Expedition battery maintenance. How to keep up 100AH/day long term?

[yuji]

I'm going to be working remotely from my laptop for weeks before having outlet access - at least that's the plan : ) so I've started to research a battery and charging setup that can handle this load.

I'm pretty stationary between locations, so the usual alternator charging-while-driving doesn't work here. If anyone has links to similar setups for supporting 100AH @12v a day, I'd appreciate it!

It seems I need somewhere around ~100 AH @ 12v per day to run my laptop and internet. It probably eats 10A/hr. I'm shocked that a fridge consumes SO MUCH less power.
I want to run a generator for as little time as possible, so it seems I need as fast of a charger as possible plus a generator that can handle the load.

I've done a ton of reading, and it's utterly confusing. I want to talk out loud and see if I'm making sense at all. If you've done anything similar and have input, anything is appreciated!

Is my understanding of this relatively correct? Assuming a X amp charger, and a battery bank of sufficient size or quality to accept said charging amps, that the battery receives X*efficiency loss of AH per hour?


30 Amp charger, Honda 2000 generator.
$200 + $1k
An IOTA 30 Amp charger takes 8Amps AC, and the output of a Honda 2000 generator which uses @ 1 gallon per 4 hours at rated capacity (13A). Doesn't sound too bad.

So theoretically, with 20% loss, could you charge 24AH per hour? I'd still need to run the generator for 4 hours to make 100AH back. Say with 40% loss through charging, 5.5 hours.

I know charge curves are different depending on discharge rates, but can we simplify here?


75 Amp charger, Honda 3000W Generator/
$300 + $1500
Just for a thought experiment, let's say I got the IOTA 75 Amp charger. It needs 18 Amps AC.

The generator required for that would be more like one of the Honda 3000W rated for 20 AC Amps @ 2-3 hours per gallon.

This could potentially charge 120 AH over 2 hours a day at 80% efficiency which sounds pretty good! Again, assuming the batteries can be charged at that rate.


Battery types; charging rate
This is another confusing part. It seems charging is recommended at max of 20% of capacity Amps.

The 75A charger would not be recommended on anything smaller than a 375AH battery bank, which I could pull off with 4x 6v golf cart batteries.

I hear charging heat losses can be heavy and that AGM batteries can be charged at any rate practically, but AGM would cost twice as much or more as my ideal 6v golf cart battery setup.

150-200AH 6v x 2 for $200-250
vs
100 AH 12v AGM for $250 which I'd want more of for capacity.

So I suppose I need to know how bad the charging heat losses are when fast-charging somehow.


Another battery issues is that discharging below X% is not recommended for battery life. This aspect can be remedied by increasing the size of the bank, so I could potentially have a huge 500AH bank which is never discharged much, correct?


Does this all compute? Batteries are confusing the hell out of me


My plan is to figure out what setup I need to run purely from a generator, then consider adding solar banks to my roof / trickle from my alternator to keep the batteries topped off and slowly charging, as I won't be on the computer ALL the time.

 

[george_tlc]

10 A/Hour for your laptop and internet ???

Where are those numbers coming from? What is your internet connection, satellite??

A modern laptop should not be drawing much more than 20 - 30W while running, so maybe 2A max from nominal 12.8V through an inverter. I just tested a Dell laptop (not the latest & greatest) through an inverter and I saw 1.75A draw from 12.8V input to the inverter.

Seems to me that before you start determining/asking what kind of charging setup you need, you really need to go and measure ACTUAL current draw and amp.hour needs for an average day...

cheers,
george.

 

[e9999]

easiest way to look at this may be in terms of power and energy.

Yes, a modern laptop should not need more than about 30W or so to run. My super duper big ass one may need about 50W when I recharge the battery after it's depleted, but runs only 30W with screen on when semi-idle. And maybe up to about 50W when the processors are super busy.
It's easy, think about a 60W incandescent bulb. Gets pretty hot right? Well, that's a bit less than 60W of "heat" power. Does your laptop dissipate more power than that? When my laptop is cranking I can feel the hot air coming out of the fan outlet to the point that it's uncomfortable.

Now A.hr (A/hr is meaningless) is a measure of energy, not power. (And only meaningful itself if you specify the voltage.)
So 100Ahr for a 12V system is about 1250W ran continuously for a period of 1hr or 100W for a period of 12hrs. (Oversimplyfing cuz the battery does not handle high and low amp loads equally well.) So about 2x as much as you'd need for a big laptop cranking hard for 12hrs straight. So that figure is not outlandish if you throw in additional electronics. Yet 100W is only 1/16 of what a 2000W EU2000i Honda can deliver 24/7 if you feed it gas. Even with converter losses there is no way that a EU2000 or even EU1000 could not support that.

If you want to run a generator for a short time, based strictly (unrealistically) on numbers, you could run the EU2000 for about 1 hr, recharging the truck battery at about 1250W, say, assuming it will take it, and you could support the laptop and all for 12hrs after that.

Note that the EUs have a 12V outlet so you would not need an inverter and battery charger with associated loss. (Although IIRC the output on the 12V is only like 10A or so, so that is meant for low rate and long-time charging.)

A fridge would not consume *much* less power than a laptop. Typical compressor-based portable fridges would draw 5A or less, maybe 3, at 12V when running or 30-60W, roughly comparable to a powerful laptop. At 30W, your laptop would draw only about 2.5A. Not that different.

Always thought that vehicle batteries like slow charging not fast if you want them to last. Trying to cram your 100Ahr in an hour in there may be trouble.

If at all possible, running a quiet EU full-time directly to the laptop -or battery with the 12V outlet- may be the ticket, it'll be so little power needed that it will be superquiet and won't have any trouble keeping up. Have a 50yds extension cord and you won't hear it at all. If you have not used one of those you'll be amazed at how quiet they are. Bypass all that fast battery charging stuff. That's what I would do if could. And you can run the radio, fridge, espresso machine, margarita blender etc as well, not a bad plus... Now, of course, if you'll be literally weeks at a time out there, that may add up in gas. But if you'll be weeks out there with no power, food and fridge may become primordial so a generator may become even more critical. You just may need a few jerry cans then I guess.

Or use a 60W solar system and you're good too -if sunny- for the laptop. Make that 100W if you need laptop and fridge.

And of course none of this charging etc makes sense with a starter battery, you'll want a dual starter/deep cycle battery if you only have one, or a secondary deep cycle if you'll use a dual battery system. Regular starter batteries won't handle deep discharge well at all.

 

[yuji]

You guys are right, I was going by my power supply's 85w, but my watt meter shows me using 60w as I type! If the battery is depleted / using CPU, it does go to 85w. I'm using a 17 inch macbook pro. It has a huge 1920x1600 screen / the video card barely keeps up. Looks like I can get it down to 50 with minimum brightness. It idles at 20w when I'm not doing anything.

That's much better.

Still, it's going to be depleted. But at this rate of 20 hours on a 100AH, it sounds much less problematic to run a generator for a while to charge it (since it doesn't need to be every day).

Yes this battery bay will be completely separate from the vehicle, I can't find a place for a clean dual battery setup.


Still, I'm curious what you folks do since after that 100AH is gone, you gotta charge it.. and I'm sure some of you run more than a laptop! Does everyone have a high amp charging setup? Trickle charge from the alternator? Anyone got tons of gear and care to share your setup!?

 

[e9999]

if you don't want to use only a generator directly to the laptop then you indeed could use one battery -or more- out there as a buffer.
You could use the single vehicle battery for that of course but I would not do so with regular fast-charging unless it's a battery that handles that better than the ones I'm familiar with (lead acid). With slow charging it's probably fine.
But if you're concerned about your single vehicle battery, then an external battery is probably a safer idea.

Taking my EU2000i as an example, it will do 1,600W full time, way more power than you need. However the 12V outlet is only about 100W. If you use the 12V outlet you avoid having to use a charger but you'd be running the generator about half the time you run the laptop.
If you use a 120V charger then you could charge faster potentially but the battery's ability to handle that will become the limiting factor. It may damage your battery if you do that repeatedly. Which is why I never use the "fast" charging cycle of my chargers, outside of true emergencies. And also why I now use a trickle charger with desulfating capability which puts out only about 1A at the most when I want to keep my batteries maintained. Note that this is only about 15W which is not enough to keep up with your laptop.

Say that you use a charger that puts 20A at 14V. That's 280W or about 5 times as much as the laptop will need. Your generator will then run 1/5 of the time the laptop runs. Now 20A is not a trivial amount for charging a battery I think. I don't think I'd be comfortable going with that every day with a lead acid battery (I don't know anything about AGMs). Admittedly this is a guessed arbitrary limit from anedoctal evidence and reading a bit about all this and gut feeling.

Basically, overall I think you will run into issues with lead/acid batteries handling fast-charging if you want to run the generator only briefly. AGM may be OK I don't know. Add to that the size and weight of the battery pack and charger and inverter and having in any case the need for a generator if solar is not enough or possible, is why I would simply run the generator directly to the laptop if at all possible. Of course, your laptop has an internal battery also which will help. You can use the generator just long enough to fully charge the laptop internal battery and then run off that battery with the generator off for possibly several hours depending on laptop. Add a fat second laptop battery would probably help a lot too. And much smaller than a 12V vehicle battery.

 

[george_tlc]

So, how about more info on you 'expedition'. Is this camping under trees/shade (no solar...) or in sun rich areas? You plan on doing a LOT of work on the computer? Do you need a super dooper mac pro power hog or are you just typing your autobiography and a low power netbook would work just fine?

You still need to do an energy budget here - if you are camping for weeks, do you have a fridge/freezer to provide food/cold ones etc or ? Other equipment that will be needing to be charged? Jacuzzi? etc...

I've run solar in the oz bush, an 85W mono-crystalline panel can put an honest 5A into a battery for most of the sun rich day. That easily keeps up with the Engel over a 24 hour period and then some. The fridge is the main power hog while camped, a few LED lights draw little and I'm not writing my autobiography while out there and there's certainly no internet access

So, solar is feasible and a 200W (or more) panel would give you at least 10A for sunny or partially overcast days. The key is to not be in a forest of trees...

cheers,
george.

 

[e9999]

personally, I'd start with a good generator and then indeed add solar later when possible as a background-charging system. Even then I'd want to have a gen along anyway though. Unfortunately, I'm not that impressed generally with the current state of affairs for panels. 100W takes a big area and rigid panels are a pain to handle, store etc. Not that cheap either. Hopefully they'll make good progress on soft panels and efficiency soon. I'm waiting.

 

[george_tlc]

I'd never take a generator in the bush - firstly I have a diesel 4wd in oz, so I'd be stuck having to haul petrol to run it. Next we discuss being out there a few weeks running a generator every day for a few hours - need more fuel and have wonderful noise to listen to when I want tranquility.

I'm personally VERY impressed with current solar panels. The 85W panel I have folds in half (hinged), takes little room compared to a generator + fuel and I don't need to 'listen' to it. I ran it in fairly overcast days last year (unseasonably rainy days) and it was still pumping out 2.5 to 3A. The mono-crystalline panels are quite efficient at running even under reasonable cloud cover. As soon as the sun would break through it was up at 5+ Amps.

We were out of about 2 weeks and at each location we made camp we'd just plug the panel in and re-orient it 3 times per day. The panel folds in half, has a built in stand to adjust the tilt angle and packs nicely in a bag. Oz$200 delivered to my doorstep there and included a reasonable charge controller. I'm an EE, so know how to measure output etc and the panel definitely performed better than my expectations. I'd previously used a much old tech (polycrystalline) Solarex 42W panel and it would be lucky to get 2A out in FULL sunshine.

The key for the OP is where is he going to be camping - if in tree cover, then a generator is his likely only option. If he's out in the open AND camping during the sunny season, then a decent solar panel will work VERY well indeed.

cheers,
george.

 

[WideAngleWandering]

Solar can be feasible. I used a 30watt panel with a 55AH battery, moving the panel to follow the sun, and kept my fridge running for 6 days w/o issues. Now I have a 100AH battery and 100watts of panels mounted to the roof rack. Out of sight, out of mind and always on if the sun is shining. I got a good deal on panels so I paid about $100 + another $40 for the controller. I made my own mounting frame and did my own wiring.

I haven't done any energy budget because I seem to have more capacity than I really need and I can always go for a drive to charge it back up. I also carry a 10A ship-to-shore charger so I can plug into AC if I need.

Something to keep in mind - you really don't want to run that battery flat all the time if you want it to last and be reliable. A solar float charger will help with battery health, though I suppose you could get that too from the generator as long as you use a good charger.

Alternators are not good chargers.

 

[peesalot]

X2 on 30 watts of solar on top of rig and 2 batts will run fridge 6+ days without issue. add in occasional running the engine or driving around and the system stays at 12 volts. I have a battery tower for mobile use that has 400 watts of 110, or 60 amp hours of 12 v. it has it's own 15 watt solar panel that folds up . it also came with lights to hang in tent and around camp, each light having its own switch.
The same company that makes the battery tower system also has a wind generator that plugs into it. the wind unit packs into a bag smaller than a standard chair and can put out really good power, especially in stormy conditions where the solar is lacking. The battery tower will run the pc for maybe 6 to 8 hours on its own with no solar or wind recharge. You can also plug the battery tower into the rig and charge it up if you need to take it in the field. I always take the solar panel because it seems to add about 4 hours until the pc depletes the tower as opposed to running pc without the solar hooked up. it does take the solar a full day to recharge the tower on its own.

 

[Bogo]

First off, if you are just writing a novel, then a tablet with bluetooth keyboard will just be 100 watts or so total a day. Very low power use. If you are like me and doing photo editing, a full high powered laptop is needed.

For your stated 100A Hours a day the battery can be no smaller than 125Amp hours if it is a deepcycle one, 80% maximum depth of discharge for deepcycle lead-acid batteries. I'd go for minimum of 2 Group 31 RV/Marine batteries which would be 200 to 230 Amp hours total, 160 to 184 Amp hours usable, depending on battery and manufacturer.

An important thing on battery bank sizing is how much you charge and discharge the battery bank per day is important. The smaller that percentage, the longer the battery bank will last. This can be dramatic. Also charging the last 10% or so of a battery is where the most damage occurs. It also takes much longer per Amp hour charged into the battery as the charge acceptance rate drops as full charge gets closer. Because of that, shut the generator off when the battery gets 90% full. A battery only needs to be 100% charged every week or two to prevent sulfication.

I selected Group 31 batteries because if they fail you can go to almost any truck stop, marina, or RV place and get replacements of the same size and type. In a pinch diesel starting batteries like used for trucks would work, but I wouldn't discharge them more than 50%.

PS, if you have the right bits along, two or three 12V lead-acid batteries in series can become a DC stick welder power source.

Solar is nice if you have sunny skies and no tree cover. for the solar charge controller I'd get a MPPT type. They will allow charging to start earlier in the day, and to go to later at night. 10% to 30% more charge per day are the numbers everybody likes to quote. On a vehicle that will be bumping around I'd go for more frames versus larger panels. So I'd get 2 100 Watt panels over 1 200 Watt panel.

On recharging a large battery bank while running the engine. Consider a second alternator. Only hook it up to the battery bank, and don't have any connection between the (+) on the battery bank and the (+) on the starer battery. Size the alternator to recharge the battery bank in 2 to 4 hours. If the charge rate is over 20% of the battery bank size, then use AGM type batteries as they should be better able to handle high charge rates.

 

[General Automag]

I'm going to be working remotely from my laptop for weeks before having outlet access - at least that's the plan : ) so I've started to research a battery and charging setup that can handle this load.

I'm pretty stationary between locations, so the usual alternator charging-while-driving doesn't work here. If anyone has links to similar setups for supporting 100AH @12v a day, I'd appreciate it!

It seems I need somewhere around ~100 AH @ 12v per day to run my laptop and internet. It probably eats 10A/hr. I'm shocked that a fridge consumes SO MUCH less power.
I want to run a generator for as little time as possible, so it seems I need as fast of a charger as possible plus a generator that can handle the load.

I've done a ton of reading, and it's utterly confusing. I want to talk out loud and see if I'm making sense at all. If you've done anything similar and have input, anything is appreciated!

Is my understanding of this relatively correct? Assuming a X amp charger, and a battery bank of sufficient size or quality to accept said charging amps, that the battery receives X*efficiency loss of AH per hour?


30 Amp charger, Honda 2000 generator.
$200 + $1k
An IOTA 30 Amp charger takes 8Amps AC, and the output of a Honda 2000 generator which uses @ 1 gallon per 4 hours at rated capacity (13A). Doesn't sound too bad.

So theoretically, with 20% loss, could you charge 24AH per hour? I'd still need to run the generator for 4 hours to make 100AH back. Say with 40% loss through charging, 5.5 hours.

I know charge curves are different depending on discharge rates, but can we simplify here?


75 Amp charger, Honda 3000W Generator/
$300 + $1500
Just for a thought experiment, let's say I got the IOTA 75 Amp charger. It needs 18 Amps AC.

The generator required for that would be more like one of the Honda 3000W rated for 20 AC Amps @ 2-3 hours per gallon.

This could potentially charge 120 AH over 2 hours a day at 80% efficiency which sounds pretty good! Again, assuming the batteries can be charged at that rate.


Battery types; charging rate
This is another confusing part. It seems charging is recommended at max of 20% of capacity Amps.

The 75A charger would not be recommended on anything smaller than a 375AH battery bank, which I could pull off with 4x 6v golf cart batteries.

I hear charging heat losses can be heavy and that AGM batteries can be charged at any rate practically, but AGM would cost twice as much or more as my ideal 6v golf cart battery setup.

150-200AH 6v x 2 for $200-250
vs
100 AH 12v AGM for $250 which I'd want more of for capacity.

So I suppose I need to know how bad the charging heat losses are when fast-charging somehow.


Another battery issues is that discharging below X% is not recommended for battery life. This aspect can be remedied by increasing the size of the bank, so I could potentially have a huge 500AH bank which is never discharged much, correct?


Does this all compute? Batteries are confusing the **** out of me


My plan is to figure out what setup I need to run purely from a generator, then consider adding solar banks to my roof / trickle from my alternator to keep the batteries topped off and slowly charging, as I won't be on the computer ALL the time.

We found some GREAT reading at Handy Bob's Solar website https://handybobsolar.wordpress.com/the-rv-battery-charging-puzzle-2/. It's written with RV use in mind, but it directly related to what you're trying to accomplish with your setup. He is no-nonsense and takes the guess work out of choosing the proper equipment. I'd recommend that you read the other links in his blog too. We ended up saving some $ by not buying equipment and cables that we didn't need and or were not optimal for our setup.

 

[Max.Powerzz]

Have you checked out goalzero.com? My brother works for them and they have some great solar options and more portable collapsible panels coming out soon. This is the route I'm going; they grew out of a nonprofit providing solar power for remote villages in africa.

 

[rusty_tlc]

The OP has Portland OR as a location, not the best climate for solar power. Even if his current trip is to more sunny climes he may want to anticipate trips closer to home when building his set-up. Therefore a generator would, IMHO, be the best choice. That does not preclude solar if the budget allows. My little Honda 1000 is very quiet, I've forgotten it was running when I placed it away from camp. I usually only use it in cool weather to keep the batteries charged so we can run the forced air heater at night. It can keep up with that need running a couple of hours a day. The Honda's are very efficient, they run a looong time on one tank, since they use the same fuel as our vehicle I rarely carry extra fuel specifically for the generator.

As inexpensive as tablets are it might make sense to use a tablet for text and data/spreadsheet tasks even if there would be an occasional need for more high power graphics. The OP could also schedule task such as photo editing etc. for when the generator is running since the generator will probably put out more current than the battery charging system can use anyway.

 

[yuji]

Thanks for sharing all of the knowledge everyone. Super helpful!

I ended up purchasing...

- 100AH Exide AGM battery for $200
- 100W mono solar panel for $250 (Almost bought the pieces and soldered them myself for $60 - whew! It probably would have fallen apart on my rack).
- Solar charge controller
- Cheap 2-15A 12v AGM 3 stage charger $60


With the key fact that my laptop uses only 50w or ~5AH I can run for quite a while.
I'll see how it goes, and will probably purchase one of the little honda generators. Probably the 2000 in the future for winter.

Re: lower power laptops, I don't really have the budget to purchase a computer specifically for mobile use. Graphics and code compiling need CPU or else it's extremely frustrating, so I don't want to lower power too much. It's still work after all

The solar panel arrives today, the battery arrives next week. Excited to test it out!

I'm curious how I'll mount it / pull wires to the rear of the truck..

 

[e9999]

Thanks for sharing all of the knowledge everyone. Super helpful!

I ended up purchasing...

- 100AH Exide AGM battery for $200
- 100W mono solar panel for $250 (Almost bought the pieces and soldered them myself for $60 - whew! It probably would have fallen apart on my rack).
- Solar charge controller
- Cheap 2-15A 12v AGM 3 stage charger $60


With the key fact that my laptop uses only 50w or ~5AH I can run for quite a while.
I'll see how it goes, and will probably purchase one of the little honda generators. Probably the 2000 in the future for winter.

Re: lower power laptops, I don't really have the budget to purchase a computer specifically for mobile use. Graphics and code compiling need CPU or else it's extremely frustrating, so I don't want to lower power too much. It's still work after all

The solar panel arrives today, the battery arrives next week. Excited to test it out!

I'm curious how I'll mount it / pull wires to the rear of the truck..

Adds up in cost pretty fast, unfortunately, already about $550 or so I guess.
Info on the solar panel would be great to have, like model, dimensions and -when you know- the output.

 

[yuji]

Adds up in cost pretty fast, unfortunately, already about $550 or so I guess.
Info on the solar panel would be great to have, like model, dimensions and -when you know- the output.

Yes unfortunately there's a decent cost!

Updates:

Battery:
battery showed up, it's 70 lbs and somehow forgot how dense batteries are... it's rather awkward to carry. It will need a strong enclosure if I want a single box of goodies to carry around w/ charger, cables, etc.

Solar panel
The solar panel I bought was from Amazon. 100w @ 250 bucks.
http://www.amazon.com/Instapark®-Bl...F8&qid=1347694163&sr=8-2&keywords=solar+panel

It showed up in great condition. Fits right on the rack. I don't know how to mount it yet, but those MC-4 connectors will be handy to snap the solar panel onto the battery and off.

Solar charger
The first one I bought had no AGM setting. Be warned! http://www.amazon.com/Sunforce-6002...94176&sr=8-2&keywords=solar+charge+controller

I ended up purchasing a Morningstar 15A charger after reading good reviews for $90 from some other site. It should arrive next Monday.

http://www.morningstarcorp.com/en/support/product.cfm?ProductId=11



AC charger
I bought a cheap charger that I regret.
http://www.amazon.com/Schumacher-SS...F8&qid=1347694638&sr=1-2&keywords=AGM+Charger
But am probably going to return it.

The battery says do not supply more than 14.5V, yet the display on the charger jumped up to 14.9V after 15A charge was on for about an hour. I will have to confirm with a multimeter, but I'm guessing this isn't good for the battery.

Interestingly, the product has many 100 good reviews. Perhaps this battery is unusual in that 14.5V max, or maybe it's not a big deal to go over the recommended, or maybe 100 people are ruining their batteries?

Considering the cost of these batteries, I am looking into better chargers with perhaps manual voltage overrides, but I'm shooting in the dark here.


Wiring
Here's the basics. The major question right now is how long to make which cables.
I can make the solar -> battery cable long, or the battery -> inverter cable long.

I like the idea of leaving the battery in the truck, but at the same time I'd like to be closer to the battery so I can monitor it.

I think I'm leaning towards leaving it in the truck, because it's really damn heavy to move around, but at the same time I wonder how bad 30 feet of resistance is?

Solar Panel
|
| (trying to decide length of cable.. )
|
Solar Charge Controller
|
Battery --------------- AC Charger
|
|
|
A 12V Hub with USB
|
An inverter (same one I use in vehicle)


Battery: $200
AC Charger: ~$50 (probably need to upgrade)
Solar Panel: $250
Solar Charger: $90 (can be brought down)
Extra MC-4 Connector: $15
12V Hub: $10
100ft 10 gauge pure copper wire: $40
Inverter: Had already

Total: $650

 

[western flyer]

Wiring
Here's the basics. The major question right now is how long to make which cables.
I can make the solar -> battery cable long, or the battery -> inverter cable long.

I like the idea of leaving the battery in the truck, but at the same time I'd like to be closer to the battery so I can monitor it.

I think I'm leaning towards leaving it in the truck, because it's really damn heavy to move around, but at the same time I wonder how bad 30 feet of resistance is?

Solar Panel
|
| (trying to decide length of cable.. )
|
Solar Charge Controller
|
Battery --------------- AC Charger
|

Total: $650

Assuming I understand your planned setup, I think you would be better off keeping the higher current 12V cables short to minimize voltage drop. Can you keep the panels close the battery, and the battery close the inverter? If so, then you can then run a normal 110V extension cord from the inverter to the AC charger for the MacBooKPro (I have a MBP too, BTW). The voltage drop in the 110v extension cord would then be less, than compared to the situation if you spaced the 12v equipment out; particularly for the larger current draw equipment. The basis for the suggestion of running the longer cable after the inverter is in the link below:

http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2439482

On the other hand, you could keep it all lower voltage (12v-18.5v) by using a 12v charger (link below) for a MBP. This would arguably reduce your inverter and charger losses (otherwise going from 12V to 110V to 18.5v). In this case, I would again suggest keeping the battery near the solar panel, and then run the longer of the cables to the low current draw of the MBP charger. Since this cable has the lower current draw of the group, this would, again, minimize voltage drop and the reduce the relative gauge of cable you would need.

http://www.amazon.com/GPK-Systems-Charger-Portable-Notebook/dp/B0056QBQNI

Does this make sense or am I whacked?

 

[Bogo]

Battery to solar panel will be of a lower current than battery to inverter. So it would be less costly to oversize for distance. Put the inverter as close to the battery as reasonable. Your distances are short so voltage drops are not much of a factor except if you are undersizing the wires.