BoatBanter.com - View Single Post - Charging the battery -- how long is okay?

Vic Smith

On Mon, 25 May 2009 12:07:19 -0400, wrote:

On Mon, 25 May 2009 05:47:40 -0400, "D.Duck" wrote:

10 feet of 12ga stranded copper will drop 0.59v at 15a.

When that is deducted from 120v it is fairly insignificant but it is
4.9% of your 12 volts.

Based on a 12AWG stranded wire resistance of 0.00159 ohms per foot, the
voltage drop would be 0.225 volts.

There maybe a few more 10ths volt drop depending on the integrity of the
clamp's connection to the battery.

You have to get back so double that ;-)

I used a calculator based on the table in the NEC. I know the AARL
table shows lower resistance. It has to do with the temperature.

Having done more jumps than I care to remember, all I know is pay for
the heaviest jumper cables you can find. Make sure the side-mount
clips are spring-tensioned and not the slide-on type.
But I don't get why anybody would care about charger clips.
Even the lightest, cheapest feeling clips have always worked fine for
me.
In fact, that's what's on my Sears charger, maybe a 50 buck model with
2 and 10 amp modes and a "start" mode.
I've started 2 cars with virtually dead batteries using that "start"
mode and those cheap clips. No problem at all.
Charges fine on the 2-amp mode with those cheap clips too.
Never used the 10-amp.
Supposed to be automatic, but I've always unplugged it after a day
charging a depleted car battery. Don't like that humming.

--Vic