Ford starter solenoid use for stereo amp power switching
 

Needing to isolate the 2 stereo amps from the battery when not in use do to them draining down my battery, even with no trigger wire signal, and don't want to constantly be switching a dedicated battery switch. I was thinking of using a 40A or so automotive relay to make/break the 12V power cable using the head units turn on lead to signal teh relay. A car stereo shop suggested a starter solenoid since it is more HD. Not sure about that thinking the solenoid isn't designed to be held closed for an extended amount of time, hense my thinking a relay is best. Can the HU's turn on lead support a relay or solenoid current draw to activate?

Thoughts/opinions?


Thanks

You need a latching relay. Standard solenoid will burn out in a matter of about a minute or so. The latching relay looks just like the starter solenoid. The difference is that when you hit the primary, it locks open. Hit it again and it locks closed.

Crydon makes solid state high amperage relays that would surfice I beleave Newark electronics sells them.

Yep what chris said. I learned the hard way. They wont last for continuous power.



Darrell.

I kinda thought the solenoid wouldn't work for that reason. What about a relay? Those are designed to be held closed.


How would I get a latching relay a signal to 'unlatch' ?


More info from my head unit install instructions.

Turn on lead limited to .3A

The amps in line fuse requirement by manufacture: 30A and 40A
My actual current draw using a clamp meter show a max draw of 5A and 30A when stereo is cranked.

Thinking a relay or sort needs a rating of 70A??? Or less being realistic?

Thanks

edited, info coming in faster than I can type. Sorry if any overlap. ;)

Guess relays are a norm for stereos. Learn something everyday.

http://www.hifisoundconnection.com/S...9420/SFV/30046

P&B makes a 40 amp std relay that you would trip with the remote turn on lead, or as lots of folks have said a latching relay, or a tractor relay (designed for continuous use)

Picked up a Stinger (actually made be White and Rogers) 80A cont. duty relay. http://www.hifisoundconnection.com/S...id/0/SFV/30046

Ran across a comment stating the quick amp power cut off may possibly cause the speakers and subs to 'pop' as the power is cut and/or restored.
Is this correct? and if so, I saw a amp turn on delay box, is this the fix? http://www.hifisoundconnection.com/S...id/0/SFV/30046

Thanks

throw a cap in series after the relay should do it. That might actually be the only legit use for those car audio capacitors.

Still think you are throwing a band aid on the problem. If the amps arent shutting off when 12v is removed from the remote turn on , there is something wrong with them. There should be no drain.

I tend to agree.

I talked with the shop that I bought my amps from and he stated it's not uncommon for them to have some draw. So not sure how much I'm going to gain by taking then in to have them check them. Plus I've read it a some stereo forum others having same issue, mainly on the cars that sit for a week or so between starts where it is more of a problem. So I just assumed it must be then.

I had checked the current draw with them off and found the mono amp to draw 32mA, 4 channel amp drawing 2mA using a high quality Fluke meter. These numbers being so low don't seem like enough to kill my battery, but in 2 weeks time, dead. Less than 1 yr old battery had checked out good.