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electrical:12v:multipoint_charging [2022/05/25 12:26] frater_secessus [why one source wins] |
electrical:12v:multipoint_charging [2022/08/21 13:53] frater_secessus [gotchas] |
Barring heroic measures((exotic alternators/regulators, [[electrical:12v:b2b|DC-DC chargers]])) the alternator is going to stop contributing at some point during Bulk charging. That is ok, the alternator provided a ton of current while it was charging. | Barring heroic measures((exotic alternators/regulators, [[electrical:12v:b2b|DC-DC chargers]])) the alternator is going to stop contributing at some point during Bulk charging. That is ok, the alternator provided a ton of current while it was charging. |
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But if you want to the charge controllers (and some [[electrical:converter|converters]]) can be convinced to stay //roughly// in sync and keep charging together. This is done by **configuring the Absorption and Float setpoints on the controllers to be the same**.((including Absorption termination setpoints like time or current)) There will be short periods where one controller makes a change before the other, but for most of the time both will be contributing at the same time. | But if you want to the charge controllers (and some [[electrical:converter|converters]]) can be convinced to stay //roughly// in sync and keep charging together. This is done by **configuring the Absorption and Float setpoints on the controllers to be the same**.((including Absorption termination setpoints like time or current)) There will be short periods where one controller makes a change before the other, but for most of the time both will be contributing at the same time. Even if they contribute unequally it is a non-issue because the voltage setpoint is being held. If a big load is added or conditions deteriorate it will be "all hands on deck" as in the Bulk stage scenario above. |
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Note: there are high-end controllers/chargers which communicate with each other to coordinate charging. That feature is beyond the scope of this article. | Note: there are high-end controllers/chargers which communicate with each other to coordinate charging. That feature is beyond the scope of this article. |
Some of these are observed, and some are theoretical. | Some of these are observed, and some are theoretical. |
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* the vagaries of voltage sag across the system may result in the various charging sources seeing slightly different voltages. Voltage Sense wires can help with this issue. | * the vagaries of voltage sag across the system may result in the various charging sources seeing slightly different voltages and therefore contributing in unpredictable ways.((probably a non-issue as long as the bank is getting properly charged)) Voltage Sense wires can help with this issue. |
* Multiple controllers set up to trigger Float from endAmps((trailing amps)) may enter float early since they are providing only some of the charging current. | * Multiple non-communicating controllers set up to trigger Float from endAmps((trailing amps)) may enter float early since they are providing only some of the charging current. |
* Multiple sources may inadvertently exceed the bank's recommended charging current | * Multiple sources may inadvertently exceed the bank's recommended charging current, or your preferred current. Example: a lithium battery wants 50A max but each charging source can make 30A. This might result in overcurrent (60A) during Bulk. |
* theoretical: low-frequency PWM controllers in parallel with MPPT controllers may confuse the MPPT with a varying Vbatt reference. | * theoretical: low-frequency PWM controllers in parallel with MPPT controllers may confuse the MPPT with an unstable reference voltage. |
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