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 =3D 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 =3D 240 + 144 =3D 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: xxx@xxx.xxx 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: xxx@xxx.xxx.edu [mailto:xxx@xxx.xxx.edu] On Behal=
f 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 fo=
rart car
Hi all,
Working on a little project for my trip to Burning Man and I am a little ou=
t 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 flo=
oded Nicad battery packs to supply an inverter capable of supporting max 15=
amp 115 Vac load (intermittent charging art car and playa bike batterys an=
d running computer) . I will be running 2 - 12 Vdc small portable evap cool=
ers (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 thi=
nk these are something like 20 watts each, so I am thinking that I need mor=
e 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 ch=
arge controller and is environmentally sealed?
I will include a provision for 24 Vdc to charge battery packs that are suit=
able 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: [EVDL] Inverter and solar charge controller project Burning Man forart car
Linear Mode
