Battery Maintenance Issues

[Dougler]

hi, I wonder if you folks might be able to help please. I've got a 1998 Boxster 986 and I don't have a driveway or a garage (I live in London...). The car gets used fairly regularly, but these days, it only has to be undriven for a few days before I notice the battery is less than optimal > drained. The constant draining of the battery, charging, replacing etc is I fear, having a negative impact on the ECU - Both my Remote Key fobs have stopped working, which may or may not be related - either way, I'm guessing it's not good for the car.

I'm assuming there's an electrical drain somewhere that needs to be tracked down and fixed, but in the meantime, has anybody got any advice on how to keep the battery topped up, when I don't have access to a plug socket? I've tried the solar panel/cigarette lighter option, and it doesn't work - presumably because it only works when the socket is active and when the ignition is off and it's locked, it's not. I'm going to try connecting the solar panel directly to the battery and trail the wires under the passenger door, but sadly, local hooligans will quite likely feel it's a right laugh to yank those out for me. So I'm somewhat wary about that option.

Does anybody have the same issue, would love to hear your solutions. Many thanks.

 

[Chappelle]

For what it is worth, the cigarette lighter socket in the 987 remains live all the time - I'd expect this to be the case with your 986. I have my 987 on a trickle charger plugged into the centre console.

There will be some battery drain all the time. My guess is twofold: first your car battery is on the way out, secondly the solar panel is just not up to the job of providing enough juice to maintain the battery. The solar panels I have experience of are simply **** and provide hardly any power.

Good luck; must be members out there who have this cracked

 

[Chappelle]

I've just had a quick look at one of the CTEK manuals

https://www.ctek.com/storage/6522FAFFDFC6509C58E0C50EB850A653769954DBC2033E7ABB1ACA8B5FF11526/d4c71f1fcf354b37bdfb3841d00adafd/pdf/media/122f6a27af714a64bb4c1a23efa9d074/MXS_5.0-manual-low-UK-EN.pdf

Surprised but it charges at 5A. Therefore you'd need a chunky 5A 60W solar charger to do the same thing (but without the sophisticated charging cycles)

 

[Motorhead]

Doug,

Unfortunately I don’t have a solution to your predicament but there was a discussion on the Cayman forum a while ago about solar panel battery charging which if I recall correctly indicated among other things that a large panel was required and that the battery needed to be charged fully for the charger to maintain the battery condition even in ideal (sunny) circumstances.

I had a thought that maybe a jump starter pack could be left connected permanently to the battery to keep it topped-up but I think not since there’s no battery overcharging protection function as far as I’m aware. Having said that, if you don’t have one already it would be a sensible purchase because you could use it on a regular basis to take the load off the battery when starting the car.

Jeff

 

[Dougler]

Thanks very much for the reply/ thoughts. The Solar charger I have isn't a 5w output, but it is 'supposed' to put out 4.8w, and is advertised as being ideal for keeping a 12v battery maintained. The battery I have is brand new (this is has been an issue for a while, which has meant I've needed to buy new batteries as they fail). That being said, the description states a 4.8W output, but the instruction manual, states a peak output of 2.4w....Which if true, could be why it's not working. Not juicy enough....but again, it does say it's supposed to maintain a 12v battery.

The one I have is this....https://www.amazon.co.uk/AA-Essentials-AA1432-Battery-Charger/dp/B084M5ZL5L/ref=sr_1_3?adgrpid=126919852223&gclid=CjwKCAiA9tyQBhAIEiwA6tdCrJTOYHW6MkPRkfvO1-iy5-U0zENzvj81gkF8C4EFM5I3lxU0KrmWcBoCY2MQAvD_BwE&hvadid=551678296053&hvdev=c&hvlocphy=1006886&hvnetw=g&hvqmt=e&hvrand=5665954306849615720&hvtargid=kwd-506204015493&hydadcr=24866_1723644&keywords=aa+solar+car+battery&qid=1645709968&sr=8-3

I'd always been told that the cigarette lighter method wouldn't work, but I ignored it and tried anyway. It didn't seem to work, so I just figured it's likely that the cigarette lighter socket wasn't active.

I'm going to try again by attaching the solar panel up directly to the battery, but before that I'm going to test the output from the panel and see if it's actually putting out what it should be. It could certainly be that a. The product doesn't actually output what it advertises or b. It's not working at all.

The Solar charger also has an EOBD connector which I've also tried, and that doesn't seem to work either.

 

[Dougler]

Jeff....I had a similar thought.....maybe having a charging unit, ready charged....that has a standard plug socket on it.....then connect that to a CTEK trickle charger, and connect to the battery. All stored neatly inside the front boot.....bit of a hassle though....If I could get a solar panel to work, it would be ideal.

 

[AndrewCS]

Remotes have their own batteries don`t they ?

Have you measured / noted battery voltage before and after / during running ?

Take it to an auto-electrician to check for excessive draw down, older cars often suffer from issues with items such as sat nav, stereos etc

 

[Dougler]

Andrew - yes, the fobs have their own batteries, my concern is more, whether the constant battery drain/rechage/replace has had an effect on the ECU and possibly the remote locking system.

The battery I put on recently was at 13.5-13.8v when I checked with a multimeter. I didn't check it after I'd driven it, to be honest.....now I'm wondering if that's the issue.....the battery isn't being effectively charged by the alternator....that's a definite possibility.....but surely if that were the case, after a long drive, it would fail to start due to not having enough juice? Yeah, agreed on the older cars and the electrical draw down, but this has nothing extra in it, not even A/C - even the radio is the standard factory fitted Becker CDR-22

 

[jockmog]

If the car isn't driven for a few days the remote key fobs will not operate and the driver's door will have to be opened with the key and the fob quickly pressed to prevent the alarm from sounding. Are you sure that there is definitely a problem with the fobs? I use solar chargers plugged into the OBD port on 2 Audis which are parked outside and they seem to work well at maintaining a charge, but they would not recharge a battery which had gone flat. On my 987 I use a CTEK plugged into the socket on the transmission tunnel which is live all the time, although I believe that on later 987's there is a time limit on how long the socket stays live after the car has stopped.

 

[Dougler]

Jockmog - Yep, aware of the sleep function....this isn't that. This is.....after 5+ days, I can't even get into the car at all, because the battery has died. I have to pull the manual bonnet release catch, get to the battery, jump that then I can get into the car.

 

[AndrewCS]

This is.....after 5+ days, I can't even get into the car at all, because the battery has died

Check the running - charging voltage when you first start it, then again when you return from a run ... does the car have an instrument panel voltmeter ?

Something seriously amiss being flat after five days, auto-electrician required ...

 

[laura]

With regard to the key operation, the key will send a radio signal to the car to activate the central locking. If the car battery is flat then the central locking won't work regardless of how good the key battery is. That's my girlie theory anyway!

Does the driver's door unlock if you insert your key in the door lock? Then you could open the bonnet from the live contact on the fuse board.

It does appear you may have another problem though - maybe alternator?

Laura

 

[malarcy]

If you haven't already checked - then make sure there is no water making its way into the car, especially under the passenger seat - blocked roof drains are the typical cause of this - and the unit under the seat in the 986 is the Alarm Control Unit (ACU) - if thats wet it could account for both fobs not responding and for current drain - hope it's not that because its expensive to fix if water damaged - but worth a check - not just the surface of the carpet but the foam underneath.

 

[stephentodd]

On your 986 the cigarette lighter socket is live all the time, it does not go off when car is locked. My car spends all winter hooked up to a CTEK charger.

 

[Dougler]

Thanks all for the comments on this one.

Update: I had the car checked by an auto electrician. No detectable battery drain...so seems I'm no closer to determining why the battery drains if it's not used for a few days. Cigarette Lighter is not live when engine is off. Key Fobs - both are flashing but only 1 is sending a signal. Needs to be re-synced to the car, cost of having that done, at Porsche main Dealer, £131 (inclusive of VAT). OEM Replacement Plastic Fob/Transmitter (minus the actual metal key), from Porsche is £170 (inclusive of VAT).

I think my next step will be to find a solar panel charger that will a. Charge at a decent rate and b. Remain effective enough, with the panel behind glass.....and then I'm probably going to try and find a way I can make a hole through the passenger footwell area, into the engine bay so I can connect the solar panel charger directly to the battery.

As an aside, I've tried the 'Live connection on the fuse board' approach to getting the bonnet open but I've never been successful. Also, my primary aim is to try and stop the battery from draining, as I fear the constant drain/charge cycle isn't great for the car or battery. Also checked the water ingress around the ACU - No issues there.

 

[Ian_959]

I would suggest the early cars do not have a constant live cigarette lighter like the later models, so battery maintainers need to connect to the battery terminals. Battery's at a push last about 3 years if not used daily as Car batteries have a finite lifespan you will see that batteries gradually deteriorate until they can no longer provide enough power to start an engine. This wear time could take three to five years and a vehicle's usage pattern is one factor contributing to the rate at which a battery will age so is the climate. Perhaps try the solar panel option via the battery or test your cigarette lighter socket as I am sure it is not live with the key out. Or have a quick disconnect battery set up and keep it indoors on maintenance charge

 

[marc_tt]

We had a similar issue and turned out to be a defective battery (that was still under warranty). Found out by swapping the battery with the battery from our people carrier and car was then fine with the other battery and the defective battery was then replaced under warranty.

The cigarette lighter socket on our 2001 986 is constantly live and as we use the car infrequently we tried using a solar panel connected via the cigarette lighter socket and found that had to place the panel outside the car as inside the windscreen significantly reduced the output from the solar panel.

We now remove the battery approx every 6-8 weeks, before low battery sets the alarm off, and trickle charge it overnight and plug a jump starter into the cigarette lighter socket when we remove the battery as car needs to be powered to lock it (as there is key lock only on drivers side).

Remember, to switch key switch to at least position 1 (accessories on) before removing the battery to prevent the alarm going off. Also, avoid running the battery flat as it can substantially reduce the battery capacity / life.

Porsche advised me that removing the battery / power has no impact on the ECU (it does clear any error codes) and the ECU quickly resets on starting the engine.

Hope this helps

 

[Dougler]

Thanks everybody for the advice & guidance. I've been told, that it's common for battery issues to be caused by a faulty control unit under the passenger seat, but I'm not having any other issues that might be caused by that.....so I'm still a bit stuck. It may just be, that the older Boxster are just battery hungry, and I just have to live with it.