Charging cranking battery

[Dave Turner]

Am I dreaming or did I see a post where someone said to disconnect the positive side when charging your cranking battery?? Reason was the charging current could damage the rectifier over time?? Any one on this?

 

[glenn property of pam]

Re: Charging cranking battery

Am I dreaming or did I see a post where someone said to disconnect the positive side when charging your cranking battery?? Reason was the charging current could damage the rectifier over time?? Any one on this?

would you realy care if it did shorten the life on a part that can be damadged so many other fun ways. I have a battery disconnect switch so I guess I do disconnect it just not for the reason listed above.

 

[Chris1956]

Re: Charging cranking battery

Dave, While rectifiers do have a threshold where voltage will damage them (as do all diodes), a battery charger will never hit that voltage, so it is perfectly safe to charge them while they are hocked up.

Do not disconnect the battery while the engine is running or you will damage the rectifier for sure.

 

[Charlie in TX]

Re: Charging cranking battery

I agree with the others. When I first started driving it was in 60s and 70s cars. Being young and broke with friends that where young and broke we often had bad batteries. We would frequently take out the voltage regulators charging or jumpstarting our cars. It is probably this time frame, and earlier, that generated the disconnect to charge rule (and the don't leave a battery on concrete rule). It does not apply with todays modern regulators.

 

[Chris1956]

Re: Charging cranking battery

Charlie, Actually back in the 60s cars has generators. They were very robust, as were the regulators. I doubt you had to disconnect anything in those days.

i.e. I had my battery cable fall off in my '64 Merc, when I was driving and the car still ran, no damage was done, except the battery did not charge up. That set the scene where we had to push start that car, at 2AM, just to get home.

 

[UncleWillie]

Re: Charging cranking battery

Am I dreaming or did I see a post where someone said to disconnect the positive side when charging your cranking battery?? Reason was the charging current could damage the rectifier over time?? Any one on this?

This make perfect sense unless you think about it for more than 10 seconds!
The Charger places ~15 volts on the battery to charge it.
The Running Engine/Alternator also places ~15 Volts on the Battery using the Rectifiers.
The results are the same.

... Being young and broke with friends that where young and broke, we often had bad batteries. We would frequently take out the voltage regulators charging or jump starting our cars...

Charging and Jump starting should not be an issue.
PUSH STARTING a car with an extremely dead battery results in a Generator/Alternator coming alive with a battery with near Zero volts on it.
This battery looks like a dead short to the charging system until the voltage gets back above ~9 volts.
The resulting current through the rectifiers can easily exceed their capacities. Failure follows.
It is OK to Push start a car with a battery that is marginally bad.
If the headlights or radio do not work, you risk the rectifiers if you push it.

 

[Silvertip]

Re: Charging cranking battery

Charlie, Actually back in the 60s cars has generators. They were very robust, as were the regulators. I doubt you had to disconnect anything in those days.

i.e. I had my battery cable fall off in my '64 Merc, when I was driving and the car still ran, no damage was done, except the battery did not charge up. That set the scene where we had to push start that car, at 2AM, just to get home.

That's not true. Many cars including GM had alternators in 1960:
https://www.google.com/search?q=196...s=org.mozilla:en-US:official&client=firefox-a

 

[Charlie in TX]

Re: Charging cranking battery

My cars included '64 Impala, '70 GTO (ie GM). If I recall correctly, they had alternators with external regulators. I had to replace many regulators. The more modern alternator with internal regulators are much more reliable.