YAVAWD - Yet Another Vanagon AUX Wiring Diagram - Fuses?

[zandr]

It's difficult to tell what's going on from your schematic since you're inconsistent about showing grounds and negative leads, but...

The dual relays really bother me. If you're going to use two relays, I suppose it's safer to wire the coils in series, because then you'll be protected against one possible failure mode. But it seems more likely that the high current side will fail (even partially - high contact resistance) and the other relay will end up carrying all the load. Since you'd then have a 60A relay in a circuit fused at 100A, you could have a problem.

If you're going to insist on two relays, rather than a single properly sized relay, at least fuse them independently.

If your only expectation of the solar panel is to keep the battery topped up while storing the vehicle, you might be OK. 30W isn't going to extend the run time of your system while camping at all.

I admire the ingenuity of using the solar controller's low-voltage disconnect to shed load from the house system. The inverter isn't connected that way, and might well have non-trivial current draw even when "off". Something to keep in mind. If you're going with giant relays already, I'd use one there.
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'87 EJ22 Full Westy "Hamish"

[RBEmerson]

Yes, you need all three 100A fuses. Although I'd look at the loads again; 100A seems a little high.

You need to guard your power sources with fuses, as you did.

By contrast, VW doesn't guard any of the three wires to the main battery. If the battery-starter lead wears through, bye-bye Westy. And probably ditto for the two leads to the fuse panel and aux. battery.

So, yes, ya done good to think about the fuses needed. Just tune their sizing a bit.

Something to research: if you're going to get serious about using solar modules, look into MPPT controllers (MPPT is a technology, not a brand).

[soap box mode] I am skeptical of many of the solar module projects seen here. Coming from an environment (marine cruising) where 200W modules are now pretty much the bare minimum, and 400W module sets are common, even 80W strikes me as wishful thinking.

Basic rules for any module (regardless of size): 1) keep it square to the sun as long as possible but certainly during local mid-day, 2) keep it cool, 3) keep it clean, 4) there's MPPT and there's a waste of money and effort.

The best power concentration is always when the panel is perpendicular to the sun's rays. Anything less and the same power is spread over a larger area or, inverting, less power on a fixed area. When the sun is at its highest, the light passes through less of the atmosphere than at sunrise or sunset. The shorter path through the air means less power is lost. The best period for solar power is around local noon on the summer solstice (sun is at its highest, the day is the longest), the worst is the winter solstice (lowest sun at local noon, shortest day).

The cooler a module is, the more efficient it is. Sunlight heats up panels. Cooler ambient air (or at least cooler air circulating under a module) helps. This is just one of those contradictions in life: the sunlight you want heats the module the way you don't want.

A dirty module is an inefficient module. Given even a good module is only about 18% efficient(!), dirt on the module isn't going to help raise that number. It will drop the number. A lot.

MPPT (maximum power point tracking) is an electrical slight of hand developed to force a module to operate in its electrical sweet spot. (For those who want to catch up on their sleep, Google on MPPT and how the module is tricked into working at the knee of its power curve. If that doesn't put out the lights, call an anesthesiologist.) What matters is not using an MPPT (technology) controller with modules of any real size is literally wasting power and money. An MPPT controller won't beat the laws of thermodynamics, but it'll find a lot more power in your solar module system than anything else.

Finally, if you can fold, bend, or roll up your fave module, please do so forthwith. It'll take up less space in the recycling bin where it belongs. Honest, of all the solar modules, thin-film modules are, by far, the least efficient. If you can't go for monocrystalline panels or polycrystalline panels, save your money for them and, in the mean time, work on optimizing your existing power system. Money spent on thin-film modules is money wasted. Honest. They look cool and the flexible panel seems neat but... see item 1) above. If the module isn't flat and square to the sun, you're not getting all you can from your module investment. And no thin-film module can flex and remain fully square to the sun. [/soap box mode]
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Lord, give me coffee to change the things I can change, and wine to accept the things I can't change.

[whynotvw]

[kamzcab86]

[RBEmerson]

[crazyvwvanman]

Most Westy people are using solar to supplement their needs, not to go completely off-grid for any extended period. The few people wanting to stay completely off-grid need more capacity, naturally.

But no matter how much of the Westy roof you cover with solar panels and no matter how much you fill the storage areas with heavy batteries there can still be circumstances under which you will not have enough of either. So the real issue is planning and balance. You have to balance the usefulness of having MORE of something with the downsides of carrying more of it. And then plan to live under the limitations that will always exist.

Mark

[whynotvw]

[sunkid]

Pardon me for reviving an old thread, even if it is my own...

Finally getting to putting it all back together here and am running into many mysteries of wiring done by previous owners. I was planning to hook my AUX battery up as described here, for example, but that would only power the cigarette lighter. Interior lights and clock were off with my main battery disconnected. If I hook up the AUX directly to an interior light, I have power on fuses 1-4 regardless of which I pull out.

Looking at the big B plug that should have pins 11 and 12 connected to cigarette lighter and clock/lights respectively, it is actually missing the #12 connector.

Any help or advice on how to best figure out what is going on here would be greatly appreciated.