Can a 10-watt Panel Safely Charge Your 12V Car Battery

Only driving a car occasionally? Then you need to keep the car battery topped up one way or the other otherwise you may not be able to start it successfully when you need to.

Because the battery gradually loses its charge over time from both self-discharge itself and continuous power drawn by the car’s electronic systems (car alarm, car computer, clock, and others) that stay On even when a car ignition is turned off.

This explains why:

A fully charged 50Ah car battery will be discharged to the recommended limit of 50% of its capacity in about 20 days.

This assumes the onboard systems continuously draw about 50mA!

If you’ve access to a 10-watt solar panel then you might want to consider using it to keep the car battery topped up. Can you do it safely?

Read on to find out if you can safely charge a car battery with a 10-watt solar panel and what the experience is like.

Can a 10-watt Solar Panel Safely Charge a 12V Car Battery?

A 10-watt solar panel is better suited to keeping an already charged car battery topped up rather than charging a drained battery.

With an estimated charging current of only 0.56 amps, a 10-watt solar panel is slow to charge.

And so, for example, it would take a minimum of 20 days to recharge a 50Ah car battery that has been discharged to 50% of its capacity!

To use the 10-watt solar panel safely to charge a 12V car battery

  • Install a charge controller to guard against overcharging the battery. Note: some 10-watt solar panels already have inbuilt charge controllers.

You might also be interested in this post: 10-watt solar panel – does it need a trickle charger?

  • Is the solar panel frame made from aluminum? Find a suitable place to mount it to receive enough sunshine without scratching the car’s body. Otherwise, a lightweight 10-watt solar panel can usually be mounted inside the car above the car dashboard – fixed on the car windscreen with suction caps.
  • Make sure to connect the solar panel battery clamps the right way. If using red and black clamps, make sure to connect red to the battery positive terminal (+) and black to the battery negative terminal (-)

How to guard against undercharging

Partially filling a battery leads to undercharging therefore limit the 10-watt solar panel to charging batteries with a capacity of 10Ah.

What Battery Size to Charge with a 10-Watt Solar Panel?

To use the 10-watt solar panel to charge batteries, preferably limit its use to 12V batteries with a capacity of 7-10Ah AGM batteries.

With such a capacity, the battery charge can be replenished in about a day.

Closing Thoughts

The 10-watt 12V solar panel is only suited to trickly charging and keeping the battery tipped up and even then make sure you use a charge controller to guard against overcharging.

Do not plan to use the solar panel for charging or discharging batteries unless their capacity is about 10Ah and lower.

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