I believe low charge is a pretty common thing on XJ's in conditions such as long periods of idling in heavy traffic, especially when several ancillaries are all pulling power. Mine also has electric fans, then add AC and lights and the alternator really struggles to keep above 10 on the gauge.

Other than trickle charging the battery when not in use, has anyone successfully upgraded their alternator, and if so, to what type of unit?


Cheers,

 

Tony,
Thread below has what I used as a replacement,as well as what my gauge reads compared to running a meter. Just above 10 may really be 12 or 13 V.

New one works great with Air and lights in heavy traffic.

https://www.jaguarforums.com/forum/x...ctures-143721/

 

Yeah, the "guage" on the fascia is a mere indicator and a bit slow in doing that.


I made a patch cord for my VOM. Plug into the cigar lighter and get real volts in real time under various load and rpm's.


If in doubt, merely replace the big brown wire from the alternator to the post ojn the fire wall with a bigger one.


My electric creds are limited. But, adding a separate ground for the alternator is redundant. If it improves the operation, it means the engine to chassis ground is inadequate. That is the strap from the transmission to the chassis. Down in the goop from the road!!!


Carl

 

Thanks guys. I had wondered if the gauge itself might be misleading me a bit, so will try and establish that before changing the alternator (which BTW was installed new only 12 mths ago according to PO, but I guess that guarantees nothing!).

Great thread Clarke, sorry I missed it in the first place. Will be handy if I end up looking for a replacement!

Carl, 'cos I never profess to be anything more than the lower end of average with electrics...can you tell me how you set up the plug-in patch lead please? is it just a cig. socket at one end connected to a remote VOM?

Cheers,

 

Well I went out and invested in a new digital multi meter for the princely sum of $16, the one I had was an ancient needle type, always hated the thing.

Ran the car for about 20km and got up to temp, then left it idling with electric fans, radio and headlights all in full flight and the MM showed a steady 12.8 (I believe 12.7-13.0 is the ok range for a healthy alternator). Meanwhile the volt gauge sat just inside the red zone, nowhere near 13.0, so it appears to confirm that the gauge is understating. Static with engine off, the battery is at 12.6 according to the MM and when placed under load it comes up to about 14.5, once again dropping to 12.8 at idle.

I've pretty much decided that while the alternator is a probably lightweight, it doesn't warrant replacement at this stage. I am interested in hooking up an auxiliary gauge though, maybe to the cig. lighter as Carl suggested, to keep an eye on things when driving. I will also need to spend some time looking at grounds affecting the gauges - fuel gauge also reads lower than actual.

 

Hi Tony

Keep in mind also that 12.6 with engine off , is actually a bit better than it looks. There is always a bit of load from somewhere (clock, radio perm 12v) and you are losing some voltage due to internal resistance in the battery. So its all really sounding fairly healthy.

Dont think it would be appropriate in a swish S3 like yours, but I put a cigarette lighter USB adapter in my truck the other day. The good bit is that it has a LED display that tells me volts, USB current load and even cabin temp :-)

The low reading fuel gauge seems to be an XJ thing, mine read about 3/4 when full. Elinor suggested trickling fuel in , which does work up to a point. I get about 7/8 ths when full, but cant really be bothered. I think the real answer is new level senders, but once again I cant be bothered unless I have other reasons to go in there, like sludgy tanks.

 

Tony:


Steve's after market guage is more sophisticated than my home made job. I might look one up!!


I had a plug left from some electronic toy that fed from the cigar lighter. I identified the center as + and soldered on a red wire. I identified the side as - and soldered on a black wire. My collection of odd cords had prods that fit my VOM. I soldered on
a red to red and black to black. If need be, mark one as black with a bit of black shrink tubing.


I have both analog and digital VOM's. Each has benefits. I alsao have on that reads by inductance. Slick.


But, I grew up with "touch to ground, if it sparks, it's hot". OK on very simple electrics. Don't even think of it now. Then to test lamps. I made up a couple of them from odds and ends. I still find places where a test lamp is better than a VOM!!


An electrical genius on another forum co9ned the term "electrickery". I liked it. I've popularized it.


Carl

 

I like the sound of your LED Steve! I already have a twin USB adapter plugged in the lighter socket for my phone etc. Where did you find your LED thingy, Autobarn? Ebay? Can always unplug it on display days so I don't upset the purist boys (as if that bothers me!).

Yep, my fuel gauge reads somewhere between 3/4 & 7/8 when full. I'm not too bothered either, just one of those niggles that would be nice to have right. One day I'll get around to pulling the tail lights out and have a look at the sender connectors on each tank.

Cheers,

 

Carl, I always get a kick of making something out of nothing, and see it works! I'm keen to find the device Steve mentioned if has multi purposes though. I'm with you on the test lamps, I also have a couple including a home made one. Over the years I've used them many more times than most other gadgets.

 

Something like this
High Power 4 in 1 Car Charger Dual USB Voltage Current Meter Tester Adapter FE | eBay

Some high power ones are and some are not. the usb lead can also influence the amount of current available. I needed a high power one to charge my phone whilst using google sat nav.
The display is quite handy. I've got a red display and a blue display. Haven't seen a green display yet, but will buy one when I do.

 

My fuel gauge reads about the same as yours for both tanks when full, the left one still has 20 litres in it when it reads empty.
I can live with that, I just run down the left tank to empty then flick over to the right.

 

The unit I was talking about was like this one 12V 24V LED CAR Volt Meter Voltmeter Cigarette Lighter Charger W Dual USB W B | eBay

We should buy a set of 4 senders and have a working bee. We would be pretty good at it by the 4th one :-)

 

Count me in!


Cheers,

 

You will need to refer to this from thime to time.

Eletrical theory as per Joseph Lucas.doc

 

I've discovered I can't be bothered either most of the time, unless I *REALLY* want full tanks. At those times, I wait for it to burp once and Then trickle it in, being careful not to run over (don't ask). One of the flappers is gone so I can actually see the fuel level in the left tank, and at that point it's full enough.

After I saw how the tanks are actually made, I stopped worrying about it, because the first couple gallons takes the gauge down a disproportionate amount. Mostly I've figured out my range on a load of gas, and watch miles more than gauge indications. After 400 miles (depending what those miles were) I start looking for a station.
(';')