solar panels + battery bank + 12v splitter + dash cam

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i bought two of these 5W panels from cabelas when they were on sale: http://www.cabelas.com/product/Sunfo...ger/747062.uts
i have the panels on the shelf behind the rear seats of my sedan. the panels easily produce enough to top off the 12v battery in full sun, and even on cloudy days. the panels have a blocking diode built in. however, i park my car in a commercial garage and the light is only sufficient to produce between 6.5-9.5 volts each, obviously insufficient to keep the 12v battery charged. so i am trying to think of a simple way to power a mobius dashcam off of these panels and a battery bank without being wired into the car's electrical system when the car is off <i dont believe i will have a problem plugging in when the car is on, if necessary, although the panels say not to have them plugged in when the car is running for some reason>.

im not sure of the answer to this question: if i am only producing 6.5-9.5 volts with each panel, and i hook the male 12v plugs on the panels to a 12v splitter/adapter like this https://www.ebay.com/itm/201134913558 or like this:http://www.amazon.com/cigarette-ligh..._cd_ql_qh_dp_t and then take a 5v usb battery bank like this <or larger/better>:http://www.amazon.com/RAVPower-6000m...dp/B007HUTXV8/and have this battery bank hooked to either the 12v 3 way splitter via a usb adapter in the splitter's 3rd female socket, or the splitter/adapter from amazon which already has a usb hookup... is this going to be sufficient voltage to charge the battery bank? i do not want to plug the splitter/adapter into the car's electrical system at all, because im thinking <not sure> that the solar panels churning out between 6.5-9.5 volts is enough to power the 5v usb ports to power the battery bank, which i would in turn use to power my 5v usb dashcam... i guess the simple version of the question is, do i need a full 12v of input to get the usb adapter to push out a measely 5v via the usb port? and also, is the 12v splitter/adapter still going to function if it's male connector is not in use?

i believe i may have a concern when it comes to the amount of current produced by the panels and i am not sure how to measure it. specs on the panel say its capable of 5W at 15v x 350mA. like i said, i can only get 6.5-9.5v in the garage, and i am unsure how to measure the current <though i do have a craftsman meter supposedly capable of reading DCA at 10A and 200m>

i really just want to keep the whole 'system' off my car's electrical system when the car is not on since the car is kind of finnicky, it gets cold here, and i cannot get the panels producing over the 12V hump without connecting them in series <which is not an option for me>.

TIA
 
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The $20 panels are only 1.8W according to the page you linked. That means you can get around 120-150 mA depending on whether the panel outputs 12V or 15V. At less than 10V, you'll get much less current and possibly not enough power to even run the 12V to 5V USB converter, let alone have it charge a power bank too. Those splitters are not built with efficiency in mind, since they expect the lighter plug to deliver stable high current 12V power. Also, given the capacity of the power bank, it'll probably take several days of full sunlight to recharge the power bank. I'm not sure which dashcam you plan on using, but I think many of them need at least 350mA continuous and possibly double that on startup or with screen on. Basically, the two panels running at half voltage will not likely provide enough power to recharge the power bank to run a dashcam for very long if at all.

KuoH
 
the 5 Watt panels were on sale for $20 when i bought it a few months back. they are like $60each at cabelas now <i will change the OP to avoid confusion>. each panel is 5W and supposedly 350mA @ 15V. i am definitely limited to 6.5v-9.5v in my garage, but i was thinking i could just slip the male end of the splitter into the car's electrical when i am actually driving. I think that would help keep the battery bank up.

do you <or anyone else> know of an efficient 12v splitter ? and also a 5v regulator that is going to run efficiently with under 12v input? i know there are some 5v regulators that will run efficiently with like 7v input, but the problem is that i really do not have the experience to create one myself and i am not really seeing much of anything in the way of written specs.. i have the 12v socket to usb adapter that came with the Mobius <which is the cam i have>.. at the moment i do not have a 12v splitter or a battery bank to try out my idea.
 
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Somebody else might be able to chime in on the Mobius power requirements, if not, you can get a USB charger doctor and measure it for yourself. You already have the most expensive parts, which are the solar panels, all that's left is to measure it's output under your proposed conditions of use. If you have a car USB charger or can borrow one, a little creative wiring should tell you if the panels will put out enough power to run one and charge a phone at the same time. I think the USB charger will need to provide at least 500 mA just to charge a power bank and be able to deliver at least 1 A if you want to run a dashcam at the same time.

KuoH

at the moment i do not have a 12v splitter or a battery bank to try out my idea.
 
solar panels !

i have a 225w and a tilting 80w fitted to my motorhome and have x2 turnigy watt meters reading volts amps etc in and out of the 250Ah batteries..

The 80w tilting produces much more than the flat 225w when facing a low winter sun.. ( can get 65 w out of it facing very low winter sun)


I can tell you this much...

A 10w combined solar aray will not keep your cams running unless in constant optimal sunlight and then you might get heat loss !


If you realy want to go the solar route.. fit a 100w flexible panel moulded to the whole roof of your car - ugly but functional !!!
 
This becomes very complex, because you have to factor how much sunlight your panels will receive, losses from the battery (likely 30% or more), and other system losses. The link below is to the US solar data, it will tell you how many kWh per M squared per day or full sunlight hours per day your panel will receive.

http://rredc.nrel.gov/solar/pubs/redbook/#maps

Assuming that the Mobius requires 330mA to keep recording, that would require 7920mA or 7.920 amps of current per day. Allowing for battery losses and other losses, we increase this by 1.5x to 11,880mA hours per day or 11.88A hours per day. I'll just round this to 12Ah per day.

Using Los Angeles, California as my example, on average a flat panel at 0 degrees tilt gets 4.9 hours per day. However, the average is very misleading, in December this drops to 2.6 per day. Thus in the 2.6 hours of full sun equivalent we must get a total of 12Ah of current. 12Ah / 2.6 hours = about 4.6 amps from our panel. 4.6A x 18volt panel = 82.8 watt panel required. Most other areas of the country will require an even larger panel. Putting the panel on the roof will provide the most sunlight.

You will also need a charge controller to avoid overcharging the battery.
 
Keep in mind the OP was planning to use this setup in a parking garage under artificial lighting. The main questions are how much power can those panels produce in those conditions, what's the most efficient option to convert the output to stable 5V and how much power the Mobius and/or power bank needs.

KuoH

This becomes very complex, because you have to factor how much sunlight your panels will receive, losses from the battery (likely 30% or more), and other system losses. The link below is to the US solar data, it will tell you how many kWh per M squared per day or full sunlight hours per day your panel will receive.
 
So solar is a daft idea !!!

But the op could fit an "efoy" to a car and this will give him 5 amps an hour and keep his battery automatically fully charged...

Its a $4000 solution !!
 
well i happened to be near a Harborfreight store and i picked up some cheap junk there just to test out <and likely return>. i parked the car in a good spot under a light in the garage and got one solar panel to read 10V and the other to read 8V. I plugged both panels into the female sockets on one of these: http://www.harborfreight.com/12-volt-dual-outlet-adapter-67073.html I then took the male socket on the linked adapter and plugged it into one of the female sockets on a 2nd adapter <exact same model>. i put the 1000mA usb car charger <that came with the mobius> in the other female socket on the adapter and the result was <insert drumroll>... not enough to charge my phone.

im still not sure how to measure current off the panels. i have a few multimeters that should be able to do it, including this one: http://www.harborfreight.com/7-function-digital-multimeter-69096.html i had it set to DCA 200m and the 10A.. if i remember right i was getting some small decimals when i hooked the red lead to the middle of the 12V plug and the black lead to the outside of the 12v plug. not sure if i was doing it right or not.

I think my next plan is to try to use some usb battery banks that i forgot i had... I have two of these: http://www.homedepot.com/p/Rayovac-7-Hour-Power-Pack-PS73-4BT6/204765391 i can stock each of them with 4 rechargeable eneloop AA's rated at 1900mah for a total of 15200mah. the only problem is that those battery banks will only put out 500mA each, which is not enough to power the Mobius <if i am not mistaken it requires 1000mA>. I am going to try to see if i can find a cable that is going to allow me to charge via usb in parallel... or maybe just go out and buy a better battery bank <i would like to try using what I have in parallel first, since they are just collecting dust>. does anyone have a link to a cable to put two usb battery packs in parallel?
 
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