The battery is the heart of the van

Without the battery, the van won’t have light, heat, cooking facilities, a water pump, or any of the other things that turn it into a useful place to hang out.

We chose to use a Lithium Ferric Phosphate (LiFePO4) battery. Lithium batteries can take a charge much faster than lead-acid batteries. They also don’t mind being left in a state of partial discharge, and they can be discharged to around 20% capacity without impacting their service life. 

700AH lithium iron phosphate battery

Our system came from Balqon in California. It also incorporates a pretty basic battery management system to prevent it from being overcharged or drained too much. Unfortunately, although Balqon’s prices are good, I can’t recommend using them. They are used to dealing with commercial customers. They do not answer the phone or respond to email. Their customer service is non-existent. I wrote more about my experiences on the Sprinter forum.

I’d be tempted to look at cells from a manufacturer like CALB. Remember – each cell is only 3.2 volts, so you need four in series for a 12v system. Four of the ones I linked to will provide 180 amp hours. Buying eight will give you 360 amp hours, which is probably a good starting point for most people.

Lead-acid versus Lithium

Lead-acid batteries don’t like being discharged beyond 50% of their capacity. They also get upset if they are left at less than 100% charge for more than a day. They weigh a lot more than lithium batteries too.

When you take into account the added usable capacity of a lithium battery, a lithium solution will weigh about one quarter as much as an equivalent capacity lead-acid battery bank. My neighbor Ken helped me place our battery into the box he designed and built. It was easy enough for two people to carry. Each one of the four equivalent lead acid batteries would have been too heavy to easily pick up. That’s a massive space and weight saving for use in a vehicle.

Two people can lift this battery into place. Notice there's a wooden cover over the terminals in case we drop something metal on to them.

So what are the downsides to lithium? One concern is that they tend to blow up. Boeing had problems with the batteries on their Dreamliner planes. Radio Control plane enthusiasts store their batteries in ammo cans and charge them very, very carefully to prevent them from getting too hot and going into “thermal overrun” (also known as “bursting into flames”). Luckily, LiFePO4 uses a different chemistry to those volatile batteries. It is thermally stable to over 500 degrees Fahrenheit, which is plenty for us.

Lithium batteries also don’t like being charged up in sub-zero temperatures. For us that means keeping the battery inside the living area of the van, and making sure that there’s warmth in the van even if we aren’t using it. Luckily, because the battery only takes up ¼ the size of a lead-acid equivalent, we’re not losing much space inside.

Another big downside is cost. The up-front cost of lithium is about 2x to 4x the equivalent cost of a lead-acid system of the same usable capacity. However, the service life of lithium battery packs is at least 10 years if they are well treated, compared to 3-5 years for lead-acid.

So, if you are prepared to start with a relatively bare-bones lithium system as opposed to one of the overpriced drop-in lead-acid replacement systems, and if you have the extra money to invest in the system up-front, then lithium at least breaks even with and may even cost less per usable amp-hour than lead-acid in the long run.

Update: We wrote some guides for choosing battery types and sizing your battery.

10 Replies to “The battery is the heart of the van”

    1. The Airtronic D2 diesel heater I installed can be set to maintain a certain temperature. Most of the time though, that’s not an issue. The van heats up really quickly when you run the heater. In the Pacific North West we don’t have too many sub-zero days either.

  1. I am loving your site! In the midst of my own Sprinter conversion in Seattle and stumbled upon you using many of the components I was leaning towards for Solar/Electric- good to see them functioning in a system.

    You did link to a CALB CA180FI 180Ah LiFePo4 Cell, which, with 8, would result in a ~380Ah 12v storage unit for ~$2k? What was the cost of the battery system unit you from Balqon?

    1. The Balqon system was ~ $4500 for 700Ah. You can find it on their web site. However, like I mentioned in the post, I wouldn’t buy from Balqon. They just aren’t set up for consumer purchases and their customer service is non-existent. I would really recommend working with a company who know their products and can explain them to you. Having someone you can turn to for advice and assistance with your setup is important.

  2. I totally agree!!! Still in the dreaming stage myself, but this site distills a LOT of information that would otherwise take many hours trolling the forums.

  3. When you put in the battery box, you cut a hole in the floor so that the batteries rested on the metal floor of the van. (I think that’s what you did; you mention cutting the hole in the wood floor where the battery box will sit.) Why not put the batteries on the finished floor? Thanks for doing this website.

    1. Hi James.

      We wanted to be able to remove the floor without moving the battery box. Turns out, that wasn’t such a big issue. If I was doing this again I’d put the battery box on top of the floor.

  4. This website is amazing! Thank you for documenting all this…I wanted to get the same battery as yours, can you tell me what kind and where you bought it?
    Thanks again!

    1. Hey Lyle, like it says in this post, the battery is from Balqon. We would not buy from them again because their customer service is terrible. It’s also possible that they’ve subsequently gone out of business. The battery cells are made by Winston. You may be able to find a different U.S. supplier.

      I suggest you check out our post on lithium versus lead acid batteries because it contains a list of people who sell lithium systems. There are lots of options out there.

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