So I am driving into the grocery market parking lot, and suddenly get lights and warnings going off.
Park car and after shopping I tried to start but "nothing happens", totally dead. Open up battery compartment to find both cables are extremely hot!
Friends offered to jump the battery, but we decided this may not be a good idea.
Tow truck it to my house, and some folks are saying it must be a dead short somewhere to create that much heat.
No smoke or burning odors observed. 99 XK8
Suggestions please.

 

With the battery out of the car try connecting an ohm meter between the positive cable and ground. That might show a dead short. That’s where I would start.

Plus an examination of all wiring looking for areas showing evidence of melting.



Z

 

Internal battery failure? Had that happen on my Ford Thunderbird many moons ago. Check for battery voltage.

 

FWIW, these battery cables sometimes fail internally as well. They heat up due to additional resistance, and the voltage to everything drops accordingly, until control modules brown out and no longer work. I would check these cables first.

Best of luck, keep us posted.

 

When you say fail internally I imagined they'd just be thick braided copper or some such which either melts or breaks - but not increase resistance. I can feel a bit of learning coming my way!

 

Thanks much. My multitester says it is a dead short between the cables (disconnected). Battery shows 1.8 volts. I have the charger on it, and will check tomorrow.
There is no apparent melting of cable coverings, and the car has been running perfectly up to this sudden failure. I doubt it is the battery which is kept on a monitor, and dated 10/19

 

Internal battery failure is caused by broken link bars ....these are internal links between cells and the lead "welding" fails goes intermittent as it's splashed with acid. Not a common fault. I always tape the battery receipt to the battery in case of a warranty claim

 

My Jaguar mechanic said he has seen this a couple of times before, and said it was an alternator problem.
I am trying to understand how..... maybe an internal short in the alternator causing a sudden meltdown of the system and battery?
I have found no evidence of melted wires. Recharged battery overnite, and it is showing 13.8 volts off the charger for 30 minutes.
My plan is to reconnect battery and see what happens.
What do you chaps think??

 

If it has an internal link bar break it can show full volts ..onece you hit the starter you will know .

You need an electrician not a mechanic.

 

Lost all electrical power - Jaguar Forums - Jaguar Enthusiasts Forum

Just sayin' - this happened to me. Changed the braided steel crimped ground strap with a solid copper one. Cheap fix.

 

Get the system tested at an auto parts store. It's likely you have a short or diode failure in the rectifier, which is internal to the alternator.

 

I would not take the risk just to reconnect the battery, the fault is there and the result could be catastrophic.
Right in front (and a little left) of the battery you will see the main fuse box. There should be three 250A fuses. Two of them are connected together (parallel) and goes to the starter and alternator.
Take out those two fuses before you reconnect the battery. You will still power up everything else in your car, but likely your problem is within your starter or alternator.
Still be careful!

 

If it does have a broken internal link then during charging this may have "reconnected" so it looks normal.
I dont think you will have any problem if you re-connect it but the chance of explosion is always present when you hit the starter so I would lay a heavy cloth over it to save a mess when you do re fit it..keep trunk open wear saftey glasses.
If its over 4 years old just go buy a new one.

a broken link bar is a very rare occurrence.

 

This is when a test light comes in handy. Pull the fuses and connect a 12v bulb in their place and you can instantly and safely see if there is a current drain where there shouldn't be.

 

Problem solved with a new (rebuilt) alternator. Also replaced a corroded negative cable, but real problem was alternator.