Lithium battery chargers

This post has been originally published in May 2019 and has been updated in September 2021.

When we wrote this blog post initially, lithium batteries for caravans were the way of the future.  Today, they are the battery of choice for many adventurers. However, the question stays:

Do you need a lithium battery charger to charge your battery?

Lithium batteries have grabbed the attention of the RV market in recent years. Their power-to-weight ratio is much better than equivalent lead acid / deep-cycle / AGM / Gel Cell batteries, and they have a higher discharge rate than those batteries as well. But, given that lithium iron phosphate (LiFePO4) batteries have very different characteristics and composition to other batteries, it raises the question as to whether they require different battery chargers. To answer that, it helps to have an understanding of how lithium batteries function.


One of the major advantages of lithium batteries is that they can deliver a very large current down to about 20% of their capacity without any damage, and with 3% or less voltage drop. That might not sound impressive until you compare it with a deep-cycle/AGM battery. The most effective way of getting a good battery life out of those batteries is to never let them discharge below 50% capacity. Doing that, a typical lifespan of about 500 – 600 charge/discharge cycles can be expected.

However, a LiFePO4 battery will deliver well over 2000 cycles, as shown in a real life experiment held at the BMPRO headquarters. And whilst lithium batteries will only have a 3% voltage drop for much of the discharge cycle, all deep cycle/AGM batteries suffer from a constant voltage drop whilst discharging; the typical range being 12.75-11.4 volts.

Like most battery types, lithium batteries have individual cells (four, in this case), which are rated at 3.2V each for a total output of 12.8V. The problem is that once an individual cell is charged, it turns off the current and, since all the cells are wired in series, they then cease charging. For this reason, any LiFePO4 battery should have its own inbuilt management system to ensure that all cells are charged equally.


So does all that change the way a lithium battery should be charged? And what does the charging profile of a LiFePO4 battery look like?

Battery charging profile

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. 

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.

Constant voltage, constant current or a trickle charge?

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 14.1V. 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.

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 14.7V).


The bottom line is that not all chargers are created equal and you need to ensure your charger, or the one you’re considering buying, such as BMPRO’s BatteryCharge range (from 4-25 Amp), includes a lithium charging profile.

Dedicated Lithium battery chargers will help ensure you maintain an economical battery life and get the best out of your lithium battery.

To learn more about lithium battery chargers, check our YouTube channel and visit BMPRO Lithium Battery Knowledge Centre.

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14 thoughts on “Lithium battery chargers”

  1. kevin munns 0409684683

    first.electricity and me do not go together, i just don’t understand it..i have a 28ft traveller van model reseliance, about5yeas old, it has a retrifrigo 12v compression fridge,i have 3 large deep cycle bats and the bastard doesn’t freeze up.i don’t normally have the mains power connected whilst not in use,but when in a c/park i do.i have been thinking of getting 3 lithium bats from “itech world’,with built in management system, do you think this would help?…recently i has a sparky in to test things,he said the bats were flat,i then got another in and he said yhe bats were fully charged he then found the charger was switched off?????the van is now in the workshop trying to find a leak in the roof, what i think i need from you is,,the lithium bats as sold by ITECHWORLD, yes i know they cost about $900.00 EACH would they be ok for my needs.maybe you could recommend someone in WA that i could speak too..i also have a 2kva Honda virtually unused and about 18 months old..Kevin

    1. Olga kustova

      Hi Kevin,
      Lithium batteries will give you longer off grid, but the charger you have may not be lithium compatible. Please get back to us with more details of your setup and we’ll advise accordingly.

    1. Olga kustova

      Hi Norm,

      The function of the BMS built in the lithium batteries is to protect the cells from misuse, for example, low voltage.
      The charger used to charge any lithium battery needs to have a dedicated lithium profile to ensure longevity and safety of lithium battery. J35C has an inbuilt charger which does not have a lithium profile. You would need to upgrade to J35D.
      Check this post for more information:

  2. Hi,
    I have a redarc bms (15 I think) charger in my outfit charging 2 100 ah batteries.
    What charger would I need to replace the redarc charger to charge 2 100 ah lithium batteries, as my power consumption over the last couple of years has increased considerably?
    Thanking you in anticipation of your reply

  3. Hi Olga
    Have just received my new van it has a BatteryPlus35-11-HA system with a RV VIEW2 Monitor in it with AGM Batteries
    i am wanting to put a 300amp lithium battery in it And inverter to run my 240 of the grid
    What will i need to put on van to let me do this and how does the 35-11-HA know it charging a lithium
    Currently not certain what else is in it other than what i mentioned not sure monitor is working as does not show enough current draw when fridge and lights are working And where in Victoria can i purchase your products i live in Blind bight 3980

    1. Olga kustova

      Good afternoon Gerry,
      To be able to change your setup to Lithium from AGM you will need to plugin an OdysseyLink103 at the BP35-II-HA (if it was not installed in your caravan, it is available, for example, through Carac in Dandenong). You will then see all the information on your phone and can control lighting and change battery types at the touch of a button.

      If you are going to use inverters and high amp loads you will also need a BC300 shunt which is also compatible with your system, this will then show you exactly what you are using. Please see the links below on both products

  4. good day. pls i will like to know in Mopower, Sukam, Luminous inverter are compatible with lithium charger or i cani know the inverter that compatible

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