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electrical:12v:alt_and_solar [2024/03/31 17:03]
frater_secessus [Augmented solar charging] |
electrical:12v:alt_and_solar [2025/01/07 12:10] (current)
frater_secessus [how alternator charging helps] |
| ====== Augmented solar charging ====== | ====== Augmented solar charging ====== |
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| Alternator + solar charging has considerable benefits over [[electrical:12v:alternator|alternator charging alone]], and over [[electrical:solar|solar alone]]. The alternator can help a small solar install punch well above its weight, [[opinion:frater_secessus:panelsizesforinsolation|acting like a much bigger install in areas of poor insolation]].((especially with PWM)) The alternator can help meet [[electrical:12v:charging#charging_current|lead bank minimum charging current requirements]]. Solar can hold the bank at a higher state of charge, thereby reducing current demands on the alternator and allowing the use of smaller [[electrical:12v:b2b|DC-DC chargers]]. | Alternator + solar charging has considerable benefits over [[electrical:12v:alternator|alternator charging alone]], and over [[electrical:solar|solar alone]]. The alternator can help a small solar install punch well above its weight, [[opinion:frater_secessus:panelsizesforinsolation|acting like a much bigger install in areas of poor insolation]].((especially with PWM)) Solar can hold the bank at a higher state of charge, thereby reducing current demands on the alternator and allowing the use of smaller [[electrical:12v:b2b|DC-DC chargers]]. |
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| Note that adding alternator charging to the mix does not necessarily require a fancy, expensive isolator; in some ways [[electrical:12v:alternator#constant-duty_solenoid|the simple solenoid]] provides best bang-for-buck with the fewest drawbacks.((see the Gotchas section)) | Note that adding alternator charging to the mix does not necessarily require a fancy, expensive isolator; in some ways [[electrical:12v:alternator#constant-duty_solenoid|the simple solenoid]] provides best bang-for-buck with the fewest drawbacks.((see the Gotchas section)) |
| Alternator charging is extremely powerful and cheap compared to typical solar installs. It works best when solar works worst: when the batteries are deeply discharged in the morning. The sun is weak then but the bank needs a large supply of current (early [[electrical:12v:charging#bulk_stage|Bulk charging]]). | Alternator charging is extremely powerful and cheap compared to typical solar installs. It works best when solar works worst: when the batteries are deeply discharged in the morning. The sun is weak then but the bank needs a large supply of current (early [[electrical:12v:charging#bulk_stage|Bulk charging]]). |
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| [[electrical:solar:charge_controller#pwm|PWM]] controllers are especially hamstrung in this scenario; since they run the panels at battery voltage (Vbatt) they produce the least power exactly when the most power is required. By the time alternator voltage (Valt) is reached PWM controllers are able to produce meaningful power. | [[electrical:solar:charge_controller#pwm|PWM]] controllers are [[electrical:solar:pwm_tweaking#pwm_s_achilles_heel|somewhat hamstrung in this scenario]]; because they run the panels ~at battery voltage((for the purposes of this discussion)) (Vbatt) they produce the least power exactly when the most power is required. Pushing up bank voltage with the alt helps the PWM make more power. |
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| Alt charging shovels current into the bank until Valt is reached, at which point it begins to taper off. Solar can take it from there. A good metaphor might be a two-stage rocket: the alternator does the heavy lift getting the rocket off the ground then the solar charging takes care of the high altitude, high speed duties. | Alt charging shovels current into the bank until Valt is reached, at which point it begins to taper off. Solar can take it from there. A good metaphor might be a two-stage rocket: the alternator does the heavy lift getting the rocket off the ground then the solar charging takes care of the high altitude, high speed duties. |
| > Use a generator or alternator to get to 85% SOC or so early in the AM, then let Solar spend all day polishing off the last 15% because that takes time more than amps. - a64pilot((https://www.cruisersforum.com/forums/f14/time-it-takes-to-fully-charge-batteries-238875-9.html#post3223983)) | > Use a generator or alternator to get to 85% SOC or so early in the AM, then let Solar spend all day polishing off the last 15% because that takes time more than amps. - a64pilot((https://www.cruisersforum.com/forums/f14/time-it-takes-to-fully-charge-batteries-238875-9.html#post3223983)) |
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| | The alternator can help meet [[electrical:12v:charging#charging_current|lead bank minimum charging current requirements]]. |
| ===== optimal alternator contribution ===== | ===== optimal alternator contribution ===== |
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