Hinged solar panel on luggage rack + 120AH battery

[fxr]

Yet another Aux battery thread.

This is one of those 'rabbit hole' projects...

It all started when Mrs fxr announced she wanted an extra cool box for veggies. No, she didn't want a extra fridge, or a $500-$900 compressor cooler, but a $45 20 litre Peltier effect coolbox. It had been ordered - so please arrange it so it can be powered.

OK, so we already had a 35AH aux battery and a Renogy 100W suitcase solar panel, with the GW solenoid combiner. This was fine for our needs of USB charging, lighting and music etc - but no way would it suffice for the 4A over at least 12 hours that the Peltier effect cooler would want.

What was needed was another solar panel, and a big-arse battery.

Having measured the $86 Walmart 120Ah group 29 deep-cycle battery I realised it'd fit sideways under the bench seat as long as it had a 5cm platform to rest on. This minimised the storage space that would have to be lost, phew.

Next, what panel - I wanted the suitcase to remain transported in the luggage rack, so decided on the slimline Renogy 100W panel, secured to the rack using these hinges:

I re-purposed the GW solenoid to connect the new battery to the alternator output, and a Blue Seas combiner to connect to the old 35Ah battery under the driver's seat. The solar panel output is fed to the re-used suitcase PWM Viewstar controller, whose output is connected to the 35Ah battery, as that'll get its volts up quickest.

I used 3-pin audio XLRs to feed the new cooler, with two outlet positions, one in the front of the bench, and one accessible through the license-plate door at the rear. The third pin is for the suitcase panel to connect to, feeding in parallel with the new panel on the roof.

_________________
Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300

[hdenter]

I like your set up with the panel over the luggage compartment. How is it for wind noise while driving? Does it cause more noise or whistling because the panel is a little higher than the roofline or does it maybe quiet things down by reducing the amount of air that buffets around in the luggage box when it is empty and open?

Hans
_________________
'79 triple white convertible bug
'84 sunroof vanagon
'85 weekender

[jimf909]

Nice hinges. I love finding good hardware that meets a need.

Good write up!
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- Jim

[Gizmoman]

Very slick
_________________
82 Vanagon Westy - AAZ 1.9 TD, HE200 Holset, WAIC, 27.75 dia tires, Electric power steering, 5-speed AAP w/.078 5th
Oversize spare carrier - stock location (no longer for sale).

[dobryan]

I use those hinges for my panel as well. They truly are quick release so when I get to a camp and desire to move the panel from the roof I can do so easily. Those hinges have several years on mine and they look like new. I use the hinges as bracket mounts, not hinged per se.
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Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

MD>Canada>AK>WA>OR>CA>AZ>UT>WY>SD
https://www.thesamba.com/vw/forum/viewtopic.php?t=620646

Building a bus for travel in Europe (euroBus)
https://www.thesamba.com/vw/forum/viewtopic.php?t=695371

The Western Syncro build
https://www.thesamba.com/vw/forum/viewtopic.php?t=746794

[singletrackrod]

The downside is you will have to park in the sun, not the shade, and move the van as the sun moves. Just my two cents.
_________________
Ella '89 Full Camper - bit by bit I'm importing the pieces from my wrecked '87
Louise '87 Full Camper - bought her new - zero hours 2.5L subie conversion. She had more add-ons and mods than I could ever count. (lost in an accident 10/25/2020)
'08 Stage 2 STI (sold)
'04 Forester XT
'00 4Runner Limited (sold)

[fxr]

[TommyBoyGomes]

The mounting solution looks good. Here are some other recommendations:

- Running a load that consumes 4A for 12 hours a day (the cooler) is a big ask for these small solar systems. In perfect conditions in full sun, your 100W panel might only generate 4-5A. This means that you'd be putting barely any amps into your battery as long as the cooler is on. Even though they're more expensive, a compressor cooler is the better tool for the job since it consumes less amps.

- Be aware of voltage drop across wires at all times. I would change the cables between your battery and the charge controller (and your XLR plugs) to much thicker cable (like 6AWG). Do some voltage drop vs cable length vs guage calcs to determine what gauge you'd need. Losing even .1 or .2V over cabling means a lot to these small systems.

- Ensure that you can adjust the voltage output from your charge controller to match the charging voltage that the battery wants. For example, if your battery wants to be charged at 14.3V, charging it at a lower voltage increases the time before fully charged significantly. When you only get 5-6 hours of full sun a day, this can be an issue. Plus, with the way those small charge controllers are programmed, odds are good that you'll be undercharging your batteries. This trashes their capacity in no time.

Just some things to think about to get the most out of your system.
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1969 Squareback, 1776cc
1990 Vanagon Multivan

[E1]

^^^ This, on all points ^^^

So far as having roof-mounted panels removable, YES! We have a 120 watt portable, charging two 100aH AGMs, with an extra 25-foot extension cord when needed, and the two primary reasons we went for a portable are to:
-- Get out of parking in the sun!
-- Angle the panel to sun-square adds at least 0.5 volts!

I've had about 1,000 days of real-world testing, so these are not theories.
_________________
‘84 Westy, 2.1L with Digijet, 5.43 R+P, GT Gears
"Adding power makes you faster on the straights.
Subtracting weight makes you faster everywhere."
— Colin Chapman

[crazyvwvanman]

The solar wiring is carrying 5-6 amps max for 100w with a PWM controller. For this current 10awg is plenty between the controller and battery, at reasonable wiring length. Controller should be placed as near to the battery as is practical in any case.

To know what is going on with charging you need to be able to measure the AMPS flowing. Voltages are helpful but insufficient.

Mark

[Vanagon Nut]

Thanks for posting pics of your install. I've long wondered about a hinged panel at the luggage rack.

Neil.
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1981 Westy DIY 15º ABA

1988 West DIY 50º ABA

VE7TBN

[TommyBoyGomes]

[crazyvwvanman]

But you don't lose anywhere near .1-.2 volts more with 10awg versus 6 awg, assuming the controller is kept reasonably near the battery like we agree should be done. I would like the controller within 2-3 feet but lets use 5 feet as an example. Assume 6 amps from the 100w panel, really a little less.
With 5 feet of wires between the controller and battery, using a 100watt panel the extra wiring loss is tiny.

For example starting with 14.30 volts at solar controller battery connections-
#6 wire would get 14.28 to the battery
#10 wire would get 14.24 to the battery

I doubt that 0.04 volt makes a difference in anyone's van lifestyle.
I would worry about real problems instead.

Mark

[fxr]

^^^^ This.

I used two 2 ft lengths of #10 to connect controller to battery (pos and neg). New panel has #10 feeding the controller - the negative is directly via the chassis. The outlets (and spare suitcase connections) are via #14 - quite adequate for what they are required to deliver.

The big new 120Ah battery has 4 ft of #8 connecting it to the alternator.

Everything performs as expected, and is more than adequate to keep Mrs fxr's veggies cool enough.
_________________
Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300

[Steve M.]

Is the black Renogy case waterproof?
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This free advice is worth exactly what you paid for it.

There are seven days in a week. Someday is not one of them.

[fxr]

[TommyBoyGomes]

[fxr]

The system has been well tested in a 3,000-odd mile trip to Baja and back. I have to report it worked even better than I had hoped.

One thing that might help others - the Renogy suitcase and slim 100W panels perform far better in parallel than in series when using the original suitcase Viewstar converter.
_________________
Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300