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electrical:12v:alternator [2024/07/16 13:26]
frater_secessus [disabling alternator charging] |
electrical:12v:alternator [2024/12/21 11:47] (current)
frater_secessus [lithium-specific VSR] |
| An interesting teardown of the Li-BIM can be seen in [[https://www.youtube.com/watch?v=pFd9Uulo9rY|this video]]. | An interesting teardown of the Li-BIM can be seen in [[https://www.youtube.com/watch?v=pFd9Uulo9rY|this video]]. |
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| | === True Amalgamated Lithium VSR === |
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| | True [[https://www.trueam.com/product/true-lithium-large-dual-battery-kit/|makes a VSR]] with 13.5v ON and 13.2v OFF setpoints. |
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| {{ https://m.media-amazon.com/images/I/81on3erSzsL._AC_UY218_.jpg?125}} | {{ https://m.media-amazon.com/images/I/81on3erSzsL._AC_UY218_.jpg?125}} |
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| Note: this type of isolator is no longer common for our uses for several reasons. Nevertheless they might be useful in some setups where bidirectional charging((where current could go either way after connection is made)) is undesirable. | Note: this type of isolator was common in the 80s and 90s. It is no longer common for our uses for several reasons. Nevertheless they might be useful in some setups where bidirectional charging((where current could go either way after connection is made)) is undesirable, or where alternator voltage is excessively high for house the battery chemistry. |
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| These are proper "isolators" and **never combine the starter and house batteries**. The isolator is a Y connection that receives power from the alternator and distributes it separately to the starter battery and house battery. The rating is the maximum input from the alternator, and the two "legs" are assumed to each have half the capacity. | These are proper "isolators" and **never parallel the starter and house batteries**. The isolator is effectively a Y connection //installed between the alternator and starter battery//.((since the existing wiring is usually ''alternator -> starter -> starter battery'' the install is either directly from the alternator or after the starter.)) It receives power from the alternator and distributes it separately to the starter battery and house battery. The isolator's Amp rating is the maximum input from the alternator. |
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| [[http://amzn.to/2gVwmKw|These isolators]] are electronic devices which use diodes to prevent backflow from either battery. **Isolators are generally brick-shaped**. Silicon diode isolators typically have a **0.7v voltage drop** ("forward voltage drop") between the alternator and house battery when running near rated capacity.((the actual drop is described by the Shockley diode equation, which exceeds the scope of this article.)) This may be desirable if the house battery is a wants lower-voltage charging like [[electrical:12v:lifepo4_batteries_thread|LiFePO4]].((caveat related to the note above - we cannot count on a stable 0.7v drop; it will likely be less at lower currents)) The slightly-lower voltage will also [[#effect_of_isolator_type_on_charge_rates|reduce charging current somewhat]]. | [[http://amzn.to/2gVwmKw|These isolators]] are electronic devices which use diodes to prevent backflow from either battery. **Isolators are generally brick-shaped**. Silicon diode isolators typically have a **0.7v voltage drop** ("forward voltage drop") between the alternator and house battery when running near rated capacity.((the actual drop is described by the Shockley diode equation, which exceeds the scope of this article.)) This may be desirable if the house battery is a wants lower-voltage charging like [[electrical:12v:lifepo4_batteries_thread|LiFePO4]].((caveat related to the note above - we cannot count on a stable 0.7v drop; it will likely be less at lower currents)) The slightly-lower voltage will also [[#effect_of_isolator_type_on_charge_rates|reduce charging current somewhat]]. |
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| It is possible to have the alternator voltage-sense the battery voltage through a diode so it sees the voltage as artificially low and so increases its output voltage. The net effect can be almost no voltage loss. | |
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| Notes: | Notes: |
| * the unidirectional nature of the diode isolator may be desirable to prevent "backflow" of higher voltage from the house bank to the chassis. | * the unidirectional nature of the diode isolator may be desirable to prevent "backflow" of higher voltage from the house bank to the chassis. |
| * diode-based isolators are typically installed //between// the alternator and starter battery. This is in contrast to solenoids and VSRs which can be daisy-chained off the starter battery. The batteries are, in effect, always isolated and never electrically combined. | * diode-based isolators are typically installed //between// the alternator and starter battery. This is in contrast to solenoids and VSRs which can be daisy-chained off the starter battery. The batteries are, in effect, always isolated and never electrically combined. |
| * It would be possible to insert [[https://amzn.to/3R2HsNk|a two-terminal diode isolator]] between the starter and house batteries | * some diode-based isolators (Victron, see above) have a feature to slightly tweak alternator voltage upwards to compensate for voltage drop across the isolator. Note that this increases alternator voltage everywhere, not just after the isolator. |
| * starter batt --> LVD or IGN --> relay --> diode isolator -> house battery. | |
| * Ctek Smartpass (see below) is a commercial packaging of this idea | |
| * some diode-based isolators (Victron, see above) have a feature to slightly tweak alternator voltage upwards to compensate for voltage drop across the isolator | |
| * isolators cannot be [[electrical:12v:alternator#disabling_alternator_charging|disabled the way DC-DC and relays can]]. | * isolators cannot be [[electrical:12v:alternator#disabling_alternator_charging|disabled the way DC-DC and relays can]]. |
| * see info on alternator self-excitation below | * see info on alternator self-excitation below |
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| * Solar charging while the isolator circuit is closed (ie, batteries connected) can pass higher-than-normal voltage to the chassis and starter battery. Workaround: see notes on HVD and DC-DC charging below. | * Solar charging while the isolator circuit is closed (ie, batteries connected) can pass higher-than-normal voltage to the chassis and starter battery. Workaround: see notes on HVD and DC-DC charging below. |
| * LiFePO4 resting voltages are high enough they may hold the circuit closed on VSRs designed for lead chemistries. Workaround: [[electrical:12v:alternator#disabling_alternator_charging|disable alternator charging]] (at least momentarily) after driving or install DC-DC. Or just let it work that way. | * LiFePO4 resting voltages are high enough they may hold the circuit closed on VSRs designed for lead chemistries. Workarounds: |
| | * [[electrical:12v:alternator#disabling_alternator_charging|disable alternator charging]] (at least momentarily) after driving |
| | * use a relay [[electrical:12v:alternator#triggering|triggered by D+]] |
| | * use a relay like [[#li-bim|the Li-Bim]] with setpoints designed for LFP |
| | * install a voltage sensing switch to control the relay, set more appropriately for LFP's resting voltage |
| | * install [[electrical:12v:b2b|DC-DC]]. |
| * Voltage-sensing relays can be unintentionally triggered((dVSR)) or "held closed"((both VSR and dVSR)) [[http://bdp.mousetrap.net/index.php/2018/10/27/side-effect-of-solar-alternator-charging/|by voltage from the solar-charged side]] in some scenarios. Workaround: address with HVD as below if desired, or with a [[electrical:12v:b2b|DC-DC charger]], or by adding a switch to disable the VSR.((a momentary-off switch would kill the connection, although an ON/OFF switch might be useful for other purposes)) | * Voltage-sensing relays can be unintentionally triggered((dVSR)) or "held closed"((both VSR and dVSR)) [[http://bdp.mousetrap.net/index.php/2018/10/27/side-effect-of-solar-alternator-charging/|by voltage from the solar-charged side]] in some scenarios. Workaround: address with HVD as below if desired, or with a [[electrical:12v:b2b|DC-DC charger]], or by adding a switch to disable the VSR.((a momentary-off switch would kill the connection, although an ON/OFF switch might be useful for other purposes)) |
| * On ignition-triggered((IGN, D+)) setups **if the key is turned to ACC but the engine not started a depleted house battery can pull down the starter battery**. Workarounds: use a VSR, a DC delay timer, a DC-DC charger, or start the vehicle immediately after inserting the key((ie, do not leave in the Accessory position which would drain the starter battery)). | * On ignition-triggered((IGN, D+)) setups **if the key is turned to ACC but the engine not started a depleted house battery can pull down the starter battery**. Workarounds: use a VSR, a DC delay timer, a DC-DC charger, or start the vehicle immediately after inserting the key((ie, do not leave in the Accessory position which would drain the starter battery)). |
| * relays and DC-DC that are triggered solely by D+ can be disabled by a switch on the D+ wire. [[https://www.reddit.com/r/VanLife/comments/1c4vjl0/is_this_renogy_a_good_dcdc_option_for_a_200ah/kzuc78v/|Additional control could be introduced]] with a relay and or delay ([[https://amzn.to/3TUEbmu|example]]) | * relays and DC-DC that are triggered solely by D+ can be disabled by a switch on the D+ wire. [[https://www.reddit.com/r/VanLife/comments/1c4vjl0/is_this_renogy_a_good_dcdc_option_for_a_200ah/kzuc78v/|Additional control could be introduced]] with a relay and or delay ([[https://amzn.to/3TUEbmu|example]]) |
| * VSR triggered by voltage can can be disabled by a switch on the thin ground wire on the VSR itself.((the VSR requires a ground to make a complete circuit to run internal electronics. Breaking this circuit turns off the VSR)) | * VSR triggered by voltage can can be disabled by a switch on the thin ground wire on the VSR itself.((the VSR requires a ground to make a complete circuit to run internal electronics. Breaking this circuit turns off the VSR)) |
| * some DC-DC can be //derated// by providing a 12v signal to the CURRENT LIMIT terminal ([[electrical:12v:b2b#renogy1|Renogy DC1212 series]], [[electrical:12v:b2b#leaptrend|Leaptrend]]) or through a setting in an app (Renogy DCC50S). | * some DC-DC can be //derated//((output intentionally reduced)) by providing a 12v signal to the CURRENT LIMIT terminal ([[electrical:12v:b2b#renogy1|Renogy DC1212 series]], [[electrical:12v:b2b#leaptrend|Leaptrend]]) or through a setting in an app (Renogy DCC50S). |
| * some DC-DC can be //disabled// by providing a 12v signal to a remote ON/OFF terminal ([[electrical:12v:b2b#victron|Victron Orion-TR]]), Kisae. | * some DC-DC can be //disabled// by providing a 12v signal to a remote ON/OFF terminal ([[electrical:12v:b2b#victron|Victron Orion-TR]]), [[electrical:12v:b2b#disabling_the_kisae|Kisae]]. |
| * on units that have a dedicated NEG ("ground", negative return) to the starter battery there may be no easy disable method. The brute force method would be to insert a relay between the starter battery POS and the unit's POS input, and control the relay with a switch. | * on units that have a dedicated NEG ("ground", negative return) to the starter battery there may be no easy disable method. The brute force method would be to insert a relay between the starter battery POS and the unit's POS input, and control the relay with a switch. |
| * bluetooth-enabled DC-DC can often be disabled or derated from the app | * bluetooth-enabled DC-DC can often be disabled or derated from the app |
| In most setups 'dwellers: | In most setups 'dwellers: |
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| * install a dedicated POS line from the starterbatt or alternator to the charger/relay/isolator | * install a dedicated POS line from the starterbatt or alternator to the combiner's input |
| * then **use the vehicle chassis/body for the NEG return path** back to the alternator/starterbatt | * run another length of dedicated POS from the device's output the house battery bank |
| | * **use the vehicle chassis/body for the NEG return path** back to the alternator/starterbatt((VSRs, DC-DC and other types with internal electronics will have a small ground wire)) |
| | * [[electrical:12v:alternator#triggering|trigger]] charging by voltage or with a 12v signal |
| Exceptions: | Exceptions: |
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| - use of an ON/OFF 12v trigger signal ("D+", "IGN", "ACC"). When the 12v signal is present the charging circuit is operational. Caveat: in this kind of setup leaving the key in the ACC position without starting the engine can drain the starter battery. | - use of an ON/OFF 12v trigger signal ("D+", "IGN", "ACC"). When the 12v signal is present the charging circuit is operational. Caveat: in this kind of setup leaving the key in the ACC position without starting the engine can drain the starter battery. |
| - voltage-sensing - 12v is always being provided to the charger. The batteries are connected when the chassis voltage is above a voltage setpoint (often ≥13.4v) and disconnected when the chassis side measures below a setpoing (often ≤13.2v). | - voltage-sensing - 12v is always being provided to the charger. The batteries are connected when the chassis voltage is above a voltage setpoint (often ≥13.4v) and disconnected when the chassis side measures below a setpoint (often ≤13.2v). |
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| In some cases both are combined for particular installs. Ex. smart alternators. | In some cases both voltage-sensing and D+ trigger are combined to work with the odd voltages that smart alternator equipped vehicles can present. |
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| A simple possible approach would be to [[electrical:solar:shallow_cycling|replace the starter battery with a marine or AGM battery]].((http://www.cheaprvliving.com/forums/Thread-Easiest-simplest-cheapest-power-set-up)) | A simple possible approach would be to [[electrical:solar:shallow_cycling|replace the starter battery with a marine or AGM battery]].((http://www.cheaprvliving.com/forums/Thread-Easiest-simplest-cheapest-power-set-up)) |
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| ===== charging trailer batteries ===== | ===== charging remote batteries ===== |
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| | ==== truck beds ==== |
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| | If the bed does not have sufficient ground connectivity to run the NEG return through the body, then you can either: |
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| | * add an additional and/or beefier ground strap between bed and frame; or |
| | * run a dedicated NEG return from the bank back to the starter batt, frame, etc. |
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| | ==== trailers ==== |
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| Some amount of power can be passed along the 7pin harness, usually enough to //maintain// the trailer battery's voltage and run small loads. For the purposes of this discussion [[https://www.etrailer.com/faq-wiring-7-way.aspx|the important wires]] in the 7-pin are: | Some amount of power can be passed along the 7pin harness, usually enough to //maintain// the trailer battery's voltage and run small loads. For the purposes of this discussion [[https://www.etrailer.com/faq-wiring-7-way.aspx|the important wires]] in the 7-pin are: |
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| * 120vac 300w [[food:cooking:excess_power#ac_inverter|rice cooker]] running on 500w MSW inverter, (~330w total after inefficiencies). | * 120vac 300w [[food:cooking:excess_power#ac_inverter|rice cooker]] running on 500w MSW inverter, (~330w total after inefficiencies). |
| * 120vac 300w wall charger for your [[lifestyle:faq_solar_generator|solar generator]] running on a 400w PSW inverter. | * 120vac 300w wall charger for your [[lifestyle:faq_solar_generator|solar generator]] running on a 400w inverter. |
| * if you have a stout enough alternator, a 120vac 700w instant pot running off an inverter. | * if you have a stout enough alternator, a 120vac 700w instant pot running off an inverter. |
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