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--- electrical:12v:alternator_details [2025/06/18 19:45]
frater_secessus [load dumps] refactored
+++ electrical:12v:alternator_details [2025/10/07 16:56] (current)
frater_secessus [dual alternators] source fo 410a
@@ Line 53: / Line 53: @@
 see [[electrical:12v:alternator_details#external_regulation|External Regulation]] below
+=== observing the regulation ===
+Some vehicle manufacturers have extended OBD2 pids that allow monitoring of the field signal that is regulating the alternator:
+  * Ford - Generator Field Control Output (%)((https://www.fordservicecontent.dealerconnection.com/pubs/content/~WVX2/~MUS~LEN/15/VX22007.HTM))
+  * GM - Generator F-Terminal Signal ((https://www.autometer.com/obd2_gm))
 === tricking the regulator ===
@@ Line 230: / Line 237: @@
   * when **loads are added** chassis voltage will drop briefly while the regulator responds.
   * when **loads are removed** chassis voltage will spike briefly while the regulator responds.
-  * if **large loads disappear suddenly and nothing is available to absorb the spike that excess voltage can damage the alternator and/or other electrics.
+  * if **large loads disappear suddenly** and nothing is available to absorb the spike that excess voltage can damage the alternator and/or other electrics.
 In typical installs there //are// places for the power in the alternator to go, chiefly the lead starter battery:
@@ Line 241: / Line 248: @@
 For a typical install the  question is:  how much charging current are we talking about, and does the alternator already handle that level of sudden disconnect under normal operation? Secessus provides this example:
-> my van's radiator cooling fans are rated at 65A((https://www.promasterforum.com/threads/180-amp-alternator-with-amp-clamp-on-output.99118/post-792681)) and turn on/off frequently.  My Li charging current is less than that.
+> my van's radiator cooling fans are rated at 65A((https://www.promasterforum.com/threads/180-amp-alternator-with-amp-clamp-on-output.99118/post-792681)) and turn on/off frequently via relay.((see below))  My Li charging current is less than that.
 In addition, the speed of the disconnect plays a part:
@@ Line 256: / Line 263: @@
   * use the lead starter batt in the circuit to absorb the spike
   * charge the bank in a manner unlikely to cause BMS disconnect in the first place
-  * for LF_-dedicated alternator setups use
+  * for LFP-dedicated alternator setups
     * consider a system that uses CANBUS or other networking protocol to inform the alternator's regulator prior to actual BMS shutdown.  The alt shuts down before the BMS so there are no spikes.
     * install a possibly-sacrificial protection device.  They are typically mounted between the alernator's B+ and B- terminals and short to ground when voltage spikes above a certain level.
-    * The  [[https://amzn.to/45ofEh4|Balmar APM-12]]   apparently uses "A TVS (avalanche diode), Littlefuse brand, unipolar, 15kW peak pulse capability, with a stand-off voltage around 20 or 22 Volts"((https://www.cruisersforum.com/forums/f14/balmar-alternator-protection-module-apm-260911-post3607461.html#post3607461))
+      * The  [[https://amzn.to/45ofEh4|Balmar APM-12]]   apparently uses "A TVS (avalanche diode), Littlefuse brand, unipolar, 15kW peak pulse capability, with a stand-off voltage around 20 or 22 Volts"((https://www.cruisersforum.com/forums/f14/balmar-alternator-protection-module-apm-260911-post3607461.html#post3607461))
-    * the Zap-Stop apparently uses a Motorola #MR2535L zener diode to short the alternator output((https://www.cruisersforum.com/forums/f14/zap-stop-fact-or-fiction-29442.html#post315900))
+      * the [[https://amzn.to/4ectIwD|Balmar TSP-12 spike protector]] may be the equivalent of the APM-12 without the LED and audio indicators.
-    * Sterling APD12 internals not documented
+      * the Zap-Stop apparently uses a Motorola #MR2535L TVS diode((the original post called it a Zener but [[https://www.alldatasheet.com/datasheet-pdf/view/5199/MOTOROLA/MR2535L.html|the datasheet for the MR2535L]] says it's TVS)) to short the alternator output((https://www.cruisersforum.com/forums/f14/zap-stop-fact-or-fiction-29442.html#post315900))
-    * the [[https://amzn.to/4ectIwD|Balmar TSP-12 spike protector]] might be the equivalent of the APM-12 without the LED and audio indicators.
+      * Sterling APD12 internals not documented
-    * mikecol recommends a "IN6277A [[[https://en.wikipedia.org/wiki/Transient-voltage-suppression_diode|TVS diode]]] in series with 5A ATC fuse. The fuse characteristics with the diode clamp makes the full circuit. I don't have data to show it works well, but worth the cheap cost for me. Fuse and diode might not survive after hit, so good to be able to check condition (I have fuse end to alt+ so can measure with voltmeter [easily]"((https://sprinter-source.com/forums/index.php?threads/85448/post-918529))
+      * mikecol recommends a "IN6277A [[https://en.wikipedia.org/wiki/Transient-voltage-suppression_diode|TVS diode]] in series with 5A ATC fuse. The fuse characteristics with the diode clamp makes the full circuit. I don't have data to show it works well, but worth the cheap cost for me. Fuse and diode might not survive after hit, so good to be able to check condition (I have fuse end to alt+ so can measure with voltmeter [easily]"((https://sprinter-source.com/forums/index.php?threads/85448/post-918529))
 ===== common modifications =====
@@ Line 381: / Line 388: @@
 Known configurations:
+  * 410A((https://www.fordtremor.com/attachments/6-7-altermators-webp.126095/)) = 250A + 160A
   * 397A = 220A + 157A
   * 332A = 175A + 157A

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