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Dead as a DoDo!


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Driving towards Dursley, 2012 Jeep GC CRD started beeping and at same time it went completely dead.   Not even hazard lights working.  Breakdown came out eventually and connected up his battery charger and lights, indicator etc came on, but when trying to start it, all it did was click.  Dead as a Dodo and had to recover us back to campsite on a flatbed.

Not sure why it suddenly died totally.  Battery is about 18 months old.

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42 minutes ago, V said:

Does this help?


It sounds like your alternator may have died. Did the mechanic test it?

There seems to be a clip on cover on the inside.  The other issue i accessing the battery under the driver's seat as cannot move the seat forward.  Vehicle has been fine with no issues starting it.  I have never had a car die on me while driving and it was a frightening experience.  No warning or anything, just a couple of beeps and then totally dead.

Luckily we were not on the M5 otherwise it would have stopped in one of the lanes creating one hell of a hazard especially as we would have been towing a caravan.  Using the connections under the bonnet I measured for 12v and nothing.  Absolutely zilch!

Jeep came back from dealership about two - three weeks ago and left parked up until we went on holiday.

When travelling down the M5 towards Somerset the Engine management light came after about 45 miles on followed by Forward Collision warning. Also when pulling out from services, the car seemed to lose power for a couple of seconds. This is why we took the car to the Jeep dealership and they replaced all the glow plugs to resolve the issue. 

Arrived at campsite and the next day when starting the cat EML and FCW lights were off.  No more issues for the next 10 days and drove back up the M5 to south Gloucester no issues and it behaved perfectly until today when it unexpectedly died on us.  Couldn't even sit in the car while waiting for breakdown as could not open windows or anything.

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Try a starter pack on the jump start posts in the engine bay, or a set of jump leads, it may give you enough power for the seats etc:  Haven’t tried it but may work. 

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If there is an issue with the alternator and it is not charging the battery, if we fitted a new battery, will it allow us to drive home the 45 miles towing our caravan and then the 25 miles to the dealership?  If anything I suspect the battery as it is a Platinum brand battery as that is all the fitter had in stock for the vehicle.  On our previous Jeep the Platinum battery failed just after it was out of warranty.  Next one will be a Bosch battery!

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To work it out reasonably accurately, you would need to know the power consumption of all of the electrical consumers in the car that will be on or come on intermittently during your journey.


Assuming a day time journey that you would not be using headlamps, summer time just means a toss up between cabin fan on or windows open. When the battery dies you either can leave the car secure or not.


Some guestimates...

Assuming battery is 55Ah 12V

Assuming starter motor averages 550A for 3 seconds, could be as much as 1000A peak and dropping to 300A.

55Ah / 550A = 0.1h

0.1h x 60 minutes = 6 minutes

So a fully charged battery will give you six minutes of cranking in theory, temperatures affect this but it's a reasonable starting point.


6 minutes = 6 x 60 seconds = 360 seconds

1% of 360 seconds = 3.6 seconds, lets say that is one engine start


Subtracting 2 engine starts for the journey gives 98% of battery capacity remaining.

55Ah/100% x 98% = 53.9Ah remaining capacity after engine start


Power consumers:

Engine fan 800W

Cabin Fan 200W

Air-conditioning 500W


Windscreen wipers 80W-150W

Electric Windows 150W

Windscreen washer ?

Indicators = 6 on car, 2 on caravan = 8 x 5W = 40W

Brake lights = 2 on car, 2 on caravan = 4 x 21W = 84W


Assuming that it is daylight and (for safety) there is light rain for half the journey requiring intermittent wipers. DRL will be on all of the time. Engine fan will likely be on for hills and everywhere under 40mph. Caravan only has black plug for lighting connected. No mobile phones charging. No radio on. No GPS on. We will see what's left for passenger comfort later.


100% DRL at 10W

50% Wipers at 80W = 50%/100% x 80W = 40W

25% Engine fan = 25%/100% x 800W = 200W

1.5% indicators brake lights = 1.5%/100% x 124W =  1.86W say 2W

50% Cabin Fan at 200W = 50%/100% x 200W = 100W


Total = 352W

352W / 12V = 29.33A, round up to 30A

53.9Ah / 30A = 1.8h = 108 minutes


Now look at where this can go wrong very quickly.

2 engine fans, not one. Traffic on journey fans on 75% of the time

75%/100% x 1600W = 1200W and increase of 1000W


Traffic Total = 1352W

1352W / 12v = 112.67A, say 112A

53.9Ah / 112A = 0.48h = 29 minutes


Add 50% air conditioning as it's a hot day

50%/100% x 500W = 250W

Hot day in traffic total = 1602W

1602W / 12v = 133.5A, say 133A which is within the range of alternators fitted to Grand Cherokee (140A-160A)

53.9Ah / 133A = 0.40h = 24 minutes


Intermittent use of A/C for comfort will only cost you five minutes, so it is worth considering using when you need to.

Optimistically, using the assumptions above, it may be possible. However, the variability of factors combined with not knowing exactly the power consumers in the vehicle you might only be driving for 30 minutes or so.


What would I do? Find the root cause of the problem and correct it. If it is the alternator, get a replacement fitted before your journey.



  • Leave the car at a garage to be fixed and rent a tow vehicle to get your caravan home and return it when the Jeep is expected to be fixed.
  • Leave the caravan at a camp site or storage site, pay for a park up/storage duration. Drop the Jeep off at a garage near the campsite. Find an alternative means to get home. Rental car, taxi, train, bus. Any items that you don't immediately need back at home can stay in the caravan. Go back to collect both Jeep and caravan when the Jeep is fixed.
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Not all brand new batteries are fully charged when you buy them. I installed one recently for my Dad and it took more than an hour on the charger before it was full. I'm guessing that was between 5% and 10% less capacity if I had not topped it up beforehand.

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Between the campsite and Worcester, the M5 road is relatively flat.  Chances of rain probably zero.  We have a small dog with us so climate control required.  Yesterday when we were stuck we had to wait for 3 hours for breakdown to arrive.  Unfortunately due to warm weather unable to sit in car for very long as unable to open windows.  Only able to open nearside doors halfway as we were across the pavement and hedge on property.  The joys of electronic gadgets in a car!


However we have arranged for breakdown to collect the vehicle and caravan tomorrow to take caravan to storage compound and then vehicle home where we can off load the camping gear from the car and remove the roofbox before the breakdown people take it to the dealer on the Monday. 😏


What I find strange is that the "Charging system light" never came on at all before the Jeep died as this normally indicates a malfunction with the alternator?  I am hoping it is just the battery that has given up the ghost as Jeep dealer will probably charge us in excess of £1000 to replace alternator.  Car which is 2012 has only done 72K and has a full Jeep dealership service history.


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In addition, using a multimeter I checked the status of the battery and reading is zero. I would normally expect to see a reading of between 1 and 5v even if alternator is faulty, but not zero.  This would normally indicate to me that the battery is totally stuffed!

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Buy yourself a C-TEK charger and connect to your battery every couple of weeks, especially if your letting the vehicle stand for 3 weeks or any length as you stated.

It'll keep the battery fully charged / ready and give piece of mind.

Just replaced the one on my JKU 2.8CRD with another Optima yellow top after 7 1/2 years, (still OK but better safe than sorry) and a s V says even a new one can require charging up, mine did.

Get your battery & alternator checked out for free at a local tyre shop once a year (usually before winter) using their Midtronics testers it will give you a print out of the volts measured, cold cranking as against rated and and important Charging test (showing Volts) for the alternator. You can keep this and compare it with the next one you get done to see how its holding up.


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With a new battery installed, check the voltage across the terminals with the engine running. If it is around 14.4V, your alternator is charging.

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1 hour ago, Surfer said:

I would normally expect to see a reading of between 1 and 5v even if alternator is faulty, but not zero.

Sounds like a strap inside the battery casing has broken away.

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Thinking more about this, all of the electrolyte may have leaked out. I guess if the water part of the electrolyte evaporates and leaves just sulphuric acid that would also bring the charge down to zero. If you can get the battery caps off to check the fluid level inside, topping up with deionised or distilled water followed by a recharge may restore the battery. I'm not entirely certain how battery sulphation occurs when the vehicle isn't used, but I think that the sloshing around of the electrolyte through movement and vibration prevents it. If the sulphuric acid in the electrolyte is being converted into sulphate deposits on the battery plates, that would reduce the acid concentration in the electrolyte and perhaps that would increase the rate at which the water in the electrolyte evaporates in heat. Just a theory.


I have restored some batteries before after topping up the electrolyte and connecting them in parallel to another fully charged battery for a few hours or overnight. Changing the connection to a smart charger afterwards. I have heard that it can also be done in about 5 to 10 minutes using an arc welding machine outside starting at the lowest amperage but I've not tried that yet. The restoration needs to gently boil the electrolyte to remove the sulphate from the plates. Hydrogen is given off during the process, so a spark can cause an explosion if the area where charging is done is not well ventilated.

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Battery is sealed as it is in the cabin under the driver's seat.  I will wait until I get home and try a jump start using our other car.  However it is pointing more and more towards a battery failure.  Probably a crap cheap brand.

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The breakdown person who came today to tow the car to the dealership was previously a mechanic by trade so knew the business.  He gave it a thorough going over and he agreed with me that there is definitely a short somewhere as it seemed the polarity was reversed.  Possibly a dead short in the alternator?

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