12V relay reliability?

[oldtrack123]

Yes, sorry T1...... I inferred both ways in the original post.
I've been working on a 'problem' for running Bernie's new fridge with the existing setup he has.
Bus on 24V.
House battery is big AGM, 12V.
Fridge is compressor 12/24/240AC.
Fridge appears to have 'strange' thermostat.
Would like to run fridge on bus battery while mobile and on house one when engine off.

Considering ignition activated changeover relay to switch power source.
Install electronic thermostat activated relay in electrical cable between switchover relay and fridge.
When 240V switched on it auto turns off DC power. (apparently?)
Sounds complicated but attempting to avoid "I forgot" syndrome!
The switchover one wouldn't get much use but the other one would get a lot more use depending on differential settings.

Hi
Sorry ,I do not know why I thought it was a 3way
Perhaps a little confused with SWMBO in hospital AGAIN


You could use a Jaycar #SY-4041 [24V coil, 30A DPDT relay] for that purpose @ about $15
Switch the coil via ignition circuit

12v to & fridge use one set of normally closed contacts

24V to the fridge use other set of normally open contacts

Peter

[BruceS]

Thankyou Peter. Pretty well along my line of thinking.
You don't see a problem with arcing/welding of points/contacts on the relay? (not solid state one?)

[oldtrack123]

Thankyou Peter. Pretty well along my line of thinking.
You don't see a problem with arcing/welding of points/contacts on the relay? (not solid state one?)

HI
NO , not with the light load compared to current rating [ contacts rated 30A @24V ], & the low frequency of operation


Peter