Car solar panel, charging + alternator.

[3_me]

Hello, I am wondering if it’s possible to add a solar panel to my car, which helps to charge the car battery, but at the same time the car has an alternator which will also charge it when the car is driven.

is it possible, or will the alternator affect the solar panel, and vice versa?

[SunEagle]

Hello, I am wondering if it’s possible to add a solar panel to my car, which helps to charge the car battery, but at the same time the car has an alternator which will also charge it when the car is driven.

is it possible, or will the alternator affect the solar panel, and vice versa?

Some RV's have the ability to charge the coach batteries from the alternator or other source. That usually requires additional equipment to make sure only one source is doing the charging and you are not backfeeding one source into the other.

When you state "add a solar panel" I hope you are also adding a charge controller to the system. Wiring the panel directly to the battery can cause it to over charge and burn up.

[3_me]

Hi, yes I would add a charge controller on the solar panel side, but I was wondering if the controller will stop the energy coming from the alternator, or if the alternator would some how damaged the controller and/or solar panel.

[Mike90250]

Adding a small "dashboard" trickle charger to a car is a pretty easy way to keep a modern car, full of electronics, topped off for weeks at a time.

If the car is a daily driver, or even 3 days a week, adding a small panel is pretty much pointless. PV panel and alternator won't really interact with each other, but % wise, the panel is too tiny to be of use compared to the high power alternator in a car.
100A alternator @ 14V = 1400 watts
10W PV panel = next to nothing.

[3_me]

Thank you for your reply. By trickle charger do you mean the portable solar panels I’ve seen that can sit on the dashboard? If so, I’d still need to know if they’re ok to use in regards to the questions above about the alternator.

The reason I am asking this is I wish to add a device 12v - 1amp, which will be on 24/7. So I’m thinking about the best solution without the battery running flat.

I’d say the car is driven almost weekly. At least a few times but there are periods when it is not driven at all for over a week.

[J.P.M.]

Also, and not for just goofs and giggles, don't forget to find some way to ensure the panel(s) stay(s) put on the vehicle in a, say, 100 M.P.H. wind event while driving into a headwind while being buffetted by cross winds and oncoming/passing vehicles.

[Mike90250]

A panel of less than 20watts, on the dashboard, is generally safe to use to maintain the car battery. it may not be safe to drive with the panel sliding around on the dash, but it won';t hurt the battery or alternator.
Some are designed to plug into the cigar lighter socket, but many cars nowdays, disconnect the socket when the ignition is OFF and the panel won't charge the battery,

[chrisski]

Thank you for your reply. By trickle charger do you mean the portable solar panels I’ve seen that can sit on the dashboard? If so, I’d still need to know if they’re ok to use in regards to the questions above about the alternator.

The reason I am asking this is I wish to add a device 12v - 1amp, which will be on 24/7. So I’m thinking about the best solution without the battery running flat.

I’d say the car is driven almost weekly. At least a few times but there are periods when it is not driven at all for over a week.

I would say solar is not the solution you’re looking for. A bigger battery or a higher than 1 amp trickle charger is.

A car battery don’t have a lot of ah usable, and probably be smaller. Right now, I go 14 hours without usable sun, which a battery would probably be OK going overnight, but if the next day is cloudy, it would not last. Putting a constant 1 amp load on the battery would probably cause it to die quite a bit quicker.

If the load maxes out at 1 amp, but usually pulls a lot less, that is different. I don’t have an alternator that I’ve used with my SCC, but I do have a 10 amp AC to DC converter that I have ran with the SCC with no issues in my RV on a cloudy day.

[3_me]

A panel of less than 20watts, on the dashboard, is generally safe to use to maintain the car battery. it may not be safe to drive with the panel sliding around on the dash, but it won';t hurt the battery or alternator.
Some are designed to plug into the cigar lighter socket, but many cars nowdays, disconnect the socket when the ignition is OFF and the panel won't charge the battery,

Thanks for the reply, I would most likely screw it down rather than let it sit there. But perhaps it's still not the solution for me.

[3_me]

I would say solar is not the solution you’re looking for. A bigger battery or a higher than 1 amp trickle charger is.

A car battery don’t have a lot of ah usable, and probably be smaller. Right now, I go 14 hours without usable sun, which a battery would probably be OK going overnight, but if the next day is cloudy, it would not last. Putting a constant 1 amp load on the battery would probably cause it to die quite a bit quicker.

If the load maxes out at 1 amp, but usually pulls a lot less, that is different. I don’t have an alternator that I’ve used with my SCC, but I do have a 10 amp AC to DC converter that I have ran with the SCC with no issues in my RV on a cloudy day.

Thank you for the reply. I'm not sure about selecting a larger battery for my car, the tray for the battery usually is quite standard size, and would probably need to be modified in some way.

The trickle charger sounds ok, but can the trickle charger also be charged by the alternator? I don't understand how it works? How does it hold enough power to charge the battery, is it something I need to charge myself at home and then attach now and then? I was looking for a permanent solution.

Perhaps a second battery?

[chrisski]

Thank you for the reply. I'm not sure about selecting a larger battery for my car, the tray for the battery usually is quite standard size, and would probably need to be modified in some way.

The trickle charger sounds ok, but can the trickle charger also be charged by the alternator? I don't understand how it works? How does it hold enough power to charge the battery, is it something I need to charge myself at home and then attach now and then? I was looking for a permanent solution.

Perhaps a second battery?

I recommend going through the stickies on batteries.

Vehicle batteries are good for delivering large amounts of energy to start a car, but are not deep cycle and won’t hold up to delivering smaller amounts of energy over long periods of time. The energy when running the vehicle comes mostly form the alternator and not the battery. A car battery’s lead is physically different from a deep cycle battery. A car battery looks like a radiator, and a deep cycle battery has more lead with holes drilled in it, like Swiss cheese.

It does come down to a power requirement. Not exactly what you’re looking for, but here is one sticky: https://www.solarpaneltalk.com/forum...battery-design

[3_me]

I recommend going through the stickies on batteries.

Vehicle batteries are good for delivering large amounts of energy to start a car, but are not deep cycle and won’t hold up to delivering smaller amounts of energy over long periods of time. The energy when running the vehicle comes mostly form the alternator and not the battery. A car battery’s lead is physically different from a deep cycle battery. A car battery looks like a radiator, and a deep cycle battery has more lead with holes drilled in it, like Swiss cheese.

It does come down to a power requirement. Not exactly what you’re looking for, but here is one sticky: https://www.solarpaneltalk.com/forum...battery-design

Thank you, I will read through that now.

If I do end up requiring a second battery, is there any topics here on installation a second battery in a car, and also how to fix a solar panel to a car?

[chrisski]

Thank you, I will read through that now.

If I do end up requiring a second battery, is there any topics here on installation a second battery in a car, and also how to fix a solar panel to a car?

I have not seen a real professional looking way to mount a panel to a car. I tape flexible panels to the roofs of RVs with Dicor Roofing tape, but that would look a bit sloppy where people can see it. For the flat glass panels, that is installed with hardware, and that looks a bit stranger on cars. I saw a decent looking panel made for a hood of a jeep, but that was extremely pricey. A tiny panel I had for a trickle charger, I would keep on the dash of the car, but it lost 2/3 rd its power going through the window.