Quote:
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Originally Posted by NickCats
Jim,
Why are you so adverse to the cigarette lighter chargers ? How great is the chance that charging through the wiring harness will fry something due to a short ? Why would Porsche choose to offer this option as part of their tequipment if there is such an inherent risk ( aside from simplicity ) ?
http://www.epiqautosport.com/pro_battery_maintainer.php#?
Thanks,
Nick |
I'm not Jim, but after reading his answer maybe I can help out here...
The "short in the wiring harness" really isn't an issue. It's not like a short would only exist from the lighter socket back to the battery, but not from the battery out to the lighter. If there's a short, and it somehow killed the battery, it's already done its damage. The battery can supply hundreds of amps, frying pretty much any wiring in its path. The little lighter socket chargers are electrically limited to just a few amps, which even the smallest wires in the harness can safely carry.
As for electrical spikes from the AC power, well... any charger could be susceptible to that. However, nowhere remotely as susceptible as computer gear. The battery is essentially a HUGE capacitor, which would soak up some spike, if it were even able to make it through the charger. I'd be far more worried leaving a car on a big charger connected directly to the battery posts, as they can output far more current, and as a result can (and have) caught on fire themselves.
As far as the charger having to work harder to "push" the current through the wiring... well, that's
not how electricity works. The charger presents a voltage to the battery, which then takes as much current as it needs (or the charger can deliver) to store in itself. If you insert some extra wiring between the charger and battery, you are essentially inserting a resistor into the circuit, which decreases the current flowing, which in turn EASES the load on the charger. It just takes longer for the battery to charge.
The only aversion that makes sense is to not want to attach one of these chargers to an old English or Italian car. With their pre-historic wiring harnesses and history of melting down when turning on the windshield wipers, you cringe everytime you turn the key!
Hope that clears things up.