Not getting the full 12 volts

Submitted: Wednesday, Apr 16, 2014 at 18:09
ThreadID: 107315 Views:1385 Replies:4 FollowUps:4
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Hey guy's. I was wiring up a reverse camera into the reverse lights a few weeks ago and decided to test it with a multimeter. It was only getting 10 volts. The camera runs off it fine but the problem is that my wipers are really slow as are the power windows. I wonder if they are having the same issue?

Its a new battery so Its got me wondering why this could be happening?

Josh
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Reply By: cookie1 - Wednesday, Apr 16, 2014 at 18:14

Wednesday, Apr 16, 2014 at 18:14
You may have a dodgy cell - if it's new take it back and they should test it for you

cheers
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Follow Up By: Member - ironJosh - Wednesday, Apr 16, 2014 at 18:43

Wednesday, Apr 16, 2014 at 18:43
The battery is running 12v. Thanks though.
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Follow Up By: Honky - Wednesday, Apr 16, 2014 at 22:16

Wednesday, Apr 16, 2014 at 22:16
What is the rest volts as 12 volt is flat? it should be 12.8 Volts and even higher if motor running.

Honky
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Reply By: Sand Man (SA) - Wednesday, Apr 16, 2014 at 18:43

Wednesday, Apr 16, 2014 at 18:43
Josh,

You haven't mentioned how you have wired the camera and monitor up but the only wire that should be connected to the reversing lights is the trigger wire that turns the camera on when reverse is selected.
The wiring in modern vehicles are quite small diameter and not rated to take a heavier current draw.

The power for the monitor should be connected to an accessory circuit rated at 10 amps or so and be preferably connected at the fuse terminal strip. Piggy back fuse holders enable you to "add a circuit" to an existing one with its own fuse. This is much better than using displacement style connectors (eg. Scotch lock) to join into the normal vehicle wiring.

In most cases a scotch lock is probably required to connect into the reversing light cable but they are notorious for poor connections.

Bill


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AnswerID: 530701

Follow Up By: Member - ironJosh - Wednesday, Apr 16, 2014 at 18:45

Wednesday, Apr 16, 2014 at 18:45
Hi Sandman, thanks mate. I tested it at 10 volts before I connected the camera and the wipers & window winder motors have been slow since I got it.

Cheers
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Follow Up By: Sand Man (SA) - Wednesday, Apr 16, 2014 at 18:56

Wednesday, Apr 16, 2014 at 18:56
Ah,

A simple process then is to check the battery terminal connections to ensure you have a sound contact.

Failing this you may need a Dealer or Auto Electrician to check the problem out.
As has already been mentioned, a battery reseller can load test the battery to confirm it is not the cause, but my guess is something is not right somewhere else if both the wipers and power windows are not working properly, especially if they are on different circuits.

Bill


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Reply By: olcoolone - Wednesday, Apr 16, 2014 at 19:13

Wednesday, Apr 16, 2014 at 19:13
I would suggest taking it to an auto elec as the problem could be out of your depth and you have problems with 3 separate circuits.
AnswerID: 530703

Reply By: Echucan Bob - Thursday, Apr 17, 2014 at 08:58

Thursday, Apr 17, 2014 at 08:58
Josh

If there is a difference between the voltage at the battery terminal and the voltage down the back, even when there is no load applied, suggests that there is a connection that has started to act like a resistor, or the main 12V wire has become resistive due to corrosion etc

Your truck is 20 yrs old (and it has been driven in the ocean, judging by your pic) so that is hardly surprising.

Using your multimeter, start measuring voltages along the wire until you isolate the problem.

Bob
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