Flat Battery

Andrew Killington · Aug 16, 2003

during the cleaning of the rear screen I open and closed the roof 3 or 4 times in fairly quick succession, tried to start the car but it wouldn' t[&o]
have I overdone it?
any advice would be gratefully recvd!

Andrew Killington · Aug 16, 2003

thanks Alan
are the boxster batteries particularly prone?
I had come back from a 30 minute spin, cleaned the rear screen and then nothing!
I' ve still got warranty so I guess I could use that although it seems a little trivial but I guess it wouldn' t hurt checking whether as you say there is something dud
Andy

Andrew Killington · Aug 17, 2003

thanks, sorted[

]

Mark_Bennett · Dec 24, 2005

Have you tried putting the key in ignition, then disconnect the battery?
I'm almost sure that does it...

Hannu · Dec 24, 2005

Sorry Mark,

No that doesn't work just tried it.
Key in ignition lights just about come on back to ACC batery lead off and alarm siren sounds,
thought it may be on a timer but if I leave the battery terminal off it just keeps going and going.

Rodney Naghar · Dec 26, 2005

Strange. I tried the same a while back, catch 22. But when I put the key in the ignition in position II or I (can't remember which) and removed the battery it was ok. It's described in the manual.

yan · Dec 26, 2005

An electrician may want to opine but I think you'll find that the alternator/regulator fitted to these cars let through far more charge current than a standard battery charger, i.e. why disconnect the battery?
If the Boxster has the same logic as the 911 then I have had this problem : never fathomed out how to get around it EXCEPT I don't disconnect the battery anymore when using my charger (Porsche Chargeomat - plugs in via cig. lighter so battery disconnection not implied).

Mark_Bennett · Dec 26, 2005

You may be right J, but I'll leave that to the experts as you say!
However the Chargeomat is not a "full-on" charger - it's a conditioner, and as such is designed to be used with the battery comnnected.
However the "normal" battery chargers are supposed to be used on disconnected batteries, unless electricians can advise they are safe after all?

jac in a box · Dec 26, 2005

Before disconnecting battery: key in ignition and turn so warning lights come on, disconnect battery -ve terminal then +ve terminal.

To reconnect; key in ignition turn to same position as above, connect +ve lead, then -ve lead.

Connecting standard battery chargers with the battery connected can damage the alternator diodes...don't do it!

To avoid getting in this situation try something like an "Accumate" charger - designed to be left connected safely to the battery (while connected) without fear of ocercharging etc. Great piece of kit

Hannu · Dec 26, 2005

Many thanks for all your advice, I will try again tomorrow, been full of the Flu since it when dead so have not needed the car.
Guess what I got for Christmas ! an optimate 111 battery conditioner, Three days to late me thinks

many thanks again to you all, Who needs OPC with you lot ?.

cFirth · Dec 27, 2005

Firstly what I have to say relates to a facelift MY04 Boxster. Other versions may be different.

The next question is why the battery discharged in the first place. In my case it is caused by forgetting to lock the car when it is in the garage. The battery will discharge in 3- 4 days if left unlocked. When locked the alarms and central locking will go to sleep after 4 days thus saving the battery. The doors can only be opened with the key in the door lock.

I have been told about the key in the ignition but it has not worked for me. However I have only ever disconnected a very flat battery. My OPC told me that when the battery voltage drops below a certain value (IIRC 9v) anything can happen with the electronics. Therefore it seems to me to be too optimistic to believe that when nothing else electronic works the alarm can be disconnected by the key in the ignition.
My only help is to say that the alarm will stop eventually (about 5 mins). I have a pair of ear defenders I wear as I disconnect the battery, and keep the garage doors shut. Not something to be tried in the open late at night if you wish to remain friendly with the neighbours.

Hannu · Dec 27, 2005

Many thanks, it worked,
I knew there must be a simple answer.
ingition on - side battery off + side battery off and just one small beep out of the alarm. Battery now on trickle charge.
In answer to cFirth its simply because the car gets little use and when it does its just short jorneys.
will have to make use of the optimate and give her some good runs in the new year.

Thanks again,

Guest · Dec 27, 2005

I use a regular charger on a 2-hours-a-day timeswitch, works perfectly. It'll do a couple of weeks fine on it's own but I always like a full battery.... my battery is always connected to the car.

Most regular chargers are full-wave-rectified but un-regulated. However they are all of the voltage that only gives you about 1 Amp when charged as the voltage difference between the battery and the charger is quite small at this point. Therefore when I connect up the charger if it shows 3 or 4 amps I know the battery needs the charge..

Careful of the Opimate type chargers - if you unplug them from the mains they slowly drain you battery (or at least mine does - another reason I use a timeswitch...)

David W. · Dec 28, 2005

Just a thought and to late for Hannu, but if you can connect the car leads to a Booster pack or similar
http://www.tools241.com/draper_tools_341_power_pack.htm
before disconnecting main battery (I know it may be difficult to keep everything connect when you do this) it will save alarm going off as well as saving radio codes. You can then charge or change battery safely.

DW

Hannu · Dec 28, 2005

HOW MUCH !!!!!

Sorry David but I think I'd rather put the codes back in.

Thanks for the though anyway.

On another subject, I've just come back from taking my son to the local car rally at Park Hall, Camelot, here in Lancashire.
Never been to a rally since I packed up in 1984 because I knew I'd get the urge again,
Anyone want to buy a Boxster ? or exchange a decent rally car ??

Only joking, I think.

Tool Pants · Dec 28, 2005

In the UK you have a horn and a siren for the alarm. We have the horn but not the siren in the US, so I have only seen pictures of your system. The horn is round metal on the end of the main battery. The horn runs off the main battery. The siren is black and red on the other end of the main battery, and it sits above the tilt sensor. The siren has a built in rechargeable battery. If someone disconnects the main battery to defeat the alarm then the siren will go off since it has it's own battery.

Therefore you are supposed to turn the ignition key on before you disconnect the main battery so the siren will not go on. No clue why this procedure is not working for you. Is there a way to disconnect the siren before you disconnect the battery?

Mark_Bennett · Dec 28, 2005

I did think it was key in ignition... I just didn't say to turn it [

]

Disconnecting the siren will set it off - which it is meant to do, so that you can't just disconnect it and steal the car. (Not without a pair of ear defenders, and attracting a lot of attention anyway!)

I think everything is working ok in this case, it's just I missed saying turn the key to the 1st or 2nd position?

David W. · Dec 29, 2005

ORIGINAL: Hannu

HOW MUCH !!!!!

Sorry David but I think I'd rather put the codes back in.

Thanks for the though anyway.

Hannu,
yes a bit pricey perhaps but once you have one (and they can be found cheaper) you may use it as a power source when camping, at a show or race track for the weekend, jump starting anything from car to mower, leave in the boot if you leave your car in airport carpark while on hols for 2-3 wks. They often have an inbuilt light and I think I have seen one with inbuilt compressor.

DW

Glyn · Dec 29, 2005

You do not need to disconnect the battery before putting it on charge, unless of course you intend to connect a commercial booster charger.
The standard domestic battery charger typically outputs 15 volts with a maximum of 12 amps although most only output 2 to 4 amps, It is perfectly safe to charge without disconnection.
The alternator cannot be damaged by charging, the diode pack within the unit provides a one way circuit for voltage, when you switch on the ignition a voltage supply is passed to the alternator "Exciter" circuit and only then will there be a current generated.
With the ignition "off" the alternator is only vulnerable to high amperages (such as an electric welder being used on the car)
A "trickle charger" may be connected and left overnight.

Dont forget to cover the battery terminals when you attach the charger leads and close the bonnet as they may touch the metal bonnet and create a short, I place the plastic battery cover over the battery with the charger clamps attached and put down the bonnet (without fully closing) also disconnect or remove the bulb for the bonnet interior light

Glyn

penfold944 · Dec 29, 2005

Well having seen a half burnt out boxster in the workshop of my local OPC - I'm defintately offering any opinion on how to charge a battery - except perhaps out of the car.

It was pitiful to see - one half of the car with the paint burnt off it and half the interior melted away. All from leaving the car on charge overnight....

*shudder*

Alan