[orton]

Had an interesting day dealing with a dead battery. Sunday I tried to start the 2017 Boxster and just got a click. Could not work on it then, so Tuesday returned to work on the problem. Sunday tried to open hood to view battery but that was not possible because latch is electric and no power means no hood open. Read the owners manual and it states that a separate battery must be used to power a contact in the driver side fuse block before hood can be opened.

So Tuesday I went back to work on the car. By Tuesday no click. Could not move car because electric parking brake was on. No power means car can not move. Tried to apply power from a 9 amp-hr 12 volt power pack but that blew the power pack fuse. So larger battery required. Removed the battery from my tractor and that did get the hood open. Brake still would not release.

Measured voltage and it was at 5.85 volts. Did read the owners manual that stated car must be driven every 5 days or the computers will run down the battery. I had driven the car a week earlier for 2 hours but that apparently was not enough to charge the battery. Light switch was not on nor were there any other power being used that I could see.

So connected a 5 amp battery charger to the battery positive post and to the remote negative post near the left front spring. Manual does state that the negative should never be connected to the battery negative terminal. So kept trying to start vehicle as the voltage increased. Finally after 5 hours when battery measured just over 12 volts the engine started. Then I also could release the parking brake. Apparently computer will not allow vehicle starting until about 12 volts is reached.

End result is wishing I had an older simpler vehicle without computers.

Wrote this to give some warning to others and explain what is required to get he car running. Also be aware that the electric parking brake immobilizes the vehicle with a low battery.

Still suspect a bad battery. Have others experienced battery failure after 3 1/2 years? Will monitor the voltage for next few days.

 

[Third]

In my experience, four years is the typical service life of a car battery, and the ordeal of a dead battery in a Cayman/Boxster, as you have experienced, is enough to drive many to rely on a battery tender during idle stretches, and to replace the battery preemptively before it dies. 3-1/2 years is a bit soon, but not unusually so. You didn't say, but your 2017 may've been built in late 2016 with a battery that itself was a few months old when it was installed. In any event, time for a new one! (Battery or car!)

 

[sobiloff]

Just think of it as an opportunity to upgrade to an AntiGravity battery that has a built-in "jump start" feature so if the primary charge is used up you can remotely engage the reserve charge and get going immediately. H7/Group-94R Lithium Car Battery – Antigravity Batteries

 

[Jack]

Just think of it as an opportunity to upgrade to an AntiGravity battery that has a built-in "jump start" feature so if the primary charge is used up you can remotely engage the reserve charge and get going immediately. H7/Group-94R Lithium Car Battery – Antigravity Batteries

1.000 bucks for a battery ????? I prefer to invest in tyres and something else....

 

[DriveInHouston]

...Tried to apply power from a 9 amp-hr 12 volt power pack but that blew the power pack fuse. So larger battery required. Removed the battery from my tractor and that did get the hood open. ...

Did you try to use a LiIon jumpstarter or just a charge storage unit?

I have a 12000 maH jumpstarter and I have jumpstarted my Mustang GT V8 monster and my wife's BMW 328i in separate occasions.

Could you please clarify?

 

[orton]

Did you try to use a LiIon jumpstarter or just a charge storage unit?

I have a 12000 maH jumpstarter and I have jumpstarted my Mustang GT V8 monster and my wife's BMW 328i in separate occasions.

Could you please clarify?

Did not have a Lilon jumpstarter. Do not know if that could be applied to the fuse block so hood could be opened to access the battery. First you have to get the hood open to get to battery. I would expect the jumpstarter to work after you have access to the battery.

I used a 5 amp trickle charger so had to wait to get the vehicle battery voltage high enough to start the vehicle.

 

[DriveInHouston]

Did not have a Lilon jumpstarter. Do not know if that could be applied to the fuse block so hood could be opened to access the battery. First you have to get the hood open to get to battery. I would expect the jumpstarter to work after you have access to the battery.

I used a 5 amp trickle charger so had to wait to get the vehicle battery voltage high enough to start the vehicle.

There are many ways to connect the Li Ion charger to the car. I haven't pulled the red pole at the fusebox to see whether the standard tethed clamps would work...

What did you use at the fuse box and blew its fuse? I understand that you used a trickle charger to charge the dead battery instead...

For the rest of the audience, this is the procedure we are talking about:

 

[JakiChan]

I keep my car on a tender. One thing I've wondered is if the battery is gone can the tender provide enough juice to at least get the hood open? (I got suckered into the official Charge-O-Mat Pro.)

 

[Third]

I keep my car on a tender. One thing I've wondered is if the battery is gone can the tender provide enough juice to at least get the hood open? (I got suckered into the official Charge-O-Mat Pro.)

As long as the battery is simply degraded (ie, it can be charged although it may not hold a charge, or can't supply enough current to turn the starter motor), then at the very least you should be able to operate the electronics including the frunk latch relay while on the tender.

 

[orton]

As long as the battery is simply degraded (ie, it can be charged although it may not hold a charge, or can't supply enough current to turn the starter motor), then at the very least you should be able to operate the electronics including the frunk latch relay while on the tender.

That did not seem to be the case. Started with battery at 5.85 volts. The hood release would not work and the emergency brake could not be released. So no access to battery and car could not be moved. Can not attach the charger to battery if you can not access the battery.

 

[orton]

There are many ways to connect the Li Ion charger to the car. I haven't pulled the red pole at the fusebox to see whether the standard tethed clamps would work...

What did you use at the fuse box and blew its fuse? I understand that you used a trickle charger to charge the dead battery instead...


View attachment 27289

I did pull the red pole out from the fuse block. My first try to open the hood was connecting a small 9 amp-hr AGM battery with positive to the pole and negative attached to the door hinge. That attempt failed because it blew the 7.5 amp fuse in the power supply. (I made the power supply to power my shower water pump in my RV conversion van.) Thought that would be enough to power the latch release. It was not so I now know more than 7.5 amps is required.

Second attempt was removing my 18hp tractor battery and carrying it to the Porsche driver door location. Used regular jump start cables to attach battery to the pole and door hinge. That was successful to open the hood but not to release the emergency brake..

Used a 5 amp charger. Kept trying to start the vehicle as the voltage increased. Used voltmeter to record the voltage. Finally at 12.02 volts it finally started. Suspect the computer does not allow a start below 12 volts.

Last bit of information was the voltage increased to 12.56 volts after I drove the car for an hour late yesterday without lights. At 1:00 PM today before driving it, the voltage was 12.47 volts so very little voltage loss overnight. Will continue to check the voltage. If Boxster is so sensitive to voltage it would be nice to have a voltmeter in the information display.

I had driven the car for 2 hours a week before battery discharged. No warning lights about battery issue.

Just reread your question about the blown fuse. Fuse was not a Porsche fuse. It was a fuse I had installed in the 9 amp-hr portable power supply.

 

[Third]

That did not seem to be the case. Started with battery at 5.85 volts. The hood release would not work and the emergency brake could not be released. So no access to battery and car could not be moved. Can not attach the a charger to battery if you can not access the battery.

Right. I'm sure the battery has to be charged to roughly 12 volts before the car's electrical system will respond. Battery tenders have adapters to charge via a cigarette lighter or auxiliary power port. That's how you get around having to open the frunk to charge the battery. The best option I've found is to leave the hood unlatched if I plan to leave the car parked for an extended period of time. (Remove the frunk light bulb if you do!) That avoids the problem of battery access entirely. Keeping a battery tender attached 24/7 should avoid the problem too.

 

[Barryng]

Would a 9 volt battery connected as described above be sufficient to release the front trunk latch?

I realize this question is probably mostly rhetorical until someone tests it. Nevertheless, this thread got me thinking about a reasonably practical method of getting access to the car battery when, say, away from home territory and maybe in the isolated parking lot of a Motel 6 surrounded by cornfields in Iowa. A nine volt snap on connector (with alligator clips on each lead) could easily be kept in the glove compartment and a new nine volt battery is available at every drug store and probably gas station.

Its unfortunate 5 Volts would not be sufficient because many devices with batteries that charge from a USB connection can also be used to charge other devices. For example, my iPad mini, with a lighting to mini USB cable will charge a small Li ion flashlight I have with a mini USB charging port. Or is it unfortunate? The original thread stated the battery was at 5.85 volts. However, that battery, due to its age and state of discharge, may not have been in great health and likely was suffering from exceptionally high internal resistance. This means the voltage dropped to almost nothing as soon as it was asked to supply any load, even a small one like the release motor. So, again, from a rhetorical perspective, testing would be necessary but would a healthy 5 volt battery do the trick?

On old fashioned cars, where electronic switches did not mediate everything, just plugging a nine volt battery into a cigarette lighter would at least energize the entire electrical system sufficiently to change a battery without losing radio etc. memories. I would not risk trying this on any new car now.

 

[Third]

I did pull the red pole out from the fuse block. My first try to open the hood was connecting a small 9 amp-hr AGM battery with positive to the pole and negative attached to the door hinge. That attempt failed because it blew the 7.5 amp fuse in the power supply. (I made the power supply to power my shower water pump in my RV conversion van.) Thought that would be enough to power the latch release. It was not so I now know more than 7.5 amps is required.
...

I'd be surprised if the latch relay required more than an amp. I suspect there were other loads turned on, or the drained battery itself attempted to draw more than 7.5 amps. (A battery charger as opposed to a general power supply has current limiting circuitry beyond a simple fuse of course.)

 

[DriveInHouston]

Orton, this last post was very informative. One last question, when you connected your 12V 9Ah battery, did you have the key on the ignition? I think you can leave it out altogether and you can still unlatch the frunk with the emergency procedure.

 

[antennahead]

Stupid question here guys. Would I be correct to assume that "if" I have a dead battery, the trunk in the rear can't be opened via the door sill switch either, once the door is unlocked with the emergency key? Like DIH, I too have a jumpstarter that works great, but it just dawned on me it's in a case in the rear trunk Time to move this to the glovebox me thinks

 

[Third]

Stupid question here guys. Would I be correct to assume that "if" I have a dead battery, the trunk in the rear can't be opened via the door sill switch either, once the door is unlocked with the emergency key? Like DIH, I too have a jumpstarter that works great, but it just dawned on me it's in a case in the rear trunk Time to move this to the glovebox me thinks

No such thing as a stupid question! And I think your concern is founded. No, you won't be able to open the rear trunk via the door sill switch if you have a completely dead battery. That said, it's possible to find yourself in the situation where the battery has sufficient capacity to open the trunk, but not enough to operate the starter motor (to start the car.)

 

[Third]

No such thing as a stupid question! And I think your concern is founded. No, you won't be able to open the rear trunk via the door sill switch if you have a completely dead battery. That said, it's possible to find yourself in the situation where the battery has sufficient capacity to open the trunk, but not enough to operate the starter motor (to start the car.)

I should've added that yes, it would be a good idea to move your jumpstarter elswhere in the car!

 

[orton]

Orton, this last post was very informative. One last question, when you connected your 12V 9Ah battery, did you have the key on the ignition? I think you can leave it out altogether and you can still unlatch the frunk with the emergency procedure.

Do not recall if key was in the ignition.

 

[orton]

Stupid question here guys. Would I be correct to assume that "if" I have a dead battery, the trunk in the rear can't be opened via the door sill switch either, once the door is unlocked with the emergency key? Like DIH, I too have a jumpstarter that works great, but it just dawned on me it's in a case in the rear trunk Time to move this to the glovebox me thinks

That is correct. Neither the hood or trunk would open with low voltage battery.