Voltage problems...

My XJ as of late is having some voltage problems. At idle it dips down to about twelve and a half.. but when I go it will go up to about thirteen and a half... new yellowtop battery and a new alternator... maybe I should start with the grounds.. can somebody tell me where to find em? And a proper procedure for cleaning them? Thanks guys. Info in sig. Yr/engine/ ect

Curious if it could be the battery temperature sensor out of specs.

Do this: engine off, measure voltage between the battery terminals, should be 12.5 volts. Start engine and recheck voltage, looking for 13.0 to 15.3, the range depends on ambient temperatures. Post up what you find.

As for grounds, the main ground cable should be to the engine block. On the later XJs like your there is a negative terminal to passenger fenderwell ground. And I'm not sure if yours still has the braided strap from the driver's side rear of the head to the firewall, if you have that I recommend replacing the strap with a 4 or 2 gauge cable.

Ground cleaning: strip down to bare metal. Treat surfaces with anti-corrosion agent (any hardware/paint store). Make the connections TIGHT.

Ok sounds like a plan. I will do this here later and post up what I find.. and ya I do have the braided strap. Its newer but not very good. Can I get this cable at wally world?

You should be able to find what you need (short battery cable) to replace the ground strap at the local NAPA, Schucks, O'Reillys (in that order).
When I upgraded all my power leads; I purchased 10' of red / black 2 gauge and 6' of red / black 4 gauge from a local Industrial Liquidator and built 2 sets. One for present and one for the future.

Got 12.5 with engine off and 13.5 with on. Ambient temp somewhere around low seventies. Got some guage 2 cable for the strap replacement. Gonna check block grounds right now. They don't appear coroded but we'll see

I hate to say anything, but those numbers are fine. The alternator doesn't do much charging until you get off of idle. What were you expecting?

I always thought it was supposed to stay at 14. At least it always did. Must be age I guess. It is 11 years old....

old_man said:

I hate to say anything, but those numbers are fine. The alternator doesn't do much charging until you get off of idle. What were you expecting?

Click to expand...

Agree, your charging Ok.