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--- electrical:12v:deep_cycle_battery [2018/12/12 16:46]
frater_secessus [Carbon foam]
+++ electrical:12v:deep_cycle_battery [2018/12/28 09:47]
frater_secessus [Non-LiFePO4 lithium-ion]
@@ Line 147: / Line 147: @@
 ===== lithium chemistries =====
+==== LiFePO4 ====
 In theory **LifePO4 lithium batteries** should be near perfect for boondocking.
@@ Line 177: / Line 180: @@
   * CF [[http://www.cruisersforum.com/forums/f14/lifepo4-house-bank-using-smarthousepower-bms-40389.html|LiFePO4 house batteries]]
-Other lithium chemistries like **"Li-ion" and "Li-po"** are rarely used. They are prone to thermal runaway (fire) and 3S packs do not line up well with 12v use.  They are fully charged at 12.6v and and 80% discharged at ~11.2v.((3.73v per cell, https://www.rcgroups.com/forums/showthread.php?2953565-Lipo-Voltage-After-80-Discharge))  These lower voltages may trigger low voltage disconnect on devices that expect lead-acid range voltages.
+==== Non-LiFePO4 lithium-ion ====
+Non-LiFeP04 Li-ion [called "li-ion" hereafter] are usually built in [[electrical:12v:parallel_serial|3S configuration]] and so run lower voltages than LFP or lead.  Usable cell voltage is 4.2v - 3v, yielding bank voltage of **12.6v - 9v**.((https://batteryuniversity.com/learn/article/confusion_with_voltages))  This lower voltage may trip [[electrical:12v:lvd|Low Voltage Disconnect]] on [[electrical:inverter|inverters]] or [[food:refrigeration|refrigerators]].
+There are hobbyists who build 4S packs and undercharge the cells to only 3.7v.  This gives an operating range of 14.8v - 12v, a much better fit for nominal 12v systems. The downside is this configuration only uses 58% of the cells' capacity and will require more cells to achieve the same amount of Ah.
+**7S builds** make a decent **24v bank**.  They are 29.4v fully charged and 21v discharged, compared to lead acid's 29.6v max voltage and 24.2v 50% DoD cutoff.  Discharging 7s li-ion to 24v((3.42v/cell) could help avoid LVD, making 35% of the cells' capacity unusable.
+v banks in general could preclude [[electrical:12v:alternator|alternator charging]], however.
+**Pro:**
+  * About half the cost of LFP for the same Ah capacity
+  * widely available
+**Con:**
+  * overcharging or physical damage can cause a runaway condition (ie fire)
+  * voltage mismatch -
-S banks make a decent 24v bank.  They are 29.4v fully charged and 80% discharged at 26.11v, compared to lead acid's 29.6v max voltage and 24.2v 50% DoD cutoff.  This could preclude alternator charging, however.

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