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electrical:12v:battery_capacity [2020/05/13 11:50]
frater_secessus [other than 20hr rates]
electrical:12v:battery_capacity [2021/05/03 10:40] (current)
frater_secessus [other than 20hr rates]
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 ====== C notation ====== ====== C notation ======
-Battery capacity in Amp-hours is written as **C**.  This notation is most useful when talking about charging/discharging rates +**Battery capacity** in Amp-hours is written as **C**.  100Ah, for example.
-Note:  most deep cycle manufacturer's rate capacity at C/20, due to Peukert effect.+C notation can also be used to describe the **relative amount of current** charging/discharging battery bank. For example a 50A load on a 100Ah bank would be C/2 (100/2 == 50).((technically C/20/2, but that form is rarely seen outside formal documents)). It may also be written as 0.5C.((decimal vs. fractional expression, can be used interchangably)) 
 +Note:  most deep cycle manufacturer's rate capacity at C/20, due to Peukert effect on lead chemistries (see below).((Lithium doesn't not have a significant Peukert effect.  Capacity measured by C/20 and by amp-counting will be nearly identical)).  In other words, a 100Ah battery will deliver 100A with a 5A load over 20 hours.
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 ===== other than 20hr rates ===== ===== other than 20hr rates =====
-For other than C/20 loads((flooded)):+Because of the Peukert effect, lead bank //measured// capacities are strongly affected by dicharge rate. Sample data below is for flooded lead acid.((Due to lower internal resistance AGM is less affected by discharge rate and lithium is barely affected at all.))  C/20 capacity is multiplied by the factor below to find projected capacity at given discharge rates. 
 +Example our battery is rated at 100Ah when drained at 5A over 20 hours.  If it is drained at 20A in 5 hours it will have an observed capacity of 70Ah (100Ah x .7).
electrical/12v/battery_capacity.1589385027.txt.gz · Last modified: 2020/10/11 19:48 (external edit)