disco_al Posted December 23, 2012 Share Posted December 23, 2012 um http://www.ebay.co.uk/itm/Low-Coolant-Level-Alarm-12V-/170927068334?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item27cc0c14ae plus one of simon's float switches from earlier Quote Link to comment Share on other sites More sharing options...
elbekko Posted December 23, 2012 Share Posted December 23, 2012 Which relay did you use Elbekko? Was it a low draw one? Err, the one that we had on the shelf The best solution is to connect it to a switched live though, I've noticed the battery is drained after about two weeks of standing still, but I can't really say if that's due to the relay. Quote Link to comment Share on other sites More sharing options...
dailysleaze Posted December 23, 2012 Author Share Posted December 23, 2012 It's working well. I had to brake hard yesterday on the motorway and the light came on, so it's reassuring Fortunately it's not had to come on in anger. Quote Link to comment Share on other sites More sharing options...
jbs Posted May 2, 2013 Share Posted May 2, 2013 Thread revival!! um http://www.ebay.co.uk/itm/Low-Coolant-Level-Alarm-12V-/170927068334?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item27cc0c14ae plus one of simon's float switches from earlier I've used this one and the original RR float switch which I got off of e-blag It's a plug and play thing so even me with limited electrickery experience can fit it and make it work-which it does and very well too John Quote Link to comment Share on other sites More sharing options...
Peaklander Posted May 12, 2019 Share Posted May 12, 2019 On 7/21/2012 at 12:21 PM, dailysleaze said: Hello. With due respect to @dailysleaze, this is the circuit that I have used for my own level alarm. I'm also using the RR cap which is presenting 683 Ohms when the level is OK. However in my case the transistor will not switch off and this is because when the cap is "open circuit" there's still around 6v across the relay coil. The reason for this seems to be that the cap isn't an open circuit but in fact is something like 50K Ohms. This doesn't seem right but is what appears to be happening - its effectively a pull-up resistor. This is what is the cap circuit is presenting to me when I stick the Fluke across. State A is level ok and state B is when it should be open circuit. Does anyone have any ideas as to what I can do?? TIA EDIT: just to add that I'm wondering whether the transistor is needed at all. The tiny relay only pulls 12mA and that might be OK for the reed switch. It would probably fix the leakage current problem too?? Quote Link to comment Share on other sites More sharing options...
steve b Posted May 12, 2019 Share Posted May 12, 2019 I have just fitted this to a 300 Tdi Land Rover with a low level buzzer , all I did was to use a standard 5 pin 2 way load switch relay to energise when ok and when it drops too low the relay drops out to make the "idle" contact and sets the buzzer off. cheers Steve b Quote Link to comment Share on other sites More sharing options...
Peaklander Posted May 12, 2019 Share Posted May 12, 2019 Hi Steve - yes I think it's just about whether the reed switch in the float sensor can manage to supply enough current and not eventually weld itself. I think that the little Omron used here would be OK as a load and it should work long term. Glad to hear yours is too. Quote Link to comment Share on other sites More sharing options...
steve b Posted May 12, 2019 Share Posted May 12, 2019 I'm pretty sure the relay I've used is low amp to energise - of course should it fail it will set the buzzer off and highlight a fault anyway . This all started with a split bottom hose on the road so by the time any symptoms appeared it was too late , head bent but machine-able and not cracked , new rad also as pressure split the rad cores - old and ripe for it ... cheers Steve b 1 Quote Link to comment Share on other sites More sharing options...
steve b Posted May 14, 2019 Share Posted May 14, 2019 I need to re-visit this and do similar to suggested above , the set up bench tested fine several times ( 20+) and was ok for about 2 days , now it's random . Any idea why this is configured like this when a very simple float switch would have been plenty , just a simple on/off .... cheers Steve b Quote Link to comment Share on other sites More sharing options...
Peaklander Posted May 14, 2019 Share Posted May 14, 2019 Oh dear. I presume that the problem with a float switch is that it would be very susceptible to the coolant sloshing around. So physically it might be stressed by that although electrically it could always be "slugged" with a timer to prevent spurious readings. What is the state of your reed switch? Is it still showing a clear change of state when liquid / no liquid when measuring continuity? As I said I think they fail through bad things happening to the contacts when asked to switch too much current. I haven't checked mine since a few days ago but the vehicle is still off the road. I'm fitting an air heater at the moment and then I will be back on the road at last and will see then if my coolant alarm is OK. Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted May 17, 2019 Share Posted May 17, 2019 I got fed up with messing about with the PRC7925 cap and instead I drilled a hole in the expansion tank and fitted a float switch I bought from RS. It took me a couple of goes to get the hole in the right place - in the first location the moving part of the switch fouled one of the internal ribs in the tank, the second hole made the outside end of the float switch foul on the back of the brake master cylinder. The float switch is just a normal open/close switch contact so it doesn't need any electronics or relays to operate a light on the dash panel. If someone can answer my question about creating new gallery albums I will post some pics. Quote Link to comment Share on other sites More sharing options...
Peaklander Posted May 18, 2019 Share Posted May 18, 2019 (edited) Time will tell I think with mine. I have added the connection to the unused transmission oil temp warning lamp and finally closed up the dash after nearly five months. I hope it works as it is. @nickwilliams, can you not just post pics direct into the thread without using gallery albums? Edited May 18, 2019 by Peaklander Quote Link to comment Share on other sites More sharing options...
nickwilliams Posted May 18, 2019 Share Posted May 18, 2019 7 hours ago, Peaklander said: @nickwilliams, can you not just post pics direct into the thread without using gallery albums? Yes, it would appear I can: That wasn't possible last time I posted pictures here! Quote Link to comment Share on other sites More sharing options...
MR-HIPPO Posted May 19, 2019 Share Posted May 19, 2019 (edited) @nickwilliams Nice. That looks like a simple low tech solution. Edited May 19, 2019 by MR-HIPPO Quote Link to comment Share on other sites More sharing options...
steve b Posted June 15, 2019 Share Posted June 15, 2019 I was about to go down the route Nick took and was chatting to a fellow local LR Independent about it , he turned round and pulled one of the circuit board jobbies out of his tool box and slapped it in my hand . It does indeed work fine so all done , any further vehicles in need of it will have the float switch in Nicks link - nice and simple . cheers Steve b Quote Link to comment Share on other sites More sharing options...
trickydicky Posted June 15, 2019 Share Posted June 15, 2019 I was thinking of using a five pin relay in the same way and connecting it to an ignition switched live so when the keys off so is the power to the relay.what do you guys think? Quote Link to comment Share on other sites More sharing options...
Roverdrive Posted June 15, 2019 Share Posted June 15, 2019 That’s what I have used and it works fine. note that not all the Range Rover style floats are the same. Some have a resistance even when “closed” others don’t. Mine is one of the latter. Quote Link to comment Share on other sites More sharing options...
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