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--- opinion:frater_secessus:charging_faster [2020/05/13 12:10]
frater_secessus [charging faster isn't always better]
+++ opinion:frater_secessus:charging_faster [2021/12/16 14:22]
frater_secessus [lithium]
@@ Line 11: / Line 11: @@
 **Lead batteries** have a **maximum amount of current** they will accept, typically [[electrical:12v:battery_capacity|C/3]] for AGM and C/5 for flooded. So if you have 100Ah of AGM the most it will want to take is something like ~33A.  Once the battery's limit is hit throwing more charging capacity at it can't charge it any faster.((it may help run loads, though))
-** Deep-cycled lead batteries have a lengthy [[electrical:12v:charging|Absorption]] stage** that cannot be sped up. Depending on use, Absorption typically requires several hours.There is a saying that "it takes 9 months to make a baby, but two women cannot make a baby in 4.5 months".  Same with absorption - it takes what it takes and you cannot hurry it in the normal sense.
+** Deep-cycled lead batteries have a lengthy [[electrical:12v:charging|Absorption]] stage** that cannot be sped up((at least not more than a few percent, see below)). Depending on use, Absorption typically requires several hours.There is a saying that "it takes 9 months to make a baby, but two women cannot make a baby in 4.5 months".  Same with absorption - it takes what it takes and you cannot hurry it in the normal sense.
 However:
@@ Line 22: / Line 22: @@
   * charging AGM at C/5 (min rate) resulted in the battery being 77.4% "full" at Vabs and being fully charged in **5hrs, 42 minutes** (76min Bulk, 4hr 26mins Absorption)
-Note that the **using 2x the charging current only sped up the whole process by 12 minutes (3.6%)** due to Vabs starting earlier but taking longer. Getting to Vabs faster could be [[electrical:solar:pwm_tweaking|preferable on PWM controllers]].
+Note that the **using 2x the charging current only sped up the whole process by 12 minutes (3.6%)** due to Vabs starting earlier but taking longer.
-Also note that for simple, timer-based Absorption configurations((like 180 minutes)) the slower charging regiment would actually complete more Absorption.((180/266mins rather than 180/310mins))
+  * **Getting to Vabs faster** could be [[electrical:solar:pwm_tweaking|preferable on PWM controllers]], as the system would be making max power for a longer period of time.
+  * **Getting to Vabs slower** could be preferable on timer-based Absorption configurations((like 180 minutes)), as slower charging regiment would reduce the required Absorption duration.((180/266mins rather than 180/310mins))
@@ Line 30: / Line 31: @@
-**Lithium batteries** can slurp up current wildly, but shouldn't for their own health.  Lithium lasts longest in sub-C use (ie, less than 100A for a 100Ah Li bank).  C/2 (50A) is a more common limit to keep from stressing them. In commercial examples the BMS will limit current to protect the cells.  A small [[electrical:12v:b2b|DC-DC charger]] can help protect bare cells from their own greediness.
+**Lithium batteries** can slurp up current wildly, but shouldn't for their own health.  Lithium lasts longest in sub-C use (ie, less than 100A for a 100Ah Li bank).  C/2 (50A) is a more common manufacturer recommendation, and folks [[electrical:12v:drop-in_lifepo4#an_approach_to_greater_longevity|striving for added longevity]] might limit it to C/5 (20A).  . In commercial examples the BMS will limit current to protect the cells.  A small [[electrical:12v:b2b|DC-DC charger]] can help protect bare cells from their own greediness.
+Limiting charging  current also makes it easier on alternators when they are used to charge Li.

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