PV panel to trickle charge 12 V battery, also while in use?

[analogo]

My watering system is powered by a 12 V AGM battery. A microcontroller wakes up every now and then and, if the sensors say that water is needed, it activates a pump (via a relay with NO connected to the 12v battery) for a few minutes. This set-up as been working flawlessly for the past few years. With a small annoyance: every few weeks I need to unplug the battery, recharge it, plug it back.

Could I simply attach one of those small photovoltaic panels with integrated charger for auto batteries (random example: https://www.amazon.com/dp/B0C9Z4NHJH), and have it trickle charge my battery, without disconnecting the circuit? Or will it cause issues when the microcontroller is awake and the pump violently starts sucking current out of the battery?

[SmallCog]

You can charge your battery whilst in use, probably. Only hiccup will be if your microcontroller isn't tolerant of the higher voltages that the battery will be charging at. Figure on it seeing up to 15V to be safe (but it shouldn't) however I presume you're already using a buck module or something so you're likely going to be OK.

Some of those little panels like you linked are unregulated and rely upon being quite small compared to the quite large vehicle battery to prevent over charging.

I'd use a solar regulator and a panel, a decent brand panel (eg Symmetry) costs hardly anything and they're commonly used industrially.

Be sure that your chosen regulator has a charge profile compatible with your battery, smaller Gel/VRLA/AGM batteries can have lower charge voltages than vehicle batteries. I'd personally use a little PWM reg for something like this.

[J-R]

What is the Ah capacity of the battery?

[analogo]

What is the Ah capacity of the battery?

12Ah, it's a Panasonic LC-PA1212P1.

Is the capacity of the battery relevant?