Differences

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

--- electrical:12v:self-jumpstarting [2024/03/05 11:04]
frater_secessus [starter battery chargers alongside DC-DC chargers]
+++ electrical:12v:self-jumpstarting [2024/03/20 19:52]
frater_secessus [waking lithium batteries]
@@ Line 44: / Line 44: @@
 Note the Smartpass does this when added to the CTEK D250-series chargers.
-===== jump packs =====
-[[https://amzn.to/2ITeBba|Lithium "jump packs"]] have become more popular.  Lithium-chemistry batteries can discharge quickly, so even relative small packs can jumpstart a car.
-'Dwellers may want to pick a jump pack that has 12v or USB outlets so it can have other uses.
 ===== maintaining starter batteries =====
@@ Line 86: / Line 82: @@
+===== waking lithium batteries =====
+Lithium banks can go dormant at low voltages in order to protect themselves:
+  - 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(("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
+===== jump packs =====
+[[https://amzn.to/2ITeBba|Lithium "jump packs"]] have become more popular.  Lithium-chemistry batteries can discharge quickly, so even relative small packs can jumpstart a car.
+'Dwellers may want to pick a jump pack that has 12v or USB outlets so it can have other uses.

RV and vandwellers wiki

User Tools

Site Tools

Differences

Page Tools