About a year ago I began receiving the dash msg "Low Battery, please start engine", or such. A day later the battery was so low, I had to get AAA to jump start me, in my garage before I could even charge it with my home charger. I drive the car 1-2 times /wk at least. Called local Jag dealer, they discovered 'Bad Battery', replaced it.
Now, about a year later, I am getting the same msg. When I installed the Batt. charger, it indicated a 40% charge. I had the charger on all day, only got to 80%, but warning light went off. After 2 days, light is back on. I drive the car for 15-20 minutes, light comes back as soon as I get in the car. I did drive one day for about 30 minutes, and the light was off until the next day. Now it is back.
I haven't called the dealer, as I am waiting for some parts to come in, but will likely do this soon. Has anyone else had problems with dealer installed batteries.
I checked and do not have any doors/trunk/hood open. No other detectable drains.

 

Sounds like a battery drain. I have had my car in the garage for as long as 6 weeks without driving and starting the car. Fires right up when I get a chance to drive the car. Have you accessed the OBD port?

 

Sort of!

I have owned English cars since 1972.

The problem today as it has always been, that mechanics are not electricians. Modern "mechanics" rely heavily on parts replacement. Often the cause.

We, the MG guys have learned it is the alternator, battery or a wiring issue. My guess is wiring.

Depending on the charger it takes up to 48 hours to fully charge a battery. While charging and for hours later they show surface charge. The charge from the charger. A full battery is 12.6 or so volts. Measured the next day. Assuming you have a decent voltmeter.

You have a circuit somewhere likely that is on that drains the battery. A trunk light drove me crazy in my young stupid days. Also a headlight switch. Electronic ignition once.

I would put a trickle charger in the trunk and charge when not driving until the garage can get to you.

It is not likely another dead battery. Although this one may be damaged. It is an ammeter, wiring diagram in smart hands that will find the minor issue.

These issues can be tough to find. A local English mechanic friend of mind hates these jobs. Can take days to find. Customers will not like that bill.

 

I installed a remote transmitting OBDII unit. Nothing showed on it, and the battery problems started shortly. Removed the unit and started charging. I have not put OBDII on since the problem.

 

I had this issue with my XK and was advised by a Forum Member to lock the doors when the car is parked. The explanation was that the cars electronics stay on for a time after the engine is turned off and locking the doors shuts down the electronics a bit sooner.

 

My reading of this based on my experience and that of others, and the history given, is quite simple: you are not driving the car often enough and long enough to keep the battery charged! Don't look for a complicated and expensive answer until 1) you have charged the battery FULLY, and 2) driven it frequently for runs of MORE than 30 minutes(not stop and go runs!).

please do this and report.

 

I have seen several posts similar to this, where if one connects something to the OBDII port, that even when one pulls said device off the OBDII port...the port is still active and will drain the battery quick. If I recall, the solution is to do a hard reset on the system by disconnecting the battery and letting it sit for a while, then reconnecting. Hopefully someone more knowledgeable than me in this will chime in with better info.

 

This is a common problem on FTs. Disconnect the battery for 10 seconds at least, then reconnect. It should then charge properly assuming that the constant discharge didn't kill the battery.

Best practice is to never connect anything to the OBDII port unless absolutely necessary.

I've never actually faced this issue since the only things that have ever been plugged in are the dealer's diagnostics/software upgrade and at the emissions station.

 

As others have said, it's likely you've latched one or more modules on by using the OBD port (or more correctly by not disconnecting in a way the car likes), and unless you do a battery reset your issue won't go away.

 

I would start with a battery reset as others have said as well. That way you can eliminate the ODB II issue. But sov211 is right on the money. You're not driving the car long enough to even put back into the battery what you take out of it when you start it. Vehicles' alternators are designed to maintain (at best) your battery, but not necessarily charge it. The high demand of today's electronics that often function after you shut off your car, along with short drives is a formula for draining batteries by itself, even without the OBD II issue. The dealer replaced your battery the first time and I would place my bet on that battery never being fully charged to start with. You even said that you only charged it to 80%. I would recommend a smart charger with leads mounted so that you can plug your car in at least once a week to maintain a full charge.

 

My personal recommendation is to drive the F every week, for at least 45 minutes.

We were called out-of-state for three weeks recently, and our F started right up even without being hooked up to the maintainer, with no warnings displayed . (After I buckled the seat belt of course, LOL)

 

​​​​​​A complicating issue is the AGM battery which needs to charge to a higher voltage than a legacy 12.6V battery which is harder for the alternator to finish. So the AGM winds up routinely operating at a low charge state and that kills them faster than expected.

It is unclear if a given car's electrical system finish-charges AGMs correctly, or if manufactures just throw these batteries in without a full understanding of their ideal charging phases.

Bottom line: a specified "for AGM" battery trickle charger is going to be cheaper than buying a new battery every couple of years. You only need to trickle to a finish-charge every couple of weeks.

 

My early 2014 has never had the battery issue. I can leave it for a week or two and it always starts right away. Never even a hint of low battery.

 

Prior to this, my car had sat for 1-1 1/2 weeks, and started with no problem. Today when I checked the car, it was completely dead! Tried to charge it and after 1-2 minutes of charging got a msg, "Battery Failure".. Tried 3 times, never got better than 50% charge, and always back to "Batt. Fail." Called Jag, and will try to get it to them on Monday. May have to call for a tow.

 

On the bright side, all your modules should have been reset by now.

 

Well, it is pretty clear that your battery is "toast". When you get a new battery installed, make sure it is fully charged - let me repeat, fully charged before installation or immdeiately after. And then keep it charged (see the threads on "CTEK charger").

 

Same with mine, and it is also in winter hibernation for aprox. 5 months a year. When in hibernation I use a Ctek charger every 6 weeks (just to "top it up" for usually 5-8 hours of charging each time).

 

Now finally figured it out. Second time this happened, exactly same time last year, a few days after my annual safety inspection, the battery completely died. No problems during rest of the year.
So inspection must use OBD port.
So how do I do battery reset?
Thanks,

 

Just disconnect any of the positive, negative or earth (ground) leads for 15 seconds or so then reconnect.
The ground lead is easiest.

 

Sounds as if OBDII testing is dangerous for Jag batteries. This should be a warning. How are we supposed to check the diagnostics?