New project here

[Indigoblue]

Hi all! Spent some time reading the posts and Also looking at past posts to gather info.

im pretty good with electric and in the process of making my own Mobil solar setup. I plan to build this hopefully on the top of my Jeep Wrangler hardtop!
The goal is to generate enough power to supply my laptop for an 8ht work day while I’m out camping this summer.

Anyone suggest a voltage needed to accomplish this? I will prob need over a 100w panel huh.

 

[MisterSandals]

generate enough power to supply my laptop for an 8ht work day

You need to supply how much power your laptop uses for anybody to calculate this answer. Can you determine how many watts it uses somehow?

Anyone suggest a voltage needed to accomplish this?

A system this size is almost always 12v and uses a 12v battery (deep cycle, AGM, LiFePO4 ...).

 

[Indigoblue]

You need to supply how much power your laptop uses for anybody to calculate this answer. Can you determine how many watts it uses somehow?


A system this size is almost always 12v and uses a 12v battery (deep cycle, AGM, LiFePO4 ...).

65 watts is the power adapter

 

[Indigoblue]

You need to supply how much power your laptop uses for anybody to calculate this answer. Can you determine how many watts it uses somehow?


A system this size is almost always 12v and uses a 12v battery (deep cycle, AGM, LiFePO4 ...).

My charger is 65 watts. I didn’t want to under shoot when completing this project.

 

[Indigoblue]

You need to supply how much power your laptop uses for anybody to calculate this answer. Can you determine how many watts it uses somehow?


A system this size is almost always 12v and uses a 12v battery (deep cycle, AGM, LiFePO4 ...).

My charger is 65 watts. I didn’t want to under shoot when completing this project

My charger is 65 watts. I didn’t want to under shoot when completing this project.

my panel was originally 100 watts but I think I’m going to need more of this to keep my MacBook going 8hrs a day if needed

 

[MisterSandals]

Look up your solar hours for your location here:
Solar Irradiance Calculator

8h x 65w = 520wh (requirement assuming 100% efficiency)

Sounds like you will need an inverter to use your Mac power supply so those are roughly 85% efficient:
520wh /.85 = 611wh
Running numbers with 5h from solar irradiance calculator:
611wh / 5h = 122w solar panel at 100% efficiency

Substitute your number for solar irradiance and you're pretty close.

If you need to account for days when the sun isn't shining, you will need a bigger battery and a larger array to charge as well as power your Mac.

 

[Indigoblue]

Perfect I’m in Florida! This is what I figured on average

 

[MisterSandals]

Perfect I’m in Florida! This is what I figured on average

Its easy to find big cheap solar panels in Florida on craigslist.
Get a 250w big panel (~$100 is possible).
Get a Victron 75/15 SCC (super reliable - its running all day unattended on your prized Jeep right?)
Costco 100ah deep cycle battery? (~$80?)

Solar Panel - electronics - by owner - sale

Solartec 205Watt, 24 Volt Solar Panel. Only used for bench testing on occasion. Kept inside 99% of time.

miami.craigslist.org

250 WATT SOLAR SALE‼️ - appliances - by owner - sale

Beautiful High Testing Panels. Pristine condition. 60 Cell Polycrystalline Weather resistant. Certified for salt mist and ammonia resistance Anti-Reflection surface treatment. 5 1/2 ft by 3ft. Buy...

miami.craigslist.org

 

[Indigoblue]

Its easy to find big cheap solar panels in Florida on craigslist.
Get a 250w big panel (~$100 is possible).
Get a Victron 75/15 SCC (super reliable - its running all day unattended on your prized Jeep right?)
Costco 100ah deep cycle battery? (~$80?)

Solar Panel - electronics - by owner - sale

Solartec 205Watt, 24 Volt Solar Panel. Only used for bench testing on occasion. Kept inside 99% of time.

miami.craigslist.org

250 WATT SOLAR SALE‼️ - appliances - by owner - sale

Beautiful High Testing Panels. Pristine condition. 60 Cell Polycrystalline Weather resistant. Certified for salt mist and ammonia resistance Anti-Reflection surface treatment. 5 1/2 ft by 3ft. Buy...

miami.craigslist.org

Yes! We have a rubicon and want to drive to Colorado and Montana this summer. Still the calculation is 5 hrs give or take according to the calculations. 120 watt is iffy and yes I think I may need bigger but I’m not sure a 250 w solar panel will fit on the small Jeep hardtop. Maybe a 150 if they make them.
Yes the Jeep will be running as we drive so that charges as well! But we want power when we are camping.

 

[Hedges]

My charger is 65 watts. I didn’t want to under shoot when completing this project

my panel was originally 100 watts but I think I’m going to need more of this to keep my MacBook going 8hrs a day if needed

Is that an AC charger, or 12V (cigarette lighter plug)?

65W is the peak output. Real question is how may watt-hours it draws while running your MacBook for 8 hours (which depends on what applications are running.)

Possible ways to answer this without measurement are, "How long does MacBook run on its internal battery" and "how long to recharge internal battery from 65W adapter".
Remaining question not as easily answered is "How much current draw from 12V battery while powering 65W adapter recharging internal battery". That would either be 12V current draw by a 12V charger or by an inverter powering an AC charger.

I would bet the smallest external battery would be more than enough, e.g. 35 Ah 12V AGM. The 65W adapter will draw about 5A from 12V battery, and 50% DoD of 35 Ah would be 17.5 Ah, 3 hours of charger operation. That's if AGM is recharged in the day and drained at night. Feeding laptop while the sun shines, would last even longer.

Assume 35Ah battery wants 0.2C charge rate, 7A or 84W. A single 100W panel would do that, and could provide 5 hours charging in a summer day, less in winter. Adjusting panel angle to track sun increases hours. Two, 100W panels with an acute 60 degree angle between them would provide flat power throughout the day. Pick an MPPT charger with no more than 10A output (if MPPT voltage is sufficient) and over-paneling with excess PV could be done without charging battery at excessive current. Could use one or more 24V panels.

You can probably use your vehicle battery, just add a PV charger for it.

 

[Indigoblue]

Is that an AC charger, or 12V (cigarette lighter plug)?

65W is the peak output. Real question is how may watt-hours it draws while running your MacBook for 8 hours (which depends on what applications are running.)

Possible ways to answer this without measurement are, "How long does MacBook run on its internal battery" and "how long to recharge internal battery from 65W adapter".
Remaining question not as easily answered is "How much current draw from 12V battery while powering 65W adapter recharging internal battery". That would either be 12V current draw by a 12V charger or by an inverter powering an AC charger.

I would bet the smallest external battery would be more than enough, e.g. 35 Ah 12V AGM. The 65W adapter will draw about 5A from 12V battery, and 50% DoD of 35 Ah would be 17.5 Ah, 3 hours of charger operation. That's if AGM is recharged in the day and drained at night. Feeding laptop while the sun shines, would last even longer.

Assume 35Ah battery wants 0.2C charge rate, 7A or 84W. A single 100W panel would do that, and could provide 5 hours charging in a summer day, less in winter. Adjusting panel angle to track sun increases hours. Two, 100W panels with an acute 60 degree angle between them would provide flat power throughout the day. Pick an MPPT charger with no more than 10A output (if MPPT voltage is sufficient) and over-paneling with excess PV could be done without charging battery at excessive current. Could use one or more 24V panels.

You can probably use your vehicle battery, just add a PV charger for it.

The charge controller I was looking at was the Renogy Wanderer and it rated I think at a 30 amp charge. So I should lower it to a 10amp charge controller? What watts does my inverter need to be ?

 

[Indigoblue]

Is that an AC charger, or 12V (cigarette lighter plug)?

65W is the peak output. Real question is how may watt-hours it draws while running your MacBook for 8 hours (which depends on what applications are running.)

Possible ways to answer this without measurement are, "How long does MacBook run on its internal battery" and "how long to recharge internal battery from 65W adapter".
Remaining question not as easily answered is "How much current draw from 12V battery while powering 65W adapter recharging internal battery". That would either be 12V current draw by a 12V charger or by an inverter powering an AC charger.

I would bet the smallest external battery would be more than enough, e.g. 35 Ah 12V AGM. The 65W adapter will draw about 5A from 12V battery, and 50% DoD of 35 Ah would be 17.5 Ah, 3 hours of charger operation. That's if AGM is recharged in the day and drained at night. Feeding laptop while the sun shines, would last even longer.

Assume 35Ah battery wants 0.2C charge rate, 7A or 84W. A single 100W panel would do that, and could provide 5 hours charging in a summer day, less in winter. Adjusting panel angle to track sun increases hours. Two, 100W panels with an acute 60 degree angle between them would provide flat power throughout the day. Pick an MPPT charger with no more than 10A output (if MPPT voltage is sufficient) and over-paneling with excess PV could be done without charging battery at excessive current. Could use one or more 24V panels.

You can probably use your vehicle battery, just add a PV charger for

Is that an AC charger, or 12V (cigarette lighter plug)?

65W is the peak output. Real question is how may watt-hours it draws while running your MacBook for 8 hours (which depends on what applications are running.)

Possible ways to answer this without measurement are, "How long does MacBook run on its internal battery" and "how long to recharge internal battery from 65W adapter".
Remaining question not as easily answered is "How much current draw from 12V battery while powering 65W adapter recharging internal battery". That would either be 12V current draw by a 12V charger or by an inverter powering an AC charger.

I would bet the smallest external battery would be more than enough, e.g. 35 Ah 12V AGM. The 65W adapter will draw about 5A from 12V battery, and 50% DoD of 35 Ah would be 17.5 Ah, 3 hours of charger operation. That's if AGM is recharged in the day and drained at night. Feeding laptop while the sun shines, would last even longer.

Assume 35Ah battery wants 0.2C charge rate, 7A or 84W. A single 100W panel would do that, and could provide 5 hours charging in a summer day, less in winter. Adjusting panel angle to track sun increases hours. Two, 100W panels with an acute 60 degree angle between them would provide flat power throughout the day. Pick an MPPT charger with no more than 10A output (if MPPT voltage is sufficient) and over-paneling with excess PV could be done without charging battery at excessive current. Could use one or more 24V panels.

You can probably use your vehicle battery, just add a PV charger for it.

yep the laptop is a AC 65 watt charger

 

[Hedges]

The charge controller I was looking at was the Renogy Wanderer and it rated I think at a 30 amp charge. So I should lower it to a 10amp charge controller? What watts does my inverter need to be ?

Depends on the battery you're using. Batteries have a maximum recommended charge current. It was if you had a small 35 Ah battery that I suggested 7A was likely max preferred charge rate, and 10A SCC would avoid exceeding that by too much. A charge controller should also have a temperature sensor if used with lead-acid battery, because charge voltage needs to vary with temperature.

Select your proposed equipment and check how the specs play together before buying.

Ideally, a system can regulate battery charge current to optimum level, but support additional PV watts and let them flow through to loads. Some integrated units may support that. Individual pieces assembled usually doesn't. Some larger systems components have this feature, but yours is to be small.

 

[MisterSandals]

What watts does my inverter need to be ?

You can do without an inverter with a "car charger"

https://www.savingology.com/ProductDetails.asp?ProductCode=Apple-85W-MagSafe-2-GPK

Thats if your Mac has MagSafe of course. They make these for Lightning and USB-C as well.

It is unlikely that you could use your cigarette lighter plug in you Jeep for this many watts (max amps will be in the manual). 85w / 12v = 7amps is pretty high for standard car plugs.

So, you would cut the cig. plug off this charger and add connectors to connect to the solar battery (or preferably a fuse/breaker).

Staying with DC power and skipping the inverter is quite a bit more efficient. Using an inverter to get AC current and then having the Mac power supply convert it back to DC.