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electrical:12v:lifepo4_batteries_thread [2017/12/09 17:49]
frater_secessus [Synopsis of C&S LiFePO4 batteries thread]
electrical:12v:lifepo4_batteries_thread [2020/10/11 19:48] (current)
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 This can make LFP banks less complex and less expensive in an RV application.  Assessing SOC by voltage is also more accurate with Fractional C charging/discharging than with high currents.   This can make LFP banks less complex and less expensive in an RV application.  Assessing SOC by voltage is also more accurate with Fractional C charging/discharging than with high currents.  
-==== LiFePO4 charging for RVs: Terrycharging ====+==== LiFePO4 charging for RVs: running barefoot ====
  
-Although his setup does not use it, T1 Terry describes a "middle 80%" approach that works well with Fractional C systems. It can eliminate the need for [[electrical:12v:BMS|BMS]] balancing+T1 Terry describes a gentle, relatively low-tech approach that can work well with vandweller use patterns It does not use a [[electrical:12v:BMS|BMS]], judging that in a vandwellers' use the BMS introduces more hazards than it alleviates.  This approach: 
-  * starts with a balanced battery when installing.+ 
 +  * starts with a balanced battery
   * uses moderate terminal voltage (13.8v) to gently rebalance cells((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-77.html#post1132126)),((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-44.html#post1096480)), and even become more balanced over time.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-109.html#post1142675))  If they do get out of balance for some reason, run more conservative SoC voltages until they can be manually rebalanced.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-294.html#post1779359))   * uses moderate terminal voltage (13.8v) to gently rebalance cells((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-77.html#post1132126)),((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-44.html#post1096480)), and even become more balanced over time.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-109.html#post1142675))  If they do get out of balance for some reason, run more conservative SoC voltages until they can be manually rebalanced.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-294.html#post1779359))
-  * charges at less than 1C, common in solar charging+  * charges and discharges at less than [[electrical:12v:battery_capacity|1C]], common in solar charging.  i.e. less than 100A with a 100Ah bank. 
   * keeps the voltage "between the [voltage] knees", 13.8v - 11.8v.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-103.html#post1140470))  This is also called the "middle 80%".   * keeps the voltage "between the [voltage] knees", 13.8v - 11.8v.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-103.html#post1140470))  This is also called the "middle 80%".
-  * does not //require// strapping((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-59.html#post1118000)) although it is a recommended best practice((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-253.html#post1574064)) +  * does not require strapping((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-59.html#post1118000)) although it is a recommended best practice((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-253.html#post1574064)) 
-  * no BMS required+ 
 + 
 +Since the defining feature of this approach is the lack of BMS, it will be referred to as "barefoot" on this page. 
  
-For lack of a better term, this barefoot (no BMS)/ middle 80% / fractional-C approach will be called **Terrycharging** below.   
  
 ==== LiFePO4 characteristics ==== ==== LiFePO4 characteristics ====
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 |  16.80|  4.20|cell damage((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-93.html#post1137808))  | |  16.80|  4.20|cell damage((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-93.html#post1137808))  |
 |  14.40|  3.60|High Voltage Cutoff((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-109.html#post1142567))  | |  14.40|  3.60|High Voltage Cutoff((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-109.html#post1142567))  |
-|  **13.80**|  3.45|**Terrycharging Vabs**, with gentle overcharge for balancing.  Max safe non-BMS voltage.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-44.html#post1096480))  |+|  **13.80**|  3.45|**barefoot Vabs**, with gentle overcharge for balancing.  Max safe non-BMS voltage.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-44.html#post1096480))  |
 |  13.60|  3.40|fully charged  | |  13.60|  3.40|fully charged  |
-|  **13.40**|  3.35|**Terrycharging Vfloat**  |+|  **13.40**|  3.35|**barefoot Vfloat**  |
 |  13.25|  3.31|20% Depth of Discharge  | |  13.25|  3.31|20% Depth of Discharge  |
 |  12.80|  3.20|50% Depth of Discharge FIXME.  Long-term storage.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-172.html#post1201146))  | |  12.80|  3.20|50% Depth of Discharge FIXME.  Long-term storage.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-172.html#post1201146))  |
 |  12.40|  3.10|80% Depth of Discharge.  Best for storage?((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-384.html#post2383574))  | |  12.40|  3.10|80% Depth of Discharge.  Best for storage?((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-384.html#post2383574))  |
-|  **11.80**|  2.95|**Terrycharging Low Voltage Disconnect**.  Min safe non-BMS voltage. ((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-103.html#post1140470))  |+|  **11.80**|  2.95|**barefoot Low Voltage Disconnect**.  Min safe non-BMS voltage. ((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-103.html#post1140470))  |
 |  11.20|  2.80|100% Depth of Discharge((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-104.html#post1140620)).  Low Voltage Cutoff.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-109.html#post1142567))  | |  11.20|  2.80|100% Depth of Discharge((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-104.html#post1140620)).  Low Voltage Cutoff.((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-109.html#post1142567))  |
  
electrical/12v/lifepo4_batteries_thread.1512859745.txt.gz · Last modified: 2020/10/11 19:48 (external edit)