Battery Tender and Full Car Cover

[graytech]

Based on some of the posts I've read here I plan to buy a "battery tender plus" to maintain my battery over the winter months.

Can I still fully cover my Z4 with the battery tender plugged in and running? Is there a risk of fire, explosion or some other reason?

[scottpettit]

[XZ-Driver]

I amtrying to do the same thing with my Z4M but outside of the garage. Where do you plan to hook up the tender? I was thinking of running the cord from the battery out throught the trunk. Still looking at how the battery cover comes off in the M so I can access the battery.

[Penguin]

You could always connect it to the jumper terminals under the hood... that's where BMW recommends chargers be connected.

[XZ-Driver]

That may be what I end up doing. I still need to figure how to take the cover off since the battery is 4 years old and some day it will need replacing. I guess I need to spend some time in the trunk to figure it out :-).

[Tm.K]

Take a look at this video and it will show you how to take the battery cover off. /www.youtube.com/watch?v=EHIfb0CW7cE

[XZ-Driver]

I just received the battery tender on Friday. I have decided to connect to terminals under the hood. I discovered that I can run the tender wire up through a gap in the back of the hood by the front fender and the driver's side windshield wiper. There is a gap at the rubber gasket next to the dirver's front fender to run the wire without crimping the cable. I can then close the hood and everything is good. BTW does anyone know how long the battery will stay sufficiently charged without any recharging? My Z3 would be left 5-6 weeks without any recharging and it would start up fine. My friend's Porsche cannot get beyound 1-2 weeks befroe the battery is dead.

[kimo]

I realize I'm coming VERY late to the party here, but here are some data points for future searchers.
Once a battery is discharged below 80%, sulfation begins to occur and irreparable damage begins. The end result is a battery that will need to be replaced before it otherwise should.
Batteries in garage queens and other NON-daily drivers begin to discharge quickly, resulting in this sulfation, thus A BATTERY TENDER IS ESSENTIAL TO BATTERY PRESERVATION in these types of vehicles.
Smart tenders are NOT the same as trickle chargers. Stay away from the latter.
Deltran is the world's top producer of smart tenders, both in terms of sales, research and quality. Many other smart tenders, i.e. Griot's, BMW, etc., are simply re-branded Deltrans.
The Deltan Battery Tender Plus is a first-class product, available on Amazon for about $45.
I have a 1992 BMW 850i, with TWO parallel batteries, that would otherwise fully discharge in less than a week (yes, it is THAT power hungry even at rest).
This garage queen is kept under a cover, with a Deltan Battery Tender Plus connected directly to pigtails on the terminals of one of the two trunk mounted batteries, cord exiting out of the closed trunk, 24 hours a day, 7 days a week, 365 days a year. It has been so connected for almost 10 years.
It starts first time, every time it is called upon to do so.
The original batteries in this car lasted 15 years!!!
I had a Mercedes SL with a single battery similarly connected, but covered OUTSIDE, for 12 years. Though driven more than the 8er, this car also started first time, every time, and the batteries lasted forever.
Mike

[Penguin]

I agree that the Battery Tender is one of the best, and perhaps the best, charger around and works well for long-term storage... I've used them for many years. That said, some people are moving to the CTEK chargers as they use a "Pulse Mode" when attached for long-term storage, vs. the constant float charge of the Battery Tender, which theoretically should reduce sulfation. I now have, and use, both; however, cannot speak to the potential benefits of pulse vs. a straight float, as the differences are long-term and subtle, requiring a lot of testing and data to confirm. However, the theory behind the benefits of pulse charging makes sense, so I have been using my CTEK for storage charging of my motorcycles.

FWIW, Bavarian Auto sells both, but recommends the CTEK for storage.

[XZ-Driver]

I will be using the Battery Tender from Deltran. I never did use a charger with my Z3 and the battery lasted 7 years. I would occasionally driven it in the winter once every 4-5 weeks and the car wold start easily. My friend has a Porsche Cayman and the battery is dead withing 2 weeks. He was not using any tender or charger and ws purchasing a new battery every year. Battery tender was $53 with accessories. Worth the price.

[lool]

Does CTEK work for GEL type motorcycle batteries? It says lead acid on the charger.

[FM]

Depends on the model. This says it works on gel batteries:

http://smartercharger.com/ctek-multi-us-3300/

[scottpettit]

of my cars from the 1913 Model T to the Z8 and they work great. You can get them on sale for 19 bucks. They are regularly $29.00.

Cheers,

Scott Pettit