Battery Flat battery AC Relay? - Civinfo
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post #1 of 24 (permalink) Old 20th March 2015, 19:16 Thread Starter
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Flat battery AC Relay?

Hi all,

OK woke up to a flat battery this morning. Car not used for only 8 days but very flat this morning. I have an hr commute to work so it's not down to short trips, etc and the battery doesn’t look that old.

Just checked that AC Relay and it's rattling so do you guys think this might be the cause and the start of bigger issues? Air con working fine so not sure myself.

I'm going to change the relay regardless as it shouldn't rattle for peace of mind. After jumping the car and driving to work and back battery is sat at 12.85volts and goes up to 14v under load so all seems ok now.

Is the car OK to drive without said relay until I can source a new one? Just a loss of air con or could I do further damage?

Any guidance from those in the know greatly appreciated.

Cheers
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post #2 of 24 (permalink) Old 21st March 2015, 10:30
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relays rattle.

Do you have hands free telephone installed?
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post #3 of 24 (permalink) Old 21st March 2015, 11:21 Thread Starter
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No factory fit hands free as I have this via my pioneer head unit.
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post #4 of 24 (permalink) Old 21st March 2015, 12:15
 
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Do a parasitic draw check with the relay installed, and one without


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post #5 of 24 (permalink) Old 22nd March 2015, 01:25
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Quote:
Originally Posted by sjgillett View Post
No factory fit hands free as I have this via my pioneer head unit.
So it might be the amp.
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post #6 of 24 (permalink) Old 22nd March 2015, 07:24 Thread Starter
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So it might be the amp.
Thanks for the reply. What do you mean by the amp?
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post #7 of 24 (permalink) Old 22nd March 2015, 12:08
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you have a non standard radio, do you have an amp hooked up to it?

Also have you cleaned your battery lately?
You can have a voltage leak just due to the dirt on the battery(no joke)
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post #8 of 24 (permalink) Old 22nd March 2015, 13:13 Thread Starter
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Hi no amp just a replacement head unit and no i haven't cleaned the battery. By this I assume you mean the terminals lol.
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post #9 of 24 (permalink) Old 22nd March 2015, 13:58
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Quote:
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you have a non standard radio, do you have an amp hooked up to it?

Also have you cleaned your battery lately?
You can have a voltage leak just due to the dirt on the battery(no joke)
I'm really interested in your explanation for this!
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post #10 of 24 (permalink) Old 22nd March 2015, 14:21
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I'm really interested in your explanation for this!
Demonstrated in the following video.

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post #11 of 24 (permalink) Old 22nd March 2015, 19:06 Thread Starter
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Originally Posted by x5252x View Post
Demonstrated in the following video.

Thanks for this. Battery looks fairly new as previously stated, tried the test and it's drawing no volts as a result of being dirty. I've given it a clean anyway prevention better than cure and all that,.

Picking new AC relay up from Honda MK tomorrow, they hold them in stock so that tells you something
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post #12 of 24 (permalink) Old 22nd March 2015, 19:30
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In practical terms, that YT clip is an exaggeration. What's being seen there (using a very sensitive meter) is a fantastically small leakage current (battery drain/leakage being measured in amps and NOT volts as he suggests) which is insignificant compared to the normal 'parasitic' drain caused by various vehicle circuits (plus reverse leakage back into the alternator).

And the first test he performed early on (checking the volt-drop between each post and its connection, to show up any resistance) should be performed under relatively high load conditions (e.g. with headlights on) to highlight any resistance present.

I think the OP needs to undertake a proper parasitic drain test by pulling fuses one at a time and then measuring the leakage current using an ammeter/multimeter across the empty fuse receptacle to find out which circuit has developed the excessive drain.

If the car has a HFT, then my money's on that!

EDIT - just seen you've decided it's the relay. This would have been easy to prove by simply removing the relay and seeing if the problem then went away...

Last edited by Jon_G; 22nd March 2015 at 19:33.
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post #13 of 24 (permalink) Old 22nd March 2015, 20:10 Thread Starter
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Haven't decided it's the relay I'm changing it regardless as this failed on my friends wife civic resulting in hundreds of pounds of damage as the ac compressor failed, new battery, etc and the initial symptoms were an unexplained flat battery. So once the relay has been changed if the problem persists I'll do the necessary parasitic draw tests etc.

I was always going to change this relay based on my friends experience and the many similar stories online. Also the fact my local dealer holds them in stock suggests they are a common failure. Also the upgraded part suggests the same.
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post #14 of 24 (permalink) Old 23rd March 2015, 20:15 Thread Starter
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New relay collected today and fitted. Dealer confirmed the relay should NOT rattle. There is definitely something loose in there and needed to be replaced. Whether it's the cause of the battery drain time will tell.
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post #15 of 24 (permalink) Old 23rd March 2015, 20:48
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It will be the resistor that's loose causing the rattle.
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post #16 of 24 (permalink) Old 23rd March 2015, 21:06 Thread Starter
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It sounds as if there is something which has come adrift in there. I might open it up and see.
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post #17 of 24 (permalink) Old 19th April 2015, 09:44 Thread Starter
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Just to update the thread I've had no more flat battery issues since swapping out the relay so fingers crossed it was the cause of the initial drain.
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post #18 of 24 (permalink) Old 19th April 2015, 15:46
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Good to hear you got it sorted, what is the part number needed to replace the relay? I'm having flat battery issues as well and I'm trying to narrow it down. Already disconnected the HFT and although the car hasn't gone flat since, I still don't trust it.

I've just pulled the relay (it's an OMRON one) and it rattles inside. Cheers
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post #19 of 24 (permalink) Old 19th April 2015, 15:53 Thread Starter
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Hi the part number on my invoice is H39794SDAA05 and was £23.57 Inc VAT. If your old OMRON one is rattling it probably should be changed. Fingers crossed it fixes your issue.
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post #20 of 24 (permalink) Old 19th April 2015, 21:39
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Cheers going to phone my local Honda tomorrow and get one ordered
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