Solar panels to help prevent 12v car battery drain in parking mode

[an1uk]

I currently have a small solar panel which I think is 1.5w and does very little. My car can sometimes be left for over a week without being used. My car is supplied as new with a 063 battery, and as the battery tray is big enough I have fitted a 096 battery instead for extra capacity. I use an A129 with the 3 wire kit.

The main options seems to consist of panels that connect to the cigarette lighter (assuming it is constantly on) with a diode to prevent battery discharge when dark. The alternative is a panel with a solar charge controller which reduce the voltage output of the solar panel from about 18v to 12v.

Any good options exist to try prevent parking mode draining the battery by trickle charging with a solar panel placed either on parcel shelf or dashboard?

At what wattage would a solar charge controller be necessary to prevent battery damage?

 

[Nigel]

At what wattage would a solar charge controller be necessary to prevent battery damage?

A typical camera uses around 3W, so your solar panel needs to average 3W day and night, summer and winter, plus if you install it inside the car then it has to deal with shadows from the roof and pillars and darkened glass designed to cut out the IR and UV which contain quite a lot of the sun power, any amount of shadow on a solar panel tends to reduce the output to near zero. Depending on the amount of sun power available where you live, you should be looking at around a 100W panel to keep the battery full, half that if you mount it outside and always park in a sunny location with no trees/buildings providing shadows.

Of course any amount of power will extend the battery life, but you tend to need it extended at night rather than daytime!
Below 20W, I wouldn't bother, spend the money on an AGM battery instead.

To prevent battery damage, all you need is a low voltage cut-off, often built into hardwire kits. If you drive for an hour a day then your 096 battery should easily keep the camera going, probably half an hour is enough if you have a decent size alternator.

 

[SawMaster]

Solar panels are all rated uncovered; adding even clear automotive or any other kind of glass over them reduces their output significantly and a 30%+ output loss may occur. Tinted windows, no matter how slight, can bring a 70%+ output reduction. Use at least 2X the panel capacity you think need to start with, and plan to add more if needed if your glass is tinted. If you use a charge controller be sure it's self-resetting so that an intermittent cloud doesn't shut it down, but restarts afterward. A simple diode of the correct rating should prevent panel-discharging of the battery and a good HWK will cover camera over-discharge.

You also need to consider which camera to use. It's not that hot in the UK but in a close parked car some cams may shut down from overheat and battery-based cams are best avoided in favor of super-caps. Some cams also draw less power in use- the B1W reigns there if the vid quality is good enough for you and it also has a low-bitrate parking firmware available for even less current draw.

Phil

 

[dashcamateur]

This earlier thread may be of interest (or the moderators may wish to merge this thread into it): https://dashcamtalk.com/forum/threa...olar-panels-for-parking-mode-dash-cams.29114/