Help needed in calculating my power needs

[roadrunner]

I'm wondering how much solar power/battery I will need. I want to go with a sealed AGM battery, one if possible. I will give what I will need etc so we're not shooting in the dark (and it's something I want to avoid being left in!) I would include more details, but I cannot find my Kill-A-Watt meter to save my life.

1 Fantastic fan vent - running most of the time
1 Fantastic 12-volt fan for moving the air around - running 12-16 hours a day
Charging a small laptop -- laptop used 4-8 hours
Small printer -- used maybe 3-5 minutes a day
Charging a smart phone -- 1-2 hours a day
Charging an electric razor -- 3-6 hours a day
Charging 2-4 AA rechargeable batteries -- 3-4 hours a day
4-5 12-volt LED lights (these hardly draw anything, say 2 on for 3-4 hours a day)
12-volt water pump (it will get water up into my solar shower system I am working on), as needed (maybe 10 minutes per day)
CB radio/WX -- 2-3 hours per day, mostly receive
Possibly a heating pad (sore back muscles in the morning), for 1-2 hours a day
And eventually (when funds permit) a 12-volt Dometic fridge or Whynter 65 qt fridge

I would add in a small microwave, but I'm sure that would require more than one battery, (I can always cook on my Coleman stove.) And storage room (and funds) both being very limited, I would prefer, if at all possible to just use one AGM battery.

I want to go with an AGM battery as I don’t want to build a battery box/vent, as I need my setup to be fairly stealthy, as I will be spending a decent amount of time in cities and small towns, and it’s one reason why I picked a plain white cargo van. I’ll buy the size that best fits my needs and (limited) budget.

I'm not sure if I'm missing anything or not, but I think that covers it. If I am missing anything obvious, feel free to point that out.

As for an inverter, I have a Jensen 300-watt unit, but I’m sure that isn’t enough, so any advice on those would be great too.

A quick side question: Does the “house” battery have to be connected to the van’s alternator, or can one just use the solar panels and a charge controller?

As for where I'll be going, well all over, Southwest, Pacific Northwest etc, so there will be cloudy days, and there will be days I'm parked under pine trees, and I already know that even a single shadow cuts down the effectiveness of a solar panel, so I'm not going off of numbers the manufacturers provide as "enough" -- I'm wanting to hear what you use and what works and doesn't work.

Also, does anyone have any recommendations on who makes the most durable, for RV type use, (yet reasonably priced) solar panels?

Any/all help is deeply appreciated!

 

[SternWake]

The Fantastic fan amp draw, between low and high speeds makes for too much of a variable.

What is this electric razor running 3 to 6 hours a day?   Like hair clippers?  Do these have any power consumption listed on them?

I have not seen anything on your list that requires more than a 300 watt inverter.

For your laptop, goto amazon electronics and type in  your laptop make and model and add 'car adapter'  This is much more efficient than using the inverter to power the original transformer that came with your laptop.  Mine cost 22$.  Actual laptop consumption also can vary greatly so estimating its electrical use is too much a variable.  'small' is not much information as to how much it can consume.  My laptop is my biggest electrical consumer, by far.  What are the specs on the provided power brick?

Adding the fridge at a later date means you need  ~ 24 amp hours of capacity and minimum of 60 watts of solar just for it.

AGM batteries, require higher initial  charge rates than flooded batteries, and, they also do not do well cycling without reaching a true full charge every so many cycles.  All lead acid batteries need to be returned to 100% every so often to keep their capacity from walking down prematurely, but AGMs are more petulant in this regard, and harder to know when they indeed are fully charged.
  Their higher price does not make them a better battery, it makes them a different lead acid battery with differing performance and charging  characteristics/ requirements

So while you technically can  get away without hooking your AGM up to your alternator, The alternator can be the best thing for your AGM, as it will meet the higher charge rates, and give you a better chance on getting the battery to full more regularly.

I understand the reasons for not wanting to hook a house battery to the alternator as it seems quite complex, but it really is not.  The benefits of doing so are vast in this lifestyle.

Your Solar panel, is this going to be a permanent roof installation, or re you planning on putting it out in the sun when it suits you?

From what I see listed, don't think you can get away with anything less than 150 watts roof mounted and expect to require upto double that.

If you really insist on not feeding the house battery with the alternator, then a higher solar wattage to battery capacity ratio is needed.

 

[roadrunner]

I would rather figure on the high side than the low side on the fan, and everything else.

The electric razor is just like any other you plug in to recharge after using it, -- the specs are long worn off, as it's old but reliable. But being old it needs to stay plugged in or it won't hold a charge for long. This is where I wish I could find my Kill-A-Watt meter, as that's better than any written specs.

The laptop is 2.15 amp hours -- I snagged a cigarette socket adapter cord for it while taking it on a 10-day motorcycle trip a few years ago; (I installed a waterproof DC outlet on the MC I was riding so I could charge it on the go), so thankfully I already have that. The AC adapter for it also says 2.15 amp hours at 40 watts. There is always a possibility of upgrading to a bigger laptop one day as well, which, like yours, would draw more power.

Well I guess I will hook up the AGM to the alternator then, and get a good solenoid.

My solar panels are going to be permanently mounted on a piece of plywood. As soon as I figure out how to best put some cross-braces on the ladder rack that is up there I can paint and mount the plywood to it, (I'm hoping 3/4 will work.) Even though I want stealth, I figure one, it's high already, and two, if I run two pieces of PVC along the length of each side of the rack it will hide the panels (unless you are above it), and looks like it's hauling pipe. Besides, I've seen a few cargo vans with vents around town; no one gives them a second glance.

150 watts minimum? Well that's a little less than I would have guessed, although my power needs aren't huge. I probably will go with 300-400 watts if I can squeeze it out of my budget, as I don't want to have to add to the panels later unless I have to. I would like to get that piece of the puzzle in one shot.

 

[SternWake]

Amps is a instantaneous measurement of current
Amp hours is a measurement of current consumption over time

So saying a laptop is 2.15 amp hours is not correct. it might draw 2.15 amps, and in one hour it will have drawn 2.15 amp hours.

Your power brick will say DC output 19.5v and 2.15 amps or numbers near those, with is right around 40 watts output, but there are inefficiencies in the conversion process. Also that it the maximum that the power supply is able to supply, the actual laptop consumption can be well below that depending on the task and the state of charge of the internal battery.

By all means go with 300 to 400 Solar watts if you can fit it.

 

[Wabbit]

Here's a link that has some tools and a lot of info.


http://www.batterystuff.com/kb/tools/

 

[akrvbob]

I think you will find you'll find that you run most things less than you are thinking and many will be seasonal. You won't run the fans in the winter and if you are a snowbird you will rarely run them.

I have 200 watts on my trailer that does me fine and I and think it will meet your needs as well. Unless you want to buy the best then I suggest you get a 200 watt Renogy kit and two batteries and try it. If it doesn't meet your need I suggest you add a second 200 watt kit and another two batteries.

If you want the best I recommend a 250 watt Kyocera panel and Blue sky controller.
Bob