Inexpensive 24V relays

[Granite Grinder]

Wondering if anyone has found a source for 24V relays that aren't too expensive.
GG

 

[canucksafari]

Hmmmmm... flame suite at the ready ... how about Lordco? Paid just over $6.00 each last year for 24V Hella 15 amp relays.

 

[Granite Grinder]

That's a good price. Correct me if I'm wrong, but 24V, 15A is more or less equivalent to a 12V, 30A... let me get my calculator out.
24V, 15A = 360 watts
12V, 30A = 360 watts

OK it's exactly the same
GG

 

[canucksafari]

What are ya worried about that inefficient 12V. Your in the big league now with 24V. Everything is twice as good, twice as powerful and twice as efficient. Of course, a converter (24V - 110V) will cost you twice as much.

 

[brownbear]

That's a good price. Correct me if I'm wrong, but 24V, 15A is more or less equivalent to a 12V, 30A... let me get my calculator out.
24V, 15A = 360 watts
12V, 30A = 360 watts

OK it's exactly the same
GG

watts on a relay are kinda not worth calculating as it's not important for the relay what work it can produce. A 15 amp relay cannot be compared to a 30 amp relay. It does not matter what the watts are.

Also a 12 volt 30 amp ultimately handles 30 amps. The 15 amp 24 cannot.

SO the main thing to think about is what is the relay. It's a set of contacts that open and close. The contacts are made to a certain size of amps.

Think of it like a river. The amount of water flowing thru the river is the current. The speed at which it travels is the pressure or "voltage". The amount of water times the speed at which it travels will be the energy in the work it does(watts or Hp).

The 24 volt coil that operates the 24 volt relay cannot be worked on 12 volts nor can the 12 volt relay run on 24.
The coil is a completely seperate load and resistance than the "figure it's rated at" Generally the larger a relay the bigger the coil is needed to make and break the contacts.

So a 30 amp 12 volt relay could not run a 15 amp 24 volt need. The 24 volts would fry the coil and the 30 amp contacts would be fine.

The contacts have no care what the voltage is. You could set up a relay that used 12 volts to turn it on and off, and have 120 volts AC flowing thru the contacts, or 240, or 24 or 1 volt. The contacts don't care. As long as the load does not pull more than the rated amperage.

If you used a 24 volt relay in a 12 volt application the power would not be great enough to put pressure on the contacts or close them quick enough. Eventually the contacts would arc till they did not have continuity.

 

[Freewheel]

I don't want to disagree with that much theory and mathematics, but I have a $3 12v relay controlling the ignition switched 24v feed on my 24-12v converter. I threw it on as an emergency measure when a $30 Bosch 24v relay failed after 3 days.
I've been waiting for it to die, but it's been working every day for a year...

obviously YMMV

 

[canucksafari]

I threw it on as an emergency measure when a $30 Bosch 24v relay failed after 3 days.
I've been waiting for it to die, but it's been working every day for a year...

obviously YMMV

So why didn't you return the Bosch one? The Bosch relays I have have been clicking on and off every day at every start-up (DRLs module home brew). You might get away with a 12V relay for a while. But if the relay has to work for you to get going down the road, why take the chance. Like BB says, it will burn out the coil eventually.

 

[Granite Grinder]

Thanks BB, I just need to get my head around 24V, in essence it's the same thing as dealing with 12V. Make sure the load isn't greater than the relay can handle, it's just the load amperage will probably be a bit different. Where as I used 30A 12V relays for everything, I might be able to use 15A 24V mostly because of the efficiency of 24V. i.e. less amperage required for the same requirement.
GG

 

[canucksafari]

GG assuming all things are equal it will be half the amps. Hypothetically speaking a winch drawing 40 amps on 12V will draw 20 on 24V to do the same amount of work (watts). But that isn't always so becuase efficiencies can be different on equiptment. You need to check the specs on it. Lights are a different thing. Nissan in its wisdom used the same gauge wiring for the Safari (24V spec) as for the Patrol (12V spec). That means I don't have to buy or build a higher gauge wiring loom to take on high wattage lights. If the old wires could handle 55 w at 12V then they can handle 110 w at 24V. No, I haven't put in 110 W globes - yet. But I do have 75/90 in there now and no smoking or hot wires on high beam.

 

[Freewheel]

So why didn't you return the Bosch one? .

I did return the Bosch one for a full refund - they didn't have anything else in stock and I had the 12v one lying around . Since it's failure would not be mission critical (I'd temporarily lose my radio and accessory power)- I am leaving it in as an experiment.

 

[jcolvin]

Not particularly cheap, but for anything under the hood I always use fully waterproof relays. I find if I don't use the waterproof ones they don't last long.

 

[canucksafari]

That's what you get for following Mat.

 

[grant mcgee]

howdy 24 volters,

I am a little slow on the draw here but I would like to share my 12 v relay experience. I am still not entirely sure how they do it but my 86 2h is 24v all araound except the headlights. So I got the idea just like you all are starting to brew, 12v 30a relay would be...really cool.

But the coil!!! No big deal. My truck (and many of yours) has 12v headlights and so naturaly there has to be 12v somewhere in the headight wiring other than imediately at the headlight. I checked the head light relay and voila, 2 taps of 12v (it is down by the drivers left foot btw).

This is where I am a little unsure. One of the 12v sources reads 12v- on a dmm and will not trigger the coil. The other is just 12v and triggers the coil nicely. And then like our friend said the contacts don't care so now we would have a 30a 24v relay for the driving lights.

Personally I used 2 relays, 2 fuses and a dpdt switch with the dual poles acting as left/right and the dual positions for on and on w/ hi beam. As for driving light coices 24v cannot be beat, so many industrial applications. I'm using 24v aircraft landing lights at 150w each from wagner (and ge) that fit generic 5"? buckets with a massive 5/8" mounting stud (top that piaa). The buckets are Dominion, from Napa, cost me 100/pr w/bulbs back in `96. The bulbs <20ea last fall, P/N 24v 4570.

Summary, 12v to 12v coils only. Go to Napa for electrical. You can only have too few fail safes.

Hope that helps. Grant.

 

[brownbear]

Thanks BB, I just need to get my head around 24V, in essence it's the same thing as dealing with 12V. Make sure the load isn't greater than the relay can handle, it's just the load amperage will probably be a bit different. Where as I used 30A 12V relays for everything, I might be able to use 15A 24V mostly because of the efficiency of 24V. i.e. less amperage required for the same requirement.
GG

The current is the current. regardless of voltage.

The main contacts are just a conductor. They are not a load device.

Conductors only see current. They do not care about the voltage, wattage or anything else.


If the original device called for a 30 amp that's what it needs.

Think of the relay like wires. The wire is rated for current it can handle. Otheriwse if the current is too great the conductor melts.

The field coil is a load, it needs the correct voltage to operate.

 

[ForealBoreal]

fxxxing thing cost me 35 bucks for a 24v and only 8 bucks for a 12v
i am glad i have a 12v truck.

 

[Freewheel]

Hey, haven't seen this thread for a while! I'm sure everyone has been waiting with bated breath for the failure of my $3 12v volt relay in the 24 volt truck.

Well, it never actually failed, but it started getting sticky after about 2 years on the truck. It would take a while to turn off,(a few extra seconds) though it always turned on immediately.

So now I've replaced it with the proper voltage and it's happy.

Experiment over. You can all start breathing again

 

[kim]

GG assuming all things are equal it will be half the amps. Hypothetically speaking a winch drawing 40 amps on 12V will draw 20 on 24V to do the same amount of work (watts).

No, what happens is the winch draws 40 amps at 24 volts, which is probably why it pulls twice as fast.

 

[canucksafari]

No, what happens is the winch draws 40 amps at 24 volts, which is probably why it pulls twice as fast.

Okay. I think I get it. If voltage is similar to water pressure (see I do remember something from the HAM course ) then the reason it pulls so fast is because of the higher voltage. So if we had a motor where we could limit the current draw; theoretically, we would be running at 12V speed if we set it to draw 1/2 the amps. Watts (power) = Voltage x Current.

 

[ForealBoreal]

acklands grainger has them for 8 bucks in the catolgue.
if you live on the water say you work for bc ferries.
and you will get it cheaper.

 

[robertguero]

I know this is a really old post but I have a box of 50 24v relays I need to get rid of.