Differences

This shows you the differences between two versions of the page.

--- electrical:12v:self-jumpstarting [2024/03/20 19:47]
frater_secessus [waking lithium batteries]
+++ electrical:12v:self-jumpstarting [2024/03/20 19:52]
frater_secessus [waking lithium batteries]
@@ Line 86: / Line 86: @@
 Lithium banks can go dormant at low voltages in order to protect themselves:
-  - the BMS turns off the DISCHARGE channel
+  - the BMS turns off the DISCHARGE channel to keep cell voltage from going any lower
+  - so the battery internally has ~11.0v or whatever but does not pass that voltage to the terminals on the outside of the battery case
   - which means smart chargers don't see battery voltage
-  - and think there's a problem so they won't start
+  - and think there's a problem so they won't start(("too smart for their own good"))
 What we need is a //dumb// voltage source to get the party restarted.  The starter battery will do nicely.
   * Rigs with IGN-triggered relays can briefly turn the key to ACC then back off.((don't leave it on ACC long or the dead Li will suck power from the starter battery.  Either turn ACC off again or actually start the vehicle.))
   * Rigs with voltage-sensing relays will have to actually start the engine or press a manual override switch to activate the VSR and wake the lithium bank.
+  * Rigs with diode- or FET-based isolators would start the engine to spin the alternator and get power flowing through the isolator to the sleeping lithium

RV and vandwellers wiki