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Post by Deleted on Apr 28, 2018 13:07:22 GMT
One for the electronic wizards.
Will a voltage sensing relay work wired reverse polarity?
Standard is:-
Battery 1+ Battery 2+ Sense wire to -
I would like to fit a VSR to the positive earth 105E engined Freeman Obviously the + from both batteries are commoned up then connected to the engine block, the - from each battery goes to a 1, both, 2 off switch, this means for the VSR to combine the batteries it needs wiring reverse polarity.
Rather than wiring up the perfectly good VSR and risk having magic smoke escaping I thought I'd ask if there is any technical reason it shouldn't work reverse polarity:-
Battery 1 - Battery 2 - Sense to +
I am guessing there is no polarity protection and sort of hoping it would not care, I'd rather not fry £40 worth of Durite VSR by going solo without any discussion and guidance on the subject.
Ta!
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Post by peterboat on Apr 28, 2018 13:11:24 GMT
It wont care Gazza its just a switch operated by a current
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Post by Deleted on Apr 28, 2018 13:22:45 GMT
It wont care Gazza its just a switch operated by a current My gut is it won't care, reluctant to find out it does care the hard way. Already dodged one bullet with the archaic wiring system on it, don't need to set myself up for another
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Post by JohnV on Apr 28, 2018 15:16:02 GMT
It wont care Gazza its just a switch operated by a current My gut is it won't care, reluctant to find out it does care the hard way. Already dodged one bullet with the archaic wiring system on it, don't need to set myself up for another Gazza, I note that it has an led indicator light ...... that would indicate to me that at least part of it is polarity conscious ..... why not just phone Durite www.durite.co.uk/default.aspx
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Post by Deleted on Apr 28, 2018 15:33:40 GMT
My gut is it won't care, reluctant to find out it does care the hard way. Already dodged one bullet with the archaic wiring system on it, don't need to set myself up for another Gazza, I note that it has an led indicator light ...... that would indicate to me that at least part of it is polarity conscious ..... why not just phone Durite www.durite.co.uk/default.aspxAh, I hadn't thought of that, the VSR will be out of sight so the led adds no functionality to the user. It may as you say indicate that positive earth is a no go. Frying it is unacceptable as it's not mine! it came off my mates Buckingham 20, his yam 28 no longer has a working charging system, he relies on a 100w panel and dual output controller for his limited charging requirements. I will drop Durite an email, they were quick to supply me a diagram for one of their marine ammeters I fitted to Fairlight. I don't have the time to flash the dynamo and rewire the Lucas reg and other sundry ancillaries to get it negative earth.
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Post by Telemachus on Apr 28, 2018 22:49:05 GMT
I would be surprised if it wasn't polarity sensitive. It depends on the technology but typically VSRs have electronics in them to detect the trigger voltage and operate the relay. I suppose some could simply work on having enough voltage to operate the relay contacts, but I think they would have a lot of hysteresis and thus it would not be a good way to design it. So my best guess is that the magic smoke would escape and/ or it simply wouldn't work.
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Post by Deleted on Apr 29, 2018 8:00:39 GMT
I would be surprised if it wasn't polarity sensitive. It depends on the technology but typically VSRs have electronics in them to detect the trigger voltage and operate the relay. I suppose some could simply work on having enough voltage to operate the relay contacts, but I think they would have a lot of hysteresis and thus it would not be a good way to design it. So my best guess is that the magic smoke would escape and/ or it simply wouldn't work. I'll post what Durite have to say. It's a 0-727-33 it does state there's a delay so that's a LED and a timer that may not like working backwards. From their technical sheet Voltage sensitive relay, 12 volt 140 amp with red LED indicator. Allows split charging of second battery bank without discharging the primary/start battery, relay makes at 13.3 volts and breaks at 12.65 volt. l 68 x w 54 x h 68mm. CE approved. Additional information A 5 second delay operates when the voltage falls below the cut-out voltage to prevent nuisance cut-out due to high intermittent loads on the battery. Supplied with self tapping screws and ring crimp terminal for ground lead. There doesn't appear to be a quick cheap and simple solution for this. The dynamo is 20a max so hardly the world's most powerful system. Both have been given tuition on the correct use of the 1, both, 2, off switch, it's in a rubbish place though - mounted inside a locker that has the helm seat pole placed on it when underway. I can see it being used incorrectly so wanted to add a layer of protection against flat batteries if inadvertently left on both. Hmmmm.
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Post by Gone on Apr 29, 2018 9:30:45 GMT
An idea - The old technology solution was to use split charge diodes, however if the dynamo voltage is a bit low - as I seem to remember they were - then the volt loss in the diodes may mean poor leisure battery charging.
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Post by Deleted on Apr 29, 2018 10:52:46 GMT
An idea - The old technology solution was to use split charge diodes, however if the dynamo voltage is a bit low - as I seem to remember they were - then the volt loss in the diodes may mean poor leisure battery charging. That's the trouble, on the face of it the VSR is ideal, in reality the positive earth set up may put the mockers on it. If it needs flashing to negative earth it will have to wait till the winter, I'm behind the curve with my jobs as it is!
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Post by JohnV on Apr 29, 2018 13:30:57 GMT
An idea - The old technology solution was to use split charge diodes, however if the dynamo voltage is a bit low - as I seem to remember they were - then the volt loss in the diodes may mean poor leisure battery charging. That's the trouble, on the face of it the VSR is ideal, in reality the positive earth set up may put the mockers on it. If it needs flashing to negative earth it will have to wait till the winter, I'm behind the curve with my jobs as it is! Just been thinking about bodges ...... I wonder if you connect the Durite across the engine battery with the polarity correct and use the (positive) output from it to operate a relay doing the connection of the negative of the leisure battery ? I seem to remember that the amperage of a dynamo is fairly low about 10 or 12A so something like a 20 or even a 45A relay (Durite do them at a very reasonable cost) could handle it. Hopefull you will catch what I mean without me having to do a drg.
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Post by Deleted on Apr 29, 2018 13:52:14 GMT
That's the trouble, on the face of it the VSR is ideal, in reality the positive earth set up may put the mockers on it. If it needs flashing to negative earth it will have to wait till the winter, I'm behind the curve with my jobs as it is! Just been thinking about bodges ...... I wonder if you connect the Durite across the engine battery with the polarity correct and use the (positive) output from it to operate a relay doing the connection of the negative of the leisure battery ? I seem to remember that the amperage of a dynamo is fairly low about 10 or 12A so something like a 20 or even a 45A relay (Durite do them at a very reasonable cost) could handle it. Hopefully you will catch what I mean without me h having to do a drg. That's a neat idea, only a couple more connection too. I think I have some 12v 40a relays kicking about at home. It would definitely prevent the magic smoke being released and still uses the VSR as the controller for charge priority
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Post by tonyb on Apr 29, 2018 14:36:59 GMT
If its a dynamo with no other electronics I would have thought it would be better you change the polarity over and then "flash" the dynamo (or close the cutout contacts for a second).
Non-electronic stuff really does not carte about polarity unless you have any permanent magnet motors in say a water pump or bilge pump. If so having swapped the battery leads over just transpose the red & black leads on the motors but in both cases I mention I doubt you would have to. The bilge pump might be a bit less effective running in reverse.
Florescent lamps would need the pos & neg transposing as well.
If its a petrol engine then swap the coil CB & IGN (+ & - on modern coils) over as well.
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Post by Deleted on Apr 29, 2018 15:23:47 GMT
If its a dynamo with no other electronics I would have thought it would be better you change the polarity over and then "flash" the dynamo (or close the cutout contacts for a second). Non-electronic stuff really does not carte about polarity unless you have any permanent magnet motors in say a water pump or bilge pump. If so having swapped the battery leads over just transpose the red & black leads on the motors but in both cases I mention I doubt you would have to. The bilge pump might be a bit less effective running in reverse. Florescent lamps would need the pos & neg transposing a swell. Time is the limiting factor to flashing it. There simply is no time to go through the lot reversing connections at all the relevant parts of the system. Johns idea is sweet and simple, VSR connection:- Battery 1+ Sense to battery 1- Battery 2+ to relay coil 85 NO Single pole Relay connections Relay coil 86 to battery 1- Relay output common 30 to battery 1- Relay output 87 to battery 2- The VSR senses battery 1 as normal, the output that would usually combine the two battery + drives the NO relay coil The contacts that would normally go to the + of whatever is being switched is used to combine the - on the positive earth system giving the desired battery combining with only a couple of extra connections and a cheap relay as the only extra component in circuit. I've a couple of batteries at work so I can demonstrate it works in practice quite easily. Poxy river is back on Strong Streams so the windows of opportunity are getting fewer and fewer too
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Post by Deleted on May 2, 2018 6:53:22 GMT
Thanks JohnV Frankenstein's Lair VSR energised LED indicator to go in the dash to show VSR is energised -it goes across the coil of the 40A relay that links the negatives. Batteries linked and taking a charge from a 12A battery charger, Using the battery tester voltage display the VSR cuts in at 13.35v and cuts out when the voltage drops below 12.58v I used the work lamp to put a load on the sensed battery. I will fit it tonight using 6mm cable I have on Fairlight Only extra cost was a slightly expensive £5.69 40a relay from Halfords, it was the quickest option for getting one in my sweaty mitts.
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Post by mouse on May 2, 2018 12:16:13 GMT
Mouse thinks he recognises those batteries!! At least they are not going to waste!
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