Need a little 12v help.....

[Waterjunky]

Hello all,
I am adding a circuit to my RV and need a little help figuring out the best way to wire it.
I am adding a large secondary fuel tank and the builder sets them up with a small transfer pump to move fuel to the primary tank. As a smart decision, a timer is used so not to over fill the primary. What's used is a Spring wound standard wall timer. Think like a bathroom fan. Cheesy but technically functional.

What I want: A digital timer that I can bury somewhere controlled by a 3 way rocker switch (momentary) that I can mount in the dash that matches the rest of the switches. Push it up and it starts the timer and it runs until it stops. Push it down and it stops no matter where in the cycle it is.

Sounds simple but what the heck to I use for a timer? Other suggestions?

I'm struggling to cut one of these into the dash:

I really want something like this visible instead. I just need to figure out the timer / relay part.

I also really like the idea of being able to turn off the timer if something goes wrong.

Thoughts?
Ideas?
Better ways to do this?

 

[monkeyswrench]

Amazon.com

Maybe something like this? There used to be other ways, but they make a packaged unit now like this. Use a momentary rocker to trigger the relay, and the relay to trigger pump. Depending on the transfer pump, may have to use it to activate a bigger relay for the current draw.

 

[paradise]

You should be able to find a delay off relay with a cancel function. The relay will get the larger gauge wire for current draw with continuous power, and you’ll just run a signal wire to your momentary switch on the dash

 

[coolchange]

Just unwind the timer.

 

[$hot]

How Does The AFC Work?

thefuelbox.com

what about one of these

 

[rivermobster]

A timer is NOT going to keep the secondary tank, from over filling the primary tank.

Does the primary tank even have a level sensor, or gauge?

I ask because mine doesn't.

 

[Waterjunky]

How Does The AFC Work?

thefuelbox.com

what about one of these

This might be a good option. More money than I was thinking but was going to have to deal with a gauge anyway.

Still trying to find the best option......

 

[Waterjunky]

A timer is NOT going to keep the secondary tank, from over filling the primary tank.

Does the primary tank even have a level sensor, or gauge?

I ask because mine doesn't.

Nope, a simple timer would not. However that is why it doesn't get tripped until there is adequate room. This is also exactly why I would want some way to shut it down. If is certain youth's fingers suddenly help out, I can unravel the situation. Because all you with kids know- that never happens......

Yes the primary tank has a gauge. It technically has saddle tanks like a OTR truck but they are the smallest tanks available and are married together. The auxiliary would just feed them. Set the timer to transfer something safe and reasonable like about 30 gallons.

 

[rivermobster]

Nope, a simple timer would not. However that is why it doesn't get tripped until there is adequate room. This is also exactly why I would want some way to shut it down. If is certain youth's fingers suddenly help out, I can unravel the situation. Because all you with kids know- that never happens......

Yes the primary tank has a gauge. It technically has saddle tanks like a OTR truck but they are the smallest tanks available and are married together. The auxiliary would just feed them. Set the timer to transfer something safe and reasonable like about 30 gallons.

If you wanted to get all tricky and shit...

You could probably have someone program a Rasberry Pi for you.

It would have to read the gauge signal wire, and then turn off the pump relay at a specified resistance.

Above my pay grade. But maybe someone on here could do this?

 

[rivermobster]

ChatGPT to the rescue...

ChatGPT - Raspberry Pi Fuel Control

Shared via ChatGPT

chatgpt.com

 

[BamBam]

Use a timed relay. they are available on Amazon. I have used delay timed relays on projects but they make some that run for different lots of time and are adjustable within that range. you would simply flip the switch to on which will close the circuit in the relay and it will run until the timer in the relay opens the circuit at the time you set. If you want it to open before the timer is up you flip the switch off and take away the power.

 

[coolchange]

Put a kill switch on the timer?

 

[JUSTWANNARACE]

Sounds like alot of extra stuff that could go wrong or fail. Why not just run a line from the bottom of one tank to the bottom of the other?

 

[gottaminute?]

Hello all,
I am adding a circuit to my RV and need a little help figuring out the best way to wire it.
I am adding a large secondary fuel tank and the builder sets them up with a small transfer pump to move fuel to the primary tank. As a smart decision, a timer is used so not to over fill the primary. What's used is a Spring wound standard wall timer. Think like a bathroom fan. Cheesy but technically functional.

What I want: A digital timer that I can bury somewhere controlled by a 3 way rocker switch (momentary) that I can mount in the dash that matches the rest of the switches. Push it up and it starts the timer and it runs until it stops. Push it down and it stops no matter where in the cycle it is.

Sounds simple but what the heck to I use for a timer? Other suggestions?

I'm struggling to cut one of these into the dash:
View attachment 1488143


I really want something like this visible instead. I just need to figure out the timer / relay part.

View attachment 1488145

I also really like the idea of being able to turn off the timer if something goes wrong.

Thoughts?
Ideas?
Better ways to do this?

Amazon.com

we used something like this for "underhood" work lights in some equipment so the batteries wouldnt go dead from the last guy who worked on it leaving it on.

ours were built with 30 minutes off delay. if you switch it off, it shuts off right then.

 

[monkeyswrench]

Sounds like alot of extra stuff that could go wrong or fail. Why not just run a line from the bottom of one tank to the bottom of the other?

Worked for semi trucks for over 50 years. A lot of RV's do that with fresh water tanks too.

 

[JUSTWANNARACE]

Worked for semi trucks for over 50 years. A lot of RV's do that with fresh water tanks too.

That's how I used to set up the auxiliary fuel tanks in all the side x side builds I did. Did in my toy hauler, never a problem. No need for an extra fuel neck either easy, simple, no electronics or pumps to fail or forget about!

 

[Waterjunky]

Sounds like alot of extra stuff that could go wrong or fail. Why not just run a line from the bottom of one tank to the bottom of the other?

My issue is the tanks are not level. The new auxiliary tank will be better than a foot higher than the primary. Its also 25 feet away.

 

[$hot]

Beuler BU509TD 12 VDC Automotive 5-Pin SPDT Time Delay Relay with adjustable timing - Delay Off

Standard automotive style relayAdjustable time delay off with 2 seconds to 3 minutes timer with internal potentiometer20 amp / 30 amp rated contactsSPDT - Single pole Dual throwLow 1volt (1k Ohm) trigger voltage

www.qualitymobilevideo.com

this is a delay off relay, pair this with a momentany switch like this. It can be set to run 2seconds - 3 minute Per activation

 

[Radioactive]

Altronix 6062

Altronix Products

6062 - Timer, Multi-Purpose, 12/24VDC 1 Second to 60 Minutes, Board

www.altronix.com

Available on amazon

 

[Waterjunky]

How Does The AFC Work?

thefuelbox.com

what about one of these

I was actually getting fairly excited about this one. It also functions as a gauge for the auxiliary tank, solving additional issues I'm working out. Just got off the phone with them and they used to sell them outright but now only with their tanks and only on Ford, Chevy and Dodge.