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--- electrical:12v:diysmartpass [2023/06/23 15:13]
frater_secessus [20A combo DC-DC + isolator: $172]
+++ electrical:12v:diysmartpass [2024/03/20 16:06] (current)
frater_secessus [DIY Ctek D250 + Smartpass setup]
@@ Line 3: / Line 3: @@
 ====== DIY Ctek D250 + Smartpass setup ======
-This article is about the Ctek combo and possible approaches to duplicating the major functionality for less money and/or better specs.
+This article is about the 1st-gen Ctek combo and possible approaches to duplicating the major functionality for less money and/or better specs.
 This article assumes you want and the bank will accept >20A of alternator charging, and that your alternator can handle it.    If you only have a 80Ah AGM then the combo setup is massive overkill.  The bare D250 would handle that with ease.
@@ Line 40: / Line 40: @@
   - 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.
+  - 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]
@@ Line 48: / Line 49: @@
 >> There are no solutions. There are only trade-offs. ― Thomas Sowell
-==== 20A combo DC-DC + isolator: $172 ====
+==== 20A DC-DC + isolator: $172 ====
 This is the simplest and cheapest option, but requires ingenuity to keep boosted voltage from leaking back to the chassis.  In this case the isolator (solenoid) is turned off by the HVD at Vfloat (conservative) or just below alternator voltage (power-maximizing).
@@ Line 61: / Line 62: @@
-==== 20A combo DC-DC + diode isolator: $173 ====
+==== 20A DC-DC + diode isolator: $173 ====
 This option is requires no HVD, but has two possible drawbacks:
@@ Line 68: / Line 69: @@
   - drop of ~0.5v.  Perhaps not a big issue since the DC-DC is boosting.
-  * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104.  [[https://amzn.to/3T9JKft|Cole-Hersee 90A diode isolator]], $69.
+  * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104.
+  * [[https://amzn.to/3T9JKft|Cole-Hersee 90A diode isolator]], $69.
-==== 20A combo DC-DC + MOSFET isolator: $224 ====
+==== 20A DC-DC + MOSFET isolator: $224 ====
 Same technology as the Smartpass.
@@ Line 76: / Line 78: @@
 Similar to the diode isolator setup above, but with MOSFETS instead of diodes.  This means no((or minimal)) voltage drop.
-  * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104.  [[https://amzn.to/3wnJpfE|Victron ArgoFET 200A isolator]] (100A for each "leg", so both starter and house batt get  ≤100A).  $120.
+  * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104.
+  * [[https://amzn.to/3wnJpfE|Victron ArgoFET 200A isolator]] (100A for each "leg", so both starter and house batt get  ≤100A).  $120.
@@ Line 84: / Line 87: @@
 The main benefit of a separate MPPT is we get to normal PV input limits, 100v+.  We also may have more control.  One can also drastically reduce cost by using PWM with nominal 12v panels, or using MPPT with cheap used higher-voltage panels.
-  * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104. [[https://amzn.to/3Aj7NjP|EpEver 20A 100v MPPT]], $80. [[https://amzn.to/3QGwihC|Cole-Hersee continuous duty solenoid]], $55. [[https://amzn.to/3AhdNti|High voltage disconnect]], $13.
+  * MPPT
-  * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104. [[https://amzn.to/3PMlFIS|HQST 20A PWM]], $19. [[https://amzn.to/3QGwihC|Cole-Hersee continuous duty solenoid]], $55. [[https://amzn.to/3AhdNti|High voltage disconnect]], $13.
+    * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104.
+    * [[https://amzn.to/3Aj7NjP|EpEver 20A 100v MPPT]], $80.
+    * [[https://amzn.to/3QGwihC|Cole-Hersee continuous duty solenoid]], $55.
+    * [[https://amzn.to/3AhdNti|High voltage disconnect]], $13.
+  * PWM
+    * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104.
+    * [[https://amzn.to/3PMlFIS|HQST 20A PWM]], $19.
+    * [[https://amzn.to/3QGwihC|Cole-Hersee continuous duty solenoid]], $55.
+    * [[https://amzn.to/3AhdNti|High voltage disconnect]], $13.
-==== 20A DC-DC + 20A DC-DC + 20A solar controller + diode isolator: $192-$253 ====
+==== 20A DC-DC + 20A solar controller + diode isolator: $192-$253 ====
-  * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104. [[https://amzn.to/3Aj7NjP|EpEver 20A 100v MPPT]], $80. [[https://amzn.to/3T9JKft|Cole-Hersee 90A diode isolator]], $69.
+  * MPPT
-  * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104. [[https://amzn.to/3PMlFIS|HQST 20A PWM]], $19. [[https://amzn.to/3T9JKft|Cole-Hersee 90A diode isolator]], $69.
+      * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104.
+      * [[https://amzn.to/3Aj7NjP|EpEver 20A 100v MPPT]], $80.
+      * [[https://amzn.to/3T9JKft|Cole-Hersee 90A diode isolator]], $69.
+  * PWM
+    * [[https://amzn.to/3pCW5eY|Renogy 20A DC-DC]], $104.
+    * [[https://amzn.to/3PMlFIS|HQST 20A PWM]], $19.
+    * [[https://amzn.to/3T9JKft|Cole-Hersee 90A diode isolator]], $69.
-==== 20A DC-DC 20A DC-DC + 20A solar controller + MOSFET isolator: $243-$304 ====
+==== 20A DC-DC + 20A solar controller + MOSFET isolator: $243-$304 ====
-  * [[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.
 ==== 50A DC-DC combo chargers:  $265-$328 ====

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