Since I started researching converting my own van back in 2018 and after completing my first build in 2019 and now starting a second one in 2020, there is a constant debate about just about every feature of the build: which van is the best choice, which insulation works best, whether to have your solar panels in series or parallel, gas vs. diesel, whether Rachel should have gotten off the plane for Ross, etc. A huge area of debate? What type of batteries you should use in your electrical system.
In Van #1 I opted for AGM batteries; specifically I chose these AGM Deep Cycle batteries. Two 12v batteries, 100 amp hours each, bringing me a total of 200 amp hours for less than $400.
After living with the Deep Cell batteries for a year in the first van, I opted for this Lithium battery for the second time around. One 12v battery, 100 amp hours, for $800.
Wait, you paid twice as much for half the amp hours???
I’m not going to get into the deep science behind the difference between the two batteries because I am not an engineer and I don’t want to give people the wrong information that could potentially be dangerous. However, if you are interested in a more in-depth explanation, this website does an absolutely amazing job of breaking down the math and science. I will also give a real-life example of my experience with the two batteries. Basically one of the largest differences between AGM and Lithium is that Lithium can be run all the way down to 0% and AGM really shouldn’t be drawn past 50% before it starts to permanently damage the battery. This means that hypothetically one 100Ah Lithium battery provides the same power as a 200Ah AGM battery, since it can only be pulled 50% (50% of 200 is 100 in case you REALLY need me to break it down). This means that you can run that Lithium battery all the way down and not have to worry about monitoring it or getting it charged again without damaging it. Additionally, if you’re concerned about space and weight, one lithium battery would be much more space efficient than two AGM batteries.
Also, just like with any other kind of battery, there is a finite lifespan for them. Traditionally, Lithium batteries can get 2,000-4,000 full charges/discharges out of them while an AGM battery may only get 400-1,500 depending on the capacity of the battery. I’m about to throw some math at you again, so be prepared. If you go through one full battery charge/discharge a day by charging phones, using your lights, etc., one AGM battery will last 400 cycles, or a little more than a year (1.095 years if we’re being exact). That same battery in Lithium form will last 2,000 charges/cycles which is approximately 5.479 years. So even though the Lithium can cost four times as much as an AGM battery, you get five times the efficiency.
There are a lot of other factors that come into play between the two batteries (usable energy, weight, discharge capacity, etc.) but you get the point.
TL;DR – Lithium batteries are much more efficient and cost-effective than AGM batteries but DAMN they are expensive.
With a setup like mine that didn’t require a ton of electrical power, one $800 battery at 100Ah was painful, but worth it for my second build. This would be a much larger upfront financial investment if you had to have 200 or 300Ah. However, your build is totally up to you! I will say that I’ve had the AGM batteries for the last year and as long as I get adequate sunshine to charge my panels/batteries every day, I don’t have any problems with them, except one time when I ran them down past 50% after a series of cloudy days. Luckily my charge controller is a smart battery monitor and once it sensed the batteries were dangerously low, it shut down my whole system to protect the batteries. This was annoying as I didn’t have any electricity until the next morning when my panels could charge again, but not the end of the world. I plan on using my AGM batteries as long as possible and eventually upgrading to the Lithium batteries when the time comes (and when I have the $$$).