1994 volvo 855 - solenoid amp draw

webstyles · Post by **webstyles** » 28 Feb 2015, 03:07

Hi Volvorinos,

The Green/Red wire that goes from the ignition switch to the starter solenoid (to activate it) has 50 volts according to electrical diagrams. I need to know how many amps that wire draws. Can't seem to find the information anywhere and I don't have an amp meter.

Why I need to know:
I want to install a hidden push switch along the wire, so that the car will only start if you're pressing the hidden button at the same time you turn the key (i.e. cut the wire and place button in between). I need to know the amperage so I can get a button that will be able to handle the load.

Thanks in advance

Post by **jreed** » 28 Feb 2015, 06:02

I haven't measured it, but I'd guess that a pushhbutton switch that can handle 10A should be OK for the short duty cycles needed on a starter solenoid.

There are descriptions in the links below suggesting a typical 5-10A current draw for the solenoid:
http://webcache.googleusercontent.com/s ... clnk&gl=us

http://forum.allaboutcircuits.com/threa ... ids.69799/

Post by **Ozark Lee** » 28 Feb 2015, 07:18

I'm not sure where 50 volts came from. The starter solenoid activates with battery voltage which is 13ish volts. There isn't all that much current either but a 5 to 10 amp rated switch should work forever.

...Lee

webstyles · Post by **webstyles** » 01 Mar 2015, 10:23

Thanks for the answers. Much appreciated.

Post by **jimmy57** » 01 Mar 2015, 11:23

That starter solenoid terminal is DIN terminal 50. DIN 30 is battery + constant, 15 is switched 12v +, 31 is ground.

Starter solenoid is 6-8A initially due to both windings being energized in the first fraction of a second but only 3-4 amps for hold-in winding for the rest of the period starter is engaged.

webstyles · Post by **webstyles** » 02 Mar 2015, 21:23

Quick follow-up: Installed the 7,5 amp push-button. Works perfectly. My car always starts in less than half a second so it's no problem. Was wondering what would happen one day when it doesn't start so easily, and if button would melt from the heat or something, but jimmy57 has just answered that nicely (Thanks!). Since the amps drop after initial contact, should not be a problem. (if it does ever happen, I'll come back here and post the results)

I'm very happy with my new little security mod. (won't post photos because that would defeat the purpose of a hidden button).
A little humour: It also crossed my mind that one day I might be out for a few drinks with friends, and i'll forget about the button and won't e able to start car

... Now my little mod also prevents me from drunk driving. What a cool little 2in1.

Thanks to everyone for your help.

Post by **jimmy57** » 02 Mar 2015, 21:57

The only time your switch is at risk would be if the battery is weak and you keep trying to get starter to engage. That is when the high amp phase could last more than 2-4 milliseconds.

I'm not sure your button rises to the level of being an alcolock though......