Running a contactor from the midnites Aux relay.

[Randaltb]

I assume I am OK to do This? 

I have an SC-05G (24 volt coil) contactor, and it appears the coil is only 7W at 24 volts.
So I "ASSUME" there should be no issue using the AUX relay to toggle the 24 volts?

Have any of you used AUX relay for the larger contactors vs just ice cubes relays?
Hate to bake a relay contact just because I missed the fine print.

F.Y.I the intent is to be able to toggle external power based on Battery voltage, to run a AC- DC charger. (Just to protect batteries)

[ClassicCrazy]

Check the specs but I think the output of the Aux is 12v . Also just in case you didn't check, make sure your contactor is  dc coil  and not ac .
I use solid state relay on a heat sink and it works fine. But if you choose a SSR make sure you get one that is protected against flyback from induction motor or add it on additional. Also when you are looking up the specs on Aux read up on the jumpers that switch it to either be a contact of supply 12v .

If you go to main forum page and search for aux ssr you will find lots of discussions and info.

Larry

[Vic]

Hi Rand..,

As Larry mentioned,   the Aux relay output is either a switched contact,  or switched 12 V DC,   depending upon the jumper configuration.

The current limit for Aux output is 200 mA  --  0.2 Amps.

Your proposed Contactor,   at 7 W from 24 V for the coil,   is around 300 mA  coil current  --  too much,   and at 24 V.

Perhaps an AC  SSR,   also mentioned by Larry.   If you DO use a coil type relay,  you will need a 'catch diode'  across the coil to get rid of the inductive kick when the Aux relay contacts open,    and so on.

FWIW, Vic

[ClassicCrazy]

Hi Rand..,

As Larry mentioned,   the Aux relay output is either a switched contact,  or switched 12 V DC,   depending upon the jumper configuration.

The current limit for Aux output is 200 mA  --  0.2 Amps.

Your proposed Contactor,   at 7 W from 24 V for the coil,   is around 300 mA  coil current  --  too much,   and at 24 V.

Perhaps an AC  SSR,   also mentioned by Larry.   If you DO use a coil type relay,  you will need a 'catch diode'  across the coil to get rid of the inductive kick when the Aux relay contacts open,    and so on.

FWIW, Vic

type there Vic you mean DC SSR
Larry

[Vic]

   ...   F.Y.I the intent is to be able to toggle external power based on Battery voltage, to run a AC- DC charger. (Just to protect batteries)

Larry said,   ...   "type there Vic you mean DC SSR"

Larry,   do not exactly just what the above means,   BUT,   it did seem that "AC - DC charger was running on AC,   SO,   an AC SSR   would be THE thing to use   ...    always a bit of guessing on things like this   WhattaIknow??   73   Vic

[ClassicCrazy]

okay Vic - I meant DC input  on SSR - maybe that is the only way they come anyway. But yeah now I see what you meant.
and I was trying to write typo but made a typo on my typo and wrote type !

Larry

[qrper]

I assume I am OK to do This? 

I have an SC-05G (24 volt coil) contactor, and it appears the coil is only 7W at 24 volts.
So I "ASSUME" there should be no issue using the AUX relay to toggle the 24 volts?

Have any of you used AUX relay for the larger contactors vs just ice cubes relays?
Hate to bake a relay contact just because I missed the fine print.

F.Y.I the intent is to be able to toggle external power based on Battery voltage, to run a AC- DC charger. (Just to protect batteries)

I designed a simple pcb that might be of help to you. It drives a 30 A automotive relay that has open contacts. You could use those to control your outboard charger. The input/control is a pull to ground. There is a circuit on board that will snap in the relay and then the current of the relay's coil is reduced by 60% The relay is mounted on the pcb. The current for the logic is so low, the classic's aux outputs wouldn't even know it's there.

mike

[Vic]

okay Vic - I meant DC input  on SSR - maybe that is the only way they come anyway. But yeah now I see what you meant.
and I was trying to write typo but made a typo on my typo and wrote type !
Larry

Hi Larry  ...   running a bit behind here   ...

OK,   sorry that I did not understand your reference.

YES,   most AC SSRs use Triacs,   and an optically-isolated DC  input for the control   --  customarily 3 - 32-ish  VDC.

FWIW,  73  Thanks for all of your contributions to this Forum!   Vic

[Randaltb]

Here is an update.
*I am not using the internal 12v.

I looked it up and found 1A max listed for the dry contacts. (AUX 1)
So 24 VDC at 7W is ~.4 Amp.

So I seem to be fine using dry contacts. (So far)
The contactor has been running fine for 2 days.

As far as DC vs AC coil, I actually think an AC coil scenario would be better. (Dry with contacts...)
Since AC with pass zero, we would see no/less potential for arcing.

Now what max voltage will the contacts safely handle?
My 1st thought is 24 VAC from a T-Stat transformer, but I wonder what a 120VAC low current would do?
** I will probably stick with 24 volts, just to be safe. (But still want to know)

[Vic]

Here is an update.
*I am not using the internal 12v.

I looked it up and found 1A max listed for the dry contacts. (AUX 1)
So 24 VDC at 7W is ~.4 Amp.

So I seem to be fine using dry contacts. (So far)
The contactor has been running fine for 2 days.

As far as DC vs AC coil, I actually think an AC coil scenario would be better. (Dry with contacts...)
Since AC with pass zero, we would see no/less potential for arcing.

Now what max voltage will the contacts safely handle?
My 1st thought is 24 VAC from a T-Stat transformer, but I wonder what a 120VAC low current would do?
** I will probably stick with 24 volts, just to be safe. (But still want to know)

Hi Rand..,

Yes the Maximum current rating for Aux dry contacts IS 1 Amp  ...   24 VDC  is probably OK,   but,   personally would use the switched 12-ish VDC output of the Aux.

You will want to use that "catch diode" (mentioned previously),   to suppress the voltage that is created by the collapsing magnetic field of the Contactor's coil.

Would NEVER,   EVER  try to use 120 VAC on the dry contacts,   ever.   You do not want 120 VAC  running around inside the Classic (or most any  other CC).

Hey,   why not just use an AC SSR ??:
http://www.crydom.com/en/products/panel-mount/easy-pick/

These run on low-current DC,   and the switched 12 V from the Classic would work fine as the control voltage.

FWIW,   IMO,   Vic