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electrical:12v:diysmartpass [2022/09/10 12:52]
frater_secessus [how it works] |
electrical:12v:diysmartpass [2022/09/10 13:26]
frater_secessus [how it works] |
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| The [[electrical:12v:b2b#ctek_d250_series|Ctek D250-series DC-DC charger]] charger and [[electrical:12v:alternator#solid_state_isolatorfet-based|Smartpass MOSFET isolator]] combine to solve an expensive problem: how to **get meaningful current //and// staged charging at the same time**. Meaningful current with the Ctek combo means "up to 100A (or 140A) during Bulk." | The [[electrical:12v:b2b#ctek_d250_series|Ctek D250-series DC-DC charger]] charger and [[electrical:12v:alternator#solid_state_isolatorfet-based|Smartpass MOSFET isolator]] combine to solve an expensive problem: how to **get meaningful current //and// staged charging at the same time**. Meaningful current with the Ctek combo means "up to 100A (or 140A) during Bulk." |
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| | ==== the problem the Ctek solution addresses ==== |
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| | [[electrical:12v:alternator|Isolators]] are great at providing Big Current during Bulk stage. But since isolators pass alternator voltage through they cannot charge the house battery to voltages higher than the alternator can put out. Because of voltage sag((lower voltage due to resistance in wiring and connections)) the charging voltage at the house bank will likely be somewhat lower. |
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| | [[electrical:12v:b2b|DC-DC chargers]] can boost alternator voltage to the required Absorption voltage but doing so with Big Current can be impossible or at least very expensive. So DC-DC chargers are usually relatively small. |
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| | Digression: this means that for **short drives** the isolator will likely return more Ah to the battery ban k than DC-DC. On **longer drives** the DC-DC will both return more current and charge at a more appropriate voltage for the battery chemistry. |
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| | What if we paralleled an isolator with a small DC-DC to get the both of best worlds? That is what the Ctek combo does. |
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| ==== how it works ==== | ==== how it works ==== |
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| The D250 provides staged (boosted) charging and the Smartpass provides Big Current during Bulk charging.((until battery voltage == alternator voltage)) The setup is pricey; as of Aug 2022 the D250 is $328 and the Smartpass 120 is $326. Total $654. There are other features in this setup((jumpstarting, starter battery maintenance)) but these main features might be replicated by the approaches described below. | The D250 provides staged/boosted charging and the Smartpass provides more during Bulk charging.((until battery voltage == alternator voltage)) Combined this means you get increased current during Bulk without needing a giant DC-DC charger. |
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| | The setup is pricey; as of Aug 2022 the D250 is $328 and the Smartpass 120 is $326. Total $654. There are other features in this setup((jumpstarting, starter battery maintenance)) but these main features might be replicated by the approaches described below. |
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| There may be an additional benefit of using a small DC-DC charger + isolator: charging current will be very high only at first when the alternator temperature is lowest and most able to handle it.((just started the engine)) | Although people tend to fixate on the MOAR AMPS!!!! aspect, there is a more subtle benefit to a small DC-DC charger + isolator combo: charging current will be very high only at first when the alternator temperature is lowest and most able to handle it.((just started the engine)) |
| ===== challenges ===== | ===== challenges ===== |
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