We have discussed the service implications of Stop-Start Systems on several occasions, but we weren’t aware of the importance of following a key charging best practice until we saw this post from the GM diagnostic master, James from Florida. We have always stressed the importance of connecting your negative lead to a chassis or engine ground when charging or jump starting. This is the safest method possible and the method that we, as manufacturers, are required to specify by UL standards, such the UL1236 Standard for automotive battery chargers. But, we didn’t realize doing so was a key to success when charging vehicles equipped with Stop-Start systems.
As James points out, “… hook up the negative charger lead to chassis ground. The reason for this is that the battery sensor module is mounted outboard of the battery terminal and if the charger is hooked directly to the terminal, current will not flow through the BSM and will not be measured. This will cause the system to determine that the battery state of charge is still low and will disable AutoStop. This will also occur any time that the battery is replaced or disconnected for any reason. The vehicle will use an estimated state of charge until a reset/learn occurs.”
We have included a full screen shot of James’ post, due to the fact that he had an update to it, only the update is publicly visible. Here’s a link to the update:
To see the original post at www.iATN.net, click on the above screen shot or click here. To access additional forum posts or participate in the discussion requires a membership with the site. There are several membership options available, about which you can learn more here.
The International Automotive Technicians Network is the largest network of automotive repair professionals in the world: a group of 80,000+ automotive professionals from over 160 countries. The members of this group exchange technical knowledge with their peers around the globe, sharing 1.8 million years of experience. iATN has been proudly serving the automotive service and repair industry and the needs of professional automotive mechanics around the world, for over 15 years.