whats needed to run a car stereo?

[the fat kid]

hello all,

this solar panel stuff is slightly confusing when you get to the numbers part. so with that said, im building a cooler radio for a guy whos taking it to the river to float in the summer. basically the setup would consist of a car battery, cheap cd player, marine grade 5.25" speakers. what kind of power would i need from a solar panel to offset the drain of the radio, or at least let the battery last all day? i know the battery being new would probably run the stereo for a good 6-8 hours anyways but i was just wondering if through the use of solar if i could extend the life of the battery for roughly 12 hours.

here are some of the solar chargers i found on amazon,

http://www.amazon.com/Sunforce-52013-1-8-Watt-Battery-Maintainer/dp/B001OG68Q4/ref=pd_sbs_auto_3

thank you in advance.

[Sunking]

Without know the power demand your question is very difficult to guestimate. However that panel you linked to is worthless. You would need around a 50 to 100 watt solar panel and a controller.

[the fat kid]

what kind of info can i find to help you help me? haha

[Sunking]

what kind of info can i find to help you help me? haha

Need 4 pieces of information:

Power input requirement of equipment.
How many hours per day it will be on
Location
Time of year use

[john p]

The hardest part is finding the power requirements of the "radio"., as its usually never stated on the device.
if its a simple 12v car radio the speakers should be 4 ohms and the "radio" out put will be about 3w per ch total 6w at max volume.
But if only low listening volume is needed the average output could be 1w per ch total 2w.
But it will be on average about 1a.if it has built in CD player about 1.25 a.

[Sunking]

The hardest part is finding the power requirements of the "radio"., as its usually never stated on the device.

All listed device have power input requirements, but point taken it will be less than what is listed for calculation.

if its a simple 12v car radio the speakers should be 4 ohms and the "radio" out put will be about 3w per ch total 6w at max volume.

Yep for a 1970 Buick Regal, but for models later than say 1985 factory radios have considerable more. Even stock low end models are 40 watts +, up to 600 watts with premium factory sound packages, and pushing 3000 custom after market installs.

Point is saying a car or mobile stereo is meaningless now day.

[john p]

That was why I gave output for a "simple" car radio. Asa I felt it be unlikely he will be didmantling a newr vehicle a nd sitting all the components around a pool to use it. As some cant even be successfully removed and still used as ther are part of the dash .
It not true they always have the power requirements listed on the device. many have nothing on them except the colour codes of the wires. and the fact they are 12v.
That is why I said it hard to know the power consumption.unless you actually measure it

[green53]

Hi, not meaning to hijack this thread, but I have an alpine head unit that is rated for 18 watts X 4 channels and want to run it 8 hrs a day plus 5 LCD 12 volt lights (3 watts each) for 6 hours at a remote camp near Muskoka Ontario, usually for 2 to 3 days only. I have one 123 watt panel so far and would ask what I should add to make this work. Thanks.

[Mike90250]

Hi, not meaning to hijack this thread, but I have an alpine head unit that is rated for 18 watts X 4 channels and want to run it 8 hrs a day plus 5 LCD 12 volt lights (3 watts each) for 6 hours at a remote camp near Muskoka Ontario, usually for 2 to 3 days only. I have one 123 watt panel so far and would ask what I should add to make this work. Thanks.

Here's the math. At one point, I'll cut the power in half, since you won't be playing at FULL volume all the time

Radio
18 x4 = 72w / 2 = 36w 36W x 8 hr = 288Wh (watt hours)

Light
5 x 3 = 15W x 6 hr = 90Wh

90 + 288 = 378wh total used
378 x 2 (accounts for system inefficiencies*) =756Wh needed to harvest each day.

Panels are only 80% of their nameplate (but I already accounted for that*)

Batteries, a 12V 80ah is a common small "marine" psudo deep cycle battery, it contains:
12 x 80 = 960 wh, so you need 2 batteries, either 2, 6v golf cart batteries in series, or 2, 12V in parallel. Each battery should be at least 80 ah. each battery should be the same. Not a truck battery paired with a boat battery

Harvest, you only have 3 solar hours in winter, 5 in summer, so you can figure the summer panel size.

756Wh needed to harvest each day:

756 / 3 = 253 STC watts of panel should do it. Add a good charge controller. and fuses, you are all set.

[john p]

Mike your figures may be correct. but you can run a 4ch radio off the car battery thats in the vehicle the radio is installed in in most cases for 4 or 5 hours and no problem to start the car.
It really depends if the user is going to be listening to the music at"reasonable " volume or is a heavy metal or disco lover that needs the volume at "11."

[green53]

Thanks Mike!

[Securityxpert4u]

Ignore the watts per channel advise...look at your fuse on your head unit (RED positive power wire), should be a 20amp or maybe 30amp (on the high side). Even if it's 30, 12Vx 30 = 360watts...this is your maximum pull... at full volume! I've been pretty darn drunk on the lake and NEVER done WOT on the volume knob...50% max (but, that's just me) Take your fuse rating (whatever that is) x 12 and that will be your maximum watts that radio will pull...PERIOD!