I have my 15 R in winter (cold) storage, and connect the battery tenderer (Ctek) only every 6 week (hardwired to the battery). It takes aprox 5 hours to fully charge each time.

 

That I cannot understand because my experience is the same as Foosh; it takes overnight for mine to reach full charge independent of how long it has been off the maintainer. If you are using a small charger rather than a maintainer, then I could understand it but I am also using a CTEK.
Larry

 

I can not explain this either. However when I did drive the car last year with many short trips over a periode (without any longer trips in between), and used the Ctek tenderer for the first time (just in case), it then took aprox 10 hours to reach fully charged.

I don't know if temperature might have something to do with it, or if cars ment for cold "nordic conditions" have different batteries or other "settings"?

I have also started the car a few times during the winter and let it run till operating temperature, also to dry up the cabin when the air has been very moist. It turns the engine with ease and starts imediately every time.

So from my experience battery drain is not an issue what so ever - at least not on my car. My garage is a couple of hundred feet from my house though, so I know that the car can not sence the presence of the key. This will cause a problem if it does sence the key, as the car will never totally "shut down" when the key is within detectable range.

 

That key issue is the first problem we had with the Mercedes as our key rack was just in the house from the garage. I learned that smart keys need to be further from the car as the car does look for the key even when locked. But, my Jaguar SA told me that the newest cars, when locked, shut everything down. I do not intend to test that theory.
Larry

 

I was told something else from my dealer when I asked, but I don't know what is correct?

It is strange with these different battery drain experiences though, and I have not a clue to what the explanation is? Very happy that I have not had any problems so far, but curious to why some others experience is so different....

 

When I bought my car it almost immediately put up an error message about "special modes or dynamic mode" not available. Dealer ended up changing a brake switch, but I'm half convinced the problem stemmed from the battery being really low due to the car sitting on the lot. I installed a harness (using the pics and Jag instructions someone posted here - thanks!) and keep it on a max 2 amp tender. It sounds to me like these cars are very sensitive to lower voltages and also may have high parasitic losses.

My plan is to keep the car on the tender 24/7 whenever it's not being driven.

Dave

 

What is the amperage on your maintainer? I use a 1.25a Battery Tender Plus, and mine takes up to 24 hrs to show a full charge. I can drive it 30 miles each way to and from work, plug it in immediately when I get home, and it still takes an overnight to fully charge.

I'm guessing you're charging at a higher amperage to get a 5 hr. charge. I think CTEK builds charger/maintainers w/ different amperage ratings.

Also, +1 on keeping the fob a sufficient distance from the car. If it's sitting on a table by the garage door, that may not be far enough.

 

My CTEK is 1.5 at the highest voltage. I am in the long time to charge group.
Larry

 

I've never measured the voltage. The car came with a maintainer which I've never used. When I test drove it, it had the low battery warning, but started immediately anyway. Haven't seen that warning since. Short trips, back and forth to work, not driving it for a week never a problem. Seems like a normal car to me.

It also occurs to me that the charging circuit may be different and less regulated than the rest of car. The electronics could be more sensitive than the battery to varying and noisy voltage. Things like blowers, seat warmers, etc. would be pretty insensitive to voltage and would generate electrical noise. Things like the various CPUs and electronic controls might be more sensitive. Two DVMs or a look at the car's schematics might answer that theory.

 

Mine is a CTEK Zaphire 45 with max charging current of 3.6 A. It is an "intelligent" charger/maintainer and goes through a sort of cyclisk charging which vary depending on the battery condition.

 

I had to start it up in the garage today, just to let the engine idle for a while and make sure everything is still ok.

It started right away even though it's two months since last time it run. After reaching operating temperature I opened the exaust and reved it just to aprox 2k rpm, and it pops and crackles like wild.

Can't wait to take it for this years first drive, but the roads are still wet with lots of salt...

Hopefully it won't be too long though....

 

Just as I thought.

Your maintainer has the ability to charge 3X faster than a Battery Tender Plus @ 1.25a, which is really just a "maintainer." The BT Plus is what most people in the US are using to keep batteries topped off.

 

Always good to find a logical explanation

 

I had a BT Plus self-destruct when connected to my Vette. Did not hurt anything except tripped the garage circuit breaker. Since then I use CTEK.
Larry

 

It's always possible to experience a premature failure on any product, including a CTEK.

I currently have 6 BTs, from 2-15 years old, and they are all still in service. I'm still using all of them (on the MB, F-Type, Jeep, Dakota, motorhome w/ 3 wired together chassis batteries, and tractor) in nearly constant use, with all the vehicles hard-wired. I also used them on a jet-ski and a boat.

I've never had a failure, and given my experience, wouldn't buy anything else.

 

Foosh,


I understand and I felt that way about BT for many years. Mine failed, I looked at reviews online and saw that my failure was not an isolated instance. So I swore off them, though I still have one. You can get a failure in any product, any time but I voted with my feet. I am just reporting my experience along with what I read. Look, I even shut off water and gas to my house when I leave for a few days or more....


Larry

 

Oh, I understand, but you're just one data point, and it's a natural reaction to dump a product after you've had a failure. I just did a quick look on Amazon and found BT rated at 4.8 out of 5, based on 3254 reviews. CTEK was rated at 4.7 or 4.8 based on 454 reviews. It's coin-flip based upon objective data.

Both are manufactured in China.