Voltage Loss

Submitted: Thursday, Mar 19, 2009 at 18:01
ThreadID: 66984 Views:1721 Replies:6 FollowUps:9
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After following the advice of Jon, {happytravelers} I have performed a current draw test and found the fuse that is protecting the curcuit that is causing the battery to drain. I have a wire from the + terminal of the battery that goes to a relay, which supplies power to the compressor under the bonnet. The fuse is just before the relay. When I remove this fuse my current draw drops from 0.20 amps down to 0.03 amps. Question is how do I fix this problem.
Regards
Krakka
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Reply By: MickeyJ - Thursday, Mar 19, 2009 at 18:10

Thursday, Mar 19, 2009 at 18:10
If you take the relay out, and leave the fuse in does the problem go away? Could be a faulty relay. They are mechanical inside, and damp dust inside could short it out. Is the relay wired correctly? The relay should not be energised unless the switch that activates your compressor is turned on. It could be wired in backwards so it is always energised, and then useing the Normally Closed terminals to turn the compressor off? Check if the relay clicks when you remove the fuse.
Cheers

Mickey
AnswerID: 354958

Follow Up By: Member - Fred B (NT) - Thursday, Mar 19, 2009 at 18:16

Thursday, Mar 19, 2009 at 18:16
Krakka, Mickey J described it better than me. Do it his way. He must have submitted his, while I was writing mine.
Fred
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Follow Up By: Krakka - Thursday, Mar 19, 2009 at 18:25

Thursday, Mar 19, 2009 at 18:25
Relay does click when removing/inserting fuse. Relay and compressor fitted by major 4wd network over six years ago. Compressor working fine.
Krakka
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Follow Up By: Member - Fred B (NT) - Thursday, Mar 19, 2009 at 18:47

Thursday, Mar 19, 2009 at 18:47
It should be wired like this:
Image Could Not Be Found

If it is, then the relay is probably faulty.
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Follow Up By: Member - Fred B (NT) - Thursday, Mar 19, 2009 at 18:48

Thursday, Mar 19, 2009 at 18:48
sorry about the upside down text and poor quality.
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Follow Up By: Bonz (Vic) - Thoughtfully- Friday, Mar 20, 2009 at 21:10

Friday, Mar 20, 2009 at 21:10
Fred B that is one the best techo drawings I have seen, and I aint taking the mickey, good on yer for doing it.
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Reply By: Member - Fred B (NT) - Thursday, Mar 19, 2009 at 18:13

Thursday, Mar 19, 2009 at 18:13
There is a good chance you have a faulty relay. Disconnect the compressor from the relay and try again. If the problem still exists, it's the relay. Hope this helps.
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Follow Up By: MickeyJ - Thursday, Mar 19, 2009 at 20:17

Thursday, Mar 19, 2009 at 20:17
If the relay is clicking when you put the fuse in (If wired as per the diagram by Fred B), then something strange is going on. A relay is just a switch that is triggered by another switch, to allow little switches inside the cabin, and the big switch to be under the bonnet, near the power (Battery) and load (compressor). So if removing the fuse that supplies power for the load makes the relay go off, something is amiss. If it is not the relay, I would be checking carefully for good grounding. THe relay is normally earthed, so when the cabin switch is turned on, it completes the circuit. If this earth was faulty, it may cause strange behaviour. Good luck, let us know what you find.

Cheers

Mickey
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Reply By: GerryP - Thursday, Mar 19, 2009 at 21:47

Thursday, Mar 19, 2009 at 21:47
Hi Krakka,

I would have to agree with MickeyJ. If the relay clicks by simply removing the fuse and with the switch in the OFF position, then it is energised when it shouldn't be.

I suggest Mick is also correct in suggesting the relay is wired incorrectly and de-energising when you switch it off and that they have used the normally closed contacts to start the compressor.

Cheers
Gerry
AnswerID: 355017

Reply By: Member - Phil G (SA) - Thursday, Mar 19, 2009 at 22:03

Thursday, Mar 19, 2009 at 22:03
Throw the relay away and simply put a 30amp switch in line.
AnswerID: 355021

Reply By: Krakka - Thursday, Mar 19, 2009 at 22:54

Thursday, Mar 19, 2009 at 22:54
Thanks for all the ideas and diagram, will give me something to occupy part of the weekend with.
Cheers
Krakka
AnswerID: 355042

Reply By: Member - Paul C (WA) - Friday, Mar 20, 2009 at 03:19

Friday, Mar 20, 2009 at 03:19
Krakka
Your meter is out slightly. With the fuse removed you should be drawing 0.00 A.

If the +ve is going direct from the battery to the relay (via fuse) then you should have a switch on your negative. Look for it.
If this switch doesn't exist, install one.
If this switch does exist, test it.

Not sure what the actual problem is but it sounds like a simple case of the relay being permanently energised.
AnswerID: 355060

Follow Up By: Krakka - Friday, Mar 20, 2009 at 06:05

Friday, Mar 20, 2009 at 06:05
It is a $15 meter Paul, I can't expect too much I guess, But as an indication it gave me an idea of where the problem lies, i hope.
Krakka
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Follow Up By: Gronk - Friday, Mar 20, 2009 at 09:46

Friday, Mar 20, 2009 at 09:46
Krakka, the exact readings with the meter aren't important ( you now know you have leakage....so it needs fixing )

Take out the relay....take it to an auto lec and get another and if not sure how to wire it....ask him to write down the proper numbers to connect it.. almost sounds like the power feed is connected to the coil and the dash switch is switching the load (compressor ?? ) but is very easy to check that sort of thing !!
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Follow Up By: Krakka - Friday, Mar 20, 2009 at 13:08

Friday, Mar 20, 2009 at 13:08
Thanks Gronk, will have a muck around tomorrow.
Krakka
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