Hi all, ( trying to do my best with my english, I'm french Canadian from Québec )

I've read some posts about " car throwing weird codes due to battery that is not full charge, due to its age"... My battery (AGM) has been in the car ( 1997 XK8 ) since may 2019, so, up to now, it's its fourth summer ( car stored in my heated garage during winters, battery disconnected from october to may ) Due to the hard winters here, I use the car only from may to october.

First episodes ( happened many times) ;
This summer, in august, often, during the first 5 minutes of driving, engine shots off while driving... No codes on the dashboard... Turn the key, re-start the engine, I'm good to go.

Second episodes ( happened many times) ;
Often, during the first 5 minutes of driving, engine shots off while driving... No codes on the dashboard... Turn the key, engine shotts off. Disconnect and reconnect the battery, engine starts and I'm good to go.

Third episodes ( happened many times)
During the first 5 minutes of driving, engine "accelerates by itself" and also "shots off" , with some codes like " engine fault", " stability control fault", "gear box fault". Disconnect and reconnect the battery, same thing happens...

Then I had the idea to connect the battery to a smart battery charger. Since we don't have snow yet , been driving the car everyday for a week, no troubles.... Runs very well....

And............ Here's the big question :

Question is, battery " not full charge ", I've read that it throws weird codes to the dashboard, but, can it also ( in addition ) "physically" ( mechanically ) make the engine go wild ?

Car will go to my mechanic in a short time, but your advice here would be appreciated ! Thanks !!!

Robin, from Québec

 

Low Battery voltage to critical components like the ECU and assorted other control modules can and will cause unpredictable engine behavior.


the electrical systems were not designed for the current lifespan of the engine. Excessive resistance in the wiring, wiring connectors, and modules themselves all contribute to reduced system voltage. The ECU and other modules are not reliable performers when asked to function with lowered voltage.

we have two ways to address the anomalies. Either replace the entire electrical system with new materials, or keep the battery on a battery tender whenever the car is not in use.


I chose the latter and more economical solution. In other words, there are at least two ways to get past a brick wall; You can either pound your head against a brick wall, or simply walk around it .

Since keeping my 2002 XKR on its tender I have eliminated the numerous gremlins that had taken up residence in the wiring. And the pleasure of ownership has returned 100%

Z

PS personally, I’d give the car a dedicated battery tender at once, and every time & whenever it sits unused, overnight or longer. And put off the trip to a mechanic unless the issues are reoccurring.

PPS. Letting a battery sit thru the winter without keeping it on a tender is an easy way to dramatically shorten battery life.

 

Having it disconnected for the winter without a monthly charge is fatal. No need to disconnect it ..better if you dont just use a battery tender . Next time dont waste your time on AMG a battery is a battery like eggs is eggs . Get the cheapest and change it when required . The life of an abused battery may well be 4 years personally I would change it . no need for a mechanic to do that .


Le débrancher pour l'hiver sans frais mensuels est fatal. Pas besoin de le déconnecter. Mieux si vous n'utilisez pas simplement un chargeur de batterie. La prochaine fois, ne perdez pas votre temps sur AMG une batterie est une batterie comme les œufs sont des œufs. Obtenez le moins cher et changez-le si nécessaire. La durée de vie d'une batterie malmenée peut très bien être de 4 ans personnellement je la changerais. pas besoin d'un mécano pour faire ça.

 

My experience owning my car for 17 years has been consistent with what everyone here says.
The car does not like a battery with low voltage. Strange things happen, like the car is possessed. Demons appear out of nowhere.
Mine developed window dip problems which corrected themselves when I figured out that the low battery was the culprit.
Now I keep the a trickle charger on the battery religiously. Works great. I have no electrical problems, period.
I installed an electrical panel in the trunk above the battery which is a great way to connect a trickle charger and monitor the battery.
I adapted a 12 volt plug to a Harbor Freight trickle charger and I simply plug it into the panel.
Below is the panel that I installed but mine has a red display, because, well, the car is red. It fits nicely above the CD player and isn't difficult to install. I love it.

 

Wow , many thanks for your good advice , my mechanic here in Québec tells me he doesn't trust "infos taken from forums" , but I beleive I'm in the right place for good advice, car has been on a "battery smart charger" for the last month, no weird problems anymore...

Now, since it's already winter here, car is in storage in my heated garage, I should let the battery connected to smart charger, all winter long ( until may 2023 ) ????

Thanks !!!

 

A qualified YES,

what brand of battery tender are you using ? There are several that are able to safely keep the battery connected indefinitely, NOCO Genius and CTEC are the most highly recommended. I would also trust the Delran Battery Tender +


Z

PS one thing for sure, if you leave the battery alone all winter long, without use or supplemental charging, come next spring it will be DOA or troublesome forever.
.

 

Bonjour Robin,

My suspicion is that your car has multiple problems.

It is possible your battery may be undercharging due to either a failing alternator, voltage regulator, or corrosion on battery power and ground connections throughout the vehicle. The alternator and voltage regulator can be easily tested - in the U.S., most auto parts stores can run basic tests for free.

A good maintenance process is to disconnect the battery and clean the battery cable terminals and battery posts, and while the battery is still disconnected, disconnect and clean the battery ground strap connections to the body. Then remove the spare tire and disassemble and clean all the components in the High Power Protection Module on the bulkhead in the trunk. Also clean the connection at the false bulkhead in the engine bay, the connections at the starter and alternator, and the engine ground strap. Clean the battery power connections at the engine bay and boot/trunk fuse boxes. Clean all the ground points you can find in the engine bay and boot/trunk. You can find these connections with help from the wiring schematics in the manual at the link below:

Jaguar X100 Electrical Guide 1997

EDIT: Sorry! I forgot to include my second thought: Another problem I suspect is that one or more of your critical relays has become weak and is intermittently unlatching, possibly due to low voltage. I would recommend using a 9 volt battery to test all the critical relays, like those for the fuel pump, fuel injection, Engine Management System, ignition coils, etc. There is a diagram in the Electrical Guide that shows the location of these relays. If a relay won't latch reliably on 9 volts through 10 successive cycles, its electromagnet has become weak and it cannot be relied upon.

A good replacement for the 4-pin relays is Bosch 0 332 019 103. It has a proper resistor in parallel with the coil to help protect sensitive computer module output transistors from the high voltage surge that occurs when the relay is deengergized and the magnetic field in the coil collapses.

Cheers,

Don

 

Hello

My battery tender is a " CTEK Multi US 3300 " . There are 2 modes ( see pic );

-14.4V ( Normal setting for wet batteries, maintenance free and for most gel batteries.
-14.7V ( Recommended for low temperatures and also, many ( not all ?????) AGM batteries ) I chose that one since I got a AGM battery... ???

Car is in heated garage, connected to the tender. Trunk will stay open all winter, not a big deal I suppose ( see pic ) ?

 

You can close the trunk on the tender cord without causing any problems. The cord will still be loose enough with the trunk closed to be able to move it in and out of the shut trunk.

I was hesitant to route the cord out of the trunk that way, but the old hands on this web site told me not to worry , so I didn’t. The trunk seal is very fat and can accommodate the tender cord easily. I’ve been routing the cord this way for nearly 5 years. No damage to the trunk seal or the cord.

Z

 

If you ar going to leave the trunk open then take the bulbs out the trunk lights as they will be loading and confusing the charger

 

I don’t know about all years, but on my 2002 XKR, if the trunk lid is left open, then the trunk lights will go out by themselves in a few minutes (never timed it to the exact second).

that happens irrespective of whether there is a tender hooked up or not.

I just close the trunk lid a matter of course to
keep any garage creatures from making a home in there. And the alarm likes it when all doors, hood / bonnet, and trunk are closed before it’s activated. The alarm talks back to me with a short “screech” whenever there has been something left open

Z

 

I agree with Don B. Your car has a underlaying issue that may be worse with low voltage.
If your car had so low voltage that it through codes and stopped while driving, you should not be able to start it again without charging the battery.
And when it comes to charging at winter you have two options;
Leave the battery connected in car and connect a smart charger at all time.
Or disconnect the battery, charge it and store it above freezing point, and charge it again before reconnecting in springtime.
I have three cars in winter storage, my 2000 XKR, my 1960 Cadillac Coupe DeVille and my wifes 2005 Mercedes SLK. I dont have three battery chargers so they have their battery disconnected and charged before storage.

 

You actually have another choice . fully charge the battery and put it in the freezer at -18 C and defrost it in the spring.

 

Hello again!

Here some news; last automn, did many driving tests while car was always connected to a smart charger when sitting; all problems gone. This spring, put on a brand new battery ( didn't take any chances since the old one was 5 years old ), runs fine for a few weeks. But, tonight, same problem came back again; scroll of death ( error codes in dashboard ), engine stalls, etc.... Then I thought " what did I do, before it happens "... Well, I put back in, the trunk mat ( hard mat ) , which I had removed, last automn, in order to keep the battery connected all winter long in my garage. Now, the rear end of this trunk mat, when we put it back in, ( need to force it a bit to get it right in place ) arrives near the HPP fuse box connector ( wired to the positive connector from battery ), would it be a hint ?

Thanks in advance, I'm , still, desperate.... Such a nice car, but complicated... !!!!

 

When you fitted the new battery did you continue to use the smart charger?
If not that is your problem.
If you dont get the front of the battery cover in the right groove it is hard to fit

 

Connect a suitable plug/socket to battery and just leave plug exposed. Most maintenance chargers come with a pigtail.

 

I have the charger connected to the battery all the time and run a mains extension lead out the trunk to a nearby mains outlet. I also have and extension socket behind the drivers seat to plug in my de humidifier in the winter.
I dont like your idea of a heated garage ... steel does not rust when frozen bad idea to keep the car hot and damp. Unless you have a powerful de humidifier in the garage I dont think its a good idea.

Just noticed this post is a couple of years old

 

Yes, new battery always plugged to smart charger when car is sitting.

 

Humidity is controlled in my garage ; always at 45 degrees. Temperature is around 13 degrees celcius.

 

For an early car, these are normally symptoms of a failing ECM board requiring repairs, typically caused by leaking/failed capacitors. I would look at pulling the ECM and visually inspect the main board. You can then decide to send it in for repairs to a reputable service provider. You can read up on the so-called capacitor plague of that time period.

Bonne chance, gardez-nous au courrant.