Jump Start
The operation of starting a vehicle with a weak battery from another battery or vehicle. The real danger to the vehicle electronics is the sparking, voltage surge and wrong polarity risk that occur during connection and disconnection. The correct order and the correct final connection point remove most of this risk.
The safe sequence is as follows: the red cable is connected first to the positive of the weak battery, then to the positive of the good battery. The black cable is connected to the negative of the good battery, and the final end is connected not to the negative post of the weak battery but to a distant chassis point on the vehicle. In this way the spark occurs away from the gas produced by the battery.
- Disconnection: is done in exactly the reverse order of connection.
- 24V warning: giving a 24V jump to a vehicle with a 12V system causes permanent damage to the electronics; the supply voltage must always be verified.
- Electronics: disconnecting sensitive units before the operation is the safest way; at the very least, the system is kept switched off during the jump start.
On products with reverse polarity protection such as the HCT402, the device draws no current on a wrong connection; this protection is not present on the HCT400. However, the protection does not cover high-energy transient events such as load dump. The soundest approach is to carry out jump starting and external charging with the kit supply disconnected.
The context where this term is used: Converting a tractor hydraulic lever to electronic control