lithium Ion batteries are:

Lithium Nickel Cobalt Aluminium (NCA)
  • 6V nominal
  • High specific energy – 200-260Wh/Kg
  • Average safety characteristics (Typically 150°C)
Lithium Nickel Manganese Cobalt Oxide (NMC)
  • Cell voltage – 3.6V nominal
  • High specific energy – 150-220Wh/Kg
  • Good safety characteristics (Typically 210°C)
 Lithium Iron Phosphate (LiFePO4)
  • Cell voltage – 3.2V nominal
  • Moderate specific energy – 90 – 120Wh/Kg
  • Excellent safety characteristics (Typically 270°C)

Why use LiFePO4 for Lead Acid replacement applications?

  • Safest form of Lithium Ion when considering temperature and abuse such as overcharge/discharge, short circuit and penetration
  • High thermal runaway point
  • Similar voltage to SLA (3.2V per cell = 12.8V)
  • Good all round performance making it flexible for many applications
  • Environmentally friendly, phosphate is not hazardous and so is friendly both to the environment and health.
  • Slow capacity loss – meaning they can sit for longer without requiring re-fresh charge.
  • High cycle life
  • Cost effective

Why is LiFePO4 safer than other Lithium battery types?

The LiFePO4 batteries are the safest type of lithium batteries.

Phosphate based technology possesses superior thermal and chemical stability which provides better safety characteristics than those of Lithium-ion technology made with other cathode materials. Lithium phosphate cells are incombustible in the event of mishandling during charge or discharge, they are more stable under overcharge or short circuit conditions and they can withstand high temperatures. LifePO4 has a very high thermal runaway temperature when compared to the other types at approximately 270oC as compared to as low as 150oC.

LiFePO4  is also more chemically robust when compared to other variants.

Why is IEC62619 certification so important?

Most reputable manufactures will have IEC62133 and / or UL1642 (now unified) for their Lithium cells. These tests are for “lithium cells and for batteries made from them for portable applications”.

The test and subsequent certification ensures safety of the cells (and batteries if tested) in conditions such as

  • Overcharge
  • Short circuit
  • Thermal abuse
  • Crushing
  • Forced discharge, etc.

Most reputable companies have undertaken the testing on their cells only and not the complete battery system.

BMPRO Invicta batteries are tested not just at the cell level, but also as the complete battery system, via certification according to the international standard IEC62619 – “lithium cells and batteries for industrial applications”. This extra step tests the cells put together into a system along with an internal Battery Management System, BMS.

Some of the safety aspects tested under IEC62619 include:

  • Assembly of cells into packs
  • Short circuit propagation (between cells)
  • BMS protection against
  • Over charge – Voltage and Current
  • Over temperature
  • Short circuit
  • Impact
  • Thermal abuse
  • Annual factory audit – to ensure consistency.

Does a BMPRO Invicta Lithium need to be installed in a special location?

No, they can be installed in any rotation and in the same location as your current Lead Acid. However, please note that the BMPRO Invcita Lithium range is NOT suitable for under bonnet applications.

How does the battery cope with Mechanical/Physical Damage?

Under the IEC and UN38.3 the batteries and cells undergo a range of mechanical abuse testing including Impact, Drop and Vibration testing, in order to pass the test the battery must not leak, vent, disassemble, rupture or ignite.

Do I charge  Lithium Battery differently to Lead Acid?

Difference in charging profiles

A charging profile is a reference to the way voltage and current vary during a full charge of a battery, and it does differ depending on the type of battery, because they are functionally dissimilar and constructed in different ways. For example, a fully charged lead acid battery will have a voltage of around 12.6-12.7V, whereas a LiFePO4 battery has voltage around 13.3-13.4V at full charge. At 20% capacity, a lead acid battery will have a voltage around 11.8V, whereas a lithium battery will hold its voltage at approximately 13V. 

Faster charging

Without getting too technical, the LiFePO4 battery has a much smaller voltage tolerance and, because of that, the ‘trickle’ charge of the deep-cycle battery does not apply. And that means a LiFePO4 battery can be charged faster while minimising the risk of overcharging.

Why multistage charger?

In discharge cycle, or when powering a load, a chemical reaction takes place that causes electrons to flow between the positive and negative electrodes via the battery electrolyte.

A charger reverses that chemical reaction, thus, recharging the battery. A typical charging voltage for a 12V battery varies between 12.9V and 14.4V. While a constant voltage and current will charge a battery quickly, it’s considerably better for a deep-cycle battery’s health if a ‘trickle’ charge is used over a longer period of time. Multi-stage chargers are considered best for this purpose.

Charging Lithium batteries

LiFePO4 batteries operate a little differently but an appropriate charge is also best for maximum battery life. Generally speaking, a constant current (only really restricted by the charger output) will flow until the battery reaches 90-95% of its state of charge (SOC). Once that point is reached, the current will reduce, while the voltage will do the opposite, rising to a cut off voltage of a theoretical 16.8V (but, in reality, is usually around 14.6V).

We recommend using BMPRO battery chargers with lithium charging profile for BMPRO Invicta batteries.

My Lithium battery has a BMS in it. If my BMS cuts out due to low voltage, will a standard battery management system “Wake up my battery” so it starts charging again?

No, you need a Lithium compatible battery management system like the BP35HA or J35D that sends out a “wake up” pulse to tell the BMS to turn back on for charge.

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15 thoughts on “Lithium Batteries FAQ”

    1. Olga kustova

      Hi Peter,
      Current model of BatteryCheck is not capable of handling lithium batteries. However, the new model, BatteryCheckPRO, which will be available later on this year, is designed specially for Lithium batteries and high current applications. We recommend to subscribe to our monthly newsletter to get the update on when it’s available.

  1. Can you connect your Lithium batteries in Parallel? It seems other major brands don’t recommend it as the Internal BMS could switch off on one battery and damage another and overall balance is thrown out ask well. What do you advise with this?

    1. Olga kustova

      Hi Scott,

      Yes the BMPRO Invicta Lithium batteries are okay to parallel and have been tested accordingly. BMPRO Invicta Lithium batteries are capable of being installed in parallel with up to 4 batteries.
      Firstly when setting up the system ensure that all batteries have been individually fully charged and have an Open Circuit Voltage (this is the measure of energy potential between the positive and negative) after being rested (no on charge for at least 1 hour) and with no loads connected within 0.2V of each other. Secondly ensure you using wiring that can carry higher amperage. Remember by paralleling the batteries you have kept the nominal voltage the same at 12V but increased the Ahr capacity and therefore the discharge and charge will be higher. Good wiring practice also means drop a fuse in on the anode (positive) side. Keep the length of the wiring between the batteries consistent as if you have one or two cables longer than others it changes the resistance within the “pack” of batteries. Double check all positives are connected together and all negatives the same – do not under any circumstances reverse the polarity and never series a parallel bank of batteries.
      Lastly, every three months ensure the new pack is fully recharged and remember that if you need to replace one battery in the pack than you will need to replace all batteries.
      Safe travels,
      12V Guru.

  2. I have a Jayco Adventurer May 2018 model with 2 x 120ah AGM batteries & bmpro control system. Can these batteries be replaced with lithium ion batteries without major changes to existing installed equipment?

    1. hi l have a slide on with currently 2 120 ah agm batterys with a c teck 12v 25 a lead acid batterie charger what the best battery in your range to replace 1 or both regard bruce

  3. We have a BMPro Genius Model 30-35 battery management system and 3×100 amp agm batteries. Are any of your Lithium batteries compatilble with that management system? We want to replace our existing batteries with Lithium.

  4. Hi, I have an off grid solar/battery system operating at 48v. My current set of SLA 2 volt batteries are in imminent need of replacement.
    I want to use LiFePo4 batteries. The best value for money seems to be 130ah 12v battery packs. It is claimed that they can be connected in series up to 48v for charging, however my understanding is that the internal BMS of these batteries will open circuit the battery once full charge is reached. If so then as I understand it the battery bank would be disconnected from the load (48v inverter) which would make them unusable.
    I suspect that I would have to use 48v lifepo4 batteries which would cost around 3 to 4 times the price for a comparable sized battery set
    Also, would I have to ensure that the maximum battery voltage is never attained? because if the battery goes open circuit this would also disconnect the load wouldn’t it?
    Are these 12v lifepo4 batteries designed for uses where they are charged and then used as separate operations?
    Maybe my only option is to buy an expensive 48v pack designed for a house supply.
    Your thoughts and advice would be greatly appreciated.
    Thanks
    Glenn

    1. Olga kustova

      Hi Glenn,

      We have addressed your question to Ryan Hammond, the supplier of Invicta lithium batteries, Sealed Performance Batteries, and here is his answer:
      We don’t recommend utilising 4 x 12V batteries in series for residential home storage applications for the following reasons:
      1. With individual batteries, each battery has its own BMS, but they do not communicate to each other, which means over time with high cycling they will get out of balance and one battery will end up not getting a full charge which will reduce the overall capacity of the system. The way around this is to regularly fully charge each battery individually, which would then require q 12V charger.
      2. With off grid applications, there is no grid to back up power, so if there is no sun for an extended period of time and the batteries run to their protection mode, then again you will need a 12V charger to wake those nits up that have don into protection mode.

      The Batteries won’t go into open circuit on a full charge providing the charge profile is set correctly and they are balanced. Price wise, when compared to low cost 12V100AH online, a good quality 48V battery pack will cost approx. 2x.

      So although it is possible to utilise 4 x 12V batteries in a 48V system its not something we recommend and given it is a residential home in which power is critical, its worth spending the extra to get something which is suited to the application so we would recommend a 48V battery pack. We do have a couple of options:

      1. Our Spectrum 2.4kWh (48V50Ah) module (19”Rack mount). These can be paralleled to increase storage requirement and will communicate to approved inverters, which solves any low voltage issue.
      2. 48V75Ah battery. These are in a standard N200 case and we sell them into golf carts. Can be paralleled to increase capacity.

  5. Hi Batterycheckpro can that give an accurate reading of 3 100ah batteries in parallel or do I need 3 Batterycheckpros? Thanks

    1. Olga kustova

      Hi Pat,
      Yes, you can use your BatteryCheckPRO with a battery bank with batteries installed in parallel. Esure that all negative connections on the batteries go through the BatteryCheck. Please note, the BatteryCheck will monitor and report on the whole system as one energy source. The BatteryCheck cannot monitor individual batteries in the bank.

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