G'day and welcome to another battery master class, now in this video i'm going to talk about
lithium batteries and specifically lithium iron phosphate or lithium ferrous phosphate batteries
of course this is a huge topic so i'm going to try and condense it down and focus on
those bits and pieces that matter to people using batteries in the outdoor recreation side of things
like four wheel driving camping caravaning or even using them on boats in this video i'm going
to compare lithium ferrous phosphate batteries to other types of lithium batteries i'm going to
compare them to agm batteries plus i'm going to tell you how to get the most out of your lithium
iron phosphate battery and take care of them first let's do a really quick comparison of
an agm battery and a lithium iron phosphate battery of the same capacity these are both 120 amp hours
the agm battery is around 30 kilos
while the lithium is just 15. if you use both these batteries from a hundred percent down to
zero percent repeatedly you get about 300 cycles out of the agm but in those same conditions you'd
get 2 000 cycles out of the lithium ferrous phosphate if you're talking about recommended
use generally an agm is recommended to only use 50 of its overall capacity meaning you'd get about 60
amp hours out of this battery a lithium ferrous phosphate's recommended capacity is about 80
so you get 96 amp hours out of this lithium iron phosphate battery that's 60% more power and if
you did use those capacities you'd get about 800 cycles out of the agm and up to 4000 cycles with
the lithium they're both sealed and safe to use in your vehicle and they're both
built and tested to withstand vibrations but it's pretty clear why lithium iron phosphate batteries
are becoming so popular they offer what many consider to be the best balance between safety
power output and lightweight let's go into a little bit of background info on lithium batteries
lithium batteries come in all different shapes and sizes and all different chemistries you've got
cylindrical cells pouch cells prismatic cells and then you've got bigger batteries that are made up
of smaller cells together most of the batteries we're all familiar with fall under the umbrella
term of a lithium-ion battery that's ion not iron like a lithium iron phosphate battery under that
umbrella term of lithium-ion batteries you've got lithium-ion batteries with a liquid electrolyte
plus you've got lithium polymer batteries or LiPo batteries that use a gel type or polymer
electrolyte but they're both technically lithium ion batteries because that definition describes
how the battery works. Underneath that you've got all your different battery chemistries
which are achieved by adding different materials or metals into the battery the most common
batteries these days are lithium cobalt oxide lithium manganese oxide, lithium ferrous phosphate
and increasingly lithium titanate oxide plus there are actually variations on those major players
so you can get a lithium nickel cobalt aluminium oxide or a lithium nickel manganese cobalt oxide
adding each of these different metals changes the lithium battery that you get
adding one of these particular metals might increase capacity and make the battery lighter
but it could be at the expense of a battery that's safer and more resilient so adding a different
type of metal might make the battery safer but weigh slightly more and you've got to factor
into that the cost of some of these rarer metals plus the supply and demand cobalt and nickel are
both going up in price because so much of it is currently used for lithium battery production
lithium iron phosphate batteries work in a similar way to most other batteries including your
typical lead acid agm battery they have a positive electrode a negative electrode and an electrolyte
inside that allows the chemical reaction to happen it means you can store power and then release it
when you need it the name comes from the fact that the lithium atom is quite unstable and tends to
want to lose the single electron that it has in its outer shell so we're taking advantage of the
fact that the lithium ion loses the electron inside the battery we can then trap those two
parts in a state of readiness they're basically wanting to get back to their original position
the lithium ions have to go through the battery whereas the electrons go through the circuit
we can take advantage of that flow of electrons to release the power inside the battery
next let's take a look at the most commonly used different types of lithium chemistry
and compare them on a couple of key points as you can see here we've got lithium cobalt oxide
lithium manganese oxide, lithium nickel cobalt aluminium oxide, lithium nickel manganese cobalt
oxide, lithium titanate oxide and last but not least lithium ferrous phosphate the first two
battery chemistries are pretty commonly used for things like cameras where you need a high amount
of power in a small lightweight package the next two are being more commonly used these days in
electric vehicles as they offer a high power output and decent cycle life lithium titanate
oxide is a fairly recent addition and is gaining popularity because of its massively long life
but as you can see from this table it's clear why lithium-ion phosphate is so good for camping and
using in vehicles while the energy density isn't as high as some of the other battery types it's
not too far off and while lithium titanate offers the highest safety and the most number of cycles
you get quite low power in return the lithium iron phosphate battery though is a jack of all trades
it's safe has a good energy density and power output as well as a long life and high amount
of possible cycles when you're talking about small action cameras or lightweight electronics
it makes a lot of sense to use some of those other types of lithium battery chemistries
but when you're talking about a big battery that you're likely going to use in a vehicle
it doesn't make that much of a difference you're still getting really good power output
many more cycles but most importantly adding those heavier iron and phosphate materials
means you're getting a much safer battery let's now take that last column for lithium
iron phosphate and compare it to the currently most commonly used camping battery the AGM. Yes, a
lithium iron phosphate might cost three times more than a lead acid AGM but let me talk you through
how they compare over the life of a battery with an agm the further you discharge your battery the
less cycles you get discharging all the way to 0% would mean about 300 cycles conversely
discharging only the top 10% of the battery down to 90% full capacity may net you around 2 000 cycles
on the other hand a lithium iron phosphate battery can be discharged all the way to 0
and still get you around 2 000 cycles so rather than lasting less than a year or about 300 daily
cycles with an agm if you used your lithium iron phosphate from 100 down to 0 repeatedly it could
last up to five and a half years and if you did only use the top ten percent of the lithium iron
phosphate battery like we mentioned with an agm it would probably outlast your vehicle and possibly
even you lithium iron phosphate and agm batteries differ in a number of other important ways too
number one is that an agm battery is made up of six 2 volt cells for a 12 volt battery
lithium iron phosphate batteries can either be made of a number of small cylindrical cells
or prismatic cells like this these batteries use a prismatic cell there are four of these in series
to make that 12 volt nominal figure each cell is capable of a range between two and a half volts
and 3.65 volts which in 12 volt terms gives you a range of 10 to 14.6 volts perfect for use in your
vehicle another big difference between an agm and a lithium-ion phosphate battery is self-discharge
agm batteries prefer to be filled right up and then left on trickle charge to make the most of
the capacity it's almost the opposite with a lithium-ion phosphate battery they don't need
to be float or trickle-charged and they'll very happily sit at a low percentage in fact if you're
storing these batteries you should leave them at around 50 percent of course there are going to be
more differences between an agm and a lithium iron phosphate battery but those are the most important
for what we're talking about and just one final note on that you might see a lithium iron phosphate
battery advertised as a drop-in replacement for a lead-acid battery but they're probably
talking about the dimensions more than the use of the battery for example you would not want
to put a lithium iron phosphate battery in your engine bay because it would be way too hot one
major difference between an agm and a lithium iron phosphate battery that deserves its own heading
is the bms lithium iron phosphate batteries need a battery management system or bms that ensures
each of the cells is getting the same amount of charge they're all balanced they're all charging
and discharging correctly and that they're within those safe operating temperatures if you're using
a small individual lithium cell say in a phone or a digital camera then the charger or the device
itself would have built-in protections to look after the batteries batteries like these that
are made up of multiple prismatic cells have a bms built in so they're an all-in-one ready-to-go unit
but some batteries or battery banks do require an external bms the bms is hugely important
and I can't stress this enough the cells in a lithium battery are quite often capable of doing
much more output and input than the bms allows but the bms is there to protect them this 120 amp hour
lithium iron phosphate battery is capable of 100 amps charge 100 amps discharge and 160 amps peak
discharge if you're looking at 100 to 120 amp hour lithium battery that only allows 30 to 50 amps of
input and output there's a good chance the bms is the limiting factor it may be a lower quality or
lower rated unit and that could be to disguise a couple of things for example lower quality lower
output cells or the fact that the bms may not have all the functions it should and by limiting that
input charging current the batteries are never going to get hot enough to get damaged so why do
you need a temperature sensor at the end of the day though it's probably just cost cutting in
these kings batteries they have a high quality bms and you know that because the 120 amp hour allows
for 100 amps input output and the 200 amp lithium iron phosphate allows for 150 amps input output
and they have those critical functions that are necessary to keep these batteries safe and healthy
most importantly the bms in these batteries will prevent each cell going below two and a half volts
or above 3.65 volts they also have a short circuit and overload function plus temperature sensors
to prevent the battery from overheating or from charging in cold temperatures and to ensure the
bms is protected these battery cases are sealed with an ip65 rating and the batteries themselves
have to pass a vigorous vibration test the bms is why you couldn't use one of these lithium iron
phosphate batteries to start your vehicle for that you'd need a dedicated lithium jump starter an agm
battery is capable of emergency jump starting a vehicle so that's something to take into account
you can rely on a good bms to protect your battery from the extremes of temperature
and for charging and discharging but it's up to you to decide how much effort you want to put in
that aids in the longevity of a battery while a bms should prevent damage that your battery
sustains from being extreme temperatures you can help it out by keeping it out of those
extreme temperatures in the first place like all batteries lithium iron phosphate do not like heat
and while they're a lot better than other lithium ion chemistries it still helps to
keep them within a good range generally between about 5 degrees celsius and 50 degrees celsius
for lithium iron phosphate charging ideally you'd keep your battery temp below about 40 degrees in
one study the same cell when fully discharged and charged over and over at 15, 25 and 35 degrees was
able to perform about nine thousand seven thousand and four thousand five hundred cycles respectively
so keeping your battery temperature down can make a big difference at the other end of the scale
your lithium iron phosphate battery shouldn't be too cold charging a lithium-ion phosphate
battery below freezing or zero degrees celsius can actually cause irreparable damage now your bms
should prevent this but if you did force charge the battery it can actually cause the lithium
to plate the anode that increases resistance and permanently drops capacity of your battery
so if you're camping in the cold and your battery doesn't seem to be working or taking any charge
it could be that the bms has disconnected it to protect it lithium iron phosphate batteries should
discharge or run your appliances all the way down to around negative 10 degrees celsius but at that
point they will suffer a small amount of temporary capacity loss negative 10 degrees is pretty rare
here in Australia particularly where most of us go camping but if you do live in North America
or Europe it might be worth looking into heated lithium batteries these use a small heater to keep
the cells warm enough that they can be charged and discharged safely now that you've ensured
your battery's warm but not too warm you've got to decide how much of the actual percentage you
want to use now you can use these batteries all the way from 100 down to zero percent and that
will get you around 2 000 cycles if you decided to only use this battery from say 90 percent down
to 10 meaning you're using 80 or 96 amp hours of its overall capacity you could do it up to 4 000
times and if you wanted to be really safe and only use your battery between about 75 and 25
getting you around half the capacity you could use your battery 8 000 times and to tie in with
that point let's take a quick look at a table that compares the battery's state of charge percentage
with the battery voltage in this table you can see the individual cell voltage and the battery
voltage which is four of those cells in series as well as the charge percentage the whole range of
a lithium iron phosphate cell is between two and a half volts and 3.65 volts but have a look at the
battery charge percentage the difference between 99 fully charged and 100 fully charged is almost
a volt now take a look at the difference between 10 charge and 0 charge 2 volts the more often you
put your lithium iron phosphate battery into these sort of ranges the more damage you're going to do
long term so if you do want to get more than 2 000 cycles and a super long life out of your battery
avoid charging it all the way to 100 even 99 can make a big difference but ideally aim for
something like 90 to 10 that's going to give you plenty of daily capacity but also hugely extend
the life of the battery and the easiest way to do that is simply to use a dedicated lithium
iron phosphate charger or dc dc charger in your vehicle that's going to look after the battery
and make sure it's in tip-top condition finally let's talk about battery storage unlike an agm
that you should really charge completely full and then ideally leave on trickle charge if
you're planning to store it a lithium iron phosphate battery is better left at around 50
capacity ideally charge it up cycle it down then charge it up and let it sit at around 50 percent
lithium iron phosphate batteries have a very very low self-discharge so even if you pulled
your battery out after a couple of months it'd still likely be sitting around the same voltage
and like most batteries lithium iron phosphates prefer to be stored at a cooler temperature
somewhere between say 10 and 25 degrees celsius hopefully that's given you a pretty good idea
of the basics of the lithium iron phosphate battery there's plenty more i could talk about but i don't
want to overwhelm you too much now if you do want more information on 12-volt setups in full
drives or over landing vehicles make sure you check out my 12 volt dual battery master class
if you have any questions on lithium throw them in the comments below and i'll see you next time