XPost: alt.home.repair, sci.electronics.repair   
   From: rod.speed.aaa@gmail.com   
      
   On Thu, 19 Jan 2023 02:28:58 +1100, Peter   
    wrote:   
      
   >  wrote:   
   >>> I always did positive first.   I will switch!   
   >>   
   >>    Think it out  first  -   then decide.   
   >   
   > I'm thinking... I'm thinking... I'm trying to think this thing out.   
   > I don't think it matters all that much which cable goes first or last.   
      
   You are wrong with the question of accidentally touching   
   the body etc with the positive lead when the negatives   
   have already been connected. Much safer to connect the   
   positive terminals first.   
      
   > As far as I can think about it, the last connection is the one that   
   > sparks.   
   > And that means the first disconnection is the one that sparks.   
      
   Sparks aren't the problem. they happen regardless of which   
   of positive and negative you connect first.   
      
   > Since you don't want that spark to be near any concentration of flammable   
   > hydrogen gas, I guess the theory that I'll concoct is you want the   
   > negative   
   > cable to be as far from that hydrogen gas as possible.   
      
   The reality is that with the battery in the engine compartment   
   with the hood up, there will be on concentration of flammable   
   hydrogen gas.   
      
   Even with the few cars that have the battery in the passenger   
   compartment or the trunk, thats still very unlikely because   
   the battery only produces hydrogen gas when it continues   
   to be charged after it is fully charged.   
      
   > That makes it the negative cable to be the last to connect.   
   > And the first to disconnect.   
   >   
   > Now, if the theory is to proceed accordingly, we have to decide which   
   > battery has the most chance of having excess hydrogen gas.   
   >   
   > The answer likely is neither will have any, but if we have to choose,   
   > which   
   > battery will have more hydrogen outgassing?   
   >   
   > (A) The donor battery (which is likely already topped off)  or   
      
   But which won't be being charged unless the engine is still running.   
      
   > (B) The recipient battery (which is likely taking the greater charge)   
      
   Only AFTER the connection has been made which allows that.   
      
   > The answer seems, to me, to be neither battery will have excess hydrogen   
   > gas, but if I was forced to choose, I guess the battery being charged the   
   > most has the most excess hydrogen gas, which would clearly be the donor.   
      
   The reality is that it isnt about hydrogen gas, its about   
   accidentally touching the body of the recipient car with   
   the positive jumper lead before it is connected to the   
   positive post of the flat battery.   
      
   > All this is just "thinking it out" so tell me if I'm wrong so I learn   
   > from   
   > your expertise (the royal your that is, as everyone has something to   
   > say).   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)