Self-jumpstarting means jumpstarting one's own vehicle without the use of another vehicle. It's done by combining house and chassis batteries by one of several methods discussed below.

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 minimize¹⁾ the amount of current flowing from house bank to vehicle chassis. This may be especially important with Li chemistries that have BMS protections.

This will be easiest if one already has some kind of isolator/combiner setup. If not, one can run jumper cables from the house bank, or physically remove the house bank and carry it to the starter battery area.

Switches used as manual isolators will self-jumpstart when in the ON position.

Solenoids/relays always self-jumpstart assuming there is enough voltage in the starter battery to energize the solenoid.²⁾ It is a mechanical connection and power will flow both ways.

Some VSRs have a provision to combine the batteries for self-jumpstarting.

Examples:

• Battery Doctor - integrated button
• Sure Power 1314 - user-added wiring³⁾
• Victron CT - user-added wiring to “start assist” terminal
• Precision Circuits BIM and Li-BIM - user added wiring to “sig” terminal⁴⁾ - see this article
• Blue Sea ML-ACR can combine banks manually or with the included remote switch

Solid state isolators are diode based and will not allow power to flow from the house battery to the starter battery. Therefore they cannot be used to self-jumpstart on their own (see below, including the Ctek exception).

As with diode-based isolators, DC-DC chargers typically cannot pass power back from the battery bank to the vehicle. Read below for workarounds and different approaches.

Exceptions:

• the BattleBorn/Wakespeed 48v/12v Bi-Directional DC-DC charger can send 50% of it's rated power to the starter battery.
• the Bluetti 800w alternator charger (DC-DC) has a starter battery maintenance function.

It adds a layer of complexity, but a relay with a switch can be used to bridge the batteries manually.

Note the Smartpass does this when added to the CTEK D250-series chargers.

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.

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