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electrical:12v:alternator_charging_hvd [2017/10/11 13:58] frater_secessus created |
electrical:12v:alternator_charging_hvd [2019/04/10 15:12] frater_secessus [how it works] |
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====== Disconnecting alternator charging at a voltage setpoint ====== | ====== Disconnecting alternator charging at a voltage setpoint ====== | ||
- | > ... what can install between the starter battery, and the lithium battery bank, to stop it from going over 13.8 volts, but still get a decent amount of amps while driving? | + | There are scenarios where one might want to prevent |
+ | - the house battery could get overcharged by higher voltages than lead-acid (lithium, for example) | ||
+ | - the combined circuit can feed higher-than-optimal voltages back from solar charge controller to the chassis' | ||
- | Given that: | + | ===== how it works ===== |
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- | Alternator charging methods combine the batteries only at certain times: | + | |
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- | by 12v trigger. | + | |
- | by voltage sensing. | + | |
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- | If you disrupt (or " | + | |
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- | So-o-o-o-o-o..... | + | |
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- | You can: | + | |
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- | Use a high voltage disconnect on the house side set to something very safe (13.5V?) that would disrupt the trigger (or ground) circuit. | + | |
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- | Example: | + | |
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- | On the way the alternator brings the house bank up to 13.5V. | + | |
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- | Caveat: | + | |
+ | [[electrical: | ||
+ | If the device' | ||
+ | Shutting down the device will require different approaches, depending on where it gets the power to operate itself. | ||
+ | ===== solenoids and relays ===== | ||
+ | {{ https:// | ||
+ | Purely Mechanical devices like solenoids and relays use 12v //trigger// or //exciter// voltage((usually from the accessory circuit)) to operate. | ||
+ | Power to these devices is disrupted by interrupting power to the trigger+, which is one of the small lugs.((or the only small lug in the case of 3 lug relays)) | ||
+ | ===== voltage sensing relays ===== | ||
+ | Voltage sensing relays (VSR) typically take power from the chassis battery and have a thin ground to complete the circuit. | ||
+ | Power to VSRs is disrupted by cutting the ground wire. One way to reestablish the ground (thereby turning the device on) is HVD --> relay NO contacts --> ground wire in/out | ||
+ | ===== solid state isolators ===== | ||
+ | Some solid state isolators have a trigger or exciter input; | ||
+ | Three lug isolators without exciter input might not be usable with HVD. |