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electrical:12v:diysmartpass [2023/06/23 15:18]
frater_secessus [20A DC-DC + 20A DC-DC + 20A solar controller + diode isolator: $192-$253] |
electrical:12v:diysmartpass [2023/07/28 17:09]
frater_secessus [challenges] |
| - stop the isolator from passing voltages >Vfloat from alternator to house bank during Float stage. This should be a minimal problem with lead batteries((which can usually [[electrical:12v:eternal_absorption|tolerate high floats]])) and with driving times limited to a few hours. It //could// be a problem with Li batteries and many hours of driving. Note: it is not clear that the Ctek combo addresses this issue. The only approaches known to prevent excessive voltage during float are the combo DC-DC and the solenoid + HVD in conservative mode (see below). | - stop the isolator from passing voltages >Vfloat from alternator to house bank during Float stage. This should be a minimal problem with lead batteries((which can usually [[electrical:12v:eternal_absorption|tolerate high floats]])) and with driving times limited to a few hours. It //could// be a problem with Li batteries and many hours of driving. Note: it is not clear that the Ctek combo addresses this issue. The only approaches known to prevent excessive voltage during float are the combo DC-DC and the solenoid + HVD in conservative mode (see below). |
| - **isolators have no control over current**. In reality the combo might make **20A+120A** (dead house bank, big alternator, cool temps, Bulk stage) or it might make **20A+1A** (when battery bank is approaching alternator voltage). There is no guarantee that the DC-DC will be making 20A, either. If your bank is only accepting 15A then having 140A theoretical on tap will not matter. | - **isolators have no control over current**. In reality the combo might make **20A+120A** (dead house bank, big alternator, cool temps, Bulk stage) or it might make **20A+1A** (when battery bank is approaching alternator voltage). There is no guarantee that the DC-DC will be making 20A, either. If your bank is only accepting 15A then having 140A theoretical on tap will not matter. |
| | - provide for [[electrical:12v:self-jumpstarting|self-jumpstarting]]. The method Ctek uses for this appears to be FET-based like main isolation: "Is a smart combination of relays (actually MOSFETS) that connects starter and service batteries. This enables current from your alternator to charge both batteries".((https://www.ctek.com/storage/5CDB4E293A03CBF6442A620EC8E49CFB548CB48E9BF93425638077279A13BBA1/ac5639c5feaa46d38411ebd69f915b5b/pdf/media/65589cee7d4342e0891e2130149be66f/SmartPass%20120S.pdf)) [Dual MOSFET packs in series? - secesssus] |
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| ==== 20A DC-DC 20A DC-DC + 20A solar controller + MOSFET isolator: $243-$304 ==== | ==== 20A DC-DC + 20A solar controller + MOSFET isolator: $243-$304 ==== |
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| * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104. [[https://amzn.to/3Aj7NjP|EpEver 20A 100v MPPT]], $80. [[https://amzn.to/3wnJpfE|Victron ArgoFET 200A isolator]] (100A for each "leg", so both starter and house batt get ≤100A). $120. | * MPPT |
| | * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104. |
| * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104. [[https://amzn.to/3PMlFIS|HQST 20A PWM]], $19. [[https://amzn.to/3wnJpfE|Victron ArgoFET 200A isolator]] (100A for each "leg", so both starter and house batt get ≤100A). $120. | * [[https://amzn.to/3Aj7NjP|EpEver 20A 100v MPPT]], $80. |
| | * [[https://amzn.to/3wnJpfE|Victron ArgoFET 200A isolator]] (100A for each "leg", so both starter and house batt get ≤100A). $120. |
| | * PWM |
| | * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104. |
| | * [[https://amzn.to/3PMlFIS|HQST 20A PWM]], $19. |
| | * [[https://amzn.to/3wnJpfE|Victron ArgoFET 200A isolator]] (100A for each "leg", so both starter and house batt get ≤100A). $120. |
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| ==== 50A DC-DC combo chargers: $265-$328 ==== | ==== 50A DC-DC combo chargers: $265-$328 ==== |
