Building a Skoolie

mcgivor · December 2016

littleharbor2 said:

mcgivor said:

For roof mounting with the dimensions given you could get 4× 250W panels, loose the front hatch add one more.
The rooftop is prime real estate, if you go with a deck, some panels on the side, over the windows which can be tilted up when parked, will shade the windows like an awning. Have the roof panels tilt to the same side and this would be the sunny side of the bus when parked.

Seems to me side mounted panels could be easily set up to pivot up and over to lay flat on the roof, although upside down, when traveling, and tilted anywhere around up to 270 degrees to the side windows of the bus. You would need to get creative with the tilt support but you would have the ability to set about any angle you want when stationary.

Actually I was thinking on one side, pivoted on top, drop down over the windows whilst on the move, with an adjustable prop to angle for optimization when parked, this way there will be some harvest whilst on the move, if the sun is on the correct side. Has anyone any knowledge regarding an altenator that could charge a 48v battery? if there is a need, a solution usually exists, somewhere, this way the battery could be charged on the move.

Estragon · December 2016

You may be able to find a 48v alternator but may be expensive. There will be more choices at 24v and lots at 12v. At 12v you could probably just add an isolator if your existing alternator is decent output.

48v is rare in mobile/marine applications, though some automakers are looking at dual 12/48v systems so maybe more choices in future. For now though you may want to rethink 48v.

mike95490 · December 2016

At the very least, you get a alternator house to replace the diodes for higher voltage, or just hope the stock voltage holds out, and run the regulator (on your house alternator) up to 48V.
Worst worst case, install a 2nd alternator, and small battery, and power an inverter to run a 48V charger

oil pan 4 · December 2016

An alternator can not develop 48 volts at idle.
So it would likely only charge while driving down the road.
My DR44G truck alternator turned into a welding alternator. It can only develop 30 volts at idle speed at full armature power.
This is a heavily modified automotive alternator that has external rectifier that develops almost 90v.
I have a plan to turn this into a 48v battery charger at some point.
An automotive alternator can be used to charge a 48v bank it just needs to be modified.
Some automotive alternators have rectifiers that can take 48v, but this appears to be the exception and not the norm.

mcgivor · December 2016

oil pan 4 said
:

An alternator can not develop 48 volts at idle.
So it would likely only charge while driving down the road.
My DR44G truck alternator turned into a welding alternator. It can only develop 30 volts at idle speed at full armature power.
This is a heavily modified automotive alternator that has external rectifier that develops almost 90v.
I have a plan to turn this into a 48v battery charger at some point.
An automotive alternator can be used to charge a 48v bank it just needs to be modified.
Some automotive alternators have rectifiers that can take 48v, but this appears to be the exception and not the norm.

How about using a permanent magnet alternator like the ones used on wind turbines?
http://www.hurricanewindpower.com/48-volt-permanent-magnet-alternator/

oil pan 4 · December 2016

Those don't have have voltage regulation and they are not designed to spin at normal alternator speeds.

mcgivor · December 2016

oil pan 4 said:

Those don't have have voltage regulation and they are not designed to spin at normal alternator speeds.

A MPPT controller can take care of regulation and pulley size could control rotation speed

oil pan 4 · December 2016

If the alternator over speeds and makes too much voltage it will fry the controller, then what mppt controller can stand under hood temperatures?
Alternator voltage regulators that go under the hood are rated to around 200°C.

Then where do you think you are going get alternator and crank pulleys that will take the 1 to 3 alternator over drive down to more like a 10 to 1 reduction?

I would use a conventional alternator modified for higher voltage. Since I already know it works.

Anyone who wants to waste time and money trying to make a wind turbine PMA into a higher voltage automotive alternator is more than welcome to.

mcgivor · December 2016

Wouldn't suggest mounting the controller in the engine compartment and reduction is possible with a little thought. Just ideas, not trying to argue the point, have read on Morningstar site that the MPPT could be used as a regulator but not PWM.

mike95490 · December 2016

mcgivor said:

Wouldn't suggest mounting the controller in the engine compartment and reduction is possible with a little thought. Just ideas, not trying to argue the point, have read on Morningstar site that the MPPT could be used as a regulator but not PWM.

It can e used as a regulator on a power supply or a battery. But an alternator is a different beast, and maybe if it's configured for WIND mode instead of solar, it could work without killing the alternator. But I worry that trying to lug down an alternator with a MPPT controller, would not be good for the alternator.

mcgivor · December 2016

mike95490 said:

mcgivor said:

Wouldn't suggest mounting the controller in the engine compartment and reduction is possible with a little thought. Just ideas, not trying to argue the point, have read on Morningstar site that the MPPT could be used as a regulator but not PWM.

It can e used as a regulator on a power supply or a battery. But an alternator is a different beast, and maybe if it's configured for WIND mode instead of solar, it could work without killing the alternator. But I worry that trying to lug down an alternator with a MPPT controller, would not be good for the alternator.

Yes you are correct it was an MPPT controller that can be used with a power supply, not PWM. Anyhow I think I have gone off on a tangent from the OP'S questions with oddball ideas, perhaps it's better to rewind to his solar needs for now. So rewind with the altenator option edited out.

mcgivor said:

littleharbor2 said:

mcgivor said:

For roof mounting with the dimensions given you could get 4× 250W panels, loose the front hatch add one more.
The rooftop is prime real estate, if you go with a deck, some panels on the side, over the windows which can be tilted up when parked, will shade the windows like an awning. Have the roof panels tilt to the same side and this would be the sunny side of the bus when parked.

Seems to me side mounted panels could be easily set up to pivot up and over to lay flat on the roof, although upside down, when traveling, and tilted anywhere around up to 270 degrees to the side windows of the bus. You would need to get creative with the tilt support but you would have the ability to set about any angle you want when stationary.

Actually I was thinking on one side, pivoted on top, drop down over the windows whilst on the move, with an adjustable prop to angle for optimization when parked, this way there will be some harvest whilst on the move, if the sun is on the correct side.

sasquatters · December 2016

Hello again guy. I have decided that without a doubt I am going to go with one of these two refrigerators. Leaning more towards the Fisher & Paykal one because it is shorter.

LG - LBN10551SW

$719
5’7”
10 cu. ft.
430kwh/yr

Fisher & Paykel - RF170BRPW6
$1749
5’6”
17.5 cu. ft.
454kwh/yr

I was watching this video earlier and they plug their refrigerator into a kill-a-watt meter. The refrigerator turned on at 93w but then quickly went down and hovered around 50-60w. Their refrigerator is a Haier Bottom Mount using 428kwh/yr.

Comments? Does it seem like I will still need a 3000+kw solar setup?

westbranch · December 2016

Please be aware that the consumption /yr decreases yearly(?) on each new model made, it is mandated by the government(s). There are 3 tiers IIRC... We got a GE 18 cu ft top freezer fridge with 319Kwh/yr in Sears 2 years ago... don't know what they might be down to now...
That height constraint may be a killer... good luck

mcgivor · December 2016

sasquatters said:

Hello again guy. I have decided that without a doubt I am going to go with one of these two refrigerators. Leaning more towards the Fisher & Paykal one because it is shorter.

LG - LBN10551SW

$719
5’7”
10 cu. ft.
430kwh/yr
Fisher & Paykel - RF170BRPW6
$1749
5’6”
17.5 cu. ft.
454kwh/yr

I was watching this video earlier and they plug their refrigerator into a kill-a-watt meter. The refrigerator turned on at 93w but then quickly went down and hovered around 50-60w. Their refrigerator is a Haier Bottom Mount using 428kwh/yr.

Comments? Does it seem like I will still need a 3000+kw solar setup?

Whatever the choice the consumption based on annual Kwh rating are all close, it comes down to personal preferences regarding size, dimensions, needs and brand reputation. With real life experience my refrigerator as the only load, same Kwh rating, with an inverter self consumption of 0.4Kwh per day (2000 W inverter, no sleep mode) and regular useage, open close, has a consumption of 1.6Kwh per day average, tracked over a 2 week period, including all system losses.This figure could be reduced if I went with a 300W inverter with sleep mode as it is an inverter type refrigerator, no inrush on start up, you would need a larger one as none of the models listed appear to be, so a larger inverter is needed, say 1000W but this is only for the refrigerator, no other loads.

So combine all other loads, time of use and come up with a Kwh figure add 30% for safty margin, add that to the refrigerator demand and a calculation of battery capacity and array size can be caculated, taking into consideration depth of discharge and days of autonomy etc. There are smart people here who can help but they all need numbers to work with.

Comments? Does it seem like I will still need a 3000+kw solar setup?
Think 3Kwh was meant.

sasquatters · December 2016

I am still unsure what numbers you are referring to. I though I have given all requested information.
Thanks.

Estragon · December 2016

One number we don't know is the starting current for the fridge. Inverter type fridges ramp up slowly, but most ac fridges have a large surge current to start the compressor, and the inverter has to be able to handle the surge. Unless otherwise stated a fridge in the US is likely that latter type. A 1500w pure sine wave inverter with decent surge probably.

mcgivor · December 2016

Assuming an effciant refrigerator uses 1000Wh per day or there about, the compressor would be somewhere around 100W, so based on that, the inrush may be in the region of 9A for a few milliseconds, any reasonably good quality 1500W PSW inverter should cover that.

sasquatters · January 2017

The Haier Bottom Mount fridge that I mentioned above, when plugged in for the very first time started at 90w and quickly (within a minute or two) worked its way down to 60w

Estragon · January 2017

Haier linked doesn't say, but looks like it could be an inverter type. "Fast cool" feature sort of suggests variable speed. Non-inverter start would like be much higher than 90w.

mcgivor · January 2017

sasquatters said:

The Haier Bottom Mount fridge that I mentioned above, when plugged in for the very first time started at 90w and quickly (within a minute or two) worked its way down to 60w

What was used to measure the wattage, my observations when testing an inverter refrigerator was that the current ramps up to a maximum then tapers down as the setpoint is reached, using a clamp on ammeter. When set to inrush there was no capture, if a Kill-a-watt meter was used perhaps it took the inrush into account and averaged the watts, have never used one so have no idea off its sampling rate or how it calculates it's measurement, someone who has had experience with one may be able to shed some light on that.

mcgivor · January 2017

To answer my own question I did a little research, it turns out that the Kill-a-watt cannot take the inrush current into account, the initial higher reading of 90w is probably the initial higher load during pressurieation and once stable drops to 60W. FWIW

mike95490 · January 2017

Estragon said:

Haier linked doesn't say, but looks like it could be an inverter type. "Fast cool" feature sort of suggests variable speed. Non-inverter start would like be much higher than 90w.

To measure the half second starting surge you need a $400 Peak Hold Amp meter. Or a 200w inverter and then you find it won't work.

mcgivor · January 2017

mike95490 said:

Estragon said:

Haier linked doesn't say, but looks like it could be an inverter type. "Fast cool" feature sort of suggests variable speed. Non-inverter start would like be much higher than 90w.

To measure the half second starting surge you need a $400 Peak Hold Amp meter. Or a 200w inverter and then you find it won't work.

Which is exactly what I did, using a $400 peak hold ammeter on an inverter refrigerator , no inrush, the current increased slowly as the compressor reached its maximum for fast cool, about 150W, then dropped to a level to maintain the setpoint, around 60W. So I highly doubt the Haier is an inverter unit, but is an efficient unit none the less.The issue is the inrush and a 1500 plus watt PSW inverter of reasonable quality should be sufficient.

Horsefly · January 2017

Just for what it is worth, I don't think you need to spend $400 to get something that will catch the inrush current. I bought this one from Amazon to find the inrush on my well pump (discussed in another thread):

http://www.amazon.com/gp/product/B019CY4FB4

It has a min/max setting which was able to catch the inrush every time.

sasquatters · January 2017

So far it definitely seems as though a 1500w inverter will be used.

Has anyone see the products from GrapeSolar?
http://www.grapesolar.com/docs/GS-S60LSQ-285-PR.pdf
http://www.grapesolar.com/docs/GS-P60-265-Fab2.pdf

They seem like really high efficiency panels.

sasquatters · February 2017

It's been a while but I have found some information.

Fridge. - 454kwh/yearly (24 hrs)
8x Light bulbs - 9w (5 hrs not all on at once)
Modem - 11.40w (24 hrs)
TV - 54w 135w max (5 hrs)
LP Water Heater - 10w (24 hrs)
Computer - 12w - 18w on load - 60w when charging
x8 Light switch - 0.59w
x16 Outlet - 0.75w

I called our electric company today and they said that we average 4kw a day. This is with the TV on for 15 hours (for work), PC, and server running 24/7, old decrepit water heater, and an older refrigerator.

Hope this helps more.

sasquatters · March 2017

bump?

Estragon · March 2017

What is the question?

Building a Skoolie

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