low voltage on startup, then fine after 20-30 seconds

[marwood82]

odd, issue i noticed the other week.

got in to drive home, fired the car up ok and then pulling out of the car park i notice the battery warning light was on. (car seemed to be running ok, headlights were on). on closer inspection i saw the battery voltage was reading 8v.
carried on driving then when i stopped at the lights about 20 seconds later, the light went out and the voltage gauge suddenly went up to 13v.

then yesterday, having not driven it since, i started it up, again battery warning light, voltage reading about 6v, this time, i noticed it start to fall, the lights on the stereo flickered and went out, the engine sounded like it was starting to struggle and then suddenly, the voltage went back up to 13 and everything came back.

is this likely just to be new battery time or could it be alternator related?

thanks

Simon.

[Rich Hanlon]

Hmm, it sounds to me like the alternator isn'tcharging for the first few seconds.

Or then again the act of starting could be pulling the guts out of a failing battery and it takesa few seconds to recover.
The fact that the issue may be progressively worsening seems to add to this theory.

So having argued it both ways...

Maybe start up 'sans' lights and rev a little before you go anywhere, see if the volts pop back up.

[TheOriginalMrP]

Sometimes my battery light fails to illuminate when the ignition is turned on from cold.

And sometimes after starting the voltage doesn't go up past 13 until about 10 seconds after startup hovering around 8 volts until it decides it's running.

The accuracy of the volt meter is pants anyway as mine usually reads 10 volts before startup with a fully charged battery.

You need the battery light to work to make the charging circuit work and a dodgy connection on the binnacle can cause issues but first things first, check your belt tension, earth points, block connections on the alternator, and voltage of your battery with both engine off and then running.

Voltages should be 12.0 - 12.9 when off
And about 13.6 - 14-5 running with no accessories running such as headlights or heater fan/Cooling fans

Hope you get it sorted!

Ben

[bjbrownie]

Mine has that problem occasionally, voltmeter says 10 volts with engine running and a blip on the throttle sends it back up to 13.5-this was a recon alternator from a good supplier which I bought 10 years ago, I did find the fan belt was a little slack and was fine after tightening.
This only seems to happen every couple of months though. 8)

[Rich H]

Check for loose alternator belt primarily, then a bad ground connection between the battery negative and chassis...

[Chris Williams]

Quote:Check for loose alternator belt primarily, then a bad ground connection between the battery negative and chassis...

One of the best upgrades I have seen and used is this: http://www.specialtauto.com/delorean-pa ... rical.html new earth cables, made such a difference to my new car. Starts easier Etc Etc

Chris

[marwood82]

cheers for the suggestions, im going to try and have a good look at it over the weekend

im thinking at the moment, its either just a drained battery or its a electrical connection issue. As if you leave it running for a few minutes, then stop it. wait about a minute then re start it, it starts fine and goes straight to 13v.

which has me thinking, the only real differences after a few minutes are going to be that some battery charging has happened and the engine has warmed up a bit (and so loose connections may have expanded enough to start working)

[lukebrynycz]

I had the same on my last startup actually. A little blip of the throttle and it went back to its usual 13v position. I'll get the earth cables checked on it's next service, cheers for the heads up guys!

[marwood82]

it seemed to have settled down, but i did notice yesterday, that with the engine idling, the voltage gauge on the dashboard never goes above 13, and seems to drop below 10 if i turn on the main beam headlights.

however getting out the multimeter and checking the battery with the engine off showed 12.5v and when i connected the multimeter to the terminal in the engine bay it was around 14.5 idling, dropping to about 13.5 with the main beam on.

is it just a dodgy gauge?

[lukebrynycz]

marwood82 Wrote:it seemed to have settled down, but i did notice yesterday, that with the engine idling, the voltage gauge on the dashboard never goes above 13, and seems to drop below 10 if i turn on the main beam headlights.

however getting out the multimeter and checking the battery with the engine off showed 12.5v and when i connected the multimeter to the terminal in the engine bay it was around 14.5 idling, dropping to about 13.5 with the main beam on.

is it just a dodgy gauge?

You've done all the right checks buddy, I would say a faulty gauge for sure. Mine occasionally has a moment to, I think that's just part of owning a Delorean. The oil pressure gauges are terrible also. :wink:

[MikeWard]

Try cleaning up the ground cable and ground strap and see if that makes an improvement.

[bjbrownie]

Don't trust the voltmeter on the dash for accuracy neither- mines under reads by almost 1v, make sure you try the reading with a good accurate electric tester, I use a good Gunson one. 8)