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opinion:frater_secessus:lifepo4_charging_voltage [2023/06/28 23:31] frater_secessus [Problems caused by excessive LiFePO4 charging voltage] |
opinion:frater_secessus:lifepo4_charging_voltage [2024/02/10 11:33] (current) frater_secessus [the full process13.6v example |
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- | ====== Problems caused by excessive | + | ====== Problems caused by lithium charging profiles ====== |
+ | |||
+ | You'd think that a " | ||
+ | ===== excessive charging voltage ===== | ||
[[https:// | [[https:// | ||
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- | ===== TLDR ===== | + | ==== TLDR ==== |
- | If this is the problem then reducing the charging voltage will cause the symptoms to improve or disappear. | + | If excessive charging voltage |
[[opinion: | [[opinion: | ||
- | ===== the full process | + | |
+ | ==== the full process ==== | ||
- reduce charging voltage (aka " | - reduce charging voltage (aka " | ||
- observe for a few days. Charging will be slower and may not finish by sundown((you may have to define or increase an Absorption/ | - observe for a few days. Charging will be slower and may not finish by sundown((you may have to define or increase an Absorption/ | ||
- | - if symptoms do clear up you can start to raise the charging voltage back up gradually (13.65v, 13.7v, 13.75v, etc) or you can leave it low. {note from secessus: | + | - if symptoms do clear up you can start to raise the charging voltage back up gradually (13.65v, 13.7v, 13.75v, etc) or you can leave it low if you are getting enough charge. {note from secessus: |
- if it starts acting up again drop charging voltage back down a notch or two | - if it starts acting up again drop charging voltage back down a notch or two | ||
- | ==== why lower-voltage charging works ==== | + | === why lower-voltage charging works === |
LiFePO4 will fully charge at voltages as low as the mid-13s, | LiFePO4 will fully charge at voltages as low as the mid-13s, | ||
- | * ≥14.0v will charge to 100% SoC with zero minutes of absorption durations: hit the voltage setpoint and //stop//. Cell voltages tend to diverge as charging voltage increases above 14.0v because they are further up the knee (see below) | + | * ≥14.0v will charge to ~100% SoC with zero minutes of absorption durations: hit the voltage setpoint and //stop//. Cell voltages tend to diverge as charging voltage increases above 14.0v because they are further up the knee (see below) |
- | * 13.8v will charge to 100% SoC with a small amount of Absorption (10-30 minutes?) and cells tend to stay in balance. | + | * 13.8v will charge to ~100% SoC with a small amount of Absorption (10-30 minutes?) and cells tend to stay in balance. |
- | * 13.6v will charge to 100% SoC with several hours of Absorption | + | * 13.6v will charge to ~100% SoC with several hours of Absorption |
- | * 13.4v will // | + | |
- | | ||
- | + | ==== why the problem occurs ==== | |
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- | ===== why the problem occurs | + | |
{{ https:// | {{ https:// | ||
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- | ===== further reading | + | ==== further reading ==== |
* [[electrical: | * [[electrical: | ||
+ | |||
+ | |||
+ | ===== lack of pseudo-float ===== | ||
+ | |||
+ | So your charge controller isn't charging even though battery state of charge is dropping? | ||
+ | |||
+ | This can be intentional behavior, caused by a Li profile that | ||
+ | |||
+ | - charges to a high voltage (see above) | ||
+ | - then allows the battery to discharge until it hits the [[electrical: | ||
+ | - at which point it charges to the high voltage again... | ||
+ | - rinse and repeat until the sun goes down | ||
+ | |||
+ | During the discharge stage the controller will appear to stop working. | ||
+ | |||
+ | To avoid this problem. configure a " | ||