Z8 Dead Battery Issue

[jmosk]

I haven't driven the car in a while and the battery is apparently dead. The security light didn't even have enough power to blink and the clock stopped. Had to manually open the door and the trunk. A trickle charger was left connected for 3 days and never showed the battery reaching full charge. It did get awfully hot though.

I tried to jump the battery from my BMW X3 and although the lights came in the car so I knew everything was connected, the car just clicked as if there was no battery and there was no attempt to turn over the engine. A new starter was installed a year ago.

Any ideas why it would not even attempt to start and just click as if there was a dead battery?

[Dogsbreath]

The car can exhibit very strange 'behaviour' with a near dead battery. Mine lit up one turn indicator lamp, one headlamp and a tail lamp. No issues since replacing the battery. If it is deeply discharged there will be no click

[tomfakes]

If your jump cables aren't thick enough, the X3 can't supply enough current to turn the engine over.

We found this out in May when someone drained their battery overnight. Andrew's jump cables weren't thick enough to jump from an X5, but after 45-60 minutes had charged the Z8 battery enough that the combined Z8 and X5 current was enough to get it going.

Those jumper cables looked thick, but it was all insulation and almost no conductor!

If your battery is to the point where it won't hold a charge, you'll be out of luck until you get a new battery or much thicker cables.

[hlmiii]

If the battery has become completely drained to the point where it can't even provide enough current and/or voltage for low level circuits it is then almost always incapable of even allowing a jump start. A complete battery failure prevents the electrical system from functioning.

This is true of this car and many other post ~2000 models that have advanced electronic systems. It is the reason why battery tenders are 100% necessary for cars that aren't driven at least once a month or so.

You will need a new battery. Even if you can get your car started its operating status will be questionable.
Battery replacement is easy and straightforward.

The age of the battery determines when it will reach the point of total failure - not only can the battery not hold a charge, but its status effectively prevents operation. The point at which this happens is due to variables such as age, prior discharge history (frequency of occurrences and depth of discharge), length of time of use vs. discharge, etc.

I've had batteries fail in cars less than two years old when not used as well as batteries fail after four+ years of flawless service. Regular use is the only prevention and insurance against failure, whether the "use" comes from regular driving or from a battery tender.

BMW has an excellent and attractively-priced tender. It's usable on virtually all cars and will make sure this doesn't happen, even over very long periods of years.

Good luck.

[jdillane]

The BMW tender works like a charm. I'm on my second tender but still running strong on my first battery. My Z8 was mfg way back in Sept 2000. Aside from the tender I cannot explain why my battery has so ably performed for me through the years. Wish I could say the same for my radio and the neon lights.

[boomster]

I always keep my motorcycles and infrequently driven cars hooked up to Deltran battery tenders when not in use, and get battery life well beyond "normal", which I believe is considered to be 3-4 years. I typically change the batteries out of an abundance of caution when they get into the 6-7 year range. I believe the BMW battery tender is actually made by Deltran.

Bill

[jmosk]

Even a jump from AAA did not start the car. The battery was only one year old but I did not use the car in perhaps 8 weeks. But as soon as a new battery was installed, off it went. I have a trickle charger (battery tender) that BMW provided just after I purchased the Z8 new. Do I need to use it if I take the car out at least once a week? Is there any advantage to ALWAYS using the trickle charger when the vehicle is sitting in my garage?

[hlmiii]

as soon as a new battery was installed, off it went.

Yay!!
In my experience the Z8 does tend to drain a battery more than more recent cars.

Do I need to use it if I take the car out at least once a week?

I would, and do. There is no reason not to.

Is there any advantage to ALWAYS using the trickle charger when the vehicle is sitting in my garage?

Yes:
1 - you'll not have to be concerned about this issue any more;
2 - it will do nothing but ensure that your battery yields the best performance and life possible* (it could go for years);
3 - no reason no to (see suggestion**, below);
4 - it will develop a habit/routine that you won't have to make yourself remember.

* even if the battery tender (NOT charger) is disconnected for a few minutes due to power blackout, car disconnect or even car usage for any length of time, the tender will go into a quasi charge mode at first. After a while it will fall back to maintenance. This is evidence that the tender actually monitors and responds to the battery conditions, no matter how fully-charged the battery is. So keeping the tender on all the time does provide servicing to the battery, regardless of whether or not "charge" is needed.

** install a tender setup that is quick and easy, that eliminates the clips under the hood chore. Get a 12v "cigarette lighter" adapter like this -
http://www.autozone.com/12v-products/12-volt-socket-adapter/victor-12-volt-double-outlet-lighter-adapter/3307_0_0/
First, cut off and use the female end at the battery - put spade lugs on the two wires on the female section. Bolt onto the battery.
Then simply plug in the male connector from the tender, close trunk lid and go away happy.

If the tender doesn't come with the male 12v adapter, then simply splice the one from the above item onto the tender.
This is all very easy and will be the cheapest + easiest + best way to ensure that the electrical system is preserved.

[boomster]

Most Battery Tenders come with two harnesses for connecting to the car, one with alligator clips and one with eyelet connectors. I use the eyelet connector harness attached directly to the battery cables, as shown in the attached photo. After replacing the trunk floorboard, the harness will extend up into the main trunk area. You can then easily plug and unplug the main lead from the Battery Tender, leaving the trunk lid slightly ajar when hooked up. Don't worry about the trunk lights, they will go off automatically after 15 minutes or so.

Bill

[jmosk]

I plugged in the BMW Battery Tender that I got with the car 10 years ago. I just installed a brand new battery since the one was dead. It's been plugged in for 6 hours and the Red light on the tender is still on and the unit is very warm to the touch. I would have expected the green light to come on pretty soon since the battery is brand new. Do you think the battery tender is no good? It might explain why, when I left it connected with the old battery for 4 days, it still was unable to fully charge the battery. According to the instructions the battery had to have at least 3 volts for the Red light to even come on. The green light indicates a full charge. I disconnected the tender as it is not operating as I would have expected it. Should I replace it? I have a type that plugs into the cigarette lighter.

http://www.amazon.com/BMW-Advanced-B...6EM2K0WBSAC5AR

[hlmiii]

I plugged in the BMW Battery Tender that I got with the car 10 years ago. ... It's been plugged in for 6 hours and the Red light on the tender is still on and the unit is very warm to the touch.

Sounds okay, probably.

I would have expected the green light to come on pretty soon since the battery is brand new.

Not necessarily, and not probably. Unless especially charged prior to installation, new batteries aren't 100% charged as they used to be. Give it 24 - 36 hours before you decide there is a problem.

When first connected to a battery, and/or reconnected after even an hour or so after driving, all good tenders go through a cycling of initialization/trickle charge/maintenance. The only thing that changes is the length of the cycles. Depending upon what the tender "sees" and how it is designed the start > full charge green light process can take surprisingly long. "Warm" is okay, while "too hot to touch" isn't.

In some instances with a very depleted but salvageable battery a tender may easily take 2+ plus days to provide full charge and show a green light.

"Do you think the battery tender is no good?

Probably not, unless it has been subject to physical knocks or some pretty good power spikes.

It might explain why, when I left it connected with the old battery for 4 days, it still was unable to fully charge the battery.

No. If the battery is dead a tender, or even a formal "charger" can do nothing.

According to the instructions the battery had to have at least 3 volts for the Red light to even come on.

That is pretty much standard for all tenders. They have to have something to work with.

If a battery gets down to such a low voltage, however, the owner should plan on replacing it soon, even if the tender can revive it to allow the car to start. Once a battery is severely discharged for a long time, or several times, it won't be able to hold much voltage or current for long, nor will it be able to be accept the necessary power from the alternator.

The green light indicates a full charge. I disconnected the tender as it is not operating as I would have expected it. Should I replace it?

Not before you work through the above and give things another try. That charger in your link is very reliable and excellent for BMW's and Z8's (and it's better on Lamborghini's than Lambo's own).

I have a type that plugs into the cigarette lighter.

This connection can work, but it won't provide the same service as directly connecting it to the battery terminals. Modern cars have circuitry that puts the car to sleep and it can often interfere with the charging by shutting down the lighter->electrical system->battery path. I have found the lighter option to be even more of an issue with the Z8, probably because it has an early generation of "smart" electronics.

FWIW - I'd take your charger, wire a female socket to the battery and plug the male jack into the socket.

I've been through your experiences, so I understand your concern and questioning. Good modern tenders do not act like traditional models and most certainly not like "chargers" or "jump starters." Tenders are made to slowly dribble low current into a battery in a controlled, variable manner. They are not made to simply get a battery up to 12 volts.

Hope this helps. Post back if you need.

[jmosk]

Good information. My tender is getting almost to hot to touch. So perhaps you are right that there might be protective circuitry that is interfering with the charging. I'll look for an adapter that I can put directly on the battery as you indicated, so the tender is connected directly to the battery and not going through the cigarette lighter.

[hlmiii]

Let us know how things settle out. Good luck.

[jdillane]

My BMW tender plugs in to the lighter and works like a charm. I'll consider the eyelet connectors with my next tender.

My tender does get warm and often takes several hours before the green light activates.

[Satch]

So far I have used Battery Tenders on two Z8s and a Z4, and all use the cigarette-lighter socket. Buffy, the black Z8, eats batteries: a new Interstate battery was replaced (under warranty) after about a thousand miles; we'll see how the replacement fares. The Blue Car—Biff, perhaps?—has had problems holding a charge since I got it, but when I asked a dealer to check it, they said the battery was fine. Two dealers later, they found it difficult to start the car after two days, so they recommended—you guessed it—a new battery. Which is in the car now, happily tended.

[hlmiii]

I'll repeat that the experiences I've had with using a tender in the cigarette lighter socket of Z8's has been unsatisfying.

The electronics are similar - although not as advanced - as current model BMW's in that they are turned off after a while with no activity. "Activity" doesn't seem to be a clear event: opening a door, clicking a remote button, keeping the hood open, etc.

I have found no certain way of keeping the Z8 "awake."

So I have reached the following conclusions:
- the car needs to be "awake" at some level to utilize the lighter socket for electrical input
- the triggers that can wake up the cars and/or make is stay awake are uncertain
- keeping a door open, a window down or a trunk lid open does not keep the car awake
- the car's ability to stay awake is dependent upon the state of the battery; a good battery encourages being awake while a battery that is in less than good condition seems to make socket charging undependable
- once socket charging is not fully recognized then it is indicative that the battery needs more direct contact with the tender through the battery terminals; using clamps under the hood may not even been sufficient
- my conclusion is that the battery's need for both voltage and amperage together with the tender's need for feedback from the battery to provide that proper level of voltage and amperage means that direct connection to the terminals is the only way to ensure proper interaction and success.

YMMV.

[ron's rocket]

I'm just not comfortable keeping my car "plugged in" and unattended 24/7. It might be worth it to extend or replace the battery cable to a length that more easily accepts a quick and easy battery cutoff switch. It might be interesting to see how long that cable is beyond the interior trunk panels.

[Satch]

The easiest cut-off switch is the old battery-post disconnector so popular with the British-car crowd. You'd have to lift the trunk floor, but I could handle that... and you'd have to remember not to close the trunk all the way unless you have handy access to the pull cable!

One other problem: Batteries should be fine if disconnected while at full charge, but discharged batteries tend to go REALLY bad if they sit and sulfate. I think I'm going to err on the side of too much trust in the Battery Tender. Besides, I now own at least four of the damn things!

[riverflyer]

Couple of weeks ago I went to start the old girl and take her for a drive....dead. I put a new battery in last fall and had the car on a tender. I guess it must be a faulty tender or ??? Any other ideas?

[tonchum]

I had this problem a few times, and was forced to buy a new battery.
Now if the car will be idle for more than two weeks, I connect a CTEK Multi-US 7002 charger directly to the battery in "supply" mode for float maintenance. (I connected the cables with eyelets directly on the battery, therefore only having to use the quick connect to apply the charger). The battery is always at 100% now, and I've not had any issues since.

[riverflyer]

Denis, thanks. I have that charger set up for my SL and will try it for the Z8. Maybe the clamps are not direct enough. John

[harvey2]

I wanted to mention that it is relatively easy to snap off the bolt that tightens the battery cable to the battery terminal. Do not torque it with abandon. I do not know what its torque spec is, but I would hazard a guess that it is less than 7 ft-lbs based on my experience breaking one off. To get a replacement, I went to a wrecking yard with a few 3-series wrecks and took a couple from one of those. Anybody know the correct torque spec for that nut?

[riverflyer]

Dead battery update. I switched to hard wired charger and it still did not work. I have a new battery and it was on tender but still went dead....or so I thought. My mechanic suggested trying another key. I did and it worked perfect. After doing this, the other key worked as well. Interesting!

[Musta10000]

Interesting seeing all the battery issues (I am most likely jinxing myself right now). I had the original battery to 2013 (2002 model) and then replaced it with one for Batteries+ for about $120. The first one died quickly and was replaced under warranty. No issues since. As most of you know I do drive mine a lot, but in the dead of winter I have it on Deltran battery tender as it will sits weeks at a time. No key issues either. The issues must be related to low usage.