Car DC Chargers

If I install a DC trickle charger (any type) in my car. Will it use so much juice such that my car will not be able to start? Is there any regulating circuitry? How do the DC chargers work and has anyone installed them in their vehicles? The only ones i have had experience with are the ones installed on our fire trucks that charge the boxlites and survivors, however in the bays at the firehouse, the trucks are connected to AC.
-ERiC

Turning on your radio would probably suck more juice from your vehicle than any flashlight charger. And I think if your vehicle is not running and you don't have your keys in the "Acc" position then the cig lighter won't output anything, so your flashlight isn't being recharged.

Originally posted by MTFD17:
If I install a DC trickle charger (any type) in my car. Will it use so much juice such that my car will not be able to start? Is there any regulating circuitry?
-ERiC

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<font size="2" face="Verdana, Arial">Have no worry about draining excessive juice from your battery. Most people don't realize how much capacity a car battery has. Mid-sized cars usually have around a 70Ah 12V battery. That's a huge amount of power. It would take a very very long time of constant draw from the charger to bring down the battery. We're talking weeks. Be aware though that on normal car batteries(Non deep-cycle or gel cell), you shouldn't drain the battery down too far. It will severely shorten the life of the battery.

If you have a car that's started and run at least every few days then there's nothing to worry about.

Voltage regulation is done by a special circuit in the alternator assembly(on newer cars) and supposedly spikes are dealt with by the battery(acts as kind of a filter). No worries in this department.

You'll be fine, go ahead and install the charger.

Also, whether your cigerette or "power point" socket has power without the keys depends on your car. On my Toyota, for example, if there's the key isn't turned to ACC, there's no power. However on my friend's Chevy Cheyenne 1500 there is power even when the key is totally pulled out.

-tibim

The cigerette socket has to be the WORST connection to get power from, whenever I purchase a car - I always run a set of wires from the battery thru a fuse into the cab with Anderson-Pole connectors for my misc stuff (Ham Radio/GPS/Etc)

" yes. no. a long time. alot. a little. " -- doesn't mean much if you don't know the facts. how much of a trickle are we talking about? 200 milliamps? 2 amps? just because a battery says "70 AH" on the side doesn't mean your car or will start if you drain 2 amps out of it for 24 hours, or for 12 hours, because draining the amps is going to lower the voltage, possibly beyond the point of being able to start the engine. a rule of thumb is that your 12 volt battery is at about 50% of it's capacity once it's down to 12.1 volts (at 77 degrees F.) a full battery hangs at 12.6 -- some starter batteries hang at a somewhat higher voltage like 12.7 or 12.8 -- with no load..
.. your mileage may vary..
what I would do if I had a drain going on my car battery while the engine was shut off would be to get one of these gizmos I see advertised at griots garage -- it senses the battery voltage and shuts off all output when the voltage falls too low, and thereby leaves enough juice in the battery to get you started..
I'll post the griots gizmo info, if I find it, here:

http://www.griotsgarage.com/catalog.jsp?&SKU=36740