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Naio's avatar
Naio
Explorer II
Jun 02, 2015

Advice for my charging situation? Solar?

Hi folks -

This is for my minivan.

I have:

- 24 hour usage around 1 kilowatt, on average. Half a kw on a lazy day (which usually = a cloudy or rainy day, for me). Max I have read on the kill-a-watt meter is 1.5 so far, but some days may be more.

- 2 @ 74 aH MK gel batteries that I use during the day, in a 24 volt system. I would like to recharge them every day, morning and evening, and use them approx 11am-4pm about 2 out of 3 days.

- 1 @ about 150 aH house battery, AGM, used at night, would like to recharge each day.

- A mini freezer that I would like to run while boondocking but I don't HAVE to. It uses 77w while running (kill-a-watt) but has a big surge when starting (would need a big inverter).

- According to kill-a-watt meter, no phantom loads when freezer is off. I have no propane, so no CO2 detector, etc.

- A bad back that makes lifting a 35lb generator completely out of the question.

- Camping habits that lean heavily towards desert and beach, very little deep shade (usually none).

- Not enough money to do solar AND a genny this year.

- Experience with 12/24v systems design and debugging (before I came here, I thought I knew a lot...) and none at all with small gas engines.

So, what do y'all think?

I'm leaning towards solar, but a genny permanently mounted inside the van, under the bed, with an exhaust vent to the outside and a fuel pump running off the van gas tank is an option. My main concern there is that I know nothing about debugging and maintaining gas engines.

Solar-wise, I could mount panels on the existing roof rack, and run the wires through the window. Am thinking a solar30, 300 watts 12v panel/s, and anderson connectors that let me hook to any of my 3 batteries. Very much subject to y'all's suggestions/improvements.

I also want to run power from the alternator. But I don't drive a lot in a day, or every day. Still, it is something.

I look forward to your comments and ideas! I have been reading a lot, in other threads, but I still feel ignorant. I'd like to get something going within the next month or so.

106 Replies

  • As much as I prefer solar I think a Honda 1000 and extended run fuel tank strapped to the back might be better.

    As for solar it will depend on how many watts you can go. With a 24v battery system you can really get some power up on the roof.

    Two panels, 450 watts, $315 total

    PWM should work fine with these in parallel.
    24v controller $68
  • Naio's avatar
    Naio
    Explorer II
    The freezer stays frozen for 3.5 days without power, and cold for a few more days after that. I switched from minifridge to freezer because of the thicker insulation, and the fact that it gets so cold -- I can freeze my food and water, and then let it thaw gradually. It's been a good solution for me.

    But, after a few days I have to either go somewhere with a power plug or have limited food choices. I can, of course, live off non-chilled food for a while. It's a convenience, not a requirement. Having a freezer all the time would be luxurious :).

    The thing about adding batteries is I am right at GVW for my rig. I can prune out enough stuff to offset solar panels' or genny weight, and maybe one more battery, but I am not going to be buying them by the dozen.
  • First, I would not mount a generator inside the van. Even with the most technical enclosures possible, it will not be a good deal. Besides the safety factor, you'll have the heat and smell to deal with, not a good situation.

    Solar would be the way to go and after you have everything setup, it is an elegant solution. You should have some more battery capacity to deal with those times of limited sun or bad weather. I have five batteries inside my trailer so building enclosed battery spaces is not that big of a deal. I would suggest to figure out if you want to keep the mini-freezer and tailor your solar around that.

    FWIW, I run a dorm fridge with the same electrical draw, approximately. I have 300AH of capacity and a single 235W module. I use a Xantrex 1000W Prowatt inverter. If it looks like I will have a bad spate of weather, I can disconnect the fridge and contents will be cold for a long time. To date, I haven't done that.

    I am looking at upgrading my system, adding another 220AH of capacity and another 235W module. This would allow me to run a small A/C for a couple of hours or use other high wattage devices at my whim. Once you get free power, you just want more...
  • 1 kW is about 83 ah. That's huge! I can get about 35 ah from a 130W panel. You need minimum 400W solar and at least twice the batteries.

    Either drastically cut power consumption or get a generator.
  • Naio's avatar
    Naio
    Explorer II
    JiminDenver wrote:
    300w mounted flat will get you 15-20 Ah during peak hours


    Is that per hour or per day? If I charge from dawn till noon, and from 4 till dark, what might I see? Depends on latitude and time of year, of course. This year my concern is southern Idaho in August and Sept...
  • Solar is cool but if you have to have something dependable, get the generator first. 300w mounted flat will get you 15-20 Ah during peak hours, less off peak and very little when the sun hides. You have to have something for those times.

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