Americanricer87

I am toying with my 95 XJ and I am not getting the best of the alt charge to the battery, power at the alt it 14.3 volts and only 13.5 at the battery and drops significantly when loads are added. now if i were to remove the sensing wire from the alt and attach it to the fuse panel in the engine bay and run a new wire from the alt to the battery, that should show the ecm the lowest voltage and supply the battery with the most. anyone tried this?

Radi

If you have 14.3 at the alternator output and 13.5 at the battery, you have a wiring or connector (or both) issue. Check the cabling between the alternator and PDC and the PDC to battery. I'd fix that instead of jacking up the regulator.

cruiser54

I agree with Radi. Hee's something very worthwhile to look into:

www.kelleyswip.com

Americanricer87

Finally got some time to work on my charging issue. Replaced the factory body ground with a real 4gauge wire and soldered on new eyelet batery connectors and used a bolt to ground it to the chassis as well instead of the stock self tapper, I know have alt voltage at the battery. It's no wonder the truck even half way charged due to such poor wire used for a ground from the factory.. thanks for the help!

cruiser54

Added grounds will help. Did you ever look at www.kelleyswip.com? Nice upgrades for your charging/electrical system.

5-90

You don't have a regulator problem - the alternator's output is correct (and yes, voltage will drop as current draw is added. cf: Ohm's Law, Watt's Law.)

What you have is a connection problem. Make sure all connections are clean and tight. It may be worthwhile to disconnect the alternator lead at one end or the other (it's an M6-1.0 flanged nut on back of the alternator - takes a 10m/m socket. It runs up into the bottom of the PDC to a funky quick-connect fitting, which is probably easier to reach and disconnect, as it should not require tools) and check the internal resistance of that lead with an ohmmeter - it may be contaminated or corroded, and either will have a negative effect on the wire's conductivity. You should get <1 ohm end-to-end (and taking the QD apart under the PDC will allow you to see if that is also clean.)

Check the two fuses labelled "Generator" in the PDC, and actually pull them out so you can check the contacts - both on the fuse and that the fuse slides into.

Losing 0.8VDC over a conductor that is less than three feet long points to either"

- a faulty or contaminated lead from point-to-point, faulty connections, dirty connections, loose connections, et al;

or

- increased conductor loss due to an insufficient wire gage used.

You don't say you've changed the alternator, so I'm assuming that it and the lead are OEM. The OEM lead is 6AWG, which should be plenty for the 70A or 90A alternator you should have (I don't fee like getting my book out at the moment, I'm enjoying the dark. My alternator reference isn't printed in Braille...)

(Meh - okeh, you've fixed it. But, this is still here for the next guy, if he needs it!)

Americanricer87

I plan on adding a few more grounds to the engine bay as I get time, the dash gauge is reading different than whats at the alt and the battery. not to concerned as its just a stock gauge. Im hoping that as I add trail lights to the under side of the body that I wont have too much load for the stock 90 amp alt.

5-90

You probably don't need to add grounds, just improve the ones you have. Start by locating the various grounds in the engine bay, the go through one at a time:
- Remove the ground lugs.
- Clean the ground lugs (fine sandpaper or a wire wheel in a drill motor. Replace if necessary.)
- Clean or replace the screw (should be either a #10 sheetmetal screw or an M8-1.25x20m/m for main grounds.)
- Strip the contact patch on the chassis down to BARE METAL (a postage stamp is plenty.)
- Coat the ground lugs and BARE METAL patch with corrosion inhibitor (do not use "dielectric grease" or WD-40 - both are non-conductive and will interfere with your grounds!)
- Reassemble. Putting a flat washer under the screw head won't go amiss, either.

Amazingly, most of the automotive electrical issues I've tracked down in the last 30 years or so have come back to shonky grounds - probably 85-90% of them! Improving your grounds can go a long way to cleaning up your electrics - the factory is silly, grounding through paint doesn't work so well...

rzldzl

+1

i have his full 1AWG kit installed with my 220A alternator.

cruiser54

The upgraded cables are the way to go.

OP, this may help with your gauge.
Improving the Instrument Panel Ground
The ground point for the complete instrument cluster on your XJ or MJ is located up under the driver’s side dash. If you lay on your back and look up under there with a flashlight, without wearing a hat, you will see a black wire attached to a shiny piece of metal almost directly above the hood release ****. The screw will have either a ¼" or 5/16" head on it.
This ground point is responsible for handling the ground circuit for the following items: Dome lamps, Seatbelt and key warning, trans comfort switch, wiper switch, headlamp switch and delay module, fog lamp switch, cargo lamp switch, all instrument panel grounds and illumination, power windows and door locks, cruise control dump valve, and a few more things.
The problem is that where the ground point is located does not have a good contact with the chassis where the ground should be. The solution is simple.
Make up a jumper wire with #10 gauge wire about 10" long. On one end, crimp on a ¼" round wire terminal. On the other end, crimp on a 3/8" round wire terminal.
Remove the screw from the existing ground wire and attach the small terminal of your jumper so that the original wire and your new jumper share the same attaching point, one over the other.
Look above the driver’s side plastic kick panel just forward of the top of the hood release ****. You will see an 8mm stud there. Attach the large terminal end there with a washer and nut over it tightened securely.
**Special note for Comanche owners: Make your jumper wire 12" long and attach it on the driver’s side kick panel close to the fusebox on the 8mm stud.**
　
Revised 11-29-2011

Americanricer87

Thanks for the info i will replace that ground.