For those of us that work in the field a lot, keeping all our devices charged is required. Luckily solar power systems have become inexpensive enough and flexible enough to easily mount on vehicles. As charging technology keeps changing, so do the charging technologies and connectors. Everything is compatible, so adapters can be used when you have a mix of old and new devices.
I’ve written other docs on power and charging issues while field mapping for more detail. This is a short tech doc on solar charging based on real world experience.
It used to be much easier to charge devices off of a 12VDC battery. Charging was slow though, so the urge for faster charging and more voltage and current was a wish list item. At one point a few years ago I could charge a laptop with a 60W charger, it just took hours. I often just let it charge all night while I was sleeping, knowing I could recharge the truck battery when the sun came out.
Older chargers may only put out enough power to charge a laptop that is turned off. If you want to work on your laptop while charging, you need more power. I found even with a 90W charger I had this problem. If you are just web surfing or doing email, power requirements are lower. Computationally intensive tasks require more power. I’m often compiling software, and with a 90W charger charging blinks on and off the entire time which gets irritating.
Chargers that plug into your vehicles hardwired cigarette lighter socket are common, and have the advantage of being able to charge off your vehicle when it’s running. These are usually a power brick with a male plug on both ends. I recently had the experience of this type of socket melting with the higher power needs of my laptop. Course then I had no way to charge anything unless it supported USB charging… Luckily it was the last day of the field mapping trip. Most campers have cigarette sockets for DC devices. I replaced all of mine with PD3.1 USB sockets that fit the same hole size.
Or you can use an adapter with USB outputs. Older chargers were power limited, and even with a 90W charger I had issues charging my laptop. It would only charge when turned off, so if I wanted to work, I was on laptop battery power.
Another issue I discovered was that some of the after market cigarette panel mount sockets for RVs use really small gauge wire. I had to rewire my old one with heavier gauge wire to handle even a 90W charge.
There are unfortunately several type of USB connectors. The original form factor is USB-A, which is the wide slot in most desktops and many laptops. Then there was the smaller USB connector shaped like a trapezoid. Most older phones and tablets used this connector. Then USB-C came around, so now we don’t have to pay attention to the proper orientation to plug in the cable. Adapters can be used between the various connectors with functionality limited to the older device.
Laptops used barrel connectors until USB started to be used for charging instead of just a communication cable. Not all laptops will charge off a USB cable, but it’s getting more common. Another issue is that not all USB cables can handle the higher power requirements. You want a USB cable that can handle 100W, these days cables that support PD3.1 can handle 240W.
Many of the after market chargers support both Quick Charge (QC), with a USB-A connector, and Power Delivery (PD) with a USB-C connector. Most devices that charge off a USB-C support PD, QC is limited to devices with a Qualcomm chipset. And many devices support using either. The nice part is you can get a full charge in a few hours, or a quick partial charge in under an hour.
PD is a standard used by multiple manufacturers, and is only supported by USB-C. This can output up to 20VDC 60W (@3A), decreasing the time it takes to charge a device. PD 3.0 can provide enough power to charge and use my older laptop. I’ve replaced most of the panel mounted cigarette sockets in my camper with PD3.1 USB sockets.
This is a newer standard for faster charging, and yet more power. Chargers that support PD 3.1 are not yet widely available. These up the power output to 20VDC-240W (@5A), and you’ll need a USB cable that supports 240W.
QC is a Qualcomm feature for fast charging. It uses a USB-A connector. This is supported by any device using a Qualcomm chipset, for example Samsung devices.
QC 4.0 is compatible with PD, so will work with any device. I haven’t yet seen any QC 4.0 chargers yet, but I’m sure that will change.
After reviewing the power requirements for many of the current higher performance laptops, I noticed a big change. The main power draw on a laptop is the graphics device (GPU), and many of the newer ones need more than 100W of power to run at full efficiency. My old laptop was high performance in it’s day… Some wanted over 300! Since PD3.1 supports up to 240W, it should be possible to charge and work on a modern laptop up to that limit, but it appears most of the current more powerful laptops don’t offer charging via USB-C anymore, and can only be powered via the barrel connector and an AC power supply. Older or less powerful laptops may charge off PD3.0 if they have support for USB charging.
Some manufacturers specify that USB charging only works with the device off. Or they’ll mention degrading performance when trying to work on the laptop while charging, which most of us do.
All of the Intel and AMD CPUs have integrated graphics support, which uses much less power than the higher performance AMD and Nvidia graphics. Course less power usually means less screen resolution, limited to 1900 x 1200 or less. That’s fine for most uses, but I work a lot with satellite imagery when mapping, so need the higher resolution. It makes a difference when trying to decide if that blob in the image is a building, or a big rock…
If you want higher resolution, you pay for it with more power consumption, which of course is the problem if you are running off a solar power system. The Nvidia GeoForce RTX 5060 is the last graphics device to use less than 200W, it only needs 145W. My old laptop with a GeoForce RTX 4050 needs 35W. Many of the current higher performance laptops, Dells, Macs, etc… have much higher power requirements, so anything with an Nvidia RTX 5070Ti, 5080, 5090, etc… probably can’t run off a 12VDC battery without an inverter or step-up transformer. Most cheap AC inverters are not very power efficient, so not a good option.
Both AMD and Intel make CPUs that are focused on mobile devices and have better power management than the desktop versions. The AMD CPUs are more power efficient than the Intel ones but with slightly lower performance.
It turns out that with a 350W solar system and two 105AH batteries, if you run Starlink, an older laptop, and a few mobile devices, over two weeks the batteries you slowly loose power. Course I also run a DC fridge, and it was summer, so a big power drain. The batteries never got fully topped off, and this was in the summer! Course I’m probably a heavier user of DC power when camping than most people.
I think after 3 weeks I’d be looking for shore power to top the batteries off, or take a few days of little to no devices usage. On driving days, I’ll charge everything off my running truck.
My old laptop has an Intel i9-12900 CPU and an Nvidia GeoForce 4050 GPU. Using a USB monitor that supports PD3.1, I made a few real world tests.
The new laptop has an AMD 370HX, Nvidia GeoForce RTX 5070.
This is where little details get interesting. The Nvidia GeoForce 5070Ti pushes the power needs beyond what USB charging will support. The combination of the AMD CPU and the Nvidia 5070 is under the 100W limit, so runs fine using PD3.1. PD3.0 only supports 3A, so can’t be used. I’m also adding a step up transformer to 20V @5A like I did for Starlink, and run the laptop off the barrel connector.