New Alternator and Battery - voltage problems

[Jeff K]

I installed a new DMC alternator (it's a Delco 105 amp unit) and Battery.

I charged the battery fully and took it for a drive. The voltage gauge is barely over 13, and with lights and AC on, the battery light comes on and off. I have a Hervey 140amp in my stock car - and it's solid as a rock - never falters. Always about 14.5 or so.

The car with the new alternator has the stock fans and DMC Texas High Intensity headlights (whatever they are). The other car has low amp fans and stock headlights.

Any suggestions?
Jeff

[stevedmc]

I installed a new DMC alternator (it's a Delco 105 amp unit) and Battery.

I charged the battery fully and took it for a drive. The voltage gauge is barely over 13, and with lights and AC on, the battery light comes on and off. I have a Hervey 140amp in my stock car - and it's solid as a rock - never falters. Always about 14.5 or so.

The car with the new alternator has the stock fans and DMC Texas High Intensity headlights (whatever they are). The other car has low amp fans and stock headlights.

Any suggestions?
Jeff

Have you checked your grounds?

[Jeff K]

Have you checked your grounds?

I did , but I will recheck them. 105 amps should be plenty for this car right?

[stevedmc]

I did , but I will recheck them. 105 amps should be plenty for this car right?

105 amps is perfect for these cars. You don't need anything higher than that. Check the ground connection going from your battery to the passenger side trailing arm first. This is your first ground connection. If this connection is poor then everything else will be poor.

A ground bus would be good but is a little work. At a minimum, I recommend running a ground connection directly from the battery to your transmission.

[Jeff K]

105 amps is perfect for these cars. You don't need anything higher than that. Check the ground connection going from your battery to the passenger side trailing arm first. This is your first ground connection. If this connection is poor then everything else will be poor.

A ground bus would be good but is a little work. At a minimum, I recommend running a ground connection directly from the battery to your transmission.

Ok Steve, I'll check that tonight. When you mean from the battery to transmission, would this replace the current negative or add an additional connection? Also, where on the transmission to you recommend connecting it.

Thanks!

[jawn101]

It's an additional connection. Battery to frame, frame to transmission. Just bolt it to one of the bolts holding the case halves together, whichever one is convenient.

I have Hervey's double ground cable and it is of excellent quality. I'm sure one could make a similar one cheaper if you were so inclined, but it's far from expensive. Made a huge difference on my car.

http://specialtauto.com/delorean-parts/images/delorean-battery-ground-wir.jpg

[Chris4099]

A couple of things to add. Verify your volt gauge is accurate with a multimeter on the battery. Those gauges aren't very accurate and shouldn't be used when directly comparing to another D. Next, make sure the positive connections are tight and clean on your alternator as well. If they are dirty and not very good, it can cause your battery light to flash at times (cleaning mine fixed that battery light issue).

+1 for adding another cable from the trailing arm bolt where the battery cable connects to and then to the transmission or engine. I picked up some 4 gauge wire at the auto parts store and ran it from that bolt to the alternator adjustment bracket bolt. It took a lot of the voltage variation out for me. Hervey's kit looks nice too and would have probably been something I would have done if it was available at the time I did the modification.

[jawn101]

make sure the positive connections are tight and clean on your alternator as well. If they are dirty and not very good, it can cause your battery light to flash at times

+1 back atcha on this one. I used a dremel with a light sanding disk to get those connections nice and shiny.

Also make sure your belt isn't slipping on the alternator, that can cause the light to flicker. Be sure it's properly tensioned and check the belt for glazing.

[stevedmc]

It's an additional connection. Battery to frame, frame to transmission. Just bolt it to one of the bolts holding the case halves together, whichever one is convenient.

What he said. I got my wire from Hervey. While you could probably make the wire yourself for a few dollars cheaper, it was super convenience to get the kit from Hervey. I immediately saw my voltage gauge read higher after connecting the ground wire to my transmission.

Eventually though, I plan to install a complete ground wire up and down the car.

[Jeff K]

It's an additional connection. Battery to frame, frame to transmission. Just bolt it to one of the bolts holding the case halves together, whichever one is convenient.

I have Hervey's double ground cable and it is of excellent quality. I'm sure one could make a similar one cheaper if you were so inclined, but it's far from expensive. Made a huge difference on my car.

http://specialtauto.com/delorean-parts/images/delorean-battery-ground-wir.jpg

I just ordered this - can't hurt right!

[jawn101]

I just ordered this - can't hurt right!

Not only will it not hurt, but wait until you see how much faster the starter turns over with it in place. I am not exaggerating in the slightest when I say that my car with already cleaned grounds went from 2 solid seconds of cranking to catching before I even hear the starter running after this cable went in. Hervey promised that in his product description and he absolutely delivered. It starts faster than my 2006 Acura now.

[Jeff K]

Not only will it not hurt, but wait until you see how much faster the starter turns over with it in place. I am not exaggerating in the slightest when I say that my car with already cleaned grounds went from 2 solid seconds of cranking to catching before I even hear the starter running after this cable went in. Hervey promised that in his product description and he absolutely delivered. It starts faster than my 2006 Acura now.

Nice to hear that Jon. Great thing about there forums is real life experiences.

I wire-wheeled my contacts to the alternator too. I'm looking forward to this mod.