I was just watching a vid by arild365 on You tube and I noticed a very scary dangerous thing.
When boosting a battery NEVER put the negative on first. The proper order is Postive on booster battery to postive on dead battery, negative on booster battery to ground point on chassis of dead battery.
ALWAYS!!!!!! Positive first, negative to a ground point on tha chassis. NEVER PUT THE NEGATIVE CABLE ON THE BATTERY POST!!!!!!!!
DOING IT ANY OTHER WAY IS EXTREMELY DANGEROUS.!!!!!!!!!
Batteries give off hydrogen gas when they are boosted or charged.
HYDROGEN GAS IS EXPLOSIVE The slightest spark can cause an explosion.
I Know this because I had a brand new truck battery explode in my face about 8 years ago.
It cost me a day in the hospital and a partial loss of my vision. Not to mention acid in the eyes is extremely painful, and nothing short of a full face sheild will protect you. Safety glasses didn't do a damn thing.
EDIT*** I've been thinking about this, and the above info was quoted from long ago learned experience and training. I was an Aircraft tech, A small engines teachers aide, and a Motorcycle mechanic. This was the info that was taught in the old days.
And I would still use it for boosting from a truck or standard battery.
HOWEVER, it is possible that these new fangled boosting units have circuitry in them that requires a different procedure. In which case Arild may be comepletely correct