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electrical:solar:charge_controller [2023/09/26 11:25] frater_secessus [how to choose] |
electrical:solar:charge_controller [2024/06/01 21:58] frater_secessus [sensors] |
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Cautionary example: | Cautionary example: | ||
+ | ==== sensors ==== | ||
+ | |||
+ | To charge correctly the controller needs to know the precise voltage and temperature of the battery bank. | ||
+ | In the best case scenario these measurements are done with an external **temp sensor** and **voltage sense**((not a typo, it's called voltage sense)) that plug into the controller or talk to the controller via bluetooth. | ||
+ | |||
+ | In the absence of external sensors the controller tries to use any internal sensors it might have. The values will be inaccurate: | ||
+ | |||
+ | * battery voltage will read [[electrical: | ||
+ | * temperature will read high because of the controller' | ||
+ | |||
+ | With lead-chemistry batteries both conditions cause [[electrical: | ||
+ | |||
+ | |||
+ | |||
+ | |||
===== specs ===== | ===== specs ===== | ||
Regardless of type, controllers will have several specifications in common. | Regardless of type, controllers will have several specifications in common. | ||
- | * **rating (or " | + | * **rating (or " |
* **12v/ | * **12v/ | ||
* **Maximum input voltage** - the highest voltage the controller should //ever// see from the solar array.((it is common to leave ~20% margin)) | * **Maximum input voltage** - the highest voltage the controller should //ever// see from the solar array.((it is common to leave ~20% margin)) | ||
+ | * **Minimum input voltage** - a PWM controller will requires panel voltage ≥ battery voltage to charge. | ||
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[note: | [note: | ||
There are //DC-DC converting charge controllers// | There are //DC-DC converting charge controllers// | ||
+ | |||
+ | |||
+ | ==== boosting ==== | ||
+ | |||
+ | Most charge controllers that convert voltage do it by //bucking// (reducing) panel voltage down to the appropriate charging voltages.((normal PWM don't reduce/ | ||
+ | |||
+ | // | ||
==== how to choose ==== | ==== how to choose ==== | ||
**PWM is a reasonable default choice** in typical scenarios((12v house power, 12v panels)); they work well enough and are inexpensive. PWM controllers can cost half or a third of their MPPT workmates for any given rated output.((10A, | **PWM is a reasonable default choice** in typical scenarios((12v house power, 12v panels)); they work well enough and are inexpensive. PWM controllers can cost half or a third of their MPPT workmates for any given rated output.((10A, | ||
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**MPPT is effectively required** when: | **MPPT is effectively required** when: | ||
* when one needs to squeeze every watt out of the panel | * when one needs to squeeze every watt out of the panel | ||
- | * using panels with nominal voltages higher than the battery bank voltage, like 24v panels with a 12v bank. To be fair, [[http:// | + | * using panels with nominal voltages higher than the battery bank voltage, like 24v panels with a 12v bank. To be fair, [[http:// |
* space available for panels is limited, as on a sailboat or small vehicle | * space available for panels is limited, as on a sailboat or small vehicle | ||
* daytime loads are hampered by [[electrical: | * daytime loads are hampered by [[electrical: |