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electrical:12v:alternator [2020/05/24 12:07] frater_secessus [gotchas] |
electrical:12v:alternator [2020/06/23 13:10] frater_secessus [limitations] |
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]].(([[electrical:12v:b2b|DC-DC chargers]] can help with the voltage)) 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. | 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]].(([[electrical:12v:b2b|DC-DC chargers]] can help with the voltage)) 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. | Vehicles with //smart// (variable voltage) alternators may not be suitable for charging with normal isolators.((https://www.redarc.com.au/how-do-i-know-if-i-have-a-variable-voltage-smart-alternator)) See [[electrical:12v:b2b|DC-DC chargers]]. |
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| See [[electrical:12v:mandatory solar|Is Solar Mandatory?]] for ideas on how to charge primarily by alternator. |
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Power from the alternator is shared with the house battery using an isolator ("Split charge relay" / SCR) of some sort. This allows the [[electrical:12v:intro|house battery]] to charge but does not allow the house battery to pull power from the starter battery. | Power from the alternator is shared with the house battery using an isolator ("Split charge relay" / SCR) of some sort. This allows the [[electrical:12v:intro|house battery]] to charge but does not allow the house battery to pull power from the starter battery. |
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==== constant-duty solenoid ==== | ==== constant-duty solenoid ==== |
- DC-DC isolators (aka //[[electrical:12v:b2b|b2b]] isolators//) that boost alternator voltage to [[electrical:12v:charging|more appropriate levels for lead chemistries]] and can do multistage charging. These have [[electrical:12v:b2b|their own page]]. | - DC-DC isolators (aka //[[electrical:12v:b2b|b2b]] isolators//) that boost alternator voltage to [[electrical:12v:charging|more appropriate levels for lead chemistries]] and can do multistage charging. These have [[electrical:12v:b2b|their own page]]. |
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==== diode-based isolator ==== | ==== solid state isolator: diode-based ==== |
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Note: this type of isolator is no longer common for our uses. | Note: this type of isolator is no longer common for our uses. |
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[[http://amzn.to/2gVwmKw|Solid state isolators]] are electronic devices which use diodes to prevent depletion of the starter battery. **Isolators are generally brick-shaped**. Diode-based isolators have a **0.5v - 1v drop** between the alternator and house battery. This may be desirable if the house battery is a wants lower-voltage charging like [[electrical:12v:lifepo4_batteries_thread|LiFePO4]]. Some solid state isolaters use FETs and diodes in tandem to reduce voltage drop. \\ Note: solid state relays can't combine batteries for self-jumpstarting. | [[http://amzn.to/2gVwmKw|These isolators]] are electronic devices which use diodes to prevent depletion of the starter battery. **Isolators are generally brick-shaped**. Diode-based isolators have a **0.5v - 1v drop** between the alternator and house battery. This may be desirable if the house battery is a wants lower-voltage charging like [[electrical:12v:lifepo4_batteries_thread|LiFePO4]]. Some solid state isolaters use FETs and diodes in tandem to reduce voltage drop. \\ Note: solid state relays can't combine batteries for self-jumpstarting. |
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| ==== solid state isolator: FET-based ==== |
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| This type of isolator is similar to the diode-based one above, except that FET components are used instead of diodes, preventing voltage drop. |
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| Example: [[https://amzn.to/2Cwjkln|Victron Argo 200A FET Battery Isolator]] |
==== manual switch ==== | ==== manual switch ==== |
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| [[https://amzn.to/2VaL8SG|{{https://m.media-amazon.com/images/I/81n-ap+0lPL._AC_UY218_.jpg?125 }}]]The simplest and least-featured isolator is a //manual switch//. |
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A [[http://amzn.to/2gsDtNc|manual battery switch]] normally has 4 positions: A, B, A+B, and Off. A would be for the starter battery and used during starting. B would be used for house use when one is not driving. A+B could be used to combine both sets for starting or for charging while driving. This kind of setup is prone to user error. A manual switch has no current or voltage losses. | A [[http://amzn.to/2gsDtNc|manual battery switch]] normally has 4 positions: A, B, A+B, and Off. A would be for the starter battery and used during starting. B would be used for house use when one is not driving. A+B could be used to combine both sets for starting or for charging while driving. This kind of setup is prone to user error. A manual switch has no current or voltage losses. |
In early morning when house battery voltage is lowest, **a plain solenoid may unintentionally allow depleted batteries to pull down the starter battery**. Workarounds: use a VSR, or start the vehicle immediately after inserting the key((ie, do not leave in the Accessory position which would drain the starter battery)). | In early morning when house battery voltage is lowest, **a plain solenoid may unintentionally allow depleted batteries to pull down the starter battery**. Workarounds: use a VSR, or start the vehicle immediately after inserting the key((ie, do not leave in the Accessory position which would drain the starter battery)). |
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==== wiring ==== | ===== wiring ===== |
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2 gauge copper wire connecting the coach and house is recommended for most alternator charging installs. SternWake recommends attaching at the alternator rather than the battery.((http://www.cheaprvliving.com/forums/Thread-Charge-house-batteries-with-DC?pid=110652#pid110652)) | 2 gauge copper wire connecting the coach and house is recommended for most alternator charging installs. SternWake recommends attaching at the alternator rather than the battery.((http://www.cheaprvliving.com/forums/Thread-Charge-house-batteries-with-DC?pid=110652#pid110652)) |
Note that you will only have to run the POS+ leg of wire to the house battery as the chassis ground is the other leg. | Note that you will only have to run the POS+ leg of wire to the house battery as the chassis ground is the other leg. |
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==== alternator hacks === | ===== alternator hacks ===== |
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There are ways to get the alternator to pump out more power: | There are ways to get the alternator to pump out more power: |