SPRINTER VAN SOLAR PANEL & ELECTRICAL SYSTEM PLANNING TIPS
Figuring out your Sprinter Van solar power and electrical needs is one of the most complicated parts of designing your Sprinter Van. While there are calculators online that you can use to determine your solar needs, there are so many nuances and considerations that those calculators aren’t all that accurate.
I’m now on my second Sprinter Van. In my first Sprinter, I had 180 watts of solar and a 375 amp hour battery bank. It was totally adequate for short trips in the sun, but during the winter when there was a lack of sun and I was running the heater, I had to pay much greater attention to my usage.
In my new Sprinter Van, I wanted a much beefier solar panel system that could accommodate full-time travel and all of the things that I need to charge while working from the van. I drew on the expertise of Outside Van, my Sprinter Van conversion company, to design a custom Zamp solar panel and electrical system based on my specific needs.
In this blog post, I go over the basic things to consider for your sprinter van solar panel and electrical system plan. The goal is to give you a better understanding of your electrical needs and help you determine how much solar and battery power you should install in your Sprinter Van.
What are you going to charge in your Sprinter Van?
The first thing you need to do when figuring out your solar panel needs is to make a list of everything you need to charge and run in your Sprinter Van. As a full-time blogger, I have quite a few electronics I need to charge in the van, like computers and cameras. I also have a fridge, LED lights, an induction stove, two fans, two e-bikes, a lightbar and a few other things that get charged from time to time. When making your list, you should try to include at least an estimate of the amps each device draws, as well as wattage for devices that run off 110 outlet power). These numbers should be easy to find via google, on the device charger, or in your instruction manuals for each device:
- 15” MacBook Pro – 1.5 amps / 87 watts
- Sony Camera – 1 amp / 100 watts
- Isotherm Fridge – 4 amps (average) – Outside Van finds that the total amp hour draw is equal to the setting number it’s on. So if you have the fridge set to 4, it will be pulling 4 amps per hour. The fridge pulls more when the compressor is on and when it’s hot outside and less when the compressor is off and in the winter.
- Induction Stove – 110 amps (max) – Induction stoves require a robust power system to operate. Most induction cooktops are 1300-1800 watts when used at high or boiling temp and drawing up to 110 amps. When you simmer, you are using 700-900 watts.
- 2 Specialized Turbo Levo Bikes – 2.5 amps each
- 2 Max Fanns – 3 amps each
- LED Lights – ~ 4 amps (max)
- Webasto Dual Top EVO – ~3 amps (max)
If I add all of that up, I have a total of 24.5 amps. That means that if everything is plugged in/running all at once, I would be drawing approximately 24.5 amps per hour or 588 amps per day. However, the only thing that really runs 24 hours a day in the van is the fridge. Everything else is plugged in or running periodically for a few hours a day at most.
So let’s estimate that the fridge draws 100 amps per day and a liberal guess for everything else is 75 amps per day for a total estimate of 175 amps per day. Remember, it’s better to overestimate your needs than to underestimate. So now we have something to start with when considering how big of a battery bank you need.
Take a tour of my new Sprinter Van!
AGM vs Lithium batteries
There’s a lot of talk about lithium ion batteries lately and a lot of companies are moving towards them. That said, a quick search of the Sprinter forum will show you that there is a lot of varying opinions about whether AGM or Lithium batteries are better. I went the Old Faithful route and chose to install AGM batteries in my Sprinter Van. So if lithium seems to be the hot new thing, why did I choose AGM batteries for my Sprinter? Here are the pros and cons of AGM batteries vs Lithium batteries for Sprinter Vans.
AGM Battery Pros
- Durability / Take abuse well
- Handle vibration and shock
- Better in cold weather and can charge in freezing conditions
- Upfront costs are cheaper
- Can mount outside
AGM Battery Cons
- Can only use 50% of total capacity – if you have 660 amps (the capacity of my system), you have 330 usable amps before you need to start charging. If they get discharged below 50% than they can get damaged. Repeated discharging below 50% will eventually require that the batteries be replaced,
Lithium Battery Pros
- Have a longer lifetime
- Can use 80% of total capacity – if you have 660 amps, you have 528 usable amps before you need to start charging. This means with Lithium, you can get away with a smaller capacity battery bank because you get more out of each battery.
Lithium Battery Cons
- Very expensive upfront costs
- Can’t handle the cold and must go inside your Sprinter Van
So that’s the general list of arguments of AGMs vs Lithium batteries, but what were MY main reasons for choosing AGM?
- The upfront cost – you can’t deny the upfront cost of Lithium is higher. Over time, if your AGMs get damaged and need to be replaced, then the lifetime costs of AGMs could exceed the Lithiums…but maybe not. In addition, lithium technology is still being sorted out. In a few years, chances are lithium batteries will be a lot cheaper and some of their kinks will be worked out. Given the large upfront costs, I didn’t want to be part of this experimental phase.
- Sizing up my battery bank – When I first got my last Sprinter Van, I didn’t get a thorough rundown of how the whole system worked or how to read the voltage meter. All of a sudden, stuff just stopped working and as it turned out I had a loose wire from my solar panels to my batteries. The AGM batteries got damaged, and I eventually had to replace all three batteries. I learned a lesson that if you want to maintain the lifetime of your AGM batteries, you need to pay close attention to make sure your voltage meter isn’t dropping below 12.0 (50%). If it is, then you need to plug in or find some sun quick. Now in my new Sprinter Van, I have a much better understanding of how the whole thing works, and I chose to size up my battery bank so it would be more than enough for my needs. Because I sized up, my batteries shouldn’t ever really drop below 50% due to the draw on the system.
- How they handle cold weather – I am based in Salt Lake City in the winter, where are temperatures are often below freezing. During winter I use my Sprinter Van on the weekend, but it also sits in my driveway for a few weeks at a time here and there. During those times, I empty my water tanks and don’t worry about running the heater. If I chose Lithium batteries, then I would probably want to run my heater at least on low 24/7 in the winter in order to prevent the Lithium batteries from getting damaged, which would be a total pain and eat up my diesel in my gas tank. And in the case that the Lithium batteries do get damaged from the cold, you’re looking at a much higher replacement cost.
Whichever you choose, I think the key is finding a quality company with a good warranty policy. Also even across AGM batteries, you’ll find varying lifestpans. The brand of AGM batteries in my Sprinter Van are called Northstar and are rated for 1000 charge cycles.
Consider the conditions you will be using your van in when determining whether you should go with AGM or Lithium batteries.
What size battery bank do you need in your Sprinter Van?
Let’s go back to that number I estimated for my daily draw of 175 amps. Multiply that by 2 = 350 amp hours. A 350 amp hour battery bank would allow you to stay off the grid with zero input from the sun for 24 hours, drawing 175 amp hours before the AGM batteries reach 50% full and need to be charged.
My 12 volt AGM battery bank (brand is Northstar) is 660 amp hours, which means I have 330 amp hours of usable power. That means that if I’m drawing 175 amps a day, I can run all the things I need to in my van for 42 straight hours (a conservative estimate) with no input before the AGM batteries reach 50% full and need to be charged.
While we overestimated our draw based on the devices I’m running in the van, this still doesn’t sound like a lot for an off-grid van with a 660 amp hour battery bank. This is where we need to talk about how the batteries get charged that makes them last longer, which I’ll get to in just a minute.
Mounting AGM Batteries Inside or Outside
First off, there seems to be a lot of questions about whether or not it is safe to mount AGM batteries inside the van. AGM batteries are different than normal lead-acid batteries in that AGM batteries are sealed. This means they don’t off-gas and are safe to store inside the van.
Why mount AMG batteries inside your van if they are ok outside?
Technically you can mount AGM batteries outside, but given the complexity of the system, wiring, and the cost, it’s a safer bet to mount them inside. That’s what my conversion company, Outside Van, suggested, and I decided to follow their expert advice.
As far as mounting location, you want the majority of your weight over the axles versus behind the rear axle or under the hood of your Sprinter Van. In my case, the batteries are located in the “garage” underneath the bed in a closed compartment over the axle. When you are mounting your batteries, you need to think about what happens if you crash your van. The batteries weigh hundreds of pounds and wherever they are mounted, it needs to be super secure or it could end up being very dangerous. Outside Van is approved by the National Highway Traffic Safety Administration because of the high emphasis they place on safety and has built custom safety-approved battery mounting brackets that will hold the batteries in place in a worst-case scenario.
My batteries are in the cabinet on the right. I can access the batteries from the top or the electrical panel from the front. The outside of the cabinet has 2 outlets where plug in our e-bikes, as well as 2 USB outlets.
Ways to charge your Sprinter Van’s battery bank
Hopefully by now, you have an idea of the type of battery and size of your bank that you want in your Sprinter Van. Now we’re going to talk about how you charge that battery bank. There are three main ways you can charge your battery bank.
- Shore power – no matter how many solar panels you have on the roof, you still want the ability to plug-in. It’s never a bad idea to top of your batteries off using shore power when the opportunity arises. Or say you get caught in a blizzard for a few days and you’re running low on power due to your heater and lack of sun. It’s a nice safety net to be able to plug-in at a friend’s house.
- Solar panels – if you have a fridge and other appliances that have a constant draw on your batteries, having solar panels allows you to stay off the grid longer. The solar panels harness the power from the sun, and then a wire runs to the batteries where the power is stored. My solar panels are made by Bend-based Zamp solar, the same company that made the solar panels on my first Sprinter Van. I’ll talk more about how to determine how much solar power to have in the next section.
- Your engine alternator – no matter what you do, I recommend hooking up your batteries to your Sprinter’s engine alternator. By doing so, your batteries are constantly charging while you are driving and if you’ve been on the road for a while, you’re going to arrive at camp with a full charge no matter if it’s sunny or not. The Sprinter factory alternator provides up to about 100 amps/hour when you are driving. When your house batteries are properly isolated, when van starts, your engine’s starting battery is the priority. The alternator will charge both at once, but more goes to the car battery until that’s topped off, and then it shifts more power to the house batteries.
What sized solar panels do you need on your Sprinter Van?
In my last Sprinter Van, I had 180 watts of Zamp Solar panels on my roof. The panels worked great in sunny conditions, but you have to remember that it’s not always going to be sunny, and in winter, direct sunlight is even more limited. On cloudy, cold winter days when I was running my heater, I was often nervous about the status of my batteries, which is an unnerving feeling when you start to approach that 50% battery level.
In my new van, I wanted to stick with Zamp solar, but I wanted to scale up in the number of solar panels on my roof. Zamp solar panels are made in the US (unlike than most solar panels that are made in China), which means they have excellent customer support. Thir panels also have an anti-reflective coating on them which helps maximize absorption. All of their panels can be purchased separately or as part of a kit which includes everything you need to install and monitor them.
Zamp Solar 80 watt kit
For my system, my goal was to NEVER have to worry about plugging in or running low on power. As a result, I ended up going with a 445-watt system. There is a single 125-watt panel in the front and four 80 watt panels that run along each side of the van. This sized solar panel system left a bit of room to still hang out on the roof, and Zamp’s 80-watt panels are skinny enough that they can fit on the side of a centered roof vent. The panels are paired with Zamp’s solar controller which shows me the current status of my batteries and how much energy is coming into the system via the solar panels.
So far this 445-watt solar panel setup, combined with the alternator, has worked perfectly. Outside Van estimated that in ideal sunny conditions, my solar panels can pull up to 30 amps per hour. In two months we haven’t had to plug-in a single time, and I haven’t seen my battery voltage drop below 12.4 (which is about 75% full). With the summer heat, there have been many nights that we’ve left both fans running all night, and we haven’t been all that careful about the lights. This initial period in my new van has led me to believe that the system is probably a little bigger than necessary, but overall I feel like Outside Van and I nailed it for my needs and lifestyle and in winter it will be just right.
Do you need an inverter?
An inverter in your Sprinter van takes the power from the batteries and converts it into AC power that comes out of your 110 wall outlets. If you have anything that needs to plugged in, or a microwave or an induction stove, you need an inverter.
I have a Magnum Energy 2000 watt 12-volt pure-sine inverter (the voltage on the inverter must match the voltage of your battery bank).
To determine how powerful of an inverter you need, you need to look at the wattage requirements of your devices. Things like an induction stove, power tools, a microwave, or blender that have a high draw require an inverter that has a high wattage rating, like mine. If all you are doing is charging one computer at a time and maybe running the occasional appliance, you can look for something in the 600-1200 watt range.
Keep in mind that a 2000 watt inverter can handle a total of 2000 watts max at any given time. This means if you have an induction stove that draws 1300 and an AC unit that draws 1500, you cannot run them simultaneously. But I can run my induction stove and charge my laptop at the same time. It’s all about being clued into your appliances and devices to make sure you aren’t misusing your system.
What about modified sine vs pure sine? The other thing to pay attention to in inverters in pure-sine vs modified sine. Modified sine inverters are less expensive, but they are less efficient and certain appliances like an induction stove won’t run properly on a modified sine inverter.
I hope this helps answer a lot of basic questions you having about setting up your Sprinter Van with solar power and a battery system that will keep you and your stuff running during your travels.
Got questions about Sprinter Van solar panels or electrical systems, leave a comment below!
Thank you to Zamp Solar for providing the solar panels for my Sprinter Van. As always, all words and opinions are my own.