voltage regulator for solar panel 12 V

Hello,
I want to create an automatic watering system thanks to arduino.
About the power source, I have a solar panel 12V and a battery 12V. But I don't know what can i use between my battery and my solar panel in order to regularize the voltage.
I think a too low voltage to recharge the battery is bad for it. I find a L7812 regulator but this electronic component allows to block voltage above 12v but not under ?
Do you know what can i use in my case ?
I use 12v because my water pump needs 12v at least.
Thank you

I have 30 watts of solar panels connected to a PWM Charge Controller that goes to a 12V LifePo4 16Ah battery. On the battery I have a 5V switching regulator to supply power to the rest of the circuit.

Between the solar cells and the battery there should be some sort of charge controller. A 7812 is not a charge controller. The Charge Controller will properly cycle charge and discharge periods.

clem64000:
Hello,
I want to create an automatic watering system thanks to arduino.
About the power source, I have a solar panel 12V and a battery 12V. But I don't know what can i use between my battery and my solar panel in order to regularize the voltage.
I think a too low voltage to recharge the battery is bad for it. I find a L7812 regulator but this electronic component allows to block voltage above 12v but not under ?
Do you know what can i use in my case ?
I use 12v because my water pump needs 12v at least.
Thank you

Your 12 volt solar panel will have a diode in series with it to stop voltage feeding back through the solar panel. So there is a 0.7 volt loss already, so you will get 11.3 volts from the panel. You should design for at least 50% higher voltage that your battery and then let the charge controller take care of matching the voltages. Your entire project needs to run from the battery, only, and let the solar panel/charger keep the battery charged.
Can we guess you have a lead/acid battery?
Paul

12V, loaded solar cells, produce about 14 to 17V unloaded volts. Allows the battery to float above 12V for a proper charge with the MPPT or PWM Charge Controller.

What is the area of your panel (square feet, square meters)?

Thank you everybody for your answer.
*I have this product : *
- battery (lead/acid) : https://www.amazon.fr/DSK-10362-Batterie-décharge-ups-sai/dp/B072VRFYLJ/ref=sr_1_5?__mk_fr_FR=ÅMÅŽÕÑ&dchild=1&keywords=batterie+12v&qid=1615278173&sr=8-5
*- solar panel : *200 x 130 x 3 mm 12V 4,2W.

Paul_KD7HB:
Your 12 volt solar panel will have a diode in series with it to stop voltage feeding back through the solar panel. So there is a 0.7 volt loss already, so you will get 11.3 volts from the panel. You should design for at least 50% higher voltage that your battery and then let the charge controller take care of matching the voltages. Your entire project needs to run from the battery, only, and let the solar panel/charger keep the battery charged.
Can we guess you have a lead/acid battery?
Paul

I didn’t know that i need a higher voltage for my solar panel. Yes its a lead acid battery. So i can’t charge a 12v battery with a 12v solar panel ??

Idahowalker:
I have 30 watts of solar panels connected to a PWM Charge Controller that goes to a 12V LifePo4 16Ah battery. On the battery I have a 5V switching regulator to supply power to the rest of the circuit.

Between the solar cells and the battery there should be some sort of charge controller. A 7812 is not a charge controller. The Charge Controller will properly cycle charge and discharge periods.

Do you have the name of several charge controller ? On internet i find different product with screen etc but i wanted only the converter without screen or button. Just the converter INPUT(different voltage) / OUTPUT (12V).
Thank you

Charge controllers without displays are quite easy to look up and very easy to find but here I'll give you a hand https://smile.amazon.com/gp/product/B0006JO0XI/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

12 volt solar panels put out from 13.8 to 17ish volts so they can charge a 12V lead acid or 12V LiFePo4 battery.

Ok thank you. And something like this ? :

https://www.ebay.fr/itm/3S-10A-12V-Lithium-Battery-Charger-Protection-Board-BMS-Li-ion-Charging-MoYXWR/383930337211?_trkparms=ispr%3D1&hash=item59640807bb:g:KN4AAOSw4qZdu5yS&amdata=enc%3AAQAFAAACgBaobrjLl8XobRIiIML1V4Imu%252Fn%252BzU5L90Z278x5ickkxFtV7J5P58ubuVigtBH%252Fe2YdHgF8GBMX%252B1KdBRh%252FDR6h5Of5i8JaZsfgjgTdgqxxeo%252FeeV3KC5B3OXlXxqFXUqDue3PUTlQGLr6jHNUwZH9hc5LqiABTlaUzGHQRJaXyGbtf2IfWLH2%252B3w0jhlJhUju1psv3izanN2S657GpTBGjSLAi9Y0g%252Bh3p%252FeiNz%252BA4izTqsexPc9Z1ecCdpnKygdTxxAQu%252FiJyEdONzQEH5rBTkmBRvdBJ%252B8qx7lr25bEqWNczZHmQDCk0KTNiurkWo2prpYBk1H0DFIDuv%252F1evxDyFTvTUoo%252BQDl3TfSWivpM4uwshAy%252BzYWc1QZgiHEcfYSSduuWkn8bXg%252BP7baKsN%252BNj5yQSmtvCbt7sm2wBuBA0okaNALDf9b1D4Hu0ur8xsodrY9XmcrcYT2SdgT1VGIJsB8Cd1fSuhsWSmxOPOL1VTqD6FDdbguBVwZiz3DWT7ApH2ZEfYdJF%252FROS7c20o8CxYP8GkOGZc2lhSvvRDswsPxMWewhHpHjRRRYeCc0p5jrxYhOsRiTfQmkQ3PDQ9%252BhtgXV2ig1PUg0KUN8UiT4VUT6gpF62xzGQ5bUL6NYxaUEiCEiXVent%252FzkG34rOMftxBD8pQtI%252FSwYXOn1NECQbfjS3LdPNXUPfk6GaBIKe63LYVY6M4hXCB22YjwLiUXhA%252BdFbs9x55ul5%252BjF5Sf3C%252Fom74pMjOuCq8LLh2sOq9B1GKHGNDJvJhljHnEKmPn6pAKiFc2OnnyDc%252FkvQSu38S0qzS7JsteTfn7ggHvH4s4tFMo%252FdRjSI0fi2qafAQs%253D%7Ccksum%3A383930337211cbbe2a7ea4c04c139563cb9c028ebc9e%7Campid%3APL_CLK%7Cclp%3A2334524

It is a lithium battery chargeur protection for 12v. In my case i use a lead acid battery. Will it work with my lead acid battery ?

www.ebay.fr/itm/3S-10A-12V-Lithium-Battery-Charger-Protection-Board-BMS-Li-ion-Charging-MoYXWR/383930337211?_trkparms=ispr%3D1&hash=item59640807bb:g:KN4AAOSw4qZdu5yS&amdata=enc%3AAQAFAAACgBaobrjLl8XobRIiIML1V4Imu%2Fn%2BzU5L90Z278x5ickkxFtV7J5P58ubuVigtBH%2Fe2YdHgF8GBMX%2B1KdBRh%2FDR6h5Of5i8JaZsfgjgTdgqxxeo%2FeeV3KC5B3OXlXxqFXUqDue3PUTlQGLr6jHNUwZH9hc5LqiABTlaUzGHQRJaXyGbtf2IfWLH2%2B3w0jhlJhUju1psv3izanN2S657GpTBGjSLAi9Y0g%2Bh3p%2FeiNz%2BA4izTqsexPc9Z1ecCdpnKygdTxxAQu%2FiJyEdONzQEH5rBTkmBRvdBJ%2B8qx7lr25bEqWNczZHmQDCk0KTNiurkWo2prpYBk1H0DFIDuv%2F1evxDyFTvTUoo%2BQDl3TfSWivpM4uwshAy%2BzYWc1QZgiHEcfYSSduuWkn8bXg%2BP7baKsN%2BNj5yQSmtvCbt7sm2wBuBA0okaNALDf9b1D4Hu0ur8xsodrY9XmcrcYT2SdgT1VGIJsB8Cd1fSuhsWSmxOPOL1VTqD6FDdbguBVwZiz3DWT7ApH2ZEfYdJF%2FROS7c20o8CxYP8GkOGZc2lhSvvRDswsPxMWewhHpHjRRRYeCc0p5jrxYhOsRiTfQmkQ3PDQ9%2BhtgXV2ig1PUg0KUN8UiT4VUT6gpF62xzGQ5bUL6NYxaUEiCEiXVent%2FzkG34rOMftxBD8pQtI%2FSwYXOn1NECQbfjS3LdPNXUPfk6GaBIKe63LYVY6M4hXCB22YjwLiUXhA%2BdFbs9x55ul5%2BjF5Sf3C%2Fom74pMjOuCq8LLh2sOq9B1GKHGNDJvJhljHnEKmPn6pAKiFc2OnnyDc%2FkvQSu38S0qzS7JsteTfn7ggHvH4s4tFMo%2FdRjSI0fi2qafAQs%3D|cksum%3A383930337211cbbe2a7ea4c04c139563cb9c028ebc9e|ampid%3APL_CLK|clp%3A2334524

It is a lithium battery chargeur protection for 12v. In my case i use a lead acid battery. Will it work with my lead acid battery ?

I’m not going to that link.

You do know a lead acid battery and a LiPo charge differently?

Use a LifePo4 or a lead acid battery and a PWM or MPTT charge controller.

12V lead-acid battery would need 14.1v charging voltage. So you should use at least a 20V solar panel

sunbird:
12V lead-acid battery would need 14.1v charging voltage. So you should use at least a 20V solar panel

Wrong.

A 12V solar cell produces up to 17V out. plenty of v's for a floating charge cycle.

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