electrical:solar:shunt_tweaking
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electrical:solar:shunt_tweaking [2024/10/21 23:01]
frater_secessus |
electrical:solar:shunt_tweaking [2024/10/21 23:02] (current)
frater_secessus |
| The **charging setpoint**, called PV OFF on the screen, is the highest voltage you want your battery to see. There are no separate Absorption voltage (Vabs) or Float voltage (Vfloat) settings, just the one PV OFF setpoint. So you have to pick a compromise. There are a couple reasons to [[electrical:solar:pwm_tweaking#the_controller_s_achilles_heel|use a higher-than-usual voltage]]: the battery will be able to run the panels at a higher voltage where they make more power (closer to Vmp). This means you can also run bigger loads without affecting the battery much or [[electrical:solar:offthepanel|even at all]]. | The **charging setpoint**, called PV OFF on the screen, is the highest voltage you want your battery to see. There are no separate Absorption voltage (Vabs) or Float voltage (Vfloat) settings, just the one PV OFF setpoint. So you have to pick a compromise. There are a couple reasons to [[electrical:solar:pwm_tweaking#the_controller_s_achilles_heel|use a higher-than-usual voltage]]: the battery will be able to run the panels at a higher voltage where they make more power (closer to Vmp). This means you can also run bigger loads without affecting the battery much or [[electrical:solar:offthepanel|even at all]]. |
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| So if you are deep cycling lead batteries daily one can use the highest charging voltage (Absorption voltage, "boost" voltage) listed by the battery manufacturer. ((Trebor English reminds us to fiddle the voltage per season since these devices don't have temp compensation)) This works because lead batteries are often underabsorped and sunlight has a limited duration. Those with flooded lead-acid remember to check your water levels! | So if you are deep cycling lead batteries daily one can use the highest charging voltage (Absorption voltage, "boost" voltage) listed by the battery manufacturer.((Trebor English reminds us to fiddle the voltage per season since these devices don't have temp compensation)) It might be ~14.4v for AGM, ~14.2v for GEL and 14.7v for FLA. This approach works because lead batteries are often underabsorped and sunlight has a limited duration. Those with flooded lead-acid remember to check your water levels! |
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| LiFePO4 is the opposite: unaffected by [[electrical:12v:psoc|partial states of charge]] and [[opinion:frater_secessus:lifepo4_charging_voltage|does not like to be held at higher voltages]]. Something like 13.6v would charge somewhere in the upper half of SoC without overcharging. 13.8v would yield gentle overcharge if desired. You will have to observe-and-correct to see how your particular setup behaves. | LiFePO4 is the opposite: unaffected by [[electrical:12v:psoc|partial states of charge]] and [[opinion:frater_secessus:lifepo4_charging_voltage|does not like to be held at higher voltages]]. Something like 13.6v would charge somewhere in the upper half of SoC without overcharging. 13.8v would yield gentle overcharge if desired. You will have to observe-and-correct to see how your particular setup behaves. |
electrical/solar/shunt_tweaking.1729551669.txt.gz ยท Last modified: 2024/10/21 23:01 by frater_secessus
