It’s a conversation we have on almost a daily basis about battery technology on social media channels and by people we meet:
Them: What battery do you guys have in there to power your stuff?
Us: We have a lithium battery.
Them: Oh, I heard they are good.. but expensive, complicated and I also heard they can explode etc! :O
Us: … Do you have 10 minutes for an explanation?

And on it goes.

Old information…

There seems to be a lot of misinformation and confusion about LFP batteries that gets bounced around in discussions at local camp sites and on online forums.

Most of the ideas are partly right, or were correct, but are no longer relevant with new technological developments.

For example, lithium iron phosphate batteries (LiFePO4 aka LFP), the ones people use in van dwellings and off grid applications, DO NOT explode into a fire ball if something shorts out or goes wrong!

Lithium-ion polymer batteries, like what many smart phones, laptop computer and or electric bicycles use, are the culprits!

So, we figured that we’d write up this basic article about why WE chose to use a LFP battery as the “house” battery to power all our appliances inside our home on wheels.

Hopefully it helps you make an informed decision before you take the plunge to either build a new battery system, or upgrade your current system.

Disclaimer:

A note before we go further: We are NOT qualified electrical engineers and we make NO claims otherwise. This article is written by and for regular folk who have a basic understanding of DC electronics and batteries.

If you are looking for a highly technical guide, comparison and examination of battery technology then you will want to search elsewhere.

And remember: Always be safe and smart when working with any form of electricity, even if it is low voltage DC.

Why LFP was our final choice for our home on wheels:

After six months of research and fact finding, we established that LFP batteries have several main benefits compared to Sealed Lead Acid (SLA) / Absorbent Glass Mat (AGM) deep cycle batteries which are commonly used in most recreational vehicles, caravans and campervans.

The information in this article is also available as a video on our YouTube channel for those who prefer to watch/listen than read:

Energy density, weight and space

The main reason LFP is such a great option is due to energy density and deeper discharge levels. The results in a battery that weighs less and takes up less space, and provided more usable power throughout its state of charge (SoC).

For example, our LFP battery (12v / 200Ah) is ~32kg and 361 (L) x 256 (H) x 224 (W) mm. As LFP can be safely and regularly discharged down to 20% SoC, there is ~160Ah of available power to be used as needed on a daily basis. Most LFP batteries will also tolerate the occasional discharge to 10% SoC if required, although it isn’t recommended to do it frequently.

In comparison, a 12v 200Ah AGM battery is ~60kg and 550 (L) x 300 (H) x 260 (W) mm. As AGM can only be safely discharged down to 50% SoC, it means there is only ~100Ah of power available to be used. 

If we want to try to match the LFP’s 160Ah figure, we would need to have 2 x 160Ah AGM batteries. This would take up even more space and weight.

Considering that we have a small space for battery storage, are very careful of our build weight, and that our estimated power consumption budget was 60-80Ah per day, LFP quickly became an attractive option – despite the price.

Charge cycles

Most quality LFP batteries are rated to 2000+ cycles, compared to 200-300 of a AGM lead acid battery.

This means that a LFP battery will generally last almost ten times longer than a AGM lead acid battery commonly used in RVs and motorhomes.

Not only does this reduce battery waste, but it also means that, despite the higher upfront cost, a quality LFP battery will generally be more cost effective over time.

This is especially the case for full-time off-grid use where the storage batteries are being charges/discharged every day.

Charge / discharge capabilities

Due to the technology and chemistry of LFP batteries, they are capable of being charged/discharged very rapidly.

This is really handy when you have a large solar PV array, high powered DC-DC (alternator) charger, or high powered inverter providing electricity to demanding appliances.

Partial charge / discharge

LFP batteries are also far more tolerant of partial charge/discharge than AGM batteries. An example of why this is beneficial is during times of poor weather when you may not have access to a AC hook up (shore power) or aren’t driving much for the DC-DC charger.

If you are only getting limited charge from the solar panels each day, you may end up with a battery that doesn’t receive a full charge each day for days or even weeks at a time.

This type of partial charge/discharge usually causes excessive wear to a standard deep cycle AGM battery, but it isn’t a problem with a LFP battery provided that it isn’t fully discharged and kept below 20% SoC (remember, 10% is the critical level).

Steady voltage

Another really nice thing about LFP batteries is that they hold the voltage steady until they are almost completely discharged, unlike all other lead acid batteries. So Peukert’s law doesn’t apply to LFP! We suggest clicking that link to learn more, as it veers into electrical engineering technical specificity that we honestly would rather avoid getting bogged down with.

The downsides of LFP

Ok, so if you have stuck with us until now you get the idea that we love LFP technology and are happy with our system.

But nothing is 100% perfect or suited to everyone’s needs and/or budget.

LFP is expensive (upfront) and more difficult to source

The primary barrier to widespread adoption of LFP for van dwellings and other off grid application has to be the significantly higher upfront (but not long term) cost and local availability.

We paid $1,500 for our Winston 12v 200Ah LFP battery kit, which included pack strapping, copper cell bridges, cell monitor and a cell balancer, plus $300 for freight to have the kit sent to us from another state.

In comparison, we could have driven a few minutes to the nearest battery store and bought two decent quality 160Ah AGM batteries for around $700 all up.

While we do not regret the extra ~$1100 we spent on our LFP battery in the long run, we can not deny that it was an expensive hit to swallow at the time considering that we had already spent a significant amount of money on our almost-completed van conversion project.

As mentioned above, the upfront cost does balance out over time as LFP batteries generally have a significantly longer usable lifespan compared to AGM, so the cost per Ah balances out over time. This is something to keep in mind.

You’ll need LFP compatible charging equipment

In addition to the extra cost of a LFP battery, there’s also the cost of needing to buy higher quality solar MPPT or DC-DC chargers that feature LFP friendly or user customisable settings to suit the different charging profile and voltage of a LFP battery.

We have a mixture of Victron and Enerdrive equipment in our van; both having a good reputation for well designed, functional and durable products that are also compatible with all battery types, including LFP. These products were not cheap to buy, but like the LFP battery, we do not regret having the higher quality equipment powering and monitoring our battery system.

This can be an issue in particular for people who already have a AGM system that is a few years old. Not only will you need to spend a fair bit up front on the LFP battery, but there’s a high likelihood that you will need to also upgrade your solar charge controller and DC-DC (alternator) charger too.

You will probably have to DIY

One final issue with LFP, and this may or may not apply to you depending on your DIY ability, is the lack of mainstream support for LFP battery setups. Basically, if you choose to get a LFP battery and you don’t have a genuine expert in your area, be prepared to DIY the installation yourself and learn a bit about the technology.

Originally we wanted to have the battery installed and set up by an auto electrician, because we found it all a bit too complicated and we were flat out doing other components of the van conversion. But after contacting a number of local professionals, every single one of them had no training or knowledge about LFP batteries and how to best set them up.

In the end we spent some extra time talking to the distributor that we bought the kit from, as well as some people on dedicated solar power forums, and did the installation and configuration (including the cell balancing) on our own.

While we don’t regret that now, as it forced us to learn about and better understand our battery and electrical system, it was very stressful at the time and did mean we had no power in the van for our first two weeks on the road… So this is something to be wary of if you’re like us and are doing a DIY build within a short time-frame..

The final word…

LFP batteries best conventional batteries in almost every way. They are safe, space and energy efficient, and perfectly suited for off grid and mobile applications.

The main downside is the upfront cost of LFP, and the additional cost of high quality charging gear that is LFP compatible.

Obviously, for people with larger vehicle or very minimalist power requirements, such as trucks and buses, where weight and space isn’t quite as mission critical, the weight/space savings won’t be as valuable as they are for folk with smaller/lighter vehicles.

If you can afford it and find a supplier of good quality cells, we say: go for it!

What sort of battery system are you using or looking to install in your van or off-grid setup? Let us know your thoughts in the comments section below!

Want to see how our battery and solar system is set up in our Sprinter van? Have a look at our tour video and see for yourself: