Capacitor Query!

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copcarguy

Copper - Posts: 122

Joined: February 12, 2003

Location: Pennsylvania, United States

Posted: March 04, 2003 at 7:22 PM / IP Logged

I am new to using capacitors in vehicle applications and was wondering what happens if your car battery goes dead and consequently then so does the capacitor. Do you then have to recharge the capacitor with the resistor card before using it? Probably an easy answer but unsure of proper operation. Any help is appreciated.

R Jackson

Owner/Installer

TRM Emergency Vehicles

Information is advice only and should be confirmed with OEM or quality test equipment.

Boyertown, Pennsylvania

copcarguy

Copper - Posts: 122

Joined: February 12, 2003

Location: Pennsylvania, United States

Posted: March 06, 2003 at 3:55 AM / IP Logged

bump...

R Jackson

Owner/Installer

TRM Emergency Vehicles

Information is advice only and should be confirmed with OEM or quality test equipment.

Boyertown, Pennsylvania

audiovector

Member - Posts: 5

Joined: March 06, 2003

Location: United States

Posted: March 06, 2003 at 6:25 AM / IP Logged

How about this scenerio. "What if the lights go off in your house because lightning caused your circuit breaker to open, after u reset the breaker. do u need to go back in the rooms to turn back on the lights?"

just a thought

RocketRanger

Member - Posts: 22

Joined: February 12, 2003

Location: United States

Posted: March 06, 2003 at 7:48 AM / IP Logged

Consider why the resistor card is used to charge the cap in the first place. It is to prevent the very large current surge from damaging contacts and starting the user. Otherwise, no harm around a sealed cap. Your not going to ignite anything which is why sparks are a concern under the hood of the car. (Jump starts\battery chargers\battery installation\anytime you connect and disconnect the terminals)

Now consider where you will be causing "sparks to fly"...

Aroung the battery, which could cause an explosion. (Not probable..BUT GO SAFE)

I'd do 1 of 2 things:

-Disconnect cap at the cap before charging car battery. Then usae resistor card to charge cap as if it were new\discharged.

-Use the resistor card between the charger and the car battery, ehich will put that initial charge on the cap without harm. 5-10 seconds is plenty of time. Then hook the charger\jump start up normally.

Otherwise, expect LARGE spark and small and insignificant damage to the connections of the charger, jumper cables, and or battery post.

GO THE SAFE ROUTE!!!! If on the road or stranded at the time. Undo your inline fuse to audio equipment before jump\charge.

Rocket...

copcarguy

Copper - Posts: 122

Joined: February 12, 2003

Location: Pennsylvania, United States

Posted: March 06, 2003 at 2:53 PM / IP Logged

Lights and capacitors are not quite the same as I understand it. Lights operate using a filament to produce light when voltage is applied using resistance to develop heat and consequently light, capacitors store potential energy to be used upon demand and when the demand drains the capacitor then the "reservoir" is dry. I wanted to know about refilling the reservoir and specifically does it regulate itself when the vehicle is jump started.

I am not concerned about sparks either just simply will the capacitor return to its charged state without any intervention needed.I believe it will but wanted to check with others with more experience than me with this equipment.

If you remove the capacitor fuse and jump start the car dosen't that mean when you replace the fuse you would still get the same spark? Just a thought.

R Jackson

Owner/Installer

TRM Emergency Vehicles

Information is advice only and should be confirmed with OEM or quality test equipment.

Boyertown, Pennsylvania

CorradoG60

Member - Posts: 15

Joined: March 11, 2003

Location: United States

Posted: March 11, 2003 at 5:30 PM / IP Logged

If your car battery dies, most likely the battey is not at 0V. Usally 10.5V is a fully dead battery (Except in a few exceptions). The capacitor only charges to the highest pontential applied to it.

The reason for the resistor used when initially charging a cap is used because for an extremely quick amount of time a fully discharged cap look like a short circuit. With out the resistor the cap will draw a high amount upf current initailly. Other wise know as Inrush current. The resistor is included to limit the curret from the initial charging or the cap. Yet when adding a resistor in-line with the resistor this slows the amount of time it takes to charge a cap.

Yet a cap that has a charge on it will not need a resistor inline to charge it again. It is only really needed if the cap is allowed to discharge fully. So if there is an inoitial charge of a couple volts on the cap it is safe to charge the system.

Yet as stated above it may spark when connecting up the battery, yet that is doe to the potential difference in the dead battery and the battery and vehicle that is being used to jump the dead car.

The FLUKE Guy.

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Capacitor Query!

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