Battery charging with cables still connected

[Tafia]

Orb the Impaler said:

Charging batteries while leaving the car connected will be absolutely fine.

What you shouldn't do with a lot of modern cars (Mercedes are a good example) is jump start them with a booster pack, although normal jump starting is fine.

OP - your voltage is only part of the problem - it's the current that the battery can supply that's going to be the issue. Also have a look what voltage the battery is putting out when you crank the engine. Notalot I suspect.

Can you say what the voltage would be on a good battery when cranking? This Honda starts right away so I wonder how I would measure the cranking volts. Perhaps a check with a battery tester is called for.

[grumpyscot]

Tafia said:

esselte said:

*Al* said:

I mentioned that years ago folks would leave their side lights on all night when parked in the street yet a mechanic told me that nowadays if they leave a car door open in the workshop overnight , it can flatten the battery.

But years ago, you probably only had one single interior bulb - if at all. In my Toyota, there's two at the mirror, two or the rear, and one in each door - i.e. 6 times the number. And the old Moggie didn't have electronic door locks, alarms, radios that needed a constant feed, etc etc. So it's no wonder batteries go flat quicker.

Mind you, back in the old days, we used to need a "parking light" left on all night - something never done nowadays.

[miniman]

mybrainhurts said:

Orb the Impaler said:

What you shouldn't do with a lot of modern cars (Mercedes are a good example) is jump start them with a booster pack,

Why, please...?

+1

Providing the negative lead is connected to a good earth point on the flat car rather than the battery negative terminal I can't see any reason why it would make a difference.

[Tafia]

miniman said:

mybrainhurts said:

Orb the Impaler said:

What you shouldn't do with a lot of modern cars (Mercedes are a good example) is jump start them with a booster pack,

Why, please...?

+1

Providing the negative lead is connected to a good earth point on the flat car rather than the battery negative terminal I can't see any reason why it would make a difference.

Isn't that to avoid sparks near the battery which could cause an explosion?

[miniman]

Tafia said:

Isn't that to avoid sparks near the battery which could cause an explosion?

Partly, but also because routing the earth through the body / engine reduces the susceptibiltiy to surges.