Inverter and solar charge controller project Burning Man for art car

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Inverter and solar charge controller project Burning Man for art car

David Chapman-9
Hi all,
Working on a little project for my trip to Burning Man and I am a little out of the loop lately on whats on the market, hoping my friends on the EVDL will chime in with recommendations. 

Mission: control 3 x 12V 15W solar panels to charge a couple of my 24 V flooded Nicad battery packs to supply an inverter capable of supporting max 15 amp 115 Vac load (intermittent charging art car and playa bike batterys and running computer) . I will be running 2 - 12 Vdc small portable evap coolers (20 W ea max) during the day and can throttle back the draw to 12 watts each at night. 

I already have 3 matching solar panels I bought and am considering finding a matching 4th (these came from Checker when they went to O'Reillys). I think these are something like 20 watts each, so I am thinking that I need more power. Am also considering building up a slightly bigger / more efficient array out of some of the new cells being sold on ebay now. 

So any recommendations for a reasonably priced inverter (2000 W ?) that is totally sealed for dust and a 24vdc charge controller for the battery pack (2 X 17 amp/hr 24 V packs)? Or a computer rated inverter that contains a charge controller and is environmentally sealed?

I will include a provision for 24 Vdc to charge battery packs that are suitable voltage.  

Trying to keep this project compact, sane and not over built / over budget. Thanks for any input. David Chapman.
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Re: Inverter and solar charge controller project Burning Man for art car

Lee Hart
David Chapman wrote:
> Working on a little project for my trip to Burning Man...
> Mission: control 3 x 12V 15W solar panels to charge a couple of my 24
> V flooded Nicad battery packs to supply an inverter capable of
> supporting max 15 amp 115 Vac load (intermittent charging art car and
> playa bike battery and running computer). I will be running 2 - 12
> Vdc small portable evap coolers (20 W ea max) during the day and can
> throttle back the draw to 12 watts each at night.

If you have DC, it's probably best to run as much as you can right off
the DC. The evaporative cooler just needs a fan, no compressor? Then it
can use a 12v or 24v motor. Can the computer be a laptop, which can also
run on DC.

You need 120vac for your art car project? How good an inverter you need
depends heavily on exactly what kind of load it is. A cheap crappy
inverter is OK for non-critical loads, but you need a really good
inverter to start large motors or other fussy loads.

It's going to be mighty hard to find a 2kw inverter that doesn't have a
fan blowing dust right across all its PC boards. The ones good enough to
survive in hot dusty conditions will be expensive!

If this is just for a one-off project, how about a motor-generator? A DC
motor running off your battery pack, spinning an induction motor with
capacitors across its output to work as an induction generator. Not
particularly efficient, but cheap and nearly indestructible.

> I already have 3 matching solar panels I bought and am considering
> finding a matching 4th

For short-term use, consider using mirrors as solar concentrators.
Double the light, and (almost) double the output. But it makes the
panels run hotter, and shortens their life. That's important for a
permanent installation, but doesn't matter much for a week.

--
*BE* the change that you wish to see in the world.
        -- Mahatma Gandhi
--
Lee A. Hart, 814 8th Ave N, Sartell MN 56377, leeahart at earthlink.net

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Re: Inverter and solar charge controller project Burning Man forart car

Cor van de Water
In reply to this post by David Chapman-9
The amount of solar power appears to be woefully short of
supplying the need for even the coolers alone.
The 20W or so solar panels are probably capable of
delivering around 1.2 Amp into a 12V battery and unless
you baby-sit the orientation, they won't give you more
than 5-6 full sun hours a day, so that is a max of
6 hours x 1.2 Amp x 3 panels = 21.6Ah at 12V.
I don't know how you connect 3 12V panels to a 24V pack,
maybe you run a DC/DC converter, but at max you can get
10.8Ah into the 24V bank which is about 260Wh.

The coolers each draw 20W and even if you throttle them
back to 12 at night, then each cooler draws:
12h x 20W + 12h x 12W = 240 + 144 = 384 Wh

So you can see that each cooler will already overwhelm
your entire solar setup.

My preference is to try and avoid the use of the inverter
for as many loads as possible.
Maybe you can't run the computer directly from the battery
but a DC/DC from 12V to 19V to feed directly into the PC
is much more efficient and cheaper (need to cut only the
cord off a broken charger and get a cheap adjustable DC/DC)
and even dropping the 24V to 19V with a linear regulator is
likely more efficient than running an inverter into the
laptop AC supply.
This of course is not possible with all loads, if there is
an AC charger that also has the correct charging profile
for its batteries then you need to feed that charger
what it expects.

Consumption of a laptop might be around 40W but the addition
of the inverter may double the draw from your batteries,
So if you ar eOKK with using the computer intermittently
and not accounting for additional loads to charge other
(bike) battery packs, then just the two coolers and occasionally
switching the inverter on will mean a minimum of 1000Wh per day
and to assume that you are not baby-sitting your panels all day,
they should probably be capable of delivering at least 200W for
5 hours to achieve that amount of energy. Add more loads and
you'd need more solar. Remove a cooler and you need less...

BTW, most solar chargers these days are automatic 12/24V switching
so you just hook them up and they figure it out.

Hope this helps,

Cor van de Water
Chief Scientist
Proxim Wireless Corporation http://www.proxim.com
Email: [hidden email]    Private: http://www.cvandewater.com
Skype: cor_van_de_water     XoIP: +31877841130
Tel: +1 408 383 7626        Tel: +91 (040)23117400 x203

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of David Chapman
Sent: Monday, June 18, 2012 10:45 AM
To: Electric Vehicle Discussion List
Subject: [EVDL] Inverter and solar charge controller project Burning Man forart car

Hi all,
Working on a little project for my trip to Burning Man and I am a little out of the loop lately on whats on the market, hoping my friends on the EVDL will chime in with recommendations. 

Mission: control 3 x 12V 15W solar panels to charge a couple of my 24 V flooded Nicad battery packs to supply an inverter capable of supporting max 15 amp 115 Vac load (intermittent charging art car and playa bike batterys and running computer) . I will be running 2 - 12 Vdc small portable evap coolers (20 W ea max) during the day and can throttle back the draw to 12 watts each at night. 

I already have 3 matching solar panels I bought and am considering finding a matching 4th (these came from Checker when they went to O'Reillys). I think these are something like 20 watts each, so I am thinking that I need more power. Am also considering building up a slightly bigger / more efficient array out of some of the new cells being sold on ebay now. 

So any recommendations for a reasonably priced inverter (2000 W ?) that is totally sealed for dust and a 24vdc charge controller for the battery pack (2 X 17 amp/hr 24 V packs)? Or a computer rated inverter that contains a charge controller and is environmentally sealed?

I will include a provision for 24 Vdc to charge battery packs that are suitable voltage.  

Trying to keep this project compact, sane and not over built / over budget. Thanks for any input. David Chapman.
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Re: Inverter and solar charge controller project Burning Man for art car

Mike Willmon
In reply to this post by David Chapman-9
Although I really like the Trace (now Xantrex) C-40 for flexibility (and
durability) from 12/24/48V systems, I have used these two from Morningstar
on both 12V and 24V systems
http://www.amazon.com/Morningstar-PS-15-ProStar-Charge-Controller/dp/B002MQNAIO

http://www.morningstarcorp.com/en/pro-star

and
http://www.civicsolar.com/product/morningstar-ss-10l-24v
http://www.morningstarcorp.com/en/sun-saver


I would also agree with Cor,  you're gonna need larger panels, or else
expect intermittent run time for your planned loads.  Is it windy out there
in Black Rock city?  small wind turbines are more eco-nomical in $$/watt
than solar.


On Mon, Jun 18, 2012 at 9:45 AM, David Chapman <[hidden email]> wrote:

> Hi all,
> Working on a little project for my trip to Burning Man and I am a little
> out of the loop lately on whats on the market, hoping my friends on the
> EVDL will chime in with recommendations.
>
> Mission: control 3 x 12V 15W solar panels to charge a couple of my 24 V
> flooded Nicad battery packs to supply an inverter capable of supporting max
> 15 amp 115 Vac load (intermittent charging art car and playa bike batterys
> and running computer) . I will be running 2 - 12 Vdc small portable evap
> coolers (20 W ea max) during the day and can throttle back the draw to 12
> watts each at night.
>
> I already have 3 matching solar panels I bought and am considering finding
> a matching 4th (these came from Checker when they went to O'Reillys). I
> think these are something like 20 watts each, so I am thinking that I need
> more power. Am also considering building up a slightly bigger / more
> efficient array out of some of the new cells being sold on ebay now.
>
> So any recommendations for a reasonably priced inverter (2000 W ?) that is
> totally sealed for dust and a 24vdc charge controller for the battery pack
> (2 X 17 amp/hr 24 V packs)? Or a computer rated inverter that contains a
> charge controller and is environmentally sealed?
>
> I will include a provision for 24 Vdc to charge battery packs that are
> suitable voltage.
>
> Trying to keep this project compact, sane and not over built / over
> budget. Thanks for any input. David Chapman.
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Re: Inverter and solar charge controller project Burning Man forart car

Mike Beem
In reply to this post by Cor van de Water
I use one or two 75 watt panel(s) [left over from my home PV installation]
to keep a Group 31 size battery supplying a 1000 watt inverter running lots
of different things when I need to go "portable solar". One example is that
I have run sound systems for outdoor weddings and events using this. I keep
a digital meter on the battery to monitor voltage, and my hand to monitor
temperature.
Michael B

On Mon, Jun 18, 2012 at 11:35 AM, Cor van de Water <[hidden email]>wrote:

> The amount of solar power appears to be woefully short of
> supplying the need for even the coolers alone.
> The 20W or so solar panels are probably capable of
> delivering around 1.2 Amp into a 12V battery and unless
> you baby-sit the orientation, they won't give you more
> than 5-6 full sun hours a day, so that is a max of
> 6 hours x 1.2 Amp x 3 panels = 21.6Ah at 12V.
> I don't know how you connect 3 12V panels to a 24V pack,
> maybe you run a DC/DC converter, but at max you can get
> 10.8Ah into the 24V bank which is about 260Wh.
>
>
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