[tommckay]

I ran my rear defrost today for the 1st time since getting the Van, It works!

However.... when I came to a red light and sat there I noticed my volt meter decline down 2.5-3 notches below the 14v mark where it normally runs just a touch under. That would be a pretty big power draw, when I left the light and got the RPMs up it returned back to normal. I turned off the rear defrost before the next light, and when I stopped there the volts didn't move.

I don't think that should be happening, but I did have everything running (radio, Defrost on high, etc.) What's your thoughts? should I be checking anything? as long as I'm mobile, it's fine....

 

[remark123]

High amperage draw when you have the rear defrost running at low engine revolutions is perfectly normal, especially with the addition of other draws, (lights, radio, blower, etc.) Rear defroster grids are resistance wired, that is they are designed to build heat by resistance across the circuit. That is why they are almost always set up on a timed circuit. Typically the defroster energizes for 10 minutes, and subsequent activations time-out after 5 minutes.

Mark

 

[tommckay]

OK, here a little example... tell me if the usual reading seems right and if the dropped voltage would be in reason.

Maybe it's the hash marks that are weirding me out. Most guages I'm used to seeing are built so the needle runs just above the center hash mark, but I think they were all marked 12v at the center mark. Am I off base?

 

[rev_les]

Mine hangs around the same place at idle with lights and accessories running.The alternator doesn't have full output at idle, that's why it goes back up once your rolling down the boulevard.

 

[astro355]

Mine hangs around the same place at idle with lights and accessories running.The alternator doesn't have full output at idle, that's why it goes back up once your rolling down the boulevard.

Yes, listen to rev_les. He is good, he is wise.

 

[tommckay]

:lol: OK, I :bow: to the wise ones :character-oldtimer: