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electrical:12v:deep_cycle_battery [2019/03/07 17:31]
frater_secessus [LiFePO4]
electrical:12v:deep_cycle_battery [2020/12/03 19:18] (current)
frater_secessus [premature failure]
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 Drawing down to 80% DoD consistently is 24% more expensive and requires much more replacement effort. [Those things are //heavy//! -- Secessus] Occasional/emergency drops to 80% DoD **followed by full charging the next day** will not inflict meaningful damage to the battery. Drawing down to 80% DoD consistently is 24% more expensive and requires much more replacement effort. [Those things are //heavy//! -- Secessus] Occasional/emergency drops to 80% DoD **followed by full charging the next day** will not inflict meaningful damage to the battery.
  
 +===== premature failure =====
  
 +Lead batteries tend to lose capacity very gradually over time, and are typically replaced when they only have 80% of their rated capacity. If a dying battery still meets your needs feel free to [[electrical:severe_battery_use|use it until it croaks]]. 
 +
 +Lead batteries can fail prematurely from [[electrical:batterycide|abuse and/or undercharging]] (usually gradual), or physical failure like cells shorting out (usually sudden).  Shorted batteries will tend to overheat when charged/discharged.
 +
 +> On FLAs, the definitive way to diagnose a shorted cell is to disconnect the battery and apply a reasonably heavy load (say, C/2 or so). Electrolyte in the shorted cell, if one is present, will boil.((https://www.cruisersforum.com/forums/f14/battery-temperature-243203.html#post3287905))
  
  
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-Common setpoints (check your manufacturer's recommendation):+Common [[electrical:solar:charge_controller_setpoints|setpoints]] (check your manufacturer's recommendation):
   * charge [[electrical:12v:battery capacity|C/10 to C/5]]((10A-20A per 100Ah of battery capacity))   * charge [[electrical:12v:battery capacity|C/10 to C/5]]((10A-20A per 100Ah of battery capacity))
   * Vfloat 13.2v when not deeply cycled;  13.8v when cycled daily   * Vfloat 13.2v when not deeply cycled;  13.8v when cycled daily
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 ==== carbon FLA ==== ==== carbon FLA ====
  
-Some manufacturers attempt to get around the [[electrical:12v:psoc|Partial State of Charge]] limitations of lead chemistries by using carbon in some form.  The idea is that the addition of carbon limits hard sulfation that can form in PSOC scenarios.+Some manufacturers attempt to get around the [[electrical:12v:psoc|Partial State of Charge]] limitations of lead chemistries by using carbon in some form.  The idea is that the addition of carbon increases the internal conductivity of the negative plate under challenging conditions, minimizing hard sulfation that can form in PSOC scenarios.
  
-In the milder form, carbon is added to the negative plates.  Trojan claims up to 15% more cycles from the RE(("Renewable Energy")) line than non-carbon FLA in PSOC use.((http://www.trojanbattery.com/new-products/smart-carbon/))  At this writing the cost premium for this <=15% increase in cycles is 21%.(($175 for T-105RE vs $145 for T-105))+In the milder form, carbon is added to the negative plates
 + 
 +> Battery manufacturers have begun including high purity conductive graphite in the negative active material of their batteriesThey have found that this type of carbon helps to maintain the essential active material conductivity that helps to control sulfation.((https://batteryvitamin.net/sulfation_remedies_demystified)) 
 + 
 + 
 +  * Rolls calls this "[[http://support.rollsbattery.com/support/solutions/articles/245858-advanced-nam|Advanced NAM]]"((negative [something] material?)) and claims 15% faster charging, increased capacity, and increased cycle life.  They state that this type of battery may have higher [[electrical:solar:charge_controller_setpoints|endAmps]] due to less internal resistance.((http://support.rollsbattery.com/support/solutions/articles/246380-end-amps-or-return-amps)) 
 +  Trojan claims up to 15% more cycles from the RE(("Renewable Energy")) line with "smart carbon"((https://www.trojanbattery.com/new-products/smart-carbon/)) than non-carbon FLA in solar-charging use.((http://www.trojanbattery.com/new-products/smart-carbon/))  At this writing the cost premium for this <=15% increase in cycles is 21%.(($175 for T-105RE vs $145 for T-105))  This would be an extra 9 months of life assuming a 5yr lifespan.
    
 +
 +===== manufacturers =====
 +
 +
 +> Each manufacturer also has their own in-house brand, e.g. Delco for Johnson Controls and Deka for East Penn. Exide and US Battery use their corporate name for their battery brand as well. Trojan sells under the Trojan, Trillium, Reliant and Ranger brand names and Concorde sells under the Concorde and Lifeline brand names.... [Interstate is a label, not a manufacturer]...  The 4 big US battery makers offer a couple price and quality tiers for their customers to choose from, but generally batteries with the same specs (AH/RC, CCA, and BCI case size) will be essentially identical. Warranty, MSRP, etc. is set by the selling brand and may differ, but the physical product is the same. -- Gary RVRoamer((https://www.irv2.com/forums/f59/trojan-t-105-or-interstate-again-486470-2.html#post5246144))
 +
 +Interstate batteries made by US Battery have "U" prefixes.((https://www.solarpaneltalk.com/forum/off-grid-solar/batteries-energy-storage/14996-trojan-t-105-vs-crown-235-and-what-s-wrong-with-parallel?p=195949#post195949))
 +
 +===== construction =====
 +
 +Generally speaking, lead batteries fall into three broad groups
 +
 +  - **starter** - relatively little lead, but thin and spongey, calcium-doped((https://www.engineersedge.com/battery/antimony_calcium_selenium_tin_alloying.htm)) plates make a huge surface area for massive currents involved with starting the engine and immediately recharging from alternator.  The addition of Calcium decreases internal resistance, increases the outgassing voltage((thereby reducing water loss)) point((http://necon.co.za/batttech.php?w=1366&h=768#openModal)), decreases self-discharge, but makes the plates more likely to be damaged by overcharging. ((https://www.engineersedge.com/battery/antimony_calcium_selenium_tin_alloying.htm))  
 +  - **deep cycle** - lots of lead formed into thick, smooth antimony-doped plates.  Can move less current but can do so for a longer time and can tolerate deeper discharge.  This comes at the cost of increased water loss and self-discharge rates.  Deep cycle batteries prefer to be floated constantly after charging.
 +  - **hybrid/marine** - plates tend to have middling thickness.  They may have calcium-doped negative plates and antimony-doped negative plates.((http://necon.co.za/batttech.php?w=1366&h=768#openModal))
 +
 +
 +
 +
 +
  
 ===== VRLA ===== ===== VRLA =====
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 ==== AGM ==== ==== AGM ====
 +
 +Note:  High quality AGM makers include "Odyssey, Lifeline, Northstar, Fullriver, Rolls and Firefly".((https://www.cruisersforum.com/forums/f14/agm-battery-failure-two-sets-in-two-years-239438-6.html#post3228496))  
 +
  
 This type of VRLA battery stabilizes the electrolyte in an Absorbent fiberGlass Mat (AGM). This type of VRLA battery stabilizes the electrolyte in an Absorbent fiberGlass Mat (AGM).
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 ==== Gel cell ==== ==== Gel cell ====
  
-This type of VRLA battery gelatinizes the electrolyte to stabilize it.  While renowned for their duty cycles, they are rarely used in campers. +This type of VRLA battery gelatinizes the electrolyte with SiO2 (silicon dioxide) to stabilize it.  While renowned for their duty cycles, they are rarely used in campers due to cost, limited charging max similar to flooded((C/5, https://www.trojanbattery.com/pdf/datasheets/Motive_T1275-AGM_DS.pdf and https://www.qsl.net/wb3gck/gel-cell.htm)), and sensitivity to overvoltage. 
 + 
 +"Lead crystal" batteries may actually be gel, since they claim the electrolyte is made of SiO2.((http://azimuthsolar.ca/getting-silicon-dioxide-sio2-batteries-charging-instructions/)),((https://www.solarpaneltalk.com/forum/solar/the-pros-and-cons-of-solar-energy/22713-why-are-there-no-lead-crystal-battery-distributors-in-the-usa-or-canada?p=272482#post272482)) 
 + 
  
 ==== Carbon foam AGM ===  ==== Carbon foam AGM === 
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 ===== chain store batteries ===== ===== chain store batteries =====
 {{ https://i5.walmartimages.com/asr/523d2f9f-6552-48c6-928c-9eebf09ab0e9_1.3ffce13c71014acbc0a6c469b62333dc.jpeg?150}}"Deep cycle" / marine batteries found at Walmart and similar chains are not actually deep cycle batteries.  Real 12v deep cycle batteries like the [[https://www.ebay.com/sch/items/?_nkw=trojan+T-1275&_sacat=&_ex_kw=&_mPrRngCbx=1&_udlo=&_udhi=&_sop=12&_fpos=&_fspt=1&_sadis=&LH_CAds=&rmvSB=true|Trojan T-1275]] are large, expensive, and very rarely seen in campers.((http://www.cheaprvliving.com/forums/Thread-Everstart-vs-Everstart-Maxx-batteries-at-Wal-Mart?pid=167108#pid167108))   {{ https://i5.walmartimages.com/asr/523d2f9f-6552-48c6-928c-9eebf09ab0e9_1.3ffce13c71014acbc0a6c469b62333dc.jpeg?150}}"Deep cycle" / marine batteries found at Walmart and similar chains are not actually deep cycle batteries.  Real 12v deep cycle batteries like the [[https://www.ebay.com/sch/items/?_nkw=trojan+T-1275&_sacat=&_ex_kw=&_mPrRngCbx=1&_udlo=&_udhi=&_sop=12&_fpos=&_fspt=1&_sadis=&LH_CAds=&rmvSB=true|Trojan T-1275]] are large, expensive, and very rarely seen in campers.((http://www.cheaprvliving.com/forums/Thread-Everstart-vs-Everstart-Maxx-batteries-at-Wal-Mart?pid=167108#pid167108))  
 +
 +It's not foolproof, but seeing a CCA (Cold Cranking Amps) spec listed on the battery suggests it is //not// a deep cycle battery: 
 +
 +> While it might be tempting to estimate the AH rating of a battery from its CCA rating, there is not a simple relationship between these two battery parameters.((https://www.mathscinotes.com/2016/12/relationship-between-battery-cold-cranking-amps-versus-capacity/))
 +
 +
  
 Having said that, if one is aware of the limitations of the battery it can play a role in the campervan, particularly as a "learner battery" that the [[electrical:batterycide|beginner often murders]].  Lifespan on these batteries can be maximized by cycling lightly, perhaps 20% [[electrical:depth_of_discharge|depth of discharge]]. Having said that, if one is aware of the limitations of the battery it can play a role in the campervan, particularly as a "learner battery" that the [[electrical:batterycide|beginner often murders]].  Lifespan on these batteries can be maximized by cycling lightly, perhaps 20% [[electrical:depth_of_discharge|depth of discharge]].
  
-**Pro**:  Local and 24hr availability in stores can valuable.  Warranties are nationwide;  save your receipt as it is usually required. +**Pro**:  Local and 24hr availability in stores can be valuable.  Warranties are nationwide;  save your receipt as it is usually required. 
  
 **Con**: Significantly less capacity than a real deep cycle bank; a group 27 wally world battery has about 1/2 the Ah capacity.  Drastically reduced longevity when cycled to 50% DoD as with most campervan usage patterns.   **Con**: Significantly less capacity than a real deep cycle bank; a group 27 wally world battery has about 1/2 the Ah capacity.  Drastically reduced longevity when cycled to 50% DoD as with most campervan usage patterns.  
  
 ===== lithium chemistries ===== ===== lithium chemistries =====
 +
 +Lithium battery banks are lighter and have higher energy density than lead-acid batteries.  The main drawback is price.  
 +
 +
 +Lithium banks come in three main forms:
 +  * "drop-in" batteries that are the same size and general voltage range as the lead batteries they replace.  Example:  [[https://amzn.to/2oVGNWj|Battle Born]]  BMS is built in.
 +  * DIY banks, often "bare" cells 3.2v cells in [[electrical:12v:parallel_serial|4S]] configuration, with or without BMS.  These are not the same size or shape as lead batteries
 +  * manufactured complete banks that do not mimic the physical shape of lead batteries 
 +
 +==== BMS ====
 +Because of the very high energy density and sensitivity to temperature and voltage extremes, most Li banks are equipped with a Battery Management System (BMS) which monitors and controls the bank and the cells in it. 
 +
 +Depending on the BMS, features may include:
 +  * protection from overcharging individual cells
 +  * "top balancing" cells, getting cell voltages to match when fully charged
 +  * protection from over-discharge
 +  * protection from excess current in charging and/or discharging
 +  * prevention of charging when temps are too low((typically freezing or below))
 +
 +
 +
 +
 +
  
 ==== LiFePO4 ==== ==== LiFePO4 ====
 +
 +[[https://amzn.to/2oVGNWj|{{ https://m.media-amazon.com/images/I/61Z6qdh47cL._AC_UL320_SEARCH213888_ML3_.jpg}}]]
 +In theory **LifePO4 (LFP) lithium batteries** should be near perfect for boondockers who [[camping:snowbirding|follow good weather]].
 +
 +[[https://amzn.to/2oVGNWj|Battle Born]] presently dominates the drop-in 12v lithium market.
  
  
-In theory **LifePO4 lithium batteries** should be near perfect for boondockers who [[camping:snowbirding|follow good weather]]. 
  
  
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   * can be damaged by heat   * can be damaged by heat
  
-For best life (and to decrease the likelihood of cell imbalance) Charge to 13.8v and disconnect voltage at 12.6v.((http://www.cheaprvliving.com/forums/showthread.php?tid=17442&pid=195503#pid195503)), ((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069.html#post740260)), ((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-4.html#post747996)), ((http://www.cruisersforum.com/forums/f14/lifepo4-batteries-discussion-thread-for-those-using-them-as-house-banks-65069-7.html#post812380))+BMS-equipped LFP banks should be charged according to manufacturer's specs Bare cell charging is discussed [[electrical:12v:lifepo4_batteries_thread|on its own page]]. 
 + 
 + 
  
-The batteries can be charged with either a [[electrical:solar:charge_controller|charge controller]] with a LifePO4 profile, or a [[electrical:12v:charging|smart charger]] with programmable setpoints.  If the latter, something like a "Bulk" charge at 13.8, minimal "absorption", and "float" in the 13.25-13.4v range.((http://www.cheaprvliving.com/forums/showthread.php?tid=14960&pid=160365#pid160365)) 
-Technomadia charge to 14.2v, use a minimal "absorption", and "float" at as the setpoint , float at 13.6v.((http://www.technomadia.com/2012/09/a-year-on-lithium-rv-batteries/)) 
  
 Further reading: Further reading:
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   * CF [[http://www.cruisersforum.com/forums/f14/lifepo4-batteries-okay-tear-me-apart-36530.html|LiFePO4 batteries]]     * CF [[http://www.cruisersforum.com/forums/f14/lifepo4-batteries-okay-tear-me-apart-36530.html|LiFePO4 batteries]]  
   * CF [[http://www.cruisersforum.com/forums/f14/lifepo4-house-bank-using-smarthousepower-bms-40389.html|LiFePO4 house batteries]]   * CF [[http://www.cruisersforum.com/forums/f14/lifepo4-house-bank-using-smarthousepower-bms-40389.html|LiFePO4 house batteries]]
 +
 +
 +
  
 ==== Non-LiFePO4 lithium-ion ==== ==== Non-LiFePO4 lithium-ion ====
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-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.  +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.  The cells could be fully charged then the output regulated back to more normal 12v voltage ranges.
  
-**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.   +**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.   
 24v banks in general could preclude [[electrical:12v:alternator|alternator charging]], however. 24v banks in general could preclude [[electrical:12v:alternator|alternator charging]], however.
  
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 **Con:** **Con:**
   * overcharging or physical damage can cause a runaway condition (ie fire)   * overcharging or physical damage can cause a runaway condition (ie fire)
-  * voltage mismatch - FIXME+  * voltage mismatch of 3S to nominal 12v systems 
 + 
 +===== health ===== 
 + 
 +Batteries are typically replaced when they can no longer provide 80% of their rated capacity.   This requires fully charging, then discharging at the 20-hr rate (C/20) until the battery is depleted.  This is impractical with house batteries that are in actual use. 
 + 
 +Because of this, we use indirect methods to assess battery health.   
 + 
 +> Quickly rising to absorption voltage during bulk and never seeing tail current drop down to previous levels are good indicators that the battery is in a declined or seriously declining state.  mainesail((https://www.cruisersforum.com/forums/f14/my-aging-northstar-group-27-a-179072.html#post2312172)) 
 + 
 + 
 +Tail current (aka endAmps, finishing amps) for healthy lead batteries is typically between C/200 and C/100 (0.5A to 1.0A at Vabs for per 100Ah of capacity).  If tail current cannot get down to (C/50) 2A we can assume there is trouble on the horizon.   
 + 
 + 
 +> I have yet to see a lead acid battery that could delivers its full storage potential at anything less than 0.75%((ie, C/133)) in tail current at absorption voltage. -- mainesail((https://marinehowto.com/how-fast-can-an-agm-battery-be-charged/)) 
 + 
 + 
 +The rise to absorption voltage is rarely useful in the field since:
  
 +  - solar charging alone is rarely able to hit charge current maximums
 +  - alternator charging is rarely able to hit Vabs
  
 +People charging off larger [[electrical:12v:b2b|DC-DC]], [[electrical:converter|shore power]], or [[electrical:generator|generators]] may be able gauge the speed at which the bank comes up to Vabs.
  
electrical/12v/deep_cycle_battery.1551997912.txt.gz · Last modified: 2020/10/11 19:48 (external edit)