Water pump running light

[Tony Cross]

I want to connect an LED to my fresh water pump so I have a visual indication at the chart table when the pump is running. When one of our tanks runs dry and it's time to switch tanks the pump runs dry, when it does that it's almost impossible to hear (it's really quiet running dry). Although the manual says it can run dry safely I'd like to know when it's doing that.

Can I just connect a suitable 12v LED (one that can take up to 14.4v of course) to the pump side of the pressure switch so that it lights when the pump is running? Or will I need something more complex?

Thank you!

 

[VicS]

I want to connect an LED to my fresh water pump so I have a visual indication at the chart table when the pump is running. When one of our tanks runs dry and it's time to switch tanks the pump runs dry, when it does that it's almost impossible to hear (it's really quiet running dry). Although the manual says it can run dry safely I'd like to know when it's doing that.

Can I just connect a suitable 12v LED (one that can take up to 14.4v of course) to the pump side of the pressure switch so that it lights when the pump is running? Or will I need something more complex?

Thank you!

No reason why you should not do that if the relevant connections on the pump are accessible. I guess you will run lighter wires to the LED than the pump power supply wires so fit a small fuse as close as possble to the connection to positive at the pump to protect the lighter wiring

 

[VicS]

Voltage surge when the pump cuts out might be a problem for an LED.

 

[jfm]

Yup, that seems perfectly sensible. I have exactly that installed during the build of my boat. I've had no problem with the LED and any voltage surge

If you want to go wild, you can buy a timer circuit off eBay for about £5 that will switch on a buzzer/bleeper if the LED/pump circuit has been energised more than a (user selectable) preset time, say 1 minute. These are very good for bilge pumps too. They don't affect the integrity of the power circuit to the pump because obviously they are parallel wired

For example http://www.ebay.co.uk/itm/Multifunc...d=100005&prg=1048&rk=2&rkt=4&sd=301011911953&

 

[William_H]

Yes an LED across the pump should be fine. LEDs can take a lot more power for short periods than their continuous rating so i don't think surge voltage will be a problem.
What might be a different option is to fit a magnetic reed switch to the wiring ot the pump. ie the reed switch sensor can be in the fuse box. The reed switch looks like a little glass fuse witha wire out each end. You wrap about 10 turns (or as many as you can) of the feed wire around the outside of the reed switch. The tiny magnetic field generated by the coils of wire carrying the 10 amps or so of pump current cuase the 2 reeds to contact one another. These contacts (the 2 wires coming out of the glass) can be used as a switch toa lamp buzzer or reven a timer and buzzer. Put a mmultimeter on ohms across the reed switch. Wrap some wire of the feed line around the switch. Experiment to see how many turns are needed to operate the switch. For really low current devices like LED lights you will need maybe 50 turns so use light wire and splice it into the circuit being sensed. Likewise if for the pump you can't get enough slack wire or enough turns use a lighter wire spliced in. If you use light wire it may be less than fuse rating so mount it where it can get hot in the case of a short in the pump without starting any fires. good luck olewill

 

[Tony Cross]

Thanks for the help!

I'll try a simple LED first and then experiment with the reed switch if that doesn't work that well, with the timer circuit thingy as a last resort...