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electrical:12v:self-jumpstarting [2024/03/20 19:47] frater_secessus [waking lithium batteries] |
electrical:12v:self-jumpstarting [2024/03/22 08:19] (current) frater_secessus [Self-jumpstarting] |
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Self-jumpstarting means jumpstarting one's own vehicle without the use of another vehicle. | Self-jumpstarting means jumpstarting one's own vehicle without the use of another vehicle. | ||
- | Note: regardless of specific method used, it will be gentlest on the system to **combine the batteries and wait a few minutes for the starter battery to come up** instead of immediately attempting to start. This will minimize the amount of current flowing from house bank to vehicle chassis. This may be especially important with Li chemistries that have BMS protections. | + | Note: regardless of specific method used, it will be gentlest on the system to **combine the batteries and wait a few minutes for the starter battery to come up** instead of immediately attempting to start. This will minimize((or eliminate, if the connection is broken prior to starting)) |
===== jumping from the house bank ===== | ===== jumping from the house bank ===== | ||
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Lithium banks can go dormant at low voltages in order to protect themselves: | 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 |
+ | - 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 | - which means smart chargers don't see battery voltage | ||
- | - and think there' | + | - and think there' |
What we need is a //dumb// voltage source to get the party restarted. | What we need is a //dumb// voltage source to get the party restarted. | ||
* Rigs with IGN-triggered relays can briefly turn the key to ACC then back off.((don' | * Rigs with IGN-triggered relays can briefly turn the key to ACC then back off.((don' | ||
- | * Rigs with voltage-sensing relays will have to actually start the engine to trigger | + | * Rigs with voltage-sensing relays will have to actually start the engine |
+ | * 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 | ||