Use computer while charging, or 'use' on battery?

b407driver

OK, so I know this sounds like a weird question, but I've seen info somewhere that I cannot now find. I am a photographer who will be boondocking for up to 7 days at a time, and am trying to develop my own set of 'best practices' before taking delivery.

Anyway, if I am remembering correctly, the basic gist was that if you are relying on solar for days on end, it was better to charge the computer while *not* using it, and use the computer only via its battery if possible.

Has anyone evaluated this, or ever heard anything about someone addressing it?

The other thing I'm curious about is charging camera batteries, as this can be a struggle for me to keep up after a good astro night (I sometimes go through 3+ LP-6 batteries in a night). I'm considering buying an after-market 6V charger, but am unsure if it's any more efficient that just using the inverter. 

Anyway, if anyone could shed me some light, I'd appreciate it! We're within a week of delivery!!!

-Jeff

DougH

On the question of how you charge the laptop and multiple camera batteries, I don't know that I've seen any DC based chargers you can clip onto the house battery bank to then charge up those Lithium packs.  My Fujifilm likes 8.4V / 0.6A for its packs, Nikons and Canons differ.  So while inefficient to use an inverter to convert to AC just to go back to an appropriate level DC current and voltage, you may have little choice. 

b407driver

I guess I was more referring to the computer (mac, in my case), side of things. IIRC, someone posited that energy was 'wasted' by both using and charging your computer at the same time, compared to using it on its battery, then charging it while not actually using it. I get that it would charge slower while using it, but it seems to me it went beyond that fact...

Sharon_is_SAM

I think this would be entirely dependent on how much you are able to recharge your TaB battery via solar.  On maximally sunny days when recharging is secure, use and charge your MAC and TaB battery at the same time.  If there was any question of not achieving a fully charged TaB battery, then run the MAC off the battery.  

Verna

If you use an inverter connected to your battery to charge the batteries, use only a Pure Sine Wave inverter to charge your computer. In a pinch, I have changed my laptop, while it was turned off, using a non-Pure Sine Wave inverter.  I feel much safer with the Pure Sine Wave. 

I do not know if you need a Pure Sine Wave inverter for your camera batteries. But if you buy a Pure Sine Wave inverter, you’ll use one on anything that needs to be plugged in while you are not connected to shore power. 

N7SHG_Ham

The only reason I can see for NOT using the laptop while charging is that takes more energy away from the house battery charging. The current used should be the same, it is just how you want to prioritize your solar use moment to moment. At the end of a week your energy usage going to the laptop should be the same regardless of on/off while charging.

klenger

I doubt that it would make any difference whether you use your computer while it is charging or after it is charged.  The bottom like is that the computer used power when in use.  If you want to cut your power use down, then don't use the computer, but that is obviously not an option.  Bottom line is that charging your computer most likely won't have that much impact on your total solar budget, unless your solar setup is on the too-small scale, in which case you really need more solar. 

Trailpixie

This question had me thinking for a while, and I have some ideas. The short answer is, unplug your laptop and work as long as possible from the computer's built-in lithium batteries. 

Laptops get hot. Hot things waste energy. charging hot things=bad. This could be a "zero-sum game" because you can waste heat energy with the onboard computer batteries or your you can waste heat energy with camper batteries. But, I think your lithium computer batteries are better able to cope with the high-power and high-heat consumption when you compare it to your camper's battery system. Then overnight charging your computer's batteries at a slower pace will be better for you camper's system. 

Of course when your laptop finally runs out of steam, then you need to plug it in. It would be nice if there were more DC  input options for laptops

Unplugging from AC power also puts the laptop into some lower power modes that are helpful for conserving power. It turns off unused processors and peripherals and decreases screen brightness. If you are familiar with your computer's advanced power settings, you can do this when you are plugged in too.

For native DC devices like computers, I wouldn't worry about pure sine wave inverters versus modified. In these cases you are going from DC to AC and then back to DC. The modified sine wave, which is square, just goes back to a flat DC circuit, so it doesn't matter. The issue becomes more about noise and you shouldn't see too much noise in a camper unless you are on the same circuit with a running fan, and even then it shouldn't be an issue when running through a good transformer with the capacitors they have.

As for charging camera batteries. This is another annoying DC to AC and back to DC problem (power lost to heat in this conversion). There are DC chargers for most camera batteries, and they work well. I use them in my car to keep charging batteries while I am on the go. I also use them in the camper. When I was driving cross country with my rooftop tent, I used my goal zero battery to charge batteries. I charged the goal zero with the car during the day and then charged the batteries on the GoalZero at night. I still carry the goal zero as a backup. It's a good little gadget. 

As for the solar side of the equation, all the standard calculations apply. I was looking at the charging brick for my high-end dell laptop. It's max power draw is 130 watts. That's a significant power consumption. In the simplest terms. One of my 100 watt solar panels in full sun runs approximately hour-for hour with my laptop (it probably doesn't draw the full 130 watts). I did some photo editing and writing on this laptop in my camper a few weeks ago and took my 100AH AGM  system down from 100% to 70% in about 6 hours (with lights and fan too).

My experience with the GoalZero suggests that the camera batteries are fairly negligible although some are more than 2000 mAH and that wouldn't seem negligible. That GoalZero is rated 14AH which is probably a bit optimistic. When I was charging all those batteries, I never ran it down more than a bar or two on its gauge. 

pthomas745

I have a Kill-a-watt and some time to waste, and I'll work on this later tonight.

pthomas745

The "results" are in.  It seems using a fully charged laptop would help conserve your trailer battery.

I have an Asus Zenbook that is about 7 years old.  It has a 13.3 inch screen, and a discrete graphics card.  An Intel i7 with 4 cores.  I ran the laptop using the discrete graphics, screen brightness 100%, Wifi connected.  Reading various internet discussions I discovered that most laptop power adapters are pretty simple.  Smaller screens, like my Asus, use a 65 watt adapter.  Larger screens will use a 90 watt adapter.  So, if you have a newer, more powerful laptop with a larger screen might want to kick up the wattage numbers by about 30 percent or so.

Measurements with a Kill-a-Watt P3.

Laptop plugged in, no programs running.  The laptop was using only 18 watts.

Laptop with only Lightroom running:  while loading images or moving through a catalog or simple editing, up to 32 watts for short periods.  With just a photo open in the Develop module, the Kill-a-Watt showed only 20 watts.

I left Lightroom running, opened up Firefox with about 6 windows, and ran a You Tube video of Bonnie Raitt singing "Its All Over Now, Baby Blue."  The laptop was using 25-30 watts.  I expected Bonnie Raitt would have moved the Kill-a-Watt even more, but apparently not.

The fully charged laptop in sleep mode and plugged in used only 3 watts.  I  unplugged the laptop and let the battery drain to 40 percent.  I closed all the programs and plugged it back in.

Laptop, charging, with no programs:  46 watts.

Laptop, charging,  Lightroom open: 49 watts.

I opened up Firefox and ran the video again, and the wattage remained 49 watts.

I closed everything out, put the laptop to sleep, and it is using 30 watts while charging.

I also tested a Canon battery charger (LC-E6) for my 7D Mk2.  On a battery that was about half discharged (two blinks, if you know how it works) the charger was drawing 9 watts.  After about a half hour, it went to the "three blink" mode and the wattage tapered down fairly quickly to only 1.7 watts.  This seems to me to be a very low power use for battery charging, hardly worth noticing.

As near as my math will take me, my laptop, charged, running Lightroom and a You Tube video, is using about 2.5 amp hours or so on 12v.  (Check my math:  30 watts divided by 12 volts=2.5 amp hours)?

But if I want to charge the laptop and run those items, the amp hour usage would be about 5 amp hours.  (Not to mention the percentage loss from the inverter inside the trailer).

So, it seems there is a good advantage to use a completely charged laptop as long as possible. 

jkjenn

When I spent 3 months FT, I had to keep a personal and a business laptop charged. I used my GZ Yeti 150 to charge camera batteries and to get my work laptop through the day. I charged my personal laptop mainly iff the TV inverter when I was doing g long drives and the Yeti 150 for other times. 

Last year, when I had a 3 week road trip, I charged almost everything g off if the GZ Yeti 1000 and kept the Yeti topped off with the Yeti topped off with the TV inverter. This included laptop, camera batteries, Gopro, and drone batteries.

I also have 12v chargers for my Canon batteries and will charge them from the T@b house batteries. 

b407driver

@Trailpixie and @pthomas745, thanks for that detailed input, that is along the lines of what I was (not) remembering. Knew someone on this forum could shed some light!

jules2go

b407driver said:

OK, so I know this sounds like a weird question, but I've seen info somewhere that I cannot now find. I am a photographer who will be boondocking for up to 7 days at a time, and am trying to develop my own set of 'best practices' before taking delivery.

Anyway, if I am remembering correctly, the basic gist was that if you are relying on solar for days on end, it was better to charge the computer while *not* using it, and use the computer only via its battery if possible.

Has anyone evaluated this, or ever heard anything about someone addressing it?

The other thing I'm curious about is charging camera batteries, as this can be a struggle for me to keep up after a good astro night (I sometimes go through 3+ LP-6 batteries in a night). I'm considering buying an after-market 6V charger, but am unsure if it's any more efficient that just using the inverter. 

Anyway, if anyone could shed me some light, I'd appreciate it! We're within a week of delivery!!!

-Jeff

Fabulous photo, Jeff!