Charging 12V lead acid from USB-C solar panel

[lutkeveld]

Hi all. I want to charge a 12V lead acid battery from a USB-C solar panel. This panel has a 5W power budget.
I don't know what it does if it has less than 5W of solar coming in, I assume it just does not work then.

What would be a good approach for this? Boost the 5V to 16V or so and then use a buck charger IC?
Or maybe a direct boost charger IC? Can't seem to find many.

[radiolistener]

Hi all. I want to charge a 12V lead acid battery from a USB-C solar panel. This panel has a 5W power budget.
I don't know what it does if it has less than 5W of solar coming in, I assume it just does not work then.

What would be a good approach for this? Boost the 5V to 16V or so and then use a buck charger IC?
Or maybe a direct boost charger IC? Can't seem to find many.

I think you will loss more power on DC/DC conversions than on battery charge.

It will be better to find solar panel with 18 V or higher with higher power rating for example 10-15W and use DC/DC down converter to 13.8V or 14.4V for charger depends on battery type and capacity.

Once I tried to charge 12V 7 Ah lead-acid battery with 18V 4W solar panel on winter, it was almost useless, due to very low current from solar panel (about 100 mA). I also wanted to listen radio receiver (Degen DE1103) but it appears that it consume more power (150 mA) than solar panel can provide. In sunny summer it would be better but not so much.

[lutkeveld]

It's for an IOT sensor, so don't need that much currently luckily.
The person who I am installing this for already has both components: a 12V 7ah battery and the USB-C solar panels.
So am looking what is the easiest path to design a circuit which connects this together.

[tunk]

The easiest is to get a panel that's designed to (trickle)
charge a 12V lead acid battery. It may even be cheaper
than boost/buck/etc.