Skip to Content

Choosing a Solar Battery Bank for a DIY Camper Van Conversion

Lithium batteries or AGM batteries? While there is no ‘one-size-fits-all’ answer to this, choosing a solar battery bank for your camper can be a daunting task. We’ve just switched over from AGM to Lithium (LiFePO4) Batteries for our battery bank. Here’s why we made our choice.

Quick note before we get started.  This is just one part of an overarching “How to Install a DIY Camper Van Electrical System” series.  If you’ve just stumbled on this article directly without seeing that, there are likely some things we’ve already covered.  If you want to check out that step by step guide, you can do that here:

Also, we have interactive solar wiring diagrams that are a complete, A to Z solution for teaching you exactly what parts go where, what size wires to use, fuse size recommendations, wire lug sizes, and all kind of other stuff to help save you time and frustration.  You can check that out here:

Switching from AGM to Lithium Batteries

The two most popular types of solar battery banks are AGM and Lithium. While flooded lead acid batteries are also an option, we aren’t going to talk about them today because of their many flaws (need to be vented, keeping up with chemistry, water levels, etc.).

When we originally installed our solar setup in our campervan, we put in Trojan AGM batteries. While we did want Lithium back then, there just wasn’t an easy, readily available drop-in battery for lithium (that we knew of). Now, however, the lithium battery industry has made huge strides and has produced a wide array of options that are easy replacements for AGM batteries. Alas, we have chosen to upgrade our battery bank from 700 amp hours of AGM to 600 amp hours of Lithium.

AGM to Lithium Batteries

Battery Capacity AGM vs Lithium

Now wait a minute, how are we upgrading if we are going from 700AH to 600AH?

AGM batteries don’t like to be drained past 50% of their capacity, otherwise it will significantly decrease the lifespan of the battery. In essence, our 700AH of AGM was effectively 350AH. Lithium, on the other hand, can be discharged 100% and not affect the lifespan of the battery, making it a true 600AH of usable battery capacity.

For the sake of easy math in this post, we’re  going to compare 200AH of usable battery capacity. That is, 2 x 100AH Battle Born LiFePO4 batteries versus 4 x 100AH Trojan AGM batteries. And while there are many, many brands out there of each type of battery, we’ve chosen these two brands because they are a) top of the line in their respective categories and b) the ones we have had personal experience with.

A Case for Lithium Batteries: Weight Savings

Battle Born LiFePO4 batteries are a direct drop-in replacement for AGM batteries, so they are very easy to install and get going. Let’s talk about some of the major pros of Lithium over AGM.

The first and most heavily weighing (pun intended) on everyone’s mind when building a camper van is weight. A 100AH Battle Born lithium battery weighs in at 29 pounds, for a total of 58 pounds for a 200AH lithium batterybank. Compare that to AGM, which weighs a whopping 69 pounds each, making the total battery bank weigh in at 276 pounds. 58 pounds versus 276 pounds. That’s a huge difference!

The Cost of AGM vs Lithium Battery Bank

The biggest drawback of a lithium battery bank for your solar setup is the upfront cost. 200AH of Battle Born LiFePO4 batteries will set you back $1,900. The Trojan AGM batteries with a bank of 4 batteries for a usable bank of 200AH costs about $1,152. So choosing AGM over Lithium will save you $748. That’s a pretty big savings, right?

Well, not so fast…

Sure, the upfront cost of lithium batteries is a major investment. But let’s talk about long-term costs and replacement costs.

Lifespan of Lithium Batteries

Battle Born lithium batteries are designed to last 3,000 to 5,000 cycles. For this example, we are going to use the worst case scenario of 3,000 cycles. A ‘cycle’ is when a battery is drained, then recharged. Again, for the sake of the example, we will say a cycle is one day (use your batteries all night, then let them charge up during the day when the sun comes up). Denver gets an average of 300 days of sunshine per year, so in Denver, we would expect this battery bank to last 10 years at full capacity.

After that initial 10 years (3,000 cycles), the battery is still expected to hold 75% of its capacity, meaning that you would still have 150AH usable battery bank.

Lifespan of AGM Batteries

Trojan AGM batteries are designed to last 1,000 cycles. But, according to Trojan’s website, they consider their battery to be bad once it reaches 50% of it’s capacity. Comparing that to Battle Born’s 75% capacity isn’t exactly comparing apples to apples. Instead, we will take this graph (from Trojan) and adjust it based on how long the AGM batteries will last until they reach 75%, or 150AH usable battery capacity.

Based on this graph, that would mean that the AGM batteries will reach 75% capacity at around 525 cycles. Using our Denver example, that will last 1 year and 9 months. And that does coincide with the generally accepted lifespan of AGM batteries lasting around 3 years to 50% capacity.

Now that you know what type of batteries you are going to use in your DIY Camper van, now is a great time to head to the next lesson and learn how many solar panels you’ll need to recharge your batteries.  Check that out here:

Everything that you are learning here is put to use in our FREE Interactive Solar Wiring Diagrams.  If you haven’t yet, check them out as they are a complete solution for a camper van electrical system.  Check them out here:

Remember, this is just one part of a full camper van electrical educational series.  To see all of the individual guides, click here:

Finally, If you found this guide helpful, It’d truly mean the world to us if you’d share it with somebody who can use it, pin it to pinterest for later reference, or share it to a facebook group when somebody has a question about this subject.  Click the bubble in the lower right corner to subscribe to be notified of future updates and as always, leave any questions you’ve got in the comments below.


Wednesday 19th of October 2022

In your diagram I can see that you have 6 lithium batteries in parallel with the positive lead at one end and the negative lead at the other. Is this how I should charge a larger lithium bank or would balance charging them be even better? Or would balance charging a lithium bank end up compromising the internal BMS of each individual cell?

Nate Yarbrough

Friday 21st of October 2022

The way I have shown in the diagram is indeed what I recommend even for larger lithium banks. If more than 6 batteries are needed, though... I'd recommend investigating larger batteries instead as paralleling more than 6 batteries gets cumbersome from a wiring standpoint.

Keith Perrin

Sunday 28th of August 2022

Nate, our boat has a domestic battery bank consisting of 4x110 Ah AGM batteries. This is a pretty typical Narrowboat setup. Weight really doesn’t matter on a boat weighing over 12 tons and initial cost is traditionally a big factor for narrowboaters.

But, a popular trend today is to add a single, say, 100 Ah LiFePo4 battery with a suitable BMS to the bank. The idea is that the LiFePo4 battery does all the heavy lifting, discharging to close to its 100 Ah limit before the AGM batteries start to discharge at all. The LiFePo4 gets to go through multiple charge/discharge cycles while the AGM batteries remain close to full charge all the time

This is a relatively new idea, so if you read 4 articles you get 5 opinions :(

I’m interested in any insight you might have.


Sunday 10th of April 2022

Hi, can you help me design my solar setup for my house, i am consuming 12kwh / day, i dont know how many solar panels i need and how many batteries to store enough energy for it?


Sunday 6th of March 2022

Super newbie question: regarding using the air conditioner, would that really affect the battery capacity needed -- since I'd only be running it when the sun is out? I'm wondering if I really need to be accurate when entering Minutes Used Per Day for the air conditioner in the spreadsheet. Awesome spreadsheet btw. Thank you for creating and sharing!


Wednesday 4th of August 2021

Such a useful resource. Thanks for making it free it really helps to give an idea of where to start and bookmark for later when actually doing the next phase