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electrical:12v:lifepo4_batteries_thread [2017/12/09 14:49]
frater_secessus [Synopsis of C&S LiFePO4 batteries thread]
electrical:12v:lifepo4_batteries_thread [2017/12/09 15:02]
frater_secessus [LiFePO4 charging for RVs: running barefoot]
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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.txt · Last modified: 2017/12/09 15:02 by frater_secessus