Lithium Batteries – what you need to know

If you’ve been thinking about a Lithium Battery, but were unsure, I’m hoping to provide some clarity on them and what you should think about before you buy. As a part of this process, I spoke to Dave from Revolution Power Australia, who specialise in Lithium batteries, and I learned a lot! Please note that I’m not an expert in this area, so I encourage you to do your own research.

Functionality

Lithium batteries offer improved functionality over their AGM and flooded alternatives in that they can be discharged to a higher level safely than their counterparts, providing more actual useable Amps. 

Most AGM battery manufacturers will not recommend discharging the battery below 50%, because the heat produced when charging them back up can damage the cells and plates, and even warp the batteries, which can significantly reduce the life of the battery.

Conversely, Lithium batteries can be safely discharged to a 100% Depth Of Discharge (DOD) (@10.5v), which provides more useable amps vs. a maximum 50% DOD for an AGM to maintain its cycle life. 

The team at Revolution Power sell their batteries based on useable Amp Hours (adhering to the Australian Standard of useable amps to 10.5v), rather than theoretical capacity, meaning you get exactly what you expect.

You can also anticipate 10x the cycle life compared to an AGM battery.  A Lithium battery cycled to 50% DOD can achieve 5,000 cycles vs. 500 cycles for an AGM battery.  This means that it is achievable for most users to obtain 10-12 years of life with a good quality Lithium Battery vs. 3-5 years with a good quality AGM. 

Cost

Lithium batteries cost more than AGM batteries to manufacture, and the price of Lithium is not coming down.  As Lithium is an Ore product and traded on the stock market along side gold, platinum and silver, all manufacturers will pay the market price. Essentially this means that the amount and quality used in batteries and the internals directly affects the production cost of the battery.  We are talking about things like the cell quality and rating, internal Battery Management System, and the actual useable capacity the battery has.   Unfortunately, most of these variables can only be evaluated after purchasing the battery, which makes choosing the right one very important, but also very difficult.

To better understand comparative costings, I’ve focused costings here on a 100AH capacity (as sold).  Lithium batteries at this capacity range in price from about $600.00 to about $1900.00.  AGM batteries of a similar size range from about $200.00 – $600.00.  So, a top-quality Lithium battery will cost you about 3-4 times the price of an equivalent AGM. 

I specifically asked the guys from Revolution about why there is such a disparity in Lithium batteries, and they provided some great info, which I’ve mentioned down in the important considerations section below.

Size

This is where Lithium batteries come into their own.  An equivalent (useable capacity) Lithium battery will take up ½ of the physical space of an AGM battery, which is great if you want to hide it somewhere.  Or alternatively, get double the power for the same space.

Comparing a Revolution Lithium battery to an AGM (100Ah)

Lithium 100Ah (100 Ah useable) – 305x165x215mm .

Lithium 60Ah Slimline (60AH useable) – 291x106x223 mm

AGM 100Ah (50Ah useable) – 307x169x210mm

Weight

Another big plus when it comes to Lithium is the weight saving.  A 105 Ah AGM battery will weigh approximately 28KG vs. 7.7KG for a 60Ah Lithium Battery, which both have very similar useable capacities.  Similarly, a 165Ah AGM will weigh 53.6 KG, where a 100Ah Lithium (with more useable power) weighs 12.8KG.

Even if you replaced a 105AH AGM with a 100AH Lithium, you would save 16KG of weight, and get double the useable capacity.  If you replaced a 165AH AGM with a 100AH Lithium, you’d save 40KG of weight, and still gain almost 20% in usable capacity.

Quick Re-charge

Aside from the weight savings, Lithium batteries also have significantly quicker re-charge vs. AGM batteries.  The low resistance in the Lithium cells allow the battery to accept the full output from the charger.  With a 30 Amp charger, a 100Ah Lithium battery can be fully charged from flat to full in just over 3 hours vs. 10+ for a 100Ah AGM battery.  This is a huge advantage with solar in that every amp that your solar panels produce are going directly into the battery.

Important Considerations before you buy

While in the long run, Lithium batteries outdo AGM batteries in pretty much every way (including whole of life cost), they are an investment up front, and there are a few more things you need to consider before you buy one.

Not all Lithium Batteries are the same

If you go online, you’ll see over $1,000.00 difference in price between some Lithium batteries that are claiming to be equivalent, based on the AH capacity.  While it is immediately tempting to go for the cheaper option, you need to do a little more homework before you buy. There are several videos going around demonstrating EBAY batteries labeled as 135Ah batteries only having 49Ah capacity to 10.5v, so you need to be diligent with your research.

Below are few more key things you need to consider when choosing between Lithium options.

C-Value

The C-rate is a measure of the charge/discharge rate of a battery over the period of 1 hour.  For a 100Ah battery a 1C rating means that you can draw 100amps continuously for 60 minutes.  For a .5C 100Ah battery, you can draw 50amps from the battery in an hour safely, and a .2C 100ah battery 20amps for 60 minutes. 

A 1C battery isn’t necessarily better than a .5C battery, it just has different parameters, which limit the battery’s capability/usage and the BMS’ (internal battery management system) specifications for maximum continuous discharge. 

To not stress the cells and achieve the longest cycle life for the battery, a 1C rated cell x 100Ah battery should contain a 100A continuous draw BMS.  A .5C cell x 100Ah battery should contain a 50A continuous draw BMS.  This means that the 100AH capacity can only be drawn safely over 2 hours for a .5C cell and that the maximum draw you can place safely on the battery is 50A. 

They key in relation to the C value here is to make sure that your hourly current draw won’t exceed the max discharge rate of the battery you choose.  If it does, you can damage the battery, and it likely won’t be covered by any warranty because you’ve chosen to use it in a manner that exceeds the manufacturers specifications.

BMS mismatch

The guys from Revolution tell me that they have seen some batteries on the market use a BMS (this is the batterys’ internal management system) designed to take up to 100A, but cells in the battery are only .5C, which means they are only designed for a 50A BMS.  This means that the battery is stressing the cells to deliver the current, which will result in reduced performance and life over time.

Apparently, the only way to tell whether the BMS is matched to the rating of the cells in the battery is to check the output voltage of the charged battery with a Multi-meter, and then apply the maximum load stated by the battery manufacturer.  Start with 50A, and the voltage should stay constant.  Up the draw to 100A and then see if the voltage drops.  If it stays the same, the BMS is matched to the cells.  If it drops, then you’ve got a mismatch.

Charging

Lithium batteries need to be charged by a charger that has a Lithium charging profile.  So, if you have an older system, you’ll need to check with the manufacturer whether they have a Lithium profile, or otherwise you’ll need to change your in-vehicle charger to be able to use it. This is critical because you don’t want to ruin the battery by not charging it properly or get a reduction in performance from such an expensive battery.

Know your realistic current draw

Before you buy a battery, whether Lithium or not, you probably need to consider your maximum current draw, based on all the things you could actually run off the system.  A 100AH 1C battery can run a 1000W invertor (divide wattage by 10 to get the amps required to run the invertor) using 1000W of power.  But if using the 1000W load on the invertor, you are putting the maximum load on your battery, so if you are running anything else concurrently, then you’ll need bigger batteries.  If you don’t forecast your current draw properly, your battery may appear to handle the higher draw, but in reality you will cook the cells of the battery as it struggles to safely deliver the power required, and this may mean you kill your battery much sooner than you should.

Summary

Lithium batteries stack up on all fronts, as long as you match the capacity of the battery to your needs, and can spare the upfront investment required.  There is no need to throw your existing batteries out just yet, but perhaps it is worth putting a few extra $ away for when the current ones give up the ghost.  It will last longer, weigh less, and give you more output than other types.

A big thanks to the team at Revolution power Australia who were very helpful in answering all of my questions. If you have a question for them, or would like more information, check out their website at https://www.revolutionpoweraustralia.com.au/ or call them on 1300 303 498.

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Comments 25

  1. Great article thanks, I have two lithium’s one powering my trolling motor in my boat and one powering my fridge in a ark box set up and both are brilliant. I heard most 12 volt lithium batteries come from the same factory’s in China and then branded by the importers, if so why the price difference? The two I have are structurally identical apart from the branding.

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      Hi Ronald,
      Our understanding is that while they may come from the same factory, that doesn’t mean they are to the same spec. As the article discussed, one could have 1C cells which means you can draw 100Amps safely (if it is a 100Ah battery), and the other may have .5C cells, which means it can only draw 50Amps safely over an hour. Also, the internal Battery Management system may not be the same. There will definitely some which are the same, but given the $ involved, if you choose the wrong one it will cost you more in the long term. The real difference is not in the external part of the battery, but the internals, and only a multimeter can help confirm that! Good question…

  2. This review is the best I have ever seen, BIG Congratulations.
    I have been looking at lithium in my set up for almost as long as lithium batteries have been looked at as serious option.
    I have just not come across this amount of info as to how they fail, or the different rates of draw on a given C rate.
    And you make it almost simple.
    You have missed your vocations, congratulations well written!!!

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      Hi John,
      Thanks for the kind words. It takes time to put these articles together and it is really nice to see that people value the content. This is exactly why we wrote the article – because no-one else out there was trying to make sense of it!

      Aiden

  3. This is in my opinion absolute rubbish in as much as it us one sided in the perceived benefits over the traditional batteries.

    I am sick and tired of all of these write ups including those who think EV vehicles are the bees knees. I am yet to read any information on the recycling of these lithium batteries. This article has no mention whatsoever of this, neither do many others.
    Lithium batteries are dangerous to recycle (they can catch fire spontaneously) and from what I’ve researched there is maybe one or two in Australia that can reprocessed.
    Lithium is a heavily mined product so the environment suffers more greatly in its production. Lead acid batteries can be 100% recycled not so lithium. Just about every imaginable power tool today is lithium battery powered. Where or who recycles these and into what, or do they go to land fill?
    Maybe a through review from cradle to grave may be appropriate when writing such articles.

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      HI George, thanks for the comment. You are right in that there are questions about the environmental impact. We will ask the question of a few providers here and find out. As far as EV’s go, we are tracking that the battery is a key reason they are not as green as they are made out to be. Thanks for the ideas – we will endeavour to include a bit on sustainability too.

    2. Lithium is mined in Australia, yes. Umm, so is lead.
      Lithium batteries exploding/catching fire? Yes but only in the Li-ion ones in phones and cars, and that is very rare now. The LFP ones used in RVs are a different chemistry and are MUCH safer. During recycle, you can be certain that a recycler will know exactly how to avoid a fire in his recycle plant – it is his business to know.
      I agree Lithium battery recycling is in its infancy, and people are lazy and chuck their standard ever ready, energizer nicad, etc in their bins already. Lead acid car/RV batteries you can drop off free at municipal tips for recycling. Same will happen with LFP batteries when they become popularly aware. No difference. What can YOU do? Lobby your council/MP to get this started in your area

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  4. Hi Thanks for the article on Lithium Batteries which will become the norm once the initial price shock passes.

    There’s one very important item you missed which may not be applicable to the Revolution battery. I have a LifeP04 lithium battery that has a built in safety system circuit that shuts the battery down should the voltage drop below a preset level of approximately 11v.

    That’s great, however, I was not aware that the battery could NOT be restarted by either solar panels, or the vehicles Red Arc battery charger. The only source that can restart this lithium is connecting it to 240v (not possible if you’re in a remote location) OR by connecting it directly to 12v battery source, to ‘wake up’ the battery.

    You may wish to have a look at why or how this works should it also apply to the Revolution battery as the supplier provides all the technical bumpf on how grand they are, but not the restart essential must know this procedure weak link information. This may prevent someone being stuck somewhere with inoperative 12v appliances such as fridge, motorised legs, motorised pop top as in my case. I found out the hard way!

    I have made a 5m long 12v set of jumper leads to connect the car battery directly to the Anderson plug connection to my slide on camper.

    Once the battery comes to life, the Red Arc and or Solar panels can do their thing and recharge the ‘flat / depleted’ battery.

    regards,

    Wayne

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    2. Good informative peice.
      Have new 4×4 (2nd hand) keenly looking at lithium crank, axillary, and house battery, and spend 10 weeks out bush at a time, fridges lighting,etc having a generator handy sounds like a must

  5. Hi, I changed over to lithium 7 months ago in my van. I have two 140 ah batteries. I had installed a full victron management system with 700 amp solar on roof. A bit of a over kill. While using a app I can see what is happening with my usage If anyone is interested Solar -Sat gin gin QLD can answer any questions.

  6. Hi, why does everyone giving a review/comparison of AGM (etc) vs lithium batteries ALWAYS fail to mention the most important safety concerns regarding using Lithium batteries? Lithium batteries suffer from the potential to spontaneously ignite (burst into flames) or explode when any of the following conditions are met: Excessive rate of overcharging if the BMS system fails, internal cell collapse, accidental short circuit and also if severely undercharged! As an Industrial Chemist I find it absolutely misleading for such critical information to be (intentionally??) left out of such (extremely biased??) comparisons! Should anyone wish to challenge these comments I will gladly PUBLICLY debate them. I will also be very surprised if this post sees the light of day! Buyers beware and thoroughly do your homework and be fully understanding of all issues surrounding Lithium as well as all other batteries for that matter.

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      G’day Ian,
      Thanks for the post. Nothing has intentionally been left out here. I’d love to know more about the safety side of this, and it sounds like you are pretty knowledgeable here. The whole point of this was what to consider before you buy, so I’d love to include more about safety!

  7. I have heard that lithium does not like heat. Are they suitable under the bonnet as a second battery. I spend my summer in the Pilbara where 50c is the norm

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      I believe they work up to 80 deg C, this is definitely one to ask the guys at Revolution. I’d always keep it out of the engine bay personally…

  8. Hi all
    I note your Revolution experts believe that Lithium ‘is definitely not coming down’. I spoke to several trade retailers recently at Perth 4wd show who all say the same. However, I believe there is a real case for substantial price relief. Western Australia produces a large proportion of the world’s lithium where several new mines have now been either mothballed or closed (at least for the foreseeable future) due to an oversupply. Could your experts explain that? One told me that the ‘cell manufacturers’ are the problem…. if this is the case, could it possibly be a simple case of ‘gouging’? I genuinely suspect so. I would think the retail price of a quality Lithium battery could and should be no more than about 60% of what it is now.
    I look forward to your comments

  9. It is interesting to note that the people that appear to strongly be against lithium batts are so aggressive in how they have conveyed their points of view.
    I think that is a shame in that they likely have very valid points, however, aggression, is something that many of us as readers/contributors, just turns most of us off and not listen.
    Also interesting that nobody has written in to report an explosion due to lithium batteries being installed, despite, that many have installed them.

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      G’day John,
      Thanks for the contribution. I’m sure that these people don’t mean for their comments to come across that way, but I think we live in a time where people are very un-trusting and also where people are generally not happy with things, and I think that this sometimes leads people to react a bit strongly at times.

  10. Do you think if your just a weekend warrior, or just a fridge in the back of the car is worth spending the extra cash for a Lithium Battery, and not all people have a healthy bank account, By the way a very interesting article.

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      Hi Mark,
      Thanks for the comments. I think overall it should last longer, and cost less over the time it works, plus it is lighter and takes up less space. But as a weekend warrior, I’d wait until my current battery gives up the ghost before I ran out and bought one. And to be honest, if I didn’t have the cash, I’d keep buying AGM…

      Aiden

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