Using Battery Maintainer - 986 Forum - The Community for Porsche Boxster & Cayman Owners

jpc763 · 10-16-2014, 09:26 AM

Hello,

This is my first winter with my 2001 S and I plan to drive it when the Colorado sun is out and there is no ice or snow on the ground. That means that I will not know how long it will be between drives.

I also know that I will be out of town for 11 days so obviously the car will be in the Garage that time as well.

So if you know you are not driving your car for a week, do you put it on a Battery Maintainer (cigarette lighter model)? 2 weeks? Month?

I do not want to have a dead battery, but I also do not want to needlessly charge the battery.

So just checking what the tribal knowledge is out there! Thanks in advance!

John

Burg Boxster · 10-16-2014, 09:50 AM

Quote:

Originally Posted by jpc763

So if you know you are not driving your car for a week, do you put it on a Battery Maintainer (cigarette lighter model)? 2 weeks? Month?

Yes. Yes. Yes. A maintainer will keep the battery well conditioned and optimally charged.

Quote:

Originally Posted by jpc763

I do not want to have a dead battery, but I also do not want to needlessly charge the battery.

You won't - same as above

Save yourself a few $ too and look into a C-tek maintainer. They make the Porsche Charge-o-Mat II (and many other OEM maintainers) but also sell under their own brand w/ more features and flexibility for 1/2 the price...

Good luck

Flavor 987S · 10-16-2014, 10:07 AM

I plug in at all times. Sometimes the car sits for a day, sometimes it sits for 5 or 6. Always for winter hibernation (6 months). Car is not a daily driver.

rfuerst911sc · 10-16-2014, 10:10 AM

My opinion is if you know you are going away for 10 + days I would NOT put it on a charger/maintainer. Why ? Not because it will over charge the battery I'm thinking safety if something goes wrong while you are gone. Chargers are man made therefore things can go wrong. Would really suck to come home to a home/garage burned to the ground because of a faulty charger. I would pop the front hood before you leave so " if " the battery goes dead you can easily open the frunk. Then I would charge the battery while you are home just in case. Just my 2 cents.

Blackcloud · 10-16-2014, 10:14 AM

Just put a battery tender junior on the battery. Snake the cord between the trunk and windshield and you're done. It will maintain the optimal charge. When you are ready to drive just unhook the charger. throw it in the spare tire pouch, and off you go.

TeamOxford · 10-16-2014, 10:41 AM

Quote:

Originally Posted by rfuerst911sc

I would pop the front hood before you leave so " if " the battery goes dead you can easily open the frunk.

If you do this, the battery will most certainly be dead and need recharging. The frunk light will be on the entire time and drain the battery.

You should remove the frunk lightbulb first if you elect this option.

Just sayin'............

TO

rfuerst911sc · 10-16-2014, 11:15 AM

Quote:

Originally Posted by TeamOxford

If you do this, the battery will most certainly be dead and need recharging. The frunk light will be on the entire time and drain the battery.

You should remove the frunk lightbulb first if you elect this option.

Just sayin'............

TO

You're saying if you pull the front hood release but NOT open the hood the light comes on ? I don't think so but could be wrong.

jpc763 · 10-16-2014, 11:37 AM

Thanks everyone. That helps a lot. I will pick up a C Tek (I was looking at a Porsche one at Suncoast parts but the C Tek looks like a newer model).

John

Blackcloud · 10-16-2014, 11:38 AM

This is just like opening the refrigerator door......does the light really go out? LOL You can test it by locking yourself in the trunk, or take a video of the light with your cell phone. Close the trunk, view video to see if it goes out. ha ha

Meir · 10-16-2014, 11:41 AM

Quote:

Originally Posted by rfuerst911sc

You're saying if you pull the front hood release but NOT open the hood the light comes on ? I don't think so but could be wrong.

TO is probably right.

the light microswitch (9) is part of the hood latch assembly (8), and will be fully depressed only when the hood is fully closed.

pony13ca · 10-16-2014, 11:42 AM

Quote:

Originally Posted by rfuerst911sc

You're saying if you pull the front hood release but NOT open the hood the light comes on ? I don't think so but could be wrong.

You are correct. I'm looking at mine right now, frunk is released, but not poped and the light is off. This is how I put my car on the maintainer, and if I go more than a day or or 2 without driving the car I plug it in.

rfuerst911sc · 10-16-2014, 12:39 PM

OK so it looks like the opinion we have on popping the front hood and it draining the battery is a solid " we don't know "

So let's drill down further. Is it safe to assume if the hood latch is pulled, but the hood is left in the down position and the light is not on does that mean no battery draw ? Or is there " some " draw but the micro switch hasn't activated to light the bulb ? I am really curious what the answer is because these cars do seem to consume battery power at rest. Maybe it's just the security system ?

cas951 · 10-16-2014, 01:27 PM

See my pics on link below.
Front trunk and jumper cable issues
I have a Batt Tender. I purchased the adapter that bolts to the Pos/Neg cables. I then routed the charging leads towards to the windshield. When I need to hook up the charger I simply pull the lead out and connect the Batt Tender. When not in use I simply tuck the charging lead under the top of the hood.

Additional benefit: If my battery ever dies I can plug in my charger and I should be able to unlatch the hood.

JayG · 10-16-2014, 01:50 PM

Quote:

Originally Posted by rfuerst911sc

OK so it looks like the opinion we have on popping the front hood and it draining the battery is a solid " we don't know "

So let's drill down further. Is it safe to assume if the hood latch is pulled, but the hood is left in the down position and the light is not on does that mean no battery draw ? Or is there " some " draw but the micro switch hasn't activated to light the bulb ? I am really curious what the answer is because these cars do seem to consume battery power at rest. Maybe it's just the security system ?

My understanding is that our cars do have a small draw when they are sitting turned off. I believe its some of the electronics that stay powered up such as the alarm, and maybe the DME and immobiliser

To completely kill all power you need to disconnect the battery which then has the effect of erasing the stored settings in the DME/ECU. When you reconnect the battery, the car will need to relearn stuff such as air/fuel mixtures and other engine settings. It may also effect any Tiptronic settings and driving modes it has learned

I could be wrong, one of the gurus here can elaborate

pjv · 10-16-2014, 02:29 PM

I find that my Boxster battery loses charge very quickly when compared to other cars that I have had, so I connect my Ctek charger/maintainer if I don't use the car for more than 3 days ( I normally use it once a week). Because my car ('04 986, Australian market) can not be charged via the cigarette socket, I have a quick-disconnect cable direct to the battery in the frunk, so I have to leave the frunk lid open. When the lid is down, but not locked, the frunk light is on, so I have disconnected the light. Since I don't really trust battery charging safety, I disconnect the battery if I am going away for a lengthy period of time.

clickman · 10-16-2014, 03:26 PM

My frunk light shuts itself off after 2? hours.

I'm completely sold on the maintainer (CTEK in my case), and hook it up any time I'm going to leave the car for a week or more. Which includes 6 months of winter hibernation.

I even bought a Canadian Tire version for another car (I couldn't get the CTEK for the right price) and it had the desulfanation cycle that I wouldn't do without.

My understanding of batteries, limited as it is, is that they will discharge on their own (batteries in the store are always fresh, or should be). Any deep cycling is death. Get the maintainer and be happy.

keysguy · 10-16-2014, 03:42 PM

I use the Battery Tender I had to buy the cigarette adapter. I can plug it directly into the cigarette lighter port and run the thin cord out the door. I can shut the door and plug it into my extension cord. Since the cord that comes with it is thin it is not pinched when i close the door. I can leave the alarm on. You should not jump start the car through the cigarette lighter but because it's such a low voltage charge it's OK to use the battery maintainer. (from what I've been told)

Joe B · 10-16-2014, 03:45 PM

Seems like we just covered this a couple of days ago. +1 for Battery Tender Jr. I stopped bothering with one when I bought an AGM battery. Now I don't do anything unless I will not be driving for 10 days or more. Then I disconnect the negative battery terminal and remove the frunk latch (2 bolts). My computer doesn't seem to notice; I just need to reset the clock afterwards (2003 S).