PRP Seats

[FIREMAN]

I just ordered a new set of PRP Seats with heaters and have a wiring question. Would it be best to wire the seat heaters off of the ignition switch? I would hate to come out to a dead battery because someone left the heaters on. Or is there a better way to set this up. 

 

[ROBERT L]

I would think that’s the best idea.  But I suck at wiring and I absolutely hate a dead battery. 

 

[SuperHunky]

They take a fair amount of juice so one way would be to have the ignition switch trigger a relay to provide battery power..then still have the individual heater switches. Relay is the dead kill switch..I'm thinking of re-working mine that way..

 

[FIREMAN]

They take a fair amount of juice so one way would be to have the ignition switch trigger a relay to provide battery power..then still have the individual heater switches. Relay is the dead kill switch..I'm thinking of re-working mine that way..

Ya that's what I was kind of thinking. 

Thanks  

 

[Fullthrottleguy]

If you are not using a switch box like Switch Pro's or others, Good seat heaters normally draw 12 amps per panel - so if you do bottom and back - that could be 24 amp on high  (12 on low) for each seat . I use a good Hella 40 Amp relay on each switch directly fused or circuit breaker to the battery or more preferably the main cut off switch.    If you go directly to battery one of the tricks I use for seat heaters and radios that I like directly to the battery is that I use the switch as a neg trigger (if possible) and take the trigger positive to the ignition switch - this way to have battery direct to eliminate current surge on other components and noise, but you only have battery power when the ignition is on, so you never drain the battery. 

On radios that is super important otherwise even running them through the main cutoff you will get noise.

 

[Bobalos]

 If you go directly to battery one of the tricks I use for seat heaters and radios that I like directly to the battery is that I use the switch as a neg trigger (if possible) and take the trigger positive to the ignition switch - this way to have battery direct to eliminate current surge on other components and noise, but you only have battery power when the ignition is on, so you never drain the battery. 

Can you post up a schematic of this?  I'm just not getting what your throwin down. 

 

[Fullthrottleguy]

Can you post up a schematic of this?  I'm just not getting what your throwin down. 

Here is a quick schematic   ---  I just finished a car like this 

the relays are standard configuration for Hella/Bosch relays 

85 energizes the relay only when the "main power" switch is closed (on)

30 is hot all the time but fused and will not draw power with ignition off. Alternating 30 goes to main power cut off switch

NOTE:Some heater switches have an indicator light and may need a ground wire as well to make the LED work

Also some seat heaters only have one "hot" going to them and the "switch" does the High/low switching 

but the idea is the same  - German heaters always have two wires high and low, China have just one wire plus ground

 

[SuperHunky]

Here is a quick schematic   ---  I just finished a car like this 

the relays are standard configuration for Hella/Bosch relays 

85 energizes the relay only when the "main power" switch is closed (on)

30 is hot all the time but fused and will not draw power with ignition off. Alternating 30 goes to main power cut off switch

NOTE:Some heater switches have an indicator light and may need a ground wire as well to make the LED work

Also some seat heaters only have one "hot" going to them and the "switch" does the High/low switching 

but the idea is the same  - German heaters always have two wires high and low, China have just one wire plus ground

View attachment 4528

Relays always confuse me even though they are simple..So is this a negative trigger scenario shown? German cars use negative trigger on everything..Maybe noise is the reason. Seems like you would switch the negative to ground it and energize..??

 

[Squatcher]

Here is a quick schematic   ---  I just finished a car like this 

the relays are standard configuration for Hella/Bosch relays 

85 energizes the relay only when the "main power" switch is closed (on)

30 is hot all the time but fused and will not draw power with ignition off. Alternating 30 goes to main power cut off switch

NOTE:Some heater switches have an indicator light and may need a ground wire as well to make the LED work

Also some seat heaters only have one "hot" going to them and the "switch" does the High/low switching 

but the idea is the same  - German heaters always have two wires high and low, China have just one wire plus ground

View attachment 4528

Only thing about this setup is make sure you have switches that will handle 30 amps. With the single wire heaters I like to run the Ignition wire to the switch and use that as the trigger so the relay power goes straight to the heater pads.  High and low Need to use this method above.   Isn't there a center pin that is the Neg trigger? been awhile since I have played with them.   Also if you use a Neg trigger and the wire shorts out(ie: bare wire rubs on metal)  it would energize the relay wouldn't it?

 

[Fullthrottleguy]

Only thing about this setup is make sure you have switches that will handle 30 amps. With the single wire heaters I like to run the Ignition wire to the switch and use that as the trigger so the relay power goes straight to the heater pads.  High and low Need to use this method above.   Isn't there a center pin that is the Neg trigger? been awhile since I have played with them.   Also if you use a Neg trigger and the wire shorts out(ie: bare wire rubs on metal)  it would energize the relay wouldn't it?

You are 100% correct that some of the switches are not rated for the full 12 amps  the heaters take and they are used to trigger the relay - I often do it that way and just wire for High power on the seats.  the high /low "in the switch" is what all the off-shore ones seem to do . "most relays do have Normally closed 87a pin as well. 

As far as Neg trigger vs Positive trigger - Yes if a wire touches ground it will trigger - but on Positive trigger if a wire touched it will blow the fuse -   In the case of using a Positive trigger for the seats on the main ignition if the wire shorts to ground - the car dies   - not ideal  

But you job as "rigger" should be protecting against abrasion.  I use dual wall marine shrink on every wire in the Sand car harness for that reason and either put all the wires in expandable sheath or lately using better quality harness tape and a lot Ty-raps. You cannot believe the wiring jobs I have seen  ...

This diagram is the way I wire low amperage switches like the kind in near-shore carbon fiber heaters two piece cushion and back (made in mexico) I find them better quality but harder and harder to find. Its a little more complex but works well

The low setting supplies power +12 to the "low connector and the ground goes to the battery  the High setting supplies power to Relay, +12v is from the battery and ground is from the relay - it seems strange but thats the way these type work

These are the only two types I have worked with other than the ones Beard used to sell - they were neat - you had a Solid state relay box you put +12V and ground to and they had a "harness to the switch and plug in for each seat.   One and done  - 5 minute install

I have tried to find those for a few years - never saw one fail either.

Relays always confuse me even though they are simple..So is this a negative trigger scenario shown? German cars use negative trigger on everything..Maybe noise is the reason. Seems like you would switch the negative to ground it and energize..??

They way I diagramed it there is a Positive trigger since its easier do with the way most Ignition switches are wired - the down side of a positive trigger on ignition  is that now  you are Fusing for a load that you only have occasionally (seat heater relays) and therefore your normal ignition switch fusing is undersubscribed and will not blow as quickly so you don't have as accurate protection as you normally would, unless you fuse the wire going to the relay triggers, and that means more fuses to "put" somewhere and more contacts that can get corroded or just fail over time (spring tension lessons over time from hot cold cycles)

Neg triggers do eliminate noise and are generally easier to wire.