Low Voltage Sensing Relay ???? --HELP!!

I have need of the following:
A relay that will handle a 15amp load and close at about 13.0-13.4vdc and
open at, say, about 12.7vdc. Is such a device available - if so where? OR what
can I put together to operate in such a manner??
The application: I want to AC power an RV refrigerator with an Inverter from
the vehicle DC charging system but automatically disconnect when RV battery is
not being charged, ie, to prevent powering Inverter from RV battery.
Ray
Reply to
R. A. Piziali
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Would this work? Buy a 12VDC relay. Hook the coil to the ignition system of the RV. Use the contacts to control the fridge. You might also look at a battery isolator. JC Whitney has a couple in their catalogue. Maybe an auto parts store would also. I once saw a device advertised that would automatically disconnect a battery if the voltage dropped below a certain point. I don't remember where though.
Dean
Reply to
Dean Hoffman
get a standard relay with 12V contacts that will handle the current you want. Drive the relay with a 2n3055 (or a more modern equivalent), drive that with a voltage comparator. On one leg of the comparator, use a 10K resistor and an 8V zener, on the other leg of the comparator, use a 10K pot - adjust the pot for the trip point you want
> > > > I have need of the following: > > > > A relay that will handle a 15amp load and close at about 13.0-13.4vdc and > > open at, say, about 12.7vdc. Is such a device available - if so where? OR > > what > > can I put together to operate in such a manner?? > > > > The application: I want to AC power an RV refrigerator with an Inverter from > > the vehicle DC charging system but automatically disconnect when RV battery is > > not being charged, ie, to prevent powering Inverter from RV battery. > > > > Ray > > Would this work? Buy a 12VDC relay. Hook the coil to the ignition > system of the RV. Use the contacts to control the fridge. > You might also look at a battery isolator. JC Whitney has a couple in > their catalogue. Maybe an auto parts store would also. I once saw a device > advertised that would automatically disconnect a battery if the voltage > dropped below a certain point. I don't remember where though. > > Dean > > > > > > >
Reply to
william_b_noble
| A relay that will handle a 15amp load and close at about 13.0-13.4vdc and | open at, say, about 12.7vdc. Is such a device available - if so where? OR what | can I put together to operate in such a manner?? | | |
We have these in the UK, so I think they will also be available in the US.....
We use two types of relay for caravan towing purposes. The older style one is fed from the ignition warning light system, which means that the relay is only made when the ignition is on and the alternator is producing a charge sufficient to turn the ignition warning light off.
The second and more recent type, simply requires a feed from the battery alone. It senses the voltage across the battery and makes the relay when the voltage indicates the battery is being charged.
Both are used for supplying fridges and charging the battery in a caravan and are rated at 20amps or better.
Reply to
Harry Bloomfield

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