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electrical:12v:alternator [2024/04/26 16:58]
frater_secessus [charging current patterns] |
electrical:12v:alternator [2024/06/06 12:36]
frater_secessus [constant-duty solenoid] constant/continuous |
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| See [[electrical:12v:alternator_details#heat|this sub-article]] on alternators and heat | See [[electrical:12v:alternator_details#heat|this sub-article]] on alternators and heat |
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| | ==== alternator current rating ==== |
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| | 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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| | see [[electrical:12v:alternator_details#current|this related article]] on assessing how much current you can safely take from the alternator |
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| ==== fuel consumption ==== | ==== fuel consumption ==== |
| ''23A x 20 minutes / 60 minutes in an hour = 7.666666667Ah'' | ''23A x 20 minutes / 60 minutes in an hour = 7.666666667Ah'' |
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| ==== alternator current rating ==== | |
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| 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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| see [[electrical:12v:alternator_details#current|this related article]] on assessing how much current you can safely take from the alternator | |
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| ==== constant-duty solenoid ==== | ==== continuous-duty solenoid ==== |
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| [[https://amzn.to/2RgAFUw|{{https://m.media-amazon.com/images/I/41zFkQ0pUIL._AC_UY218_ML3_.jpg?75 }}]]A [[http://amzn.to/2fZCfEr|constant-duty solenoid]] is an electromechanical device which uses an electromagnet to complete the charging circuit when the engine is running. The basic idea is the relay uses a low-current circuit((typically from the vehicle ignition)) to activate a higher-current circuit.((from starter battery to house battery)) | [[https://amzn.to/2RgAFUw|{{https://m.media-amazon.com/images/I/41zFkQ0pUIL._AC_UY218_ML3_.jpg?75 }}]]A [[http://amzn.to/2fZCfEr|continuous-duty solenoid]] is an electromechanical device which uses an electromagnet to complete the charging circuit when the engine is running. The basic idea is the relay uses a low-current circuit((typically from the vehicle ignition)) to activate a higher-current circuit.((from starter battery to house battery)) |
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| Note: some solenoids only have three terminals: 2 big load terminals and 1 small control terminal. This type gets the "ground"((return circuit)) through the body of the solenoid. The pic above is of a "three post" solenoid -- the case is grounded to the chassis through the metal feet. | Note: some solenoids only have three terminals: 2 big load terminals and 1 small control terminal. This type gets the "ground"((return circuit)) through the body of the solenoid. The pic above is of a "three post" solenoid -- the case is grounded to the chassis through the metal feet. |
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| === starter relays vs constant duty relays === | === starter relays vs continuous duty relays === |
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| While they may be externally identical, starter relays and constant duty relays are built differently inside.((https://aviondemand.com/insider/starter-solenoids-and-continuous-duty-solenoids/)) | While they may be externally identical, starter relays and continuous duty relays are built differently inside.((https://aviondemand.com/insider/starter-solenoids-and-continuous-duty-solenoids/)) |
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| The **starter relay** needs to switch huge currents for brief amounts of time. The switching has to be very fast and powerful to minimize arcing. To achieve this the solenoid will pull several amps to run a powerful electromagnet. The solenoid will not overheat because it is only "on" for a few moments. The control terminals typically have resistance of 3-4 ohms. | The **starter relay** needs to switch huge currents for brief amounts of time. The switching has to be very fast and powerful to minimize arcing. To achieve this the solenoid will pull several amps to run a powerful electromagnet. The solenoid will not overheat because it is only "on" for a few moments. The control terminals typically have resistance of 3-4 ohms. |
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| The **constant duty relay** is used for much longer periods of time and is rated for less current. The lower current means the connection doesn't have to be slammed closed as fast with a powerful electromagnet. As a result this relay type typically draws <1A and the control terminals have resistance of 15-30 ohms. | The **continuous duty relay** is used for much longer periods of time and is rated for less current. The lower current means the connection doesn't have to be slammed closed as fast with a powerful electromagnet. As a result this relay type typically draws <1A and the control terminals have resistance of 15-30 ohms. |
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| Note that per Cole-Hersee even a CD relay will get hot: | Note that per Cole-Hersee even a CD relay will get hot: |
| - use [[electrical:12v:b2b|a DC-DC charger]] to get at least the correct charging voltage | - use [[electrical:12v:b2b|a DC-DC charger]] to get at least the correct charging voltage |
| - if charging by relay only, use Crtical size wire to get the most voltage and current to the lead house battery | - if charging by relay only, use Crtical size wire to get the most voltage and current to the lead house battery |
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| | ==== triggering ==== |
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| | The setup needs to be //triggered// (told when to start/stop) so that it isn't connected all the time. There are two main methods: |
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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. |
| | - 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). |
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| | In some cases both are combined for particular installs. Ex. smart alternators. |
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| ===== alternator hacks ===== | ===== alternator hacks ===== |
| ==== workaround: heavier wiring ==== | ==== workaround: heavier wiring ==== |
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| It's also possible to run a separate and heavier cable from the TV to the trailer; this would minimize voltage sag. If a plain isolator is used with heavier wiring the voltage will still be insufficient to fully charge lead batteries. | It's also possible to run a separate and (much) heavier & more expensive cable/connector from the TV to the trailer; this would minimize voltage sag. |
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| Heavier cabling + a DC-DC charger could provide correct voltage to the trailer battery. | |
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| ===== isolator without a house battery ===== | ===== isolator without a house battery ===== |
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| This setup would be: starter battery -> isolator -> inverter -> 120vac devices | This setup would be: starter battery -> combiner((A $25-$40 VSR (often marketed as a smart battery isolator) might be easiest. Could go even cheaper with a regular relay but you'd have to hunt for a D+/IGN signal.)) |
| | -> inverter -> 120vac devices |
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