cctv solar powered via car battery

[Dart]

Hi
Has anyone powered there cctv by a solar powered car battery, I am thinking of giving it a try, my total current drain would be about 5 amps max.

I also have other uses for a 12 volt dc current, to power my radiator fans that I have fitted to the bottom of my double panel rads on my central heating, again taking about 5 amps, these will only be on for about 3 hours a day max in the heating season.

Any help would be appreciated battery is a calcium for a ford focus mk3 a spare for my car when it fails. Been looking at a 100watt solar panel and voltage controller.

I have been using solar power for sum years to keep the battery on my cars topped up, never had a flat battery for years touch wood.

Dart

 

[sparkymarka]

No

 

[SimonH2]

OK, first off a "car battery" isn't the right type of battery. You need something specifically designed for deep discharge - eg a "leisure" battery or some of the industrial deep cycle types.

Here are the steps you'll need to work through to end up with a system that works :

1) Calculate the total load.
"5A max" isn't good enough - you need to work out the actual load, and then the total energy required over each 24 hour period.

Incidentally, if you look at battery specs, you find that many of them give capacities in terms of Watts rather than (or in addition to) Amp-hours. The reason for this is because many loads (eg computers on battery backup) take a constant power so the current increases as the battery terminal voltage drops. So you will find voltage-time curves for different loads expressed in terms of amps and also in terms of watts.

Since your loads will (mostly) come under this description, it'll be more accurate to work in terms of watt-hours - but the calculations will only be approximate anyway so it's not critical.

And don't forget to include everything else you think you might want to run off the batteries.

2) Now work out how much solar panel you need in order to provide the total daily load during the hours of daylight under worst case conditions.
So (just picking numbers to make the numbers easy), say you expect 8 hours daylight minimum, and your daily load is 60W x 24Hr = 1440 WHr, then you'll need a minimum of 180W from your panel in order to supply that load. In practice you'll need more as the battery charge/discharge isn't 100% efficient.

3) Calculate the storage required.
Taking the numbers above, you'll need to run for about 16 hours off battery - then when the sub comes up the panel supplies the load and starts to recharge the battery. So you need as absolute minimum (using these figures) of 80AHr or 196WHr. That really really is a minimum and in practice won't work reliably.
Firstly, you'd be fully discharging the batteries every night - so that'll give them a short life. Secondly it assumes you never have any of those really dark days when the panel doesn't really work well.

Having "significantly" more battery capacity than that gives several things :
a) Under normal conditions, you only partially discharge the batteries which will make them last longer.
b) You'll have more reserves to see you through those very dark days.


Now there are a few other things that come to mind.

You ideally need an undervoltage cut out - so if you've got not enough battery and solar panel, it'll turn off (some of) the load to avoid over-discharging the batteries which will reduce the chance of damage.

As you'll be needing to size the solar panel for winter, in summer it's going to be very much oversized for summer. So you'll need a charge controller to avoid boiling your batteries dry.


I think by now you'll have realised it's not a trivial thing to do.

What you haven't said is why ! Is this for an off-grid installation and you want to run stuff without needing a genny running 24 hours a day ? Or was this one of those "could I save a few pennies off the lecky bill" sort of thoughts - in which case, forget it, it'll never even repay it's capital costs.

 

[Dart]

Hi
Simon H2
Thanks for your informed reply, I agree it can take years or never for advancements to pay for themselves.

The advantage with generating your own power you are not dependant on mains electricity this can be cut off without notice, leaving your security system non operational.

My thoughts are that one day maybe soon when batteries have improved we will all be self sufficient in providing our own power. look at the space stations. The biggest problem in our country would be for us to keep warm in the winter, but I think that will be solved in the next 20 to 50 years. A new improved form of microwave

Most appliances can be made to be powered by 12volts, but I think the norm will of 50 volts, four batteries in series.

I remember a conversation I had with work mates about 50 years ago saying that televisions in about 20 years time would be like a mirror that you hang on the wall, they all looked at me and thought we have a right one here it took a little bit longer but it happened.
At that time you had to park your car with a side light, so every night they would go and switch on there lights. I made and fitted an automatic switch for my car, based on a light sensitive cell, it cost very little, but saved me time.

Getting back to my suggestions for a solar powered cctv I agree the battery is the problem, I think the drain on the car battery may not be too much, compared with the capacity of the battery. I have had car batteries last for 8 years in the past. I know with silver calcium the life expectancy is about 4 years and would not be cost effective. but once installed could be maintenance free for a few years. Its been a lot of years since I have been to college so I would not know where to start in calculating the exact requirements for such a system. The size and cost of the solar panel to power the project needs to be considered

I study projects I have in mind for some time before I go ahead with them. most are only thoughts and never come about.

I believe knowledge is important and should be passed on

Dart

 

[SimonH2]

I repeat - the drain on the battery isn't the problem.
The problems you need to solve are :
1) How much panel do you need to have in order to supply the daily energy requirements in worst case conditions (dull, short, winters day).
2) How much battery capacity do you need to ride through the nights.

As another thought, if you look around, there are quite a few road signs illuminated in this way. A lot of them have a solar panel and a small wind turbine. The winter days with no wind tend to be bright, and it's not frequent to get days that are both dull and wind free (though they do occur).

If the sole requirement is to avoid the CCTV going off when the mains does, then just work out the "ride through" time you need (ie how long a power cut you want to cater for) and size the battery for that. Then keep it charged with a float charger/power supply. Finally, run the CCTV stuff from it.
Or just use an off the shelf UPS and possibly extra batteries.

 

[Dart]

Hi
Simon H2
I agree with you solar is the way to go, that's why the government is investing loads of money into it. We are still in the early stages of solar power there is still a long way to go I understand the Japanese are now working on solar panels about the same size as our average roof tile, this will look a lot more pleasant to the eye, instead of a being a carbuncle on the landscape.

As I said in my first post I have used solar panels to keep my car batteries topped up on my cars for over 10 years now I think they may have paid for themselves. I always had flat batteries in the winter or kept them on charge from the mains I can go for weeks without using my car, and when I needed the car the battery was flat, connect the solar panels and forget, peace of mind knowing the car will start.

I do not know how long solar and wind powered road signs have been out, I first spotted them about 10 years ago. The next step will be solar powered lighting standards. You have to keep up with the times if you never try you never achieve anything in life.

I look into projects that I would like to build, The fan assisted radiators all automatic will pay for themselves in 3 years, I would like these to be solar powered along with my cctv and house alarm. I will look into the cost to see if it is worth while.

Have you ever calculated the cost of installing and maintaining a condensing boiler against the traditional boiler you will find it is probably not cost effective, but you have no choice today government legislation.

Dart

 

[SimonH2]

I have used solar panels to keep my car batteries topped up on my cars

So have I - that's a considerably different situation though. For this you are only compensating for any key-off loads and the battery internal self discharge.
And if the car isn't in a convenient place, then using a mains powered float charger isn't very easy.

As well as using solar panels (for the Land Rover I don't use that often), I've also rigged up wiring so I can leave a float charger inside and just plug a lead into the 12S socket on the back of the car. For the old Land Rover I used to use for my daily commute - V8, sometimes fickle at starting, short commute - it was a godsend being able to just plug in and overnight it would be fully topped up. Without spending out on some largish panels, I'd not get the same charge top up from solar.

Different challenges, different tradeoffs.

The next step will be solar powered lighting standards.

I doubt it. While they would be cheaper to install since they don't need a power cable, the ongoing maintenance costs will be considerable and probably far higher than any savings. While batteyr tech is improving, there isn't anything that doesn't wear out or otherwise need maintenance - and maintenance costs serious money. It's not the cost of the battery which is probably not significant - but the cost of the team, traffic management (depending on class of road), the costs associated with employing the extra people needed, and possibly additional costs either for adding redundancy or maybe penalties if some targets for reliability aren't met.

But self contained lighting has it's uses - but not if mains power is reasonably available.

Have you ever calculated the cost of installing and maintaining a condensing boiler against the traditional boiler you will find it is probably not cost effective

Yes I have - I'll have one to do sooner or later, but for the moment doing away with the combi function (I installed a thermal store) has made the old thing pretty reliable. Also consider that a great many retrofit condensing installs will not in fact achieve much (if any) saving because they are attached to a system designed to prevent them condensing.

 

[Dart]

Hi Simon H2

I have tried trickle charging, the charger I bought cost almost as much or more than the solar panels, plus I had to remember to switch it on, I lower down a window, (Car in garage) connect the solar charger via a cigar lighter I fitted (Mk 3 Focus) and forget. I am trying to cut down on my electric bills.

Solar powered lighting standards, I will not be around in 20 years time, will you promise to eat your cap if you are wrong ?.
We could discus this all day and still not agree there advantages and disadvantages on both. I have had to install an overhead power supply to a project in the past for a treatment plant and the cost was unbelievable.

The main disadvantages of solar power is what happens when we have 3 or 4 days of fog or cloudy weather. The answer is to fit a auto back up from the mains. or to compensate with a larger battery and solar cells.

We have to move on with the times and to learn lessons from our mistakes or other peoples mistakes even better or we will never progress.

Dart

 

[EightyTwo]

The solar panels on my roof (13 x 230W) produced 1100 WHrs today... Makes you think, doesn't it! (20,000 on a long, sunny, summer day...)

 

[SimonH2]

Which is less than the OP needs according to the information I've inferred from his postings.

And also demonstrates the fundamental issue with Solar PV as a power source (at least in this country).

<soapbox>As I say, barring some fairly major breakthroughs, if there is mains power available then it's going to be seriously difficult making any sort of cost benefit work out for running things from solar or wind. Of course, in the case of big arrays on roofs, the cost benefit is entirely due to artificial economics - aka subsidies - in the name of greenwash.</soapbox>

 

[Dart]

Hi SimonH2
I appreciate your comments, I agree with most of what you have to say, but we have not seen the best of solar, the best is still to come. Batteries still need to be improved again I think a big break through will happen due to the money being invested into battery powered cars.

That is the point of the forum to have a helpful discussion with one another where we can without taking offence.

Dart

 

[EightyTwo]

I think that flywheels could be a good source of energy storage. I understand that some research has been done into flywheels about the size of a big propane cylinder, evacuated and with a motor/generator at one end. They spun them up to over 10,000rpm and left them for ages with hardly any loss of speed. I also remember a experimental bus that had a huge horizontal flywheel in the bottom. It was spun up overnight in the depot and then a variable drive was used to power the wheels. 'Braking' was achieved by adjusting the drive ratio to force the bus's kinetic energy to spin the flywheel up again. This must have been in the 70's - I wonder how it worked out.

 

[SimonH2]

Indeed flywheels have been used for storage - most recently in Formula1 racing where some teams do exactly as you say, use a flywheel in an evacuated (or more likely, helium filled) casing.
In general though, it has it's own difficulties. Weight is one, unless you spin to exceedingly high speeds then the power-weight ratio is poor. Another than comes to mind is the presence of gyroscopic effects which under some circumstances could make vehicle handling "interesting".

Another notable use of flywheel storage was at the Joint European Torus (JET) project at Culham in Oxfordshire. From that Wikipedia page :
Because of the extremely high power requirements for the tokamak, and the fact that power draw from the main grid is limited, two large flywheel generators were constructed to provide this necessary power. Each 775 ton flywheel can spin up to 225 rpm.[2] One generator provides power for the 32 toroidal field coils, the other for inner poloidal field coils. The outer field coils draw their power from the grid.

IIRC from a visit maaaany years ago, the flywheels aren't round - at least when stationary. Centripetal forces are such that the rim flexes when run up until it's round when at full speed. They are also built horizontal in pits in case of failure - don't want scrapnel all over Oxfordshire !

 

[bernardgreen]

The Swiss had a bus with a flywheel storage system in the 1940.

http://photo.proaktiva.eu/digest/2008_gyrobus.html

The gyroscopic effect of the spinning flywheel and the prescession forces that occur if anything tries to change the axis of rotation have meant some very large flywheel storage systems have had to have the axle of the flywheel lined up parallel to the earth's axis of rotation.