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electrical:12v:alternator [2019/06/23 20:43]
frater_secessus [alternator hacks] |
electrical:12v:alternator [2019/10/01 12:33]
frater_secessus [limitations] |
| ===== limitations ===== | ===== limitations ===== |
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| Alternator charging is generally only practical for the [[electrical:12v:charging|bulk charge stage]] due to relatively low voltage output and the [[electrical:12v:charging|long time periods required for absorption]]. It is unlikely to get the house battery completely charged unless one is driving significant distances. This can have an impact on battery longevity. If one drives often [[electrical:12v:alt_and_solar|a combination of the alternator doing bulk charging and a small solar doing the rest]] is good match. | Alternator charging is generally only practical for the [[electrical:12v:charging|bulk charge stage]] due to relatively low voltage output and the [[electrical:12v:charging|long time periods required for absorption]]. It is unlikely to get the house battery completely charged unless one is driving significant distances. This can have an impact on [[electrical:batterycide|battery longevity]]. If one drives often [[electrical:12v:alt_and_solar|a combination of the alternator doing bulk charging and a small solar doing the rest]] is good match. |
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| | See [[electrical:12v:mandatory solar|Is Solar Mandatory?]] for ideas on how to charge primarly by alternator. |
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| | ===== effect on alternator ===== |
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| | Charging the house batteries from the alternator increases the load on the alternator and can be expected to contribute to somewhat earlier failure. The shortened life may be trivial if alternator charging is done thoughtfully, and may be sudden if done without considering the effects of higher alternator loading. |
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| | SternWake reports **idling while charging causes a sharp increase in alternator temperature**.((http://www.cheaprvliving.com/forums/Thread-Longer-alternator-life-when-used-to-charge-house-batteries?pid=182096#pid182096)) To avoid this, do your alternator charging while driving. This will ensure airflow over the hot alternator. |
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| | Lithium in particular has low internal resistance and can pull [[electrical:12v:battery_capacity|1C]] (100A for an 100Ah bank) or more. Most AGM will pull about C/3 (33A for a 100Ah bank) but premium brands may do more. Flooded lead-acid batteries tend to pull less current (C/5, 20A per 100Ah of bank). Victron posted [[https://www.youtube.com/watch?v=jgoIocPgOuga video]] showing it is possible to "smoke" an alternator while charging lithium. |
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| | Since lithium does not care much about [[electrical:depth_of_discharge|state of charge]], there is little reason to go for maximum force charging. Some Li bank owners use [[electrical:12v:b2b|DC-DC isolators]] which limit themselves to a particular output (20A, 60A, 100A, etc).((https://shop.pkys.com/Alternator-Lithium-Battery.html)) |
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| | Reasonable charging rates can also be easier on the alternator when charging suddenly stops, whether by completion((same reason headlights are turned on at the donor car when jumpstarting)) or BMS intervention. |
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| | Blue Sea makes an [[https://www.bluesea.com/resources/91|alternator field disconnect]] which shuts down alternator power just before disconnecting the load, but this may be chiefly applicable to marine alternators. Others have discussed installing a small lead-acid battery parallel to the Li bank; in theory this could soften the blow from Li leaving the circuit. Other sources suggest the presence of the starter battery would be sufficient.((https://shop.pkys.com/Alternator-Lithium-Battery.html)) |
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| Charging the house batteries from the alternator increases the load on the alternator and can be expected to contribute to earlier failure. SternWake reports **idling while charging causes a sharp increase in alternator temperature**.((http://www.cheaprvliving.com/forums/Thread-Longer-alternator-life-when-used-to-charge-house-batteries?pid=182096#pid182096)) So don't idle it! | |
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| Also see [[electrical:12v:mandatory solar|Is Solar Mandatory?]] for ideas on how to charge primarly by alternator. | |
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| ===== isolators ===== | ===== isolators ===== |
