Solar panel charged car battery - issues with electronics - Page 1
Forum section: electronics / general

author: AlgoryThm
author_rank: Newbie
timestamp: August 22, 2020, 07:06:18 pm
content: Hello! I'm newly registered to this forum but I watch Dave's videos for a few years now, so I'd like to thank all the people that are responsible for this amazing community!What I'd like to ask and didn't find a direct answer to, after some research is this:I have a car which I rarely move and I'd like to permanently install a solar panel and charger, in order to maintain the battery in good condition. The reason I'm not removing the battery to charge it at a separate place is because it is too much of a trouble.The car has two audio amplifiers installed, plus a good head unit, which I wouldn't like to damage in any way.So my question is this: Would I have any kind of trouble if I connected a cheap Chinese solar charger directly to the battery? I know the output power is in the form of pulsed DC and not pure DC, that's why I'm asking...Also, since I already have battery cables that go to the back of the car, to the amplifiers, I was thinking of connecting the solar charger to those terminals and not closer to the battery. But I guess this is going to affect the amplifiers even more...So any opinions are welcome and thank you all in advance!

author: fourfathom
author_rank: Super Contributor
timestamp: August 22, 2020, 08:28:17 pm
content: As long as your connections to the battery are solid, any pulsed power from a small-to-medium solar panel controller will do no harm to any attached electronics.But do you even need a controller? I have some cars that seldom move (they do run and are kept in good shape), and I use one of those tiny solar panels to keep the battery from being sucked dry by self-discharge and phantom drain from the always-on systems. These tiny panels are only a few watts, and the number of cells is lower than a "regular" panel so they won't over-charge the battery with excess current or voltage. They don't have a controller, just a direct connection to the battery through a blocking diode (I think). These panels are dirt-cheap, too. I keep one on the dashboard, under the windshield, and they get enough sun to maintain the battery. These panels would be useless to try and charge a depleted battery, but they do the job I need. These panels often include a cigarette-lighter plug, but most cars disconnect that socket when the ignition is off. I use the supplied clips to connect directly to the battery. These panels probably aren't waterproof though.Here's the one I have. It's 5W.

author: David Hess
author_rank: Super Contributor
timestamp: August 22, 2020, 08:46:14 pm
content: As long as it is regulated to limit the voltage to about 14.2 volts maximum, it will be fine.

author: AlgoryThm
author_rank: Newbie
timestamp: August 23, 2020, 09:12:57 am
content: Thank you both very much for your quick replies! Well 5W unfortunately isn't enough in my case...My alarm consumes 100mA which means 29W/24h. Assuming the 5W solar panel gives max 2.5-3W when under direct sunlight, 1,5W max when there's no direct sunlight and for 10h of day time, that gives max 20W per day.But a 10W cheap foldable one would be perfect. The only thing that troubles me is that the regulator/buck converter is going to be connected directly to the amplifier battery terminals, but if you say it is ok then I'll try it.

author: orsolyahim
author_rank: Newbie
timestamp: January 11, 2023, 06:30:28 pm
content: Did anyone manage to actually build a system that would allow charging a car from a solar panel?

author: bidrohini
author_rank: Regular Contributor
timestamp: January 19, 2023, 02:32:42 pm
content: Quote from: orsolyahim on January 11, 2023, 06:30:28 pmYou can check it out:https://octopusev.com/ev-hub/charging-electric-cars-with-solar-panels

author: David Hess
author_rank: Super Contributor
timestamp: January 20, 2023, 01:36:54 pm
content: Quote from: orsolyahim on January 11, 2023, 06:30:28 pmIt is an easily solvable problem, and solar charge controllers for car batteries do exist.