Without going into too much detail, RV electrical systems are simple (ish) to understand, but can be annoyingly complicated to deal with. The biggest thing you need to know is that you are generating and storing your own power, and that the amount of power you can generate and store is limited.*
Conclusion: RVers – especially those like us who boondock (camp without hookups) nearly all the time – need to be super-conscious of electrical usage.
So… how do we keep our laptops charged? (Especially because we’re pretty heavy users.)
We’re both Mac users, so enter the HyperMac! The MacBook (Amy) and MacBook Pro (Jay) batteries have about 70 watt-hours of capacity. Nice, but not nice if you have to recharge off of a limited supply of juice, especially useless 12v juice. The HyperMac is a perfect solution. Our new (purchased lightly used, actually) 150 watt-hour HyperMac provides about 2.5x battery life for either of us while offering intelligent voltage switching for the MacBook Pro, which operates at either 16.5v normally, or 18.5v during intensive tasks. One other awesome feature is that the HyperMac not only keeps the computer alive, but can also charge the computer’s battery. Fun! We also have a HyperMac cigarette lighter charger, so we can charge our computers while driving as well.
After using the HyperMac for a few weeks we are thrilled with it. Its USB port can charge our Pre Plus, keeping our computers and internet going for a long while. The only downsides are the relatively long charge time (about 4 hours from fully drained to fully charged) and its somewhat inaccurate battery level monitors. Also, the 150 watt-hour HyperMac’s size isn’t ideal for someone wanting to tote it around, but is fine for us in an RV. I haven’t seen the smaller versions, so I can’t speak for their size.
Separately, here’s a shout out and thank you to our ADA readers. You know who you are!
posted by jayhorowitz
*Second biggest thing to know: Without an inverter / with the generator off, your outlets are 12v, which is somewhat useless.
Our Take on Freedom: Escaping the 9-to-5 Before 25 
Wouldn’t built-in solar panels be an easy solution? Especially for you guys as you travel through the hot-lands.
Ah, solar. It’s complicated and pretty simple at the same time, so here’s a pretty long answer. First off, we’re getting solar panels at the end of this week, so… yes. On the other hand, the solar panels charge our 12v coach battery, which doesn’t help us charge our computers. But it could if we get an inverter to change 12v power to 120v. The inverter would probably only be used when the solar panels are putting out close to their ~7 amp max, as otherwise we’re drawing down on our 12v battery instead of using part of the solar panel output to power our electronics.
If the panels are putting out charge and we’re not using the RV battery, they’ll be charging our RV battery, which is something we independently need if we don’t want to drive or use our generator much. (Now we have two ways to charge the RV battery: driving (the alternator charges the battery) or using our generator, which also allows us to use A/C and the microwave. We need to ‘exercise’ our generator anyway, but would prefer to not have to use it much.)
Hope that made some sense! I’ll probably be posting on solar sometime early next week, so you got a free preview đŸ™‚
Like any power source, it’s useless if you have to invert, convert or transform, as the line loss can be quite taxing. So, in essence, if you’re starting with 12 volts, you should make every effort to place 12 volt loads on your system. That way you’ll maximize your precious energy. There are 12 volt battery chargers you can get for your computers. If you have additional computer batteries you can place those on charge while you’re driving or using solar panels. Inverting from 12 to 120 only to bring that voltage back down to 18 burns a lot of energy. Try to think in 12 volts and invert only when absolutely necessary.
The problem with a 12v charger for my MacBook Pro is that (a) the few that are available have been a bit unstable, and (b) I need intelligent voltage switching. The MBP operates at either 16.5v normally, or 18.5v during intensive tasks.
Also, I’ve heard that 12v products tend to be of lesser quality than 120v products. What has your experience been with that?
I think we’ll mostly run the inverter when our battery is close to full and we’re still getting power from the solar panels. I figure that at peak output the 7 amps from the panels is reduced to ~6.8 amps with ~3% line loss. The inverter then kills another 10%, so we’re down to 6.1 amps. My computer pulls around 5 amps (after conversion to 12v) at its max, so I should be okay. But am I missing something?
Thanks for your help!
Jay
Hey Jay,
Doesn’t sound like you’re missing anything. You’re using just what you generate, and it seems like you have it all worked out. I prefer a system that generates energy and stores it for a complete cycle of usage over a 24 hour period. That’s why I want to invert as little as possible. As far as 12 volt products go, I’m really going to be using lighting the most, and that’s all going to be LED, which is amazingly bright and runs very cool. The water pump is 12 volts as well, and those are designed for that. And, my razor gets charged from the inverter for a brief period and runs on a battery for several days. So, that’s my 12 volt story. I don’t really have any more needs, other than my computer, which I’m hoping to charge via the 12 volt system. I’m researching those chargers now, and those are what I hope to use for my van once it’s complete. I have a pc laptop.
I didn’t know you had multiple ADA’S who were reading your blog, though I have been touting your blog to my co-workers.
It was kind of a random thing to include in your post on laptop charging, any reason?
Seems like you guys are having an amazing time. Keep it up!
nice post