Jump-start with smart charge
Q I read in CM recently that you should never attempt to jumpstart a vehicle fitted with a smartcharge system. I would be very grateful if you could clear up a few questions I have regarding this. Does this advice mean to not use a car with a smart-charge system to give a jump-start, receive a jump-start, or both? How do you tell if a car is fitted with a smart-charge system? If a car has a stop-start system fitted does this mean it must have a smart-charge system? How would a breakdown recovery service start a car fitted with a smart-charge system if the battery was flat?
I have seen jump leads for sale with a surge protector fitted to them, so would they be of any use regarding a smart charge system? Would a booster pack be a better option? If so, are there any precautions to take regarding a car with a smart-charger? My wife has a 65-plate Nissan Qashqai 1600 petrol with a stop-start system – would that have a smart-charge system? Jeremy Pardey
A Starting with your questions in order, all modern vehicles are now fitted with much more complex electronics and, with or without a smart-charge system, precautions must be taken. Any electrical surge resulting from a jump-start can result in either of the connected vehicles suffering damage. The golden rule is to never connect or disconnect the jumpleads with the engine running.
The following procedure is generally regarded as safe: Connect the red jump lead to the positive connection on the donor vehicle and then to the positive terminal of the flat battery, then connect the black lead to the negative terminal of the donor vehicle and to a suitable body earth point of the vehicle requiring the jump-start. Start and run the donor vehicle, which should transfer some charge to the flat battery, then turn off the donor vehicle and attempt to start the vehicle needing the jumpstart. Once started, allow the engine to run for a short time before turning off and disconnecting the jump-leads. If the vehicle does not start after this process when disconnected, the possibility that the battery has failed is high.
When considering whether to jumpstart a vehicle, the safest advice is to assume that all modern vehicles are fitted with a smart-charge system. Your wife’s Nissan does have an intelligent charging system. In most cases, a recovery service will be equipped for such situations by using an intelligent jump-pack that will alleviate any potential problems. Jumpleads with a surge protection system can help, but they are not necessarily the full answer. It is also the detection of voltage which will determine the charge rate, and when the leads are connected this will be altered by the state of the jump battery, so it is still vital to not disconnect the jump leads from a running engine.
As a standby device, I would recommend the GB40 1000A NOCO Jump Starter: https://no.co/gb40. This retails for around £99 and can also be used to charge Usb-connected devices, such as mobile phones. It provides sparkproof connections and reverse polarity protection, making it safe and easy to use. It can be left for up to a year before it will need to be charged, so can be stored in the vehicle in case of emergencies.