Software developer looking to work in the sticks

[505HPC6Z06]

I want to run my laptop off-grid to do my work and I'm looking to find out what energy source options exist for my use case. My laptop is a MacBookPro 17" and I've measured 110W @120V draw running full tilt. The laptop power adapter says 85W. The inverter I have is a 400W modified sine wave unit. I have a cellular booster, but that runs off USB as does my cell phone. I would like to work for 4 hours.

I'm in SO CAL and thought solar would give me what I need, but after searching here it seems like I would need to carry quite a bit of gear. The panels, inverter, charge controller and battery. Then I will need a chair and the laptop gear too. Maybe that wouldn't be a big deal. Its hard to say because I don't know what I'm doing. My target carry weight limit for the energy source is about 15 lbs per hand.

Would you share what energy source options exist that I could leverage here?

[sdold]

If it was me, I'd look for an external battery that is designed to plug directly into the laptop, and charge it up every night and take it with me each day. It will probably be smaller and lighter than any other solution.

[jflorey2]

I want to run my laptop off-grid to do my work and I'm looking to find out what energy source options exist for my use case. My laptop is a MacBookPro 17" and I've measured 110W @120V draw running full tilt. The laptop power adapter says 85W. The inverter I have is a 400W modified sine wave unit. I have a cellular booster, but that runs off USB as does my cell phone. I would like to work for 4 hours.

I'm in SO CAL and thought solar would give me what I need, but after searching here it seems like I would need to carry quite a bit of gear. The panels, inverter, charge controller and battery. Then I will need a chair and the laptop gear too. Maybe that wouldn't be a big deal. Its hard to say because I don't know what I'm doing. My target carry weight limit for the energy source is about 15 lbs per hand.

Would you share what energy source options exist that I could leverage here?

Lightest panel I know of is the Windy Nation 100 watt panel. They are honestly not great panels, but they are light and flexible (about 4 pounds for a 100 watt panel) and they do come close to their ratings.
For batteries you can get a 20ah 12.8 volt LiFeSO4 battery that weighs about 5 pounds. But as others have mentioned, if you are going to take something like that, you don't need the solar panel. Just recharge it in your car.
You'd have to add a charge controller and a "car adapter" for the Macbook to allow it to operate off 12 volts. (I'd skip the inverter; no reason boosting 12 volts all the way to 120 volts AC just to drop it back down to 20 volts for your laptop.)

[505HPC6Z06]

If it was me, I'd look for an external battery that is designed to plug directly into the laptop, and charge it up every night and take it with me each day. It will probably be smaller and lighter than any other solution.

That would be too easy

Apple doesn't offer an external battery. I'd like to pull energy from the A/C power adapter.

[505HPC6Z06]

Lightest panel I know of is the Windy Nation 100 watt panel. They are honestly not great panels, but they are light and flexible (about 4 pounds for a 100 watt panel) and they do come close to their ratings.
For batteries you can get a 20ah 12.8 volt LiFeSO4 battery that weighs about 5 pounds. But as others have mentioned, if you are going to take something like that, you don't need the solar panel. Just recharge it in your car.
You'd have to add a charge controller and a "car adapter" for the Macbook to allow it to operate off 12 volts. (I'd skip the inverter; no reason boosting 12 volts all the way to 120 volts AC just to drop it back down to 20 volts for your laptop.)

How do I calculate how much time I would be able to draw off of a 20ah 12.8 volt LiFeSO4?

I have the inverter already, its used in my car. As an aside, I bought it at Oreilly (sp) auto parts because they honor the manufacturers warranty at the store. If it breaks during that time (1 year), they exchange it on the spot.

[sdold]

How do I calculate how much time I would be able to draw off of a 20ah 12.8 volt LiFeSO4?

This will help:

http://www.solarpaneltalk.com/showthread.php?5334-Solar-Off-Grid-Battery-Design

Somebody check my math, but you mentioned 110 watts for four hours per day. It sounds like you would need something like this:

110W for 4 hours = 440 Wh/day.

With a PWM charge controller, the panel would be about 880 W / 4 sun hours per day, or a 220W panel (maybe 30% bigger in winter, smaller in summer).

And the battery, if you need 440 Wh/day, discharged 50% would require an 880 Wh battery, or around 75 Ah. I don't know if 50% is appropriate for these batteries.

That sounds like a lot to carry!

Steve

[LETitROLL]

How do I calculate how much time I would be able to draw off of a 20ah 12.8 volt LiFeSO4?

I have the inverter already, its used in my car. As an aside, I bought it at Oreilly (sp) auto parts because they honor the manufacturers warranty at the store. If it breaks during that time (1 year), they exchange it on the spot.

I think you can discharge those down pretty low, so just ballpark 15ah (75% DOD) x 12v = 180wh

Won't your laptop already be fully charged when you head out for the day?, how long does it last on a charge before you would have to start using the battery power. Normally if you are returning to a car or home every day it is not going to be worth messing with the solar panel and CC, etc. just carry whatever battery(ies) it takes to make it through and recharge it/them every nite.

[Sunking]

I want to run my laptop off-grid to do my work and I'm looking to find out what energy source options exist for my use case. My laptop is a MacBookPro 17" and I've measured 110W @120V draw running full tilt. The laptop power adapter says 85W. The inverter I have is a 400W modified sine wave unit. I have a cellular booster, but that runs off USB as does my cell phone. I would like to work for 4 hours.

I'm in SO CAL and thought solar would give me what I need, but after searching here it seems like I would need to carry quite a bit of gear. The panels, inverter, charge controller and battery. Then I will need a chair and the laptop gear too. Maybe that wouldn't be a big deal. Its hard to say because I don't know what I'm doing. My target carry weight limit for the energy source is about 15 lbs per hand.

Would you share what energy source options exist that I could leverage here?

Where to begin? Well let's just get right down to the show stopper.

150 watt Solar Panel weighs 25 to 28 pounds.
12 volt 100 AH AGM battery weighs 150 pounds.

One you add your Inverter, controller, wiring, and some sort of support for the panel you are well over 200 pounds. You need to grow 10 more arms and hands.

If it were me I would just buy a laptop that has a battery that can give you 6 hours run time, and charged at home while you sleep. Would be a whole lot less expensive and under 10 pounds.

Edit note:

I know of no laptop that burns 110 watts. Laptop batteries aree limited to about 100 wh capacity. That is less than 1 hour run time if it were to use 110 watts. WTF do you have? A 1980's model?

[Sunking]

How do I calculate how much time I would be able to draw off of a 20ah 12.8 volt LiFeSO4?

Makes no difference if it is Lithium or not. The formula applies to any batteries.

Hours = [Battery Voltage x AH] / watts.

So

[12 volts x 20 AH] / 110 watts = 2.18 hours. 5th grade math

[jflorey2]

How do I calculate how much time I would be able to draw off of a 20ah 12.8 volt LiFeSO4?

20x12.8=256 watt-hours. If it's 100 watts (which it isn't) then that's 2.5 hours to draw it down to zero, so you should count on no more than about 1.5 hours.

I have the inverter already, its used in my car.

Uh - OK. If you don't care much about weight or efficiency, by all means, use the inverter. (In that case, just get some VRLA batteries and carry them; they are much cheaper and easier to source.)

[SPFycool]

I would like to work for 4 hours.

Surely a Macbook can work for 4+ hours on a good charge. Unless you are doing some VERY high intensity CPU or graphic work, you shouldn't have a problem just using the internal battery in most instances.

My target carry weight limit for the energy source is about 15 lbs per hand.

If you REALLY want something to give you peace of mind or some backup power, there are a few options that will fit your bill with minimal weight and complexity.

The least expensive option is an external battery to recharge your laptop. Lithium is definitely your only real choice here to keep weight down, but cost is much higher than SLA or flooded batteries.

Or you can get a kit with folding panel and a battery pack with inverter.

Check out the AspectSolar Energybar. You can compare all the bundles in the link to get an idea of prices. You can get the battery pack itself, then add the panels later if you so choose. They all carry 5-year warranty.

There are other types of "solar suitcases", but I worry about their long-term reliability.

EDIT: Forgot to mention you will NOT need your current inverter if you go with the battery pack above. It has an internal inverter.

[505HPC6Z06]

Won't your laptop already be fully charged when you head out for the day?, how long does it last on a charge before you would have to start using the battery power. Normally if you are returning to a car or home every day it is not going to be worth messing with the solar panel and CC, etc. just carry whatever battery(ies) it takes to make it through and recharge it/them every nite.

The laptop might be charged when I head out, but it might not be. The battery runtime depends on the project I'm working on. The idea was to plan for worse case scenario.

[505HPC6Z06]

Where to begin? Well let's just get right down to the show stopper.

150 watt Solar Panel weighs 25 to 28 pounds.
12 volt 100 AH AGM battery weighs 150 pounds.

One you add your Inverter, controller, wiring, and some sort of support for the panel you are well over 200 pounds. You need to grow 10 more arms and hands.

If it were me I would just buy a laptop that has a battery that can give you 6 hours run time, and charged at home while you sleep. Would be a whole lot less expensive and under 10 pounds.

Edit note:

I know of no laptop that burns 110 watts. Laptop batteries aree limited to about 100 wh capacity. That is less than 1 hour run time if it were to use 110 watts. WTF do you have? A 1980's model?

Like always, I'm way in over my head

The laptop is spec'ed here. The processor is an i7 having 4 cores and 8 threads running at 2.5GHZ. When the processor is running 100%, the battery drains faster than a Nickle Cadmium. The battery won't last through a movie VIA DVD playback. The battery is good, its only had 265 cycles since 2011.

The power draw measurement was taken with the Kill A Watt meter. Apple states 7 hour run time, that is a pipe dream.

[505HPC6Z06]

The least expensive option is an external battery to recharge your laptop. Lithium is definitely your only real choice here to keep weight down, but cost is much higher than SLA or flooded batteries.

Or you can get a kit with folding panel and a battery pack with inverter.

Check out the AspectSolar Energybar. You can compare all the bundles in the link to get an idea of prices. You can get the battery pack itself, then add the panels later if you so choose. They all carry 5-year warranty.

That is a pretty cool product. Handy as a pocket on a shirt.

[SPFycool]

That is a pretty cool product. Handy as a pocket on a shirt.

Yeah. I plan on getting one of them (battery pack only) in the Spring. Nice kit for camping or short treks to charge/power portable electronics.

When it comes to small-scale, it really is not worth building something with all that complexity. The whole point of being small is for easy of mobility and set-up/breakdown. No need for hulking flooded batteries, wires all over the place, etc.