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electrical:12v:alternator [2022/06/23 11:15]
frater_secessus [effect on alternator] |
electrical:12v:alternator [2022/07/16 11:47]
frater_secessus [sizing an isolator] |
| ===== effect on alternator ===== | ===== effect on alternator ===== |
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| {{ https://img.mousetrap.net/misc/transit250alternator.jpg?150}}Charging the house batteries from the alternator increases the load on the alternator and can be expected to contribute to somewhat earlier failure. In practice it's usually a non-issue if one avoids overheating((as when idling)) or overloading((as with giant AGM or lithium banks)) the alternator; alternator failures from aux battery charging are quite rare. | Charging the house batteries from the alternator increases the load on the alternator and can be expected to contribute to somewhat earlier failure. In practice it's usually a non-issue if one avoids overheating((as when idling)) or overloading((as with giant AGM or lithium banks)) the alternator; alternator failures from aux battery charging are quite rare. |
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| > I have created hundreds of designs and installed around 100 systems, many with isolators or solenoids. In four plus years not one customer has come to me saying that their alternator failed. I do tell them not to sit in a hot parking lot idling their engine to charge their batteries. -- jimindenver((https://vanlivingforum.com/threads/new-wiring-sketch.43877/post-544396)) | > I have created hundreds of designs and installed around 100 systems, many with isolators or solenoids. In four plus years not one customer has come to me saying that their alternator failed. I do tell them not to sit in a hot parking lot idling their engine to charge their batteries. -- jimindenver((https://vanlivingforum.com/threads/new-wiring-sketch.43877/post-544396)) |
| ==== alternator current rating ==== | ==== alternator current rating ==== |
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| In general, vehicles with higher-rated alternators (150A, for example) will handle the extra charging duties better than vehicles with lower-rated alternators (60A, for example). The rating in Amps will be listed on the window sticker, often on the alternator housing itself, or can be looked up using a VIN decoder for your automaker. | {{ https://img.mousetrap.net/misc/transit250alternator.jpg?150}} |
| | In general, vehicles with higher-rated alternators (150A, for example) will handle a given load better than vehicles with lower-rated alternators (60A, for example). The rating in Amps will be listed on the window sticker, often on the alternator housing itself, or can be looked up using a VIN decoder for your automaker. |
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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. Victron posted [[https://www.youtube.com/watch?v=jgoIocPgOuga|a video]] showing it is possible to "smoke" an alternator while charging lithium. Since lithium does not care much about [[electrical:depth_of_discharge|state of charge]], **there is little reason to go for maximum force lithium 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)) | Lithium in particular has low internal resistance and can pull [[electrical:12v:battery_capacity|1C]] (100A for an 100Ah bank) or more. Victron posted [[https://www.youtube.com/watch?v=jgoIocPgOuga|a video]] showing it is possible to "smoke" an alternator while charging lithium ([[electrical:12v:drop-in_lifepo4#but_that_victron_video|rebuttal]]). Since lithium does not care much about [[electrical:depth_of_discharge|state of charge]], **there is little reason to go for maximum force lithium 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. 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)) | 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. 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)) |
