Also, people should understand the difference between a battery maintainer (like a CTEK) and a battery charger--they are not the same. A CTEK is not designed to charge a battery (even from 50% depletion). There is not enough amperage to do this efficiently in these units. They *will* eventually charge a drained AGM or LA battery but it will take a long time. They are meant to top off a mostly- or completely-charged battery and then keep it there and regulate the cells and accommodate the discharge over an extended period of non-use. If you want to do it right, get yourself a real 2A/10A/50A battery charger, put it in the 10A mode and let it sit overnight on that. Then connect the CTEK and let it do its thing from there and for future battery maintenance. A truly depleted battery could take *days* to fully charge from a CTEK and may never get there if the battery is too discharged.

 

I went for another drive and was relieved to find that the folding mirror had resolved itself. The dynamic valves were also functioning properly.

However, I noticed that when I put the car in sport mode while at a stop and then drove normally without pressing the gas, the car was not as responsive when I tried to accelerate quickly. I had to switch out of sport mode and then back in for the gears to shift down and the RPMs to rise, urging me to go faster. I'm curious if anyone else has had a similar experience?

Regarding the CTEK, I plan on purchasing one for the winter. Although I got a brand new battery that had a seal, I will give it a week or so to see if I have any issues starting the car. I hope it was just a bad battery that I had and it's not anything else that's draining it. Thank you to everyone who has offered their advice, your input has been greatly appreciated!

 

I usually put it into Sport Mode while in motion and you can see/hear/feel the RPMs rise. However, if at a stop or in motion with your foot off the accelerator sometimes there is no change when switching to Sport Mode. Both my former 2018 Base V6 RWD and my current 2023 R-Dynamic AWD do this. I just quickly switch it back to Normal and then back to Sport and it's fine (I've never had it not go into Sport mode when doing it a second time). The fact that both cars do it (and also yours) leads me to believe this is normal (albeit incorrect) behavior.

 

Same battery I installed a few years ago. Car has sat for a few weeks at a time, stored over the winter (on Battery Tender Jr. maintainer), and it’s been fine.

 

I bought a new AGM battery for my Mazda CX 5 a few months ago. The date code on the battery was a month prior to my purchase so it was a fresh one. Before installing it, I connected it to my CTEK unit. It was on the CTEK for about 8 hours before it showed the fully charged state. So I wouldn't necessarily trust a brand new battery to be fully charged when you buy one. I also have one of those Harbor Freight chargers which of course is a different beast than a CTEK but I don't use it much since I have the CTEK for my Jaguar. But it would have also been a good thing to use to top off the new battery before installation.

Jaguars aren't the only cars to drain the batteries after some period of non-operation. A friend called me the other day and her daughter's year old Toyota Camry had a dead battery after sitting for less than two weeks. Triple A came out with one of those portable jumper packs and got it started and then told her to drive it for at least 30 miles to get the battery charged up again. Modern cars seem to be very finicky due to all the electronics and parasitic draw needed to keep all of the memory programs or computerized systems active.

 

New batteries are often not fully charged. They could have sat for months. Why put off the purchase of the CTEK? It could very well be the solution to your issues.

 

I bought my car new but it had been on the lot for a while. The dealer installed a brand new battery when I picked it up. I had to wait for them to do the install.

I drove the car 400 miles back home. When I got it home I put it on the CTEK. It took it two full days to fully charge the battery.

 

Sounds like others would have the same experience. Strange behavior indeed!

 

Thanks for confirming AGM battery being good.

Point noted on CTEK & even new batteries not being fully charged. Since it stands for 5 days a week, likely not a bad idea on putting on CTEK to replenish & maintain it. Is this the CTEK I should be getting? Do you keep your hood up the whole time or is there enough clearing space for the hood to close?

CTEK - 40-206 MXS 5.0 Fully Automatic 4.3 amp Battery Charger and Maintainer 12V https://a.co/d/fovbFou

 

That's probably the most popular model people have here, including myself. The best (and proper) way to connect it is using the permanent pigtails in the trunk (search for "CTEK install" on here and you should find plenty of instructions/photos). You can then open the trunk lid, connect the CTEK using the quick disconnect plug, and then close the lid completely (the cord will be sandwiched by the gasket but will not be damaged) and the car can sip away indefinitely.

Word of advice/caution if you do connect it in the trunk (or under the hood but close it): make yourself a big sign that says "CTEK connected in trunk" and leave it on the driver's seat while it's connected. Invariably you will forget it's connected (or someone else who doesn't even know about it may use the car) and they will drive off/reverse without disconnecting it first. I have a laminated 8.5 X 11 pink card stock sheet that says this in big letters and it has saved me (and the car) more than once.

 

I bought a new battery just over a year ago from Costco. It lasted 11 months which thankfully it was essentially free to get another one out of Costco but I drive my car sparingly as well which made me quickly realize I needed it plugged into a charger most of the time. I bought a CTek like many others on here and have it plugged in about anytime the car will sit for more than 12 hours. These cars really do seem to draw heavily on the battery when not driven. I also didn't realize but someone pointed out if the car isn't locked it draws even more power. I almost always kept the car unlocked.

 

It seems that the car may automatically lock itself if it is left unattended for a certain period of time. I have observed that when I use the keyfob to unlock the car but do not open the doors, it locks again. However, I am unsure what happens if I drive the car, exit without locking it, and walk away. Based on your observations, it appears that the car does not lock itself in this scenario.

That's a great idea to leave a note, I'll make sure to do that. I'm going to place my order now and do some research on the installation process. Hopefully, it will be simple and easy to follow.

 

+1 on the sign. I have one as well. Also have a sign I hang from the mirror that says, "Please do not wash" for when I take it to the dealer.

 

I park in my garage, unlocked, with no charger. I drive infrequently and I have never noticed a large battery drain. I have not driven the car since Monday and I know that when I got out to the garage later today, it will fire right up. I have also taken a three week vacation and left my car in my garage, unlocked. When I returned, it fired right up with no issue. I don't use a trickle charger or anything else. If you feel you need to plug the car in if you aren't using it for more than 12 hours, you have an issue. The first thought is the dreaded ODBII issue. If not that, there is some sort of parasitic pull that is not normal.

 

According to my calculator it would take around 9-10 hours to charge a 50% depleted battery with a 5A CTEK, which seems reasonable to me.

The manual for my MXS 5.0 even has a table giving time to charge for an 'empty' battery so CTEK seem to think they are suitable.