I went to the aid of a friend with a flat battery with my portable jump starter only to find it was dead.

 

I'm thinking of replacing it with the Genius Boost GB40 but it sounds like there may be an issue with chargers/boosters in general with cars with stop/start technology.

 

Anyone with any info on this device or the possible problem in general?

If jump starting cars with start/stop the negative lead must be connected to the nearby post not the battery.

 

Thanks very much. I must go and have a look for that now!!!

Spent ages looking for something green and the picture in the manual isn't that good for my eyesight.

 

I think this is it, even if it's not green, as the photo above here is a lot clearer.

It's just green in the photo to show what part you're looking for.
If you look where the arrow is pointing to it's black.

A-ha! You are, of course, correct. 

Thanks.

Might be a daft question, but why only clamp negative to that post when jump.starting? As far as I can see it only goes to batt negative terminal anyway.

Just curious 

49 minutes ago, BigDave982 said:

Just curious 

 

Me too

I have no idea but assumes it bypasses something.

"smart charging"  systems have the monitoring ecu on the earth cable connection and are therefore not fried by a sudden shock on connection (directly)

6 hours ago, BigDave982 said:

Might be a daft question, but why only clamp negative to that post when jump.starting? As far as I can see it only goes to batt negative terminal anyway.

Just curious 

The battery management system uses the cable between the post and the battery negative as a current sensing resistor, if you don't connect to the post when using a charger the battery management system will think the battery is still in a poor state of charge and will start disabling current consumers even though the battery will be well charged.

2 hours ago, PetrolDave said:

The battery management system uses the cable between the post and the battery negative as a current sensing resistor, if you don't connect to the post when using a charger the battery management system will think the battery is still in a poor state of charge and will start disabling current consumers even though the battery will be well charged.

 

Thanks for the reply , knew there had to be a reason

but it was jump starting not charging under discussion

17 hours ago, cheshire_cat said:

but it was jump starting not charging under discussion

Same applies, when you jump start you are also charging the battery - because the starter motor isn't turning for the entire time that the jump leads are connected