Trickle charging 12V battery in Taycan through OBDII port?

[Gino]

I’ve connected a trickle charger to my 2006 Dodge Sprinter through the OBDII port and it works perfectly to maintain my engine starting battery.
I’m hoping I can add a trickle charger to my 2021 Taycan to always keep a trickle charger connected to maintain the 12V Lithium battery.
My service advisor didn’t know if this is possible and I assume I should be able to do this as long as I use the proper trickle charger for lithium batteries.
I’m hoping someone out there will be able to guide me since I don’t want to risk attaching a charger to the IBDII port and causing a problem or damage the 12V battery.

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[wmras]

I’ve connected a trickle charger to my 2006 Dodge Sprinter through the OBDII port and it works perfectly to maintain my engine starting battery.
I’m hoping I can add a trickle charger to my 2021 Taycan to always keep a trickle charger connected to maintain the 12V Lithium battery.
My service advisor didn’t know if this is possible and I assume I should be able to do this as long as I use the proper trickle charger for lithium batteries.
I’m hoping someone out there will be able to guide me since I don’t want to risk attaching a charger to the IBDII port and causing a problem or damage the 12V battery.

It is possible, but you may have to increase the OBDII port fuse slightly (4 to 5 Amps? - check the manual or fuse box). The smallest, simple wall-plug Battery Tender has slightly more current than the fuse rating on our Taycan. It works for us.

 

[Gino]

It is possible, but you may have to increase the OBDII port fuse slightly (4 to 5 Amps? - check the manual or fuse box). The smallest, simple wall-plug Battery Tender has slightly more current than the fuse rating on our Taycan. It works for us.

I was reading some articles which said the Taycan fuse is 5amp on the OBDII port. If this is the case I should be able to use a 3A or 4A lithium ion battery trickle charger to simply make sure my 12v battery is always maintained perfectly. I used to put a small 1.5A Battery Tender connected to the cigarette lighter outlet on my 2000 Porsche Boxster since it would sometimes sit for months without being used. This worked perfectly but my Porsche dealer told me I can’t charge the 12V battery through the cigarette lighter outlet. Not sure why unless they intentionally power the cigarette light port from the main battery to avoid draining the 12V battery down.
It appears you have been able to put a trickle charger on your Taycan connected through the OBDII port successfully.
I’m hoping I can simply connect a lithium ion trickle charger to the OBDII port every time I park it instead of having to open up the hood and connect the trickle charger directly to the 12V battery which would be a pain in the ass to do all the time.
Any advice is greatly appreciated. Thanks

 

[daveo4EV]

after Porsche fixed the horrible no good 12V battery death problem while plugged in - I had no further problems with 12V drain - and the big battery charges the little battery when it needs to - even when the car is left alone.

why are you concerned about this - Porsche's instructions to leave the vehicle plugged in should maintain both the 12V battery and big battery.

I'm not sure what problem you're trying to avoid?

of all the problems with the Taycan the 12V battery dying is not the one I'd be focusing on.

 

[SteveDC]

after Porsche fixed the horrible no good 12V battery death problem while plugged in - I had no further problems with 12V drain - and the big battery charges the little battery when it needs to - even when the car is left alone.

why are you concerned about this - Porsche's instructions to leave the vehicle plugged in should maintain both the 12V battery and big battery.

I'm not sure what problem you're trying to avoid?

of all the problems with the Taycan the 12V battery dying is not the one I'd be focusing on.

I had my 12 volt die on me just a few days ago. Car was left for about 3 weeks. I had previously left the car for similar periods without issue. I’m concerned that a dashcam I installed (Viofo 2 camera set up) may be draining battery *during use while driving* such that, when parked, even where I use a kill switch to disconnect the cam, there may not be sufficient remaining charge at vehicle shutdown to avoid another brick situation. There’s a problem somewhere. Maybe you have to drive it a minimum number of hours each week, or some such rule.
A related issue, assume the 12 volt is just about to fail, how long does it take to restore full charge when the vehicle is then turned on? You can’t tell from the dash display, it seems. I’ve read here that you cannot rely on the 12 volt voltage display on the dash to judge the SOC of the 12 volt.

 

[Gino]

after Porsche fixed the horrible no good 12V battery death problem while plugged in - I had no further problems with 12V drain - and the big battery charges the little battery when it needs to - even when the car is left alone.

why are you concerned about this - Porsche's instructions to leave the vehicle plugged in should maintain both the 12V battery and big battery.

I'm not sure what problem you're trying to avoid?

of all the problems with the Taycan the 12V battery dying is not the one I'd be focusing on.

I have 3 vehicles at the moment and I keep a trickle charger on the 2 ICE vehicles to make sure the starting batteries always are fully charged.
I wanted to do the same with my Porsche Taycan so worst case if my 12v battery does die I will be able to charge it through the OBDII port.

 

[satchurator]

The right thing to do here is to get Level 2 charging installed in your garage. That will cost less than repairing a fried ODBII port, and will solve for tending to the 12V LV battery. One non-improvised thing to plug in and have peace of mind.

If you are very reluctant to add a 50A circuit for L2 charging, you could still have an electrician come check your current setup and tell you if you are safe to run 12A continuous through your 110V garage outlet. If there is good quality cable, a good quality outlet, nothing else sharing the circuit, and a dedicated 15A or 20A circuit and breaker, you should be fine to run level 1 charging indefinitely with a high quality charger.

The Porsche guidance on max 8 hours @ L1 is accounting for the flaws of the PMCC and PMC+ chargers, combined with the likelihood of crappy older home wiring and the risk of other draws upon the same circuit.

 

[Charlie]

I’ve connected a trickle charger to my 2006 Dodge Sprinter through the OBDII port and it works perfectly to maintain my engine starting battery.
I’m hoping I can add a trickle charger to my 2021 Taycan to always keep a trickle charger connected to maintain the 12V Lithium battery.
My service advisor didn’t know if this is possible and I assume I should be able to do this as long as I use the proper trickle charger for lithium batteries.
I’m hoping someone out there will be able to guide me since I don’t want to risk attaching a charger to the IBDII port and causing a problem or damage the 12V battery.

I have a 2020 4S and used that exact OBD adapter with their charger as a trickle charger for three years. I only started and moved the car around the drive all winter and it worked great.

 

[Gino]

Unfortunately I can’t run 240 in my detached garage without digging up the common area driveway which I don’t own. I will likely just stick to level 1 charging at no more than 8 hours since Porsche told me it doesn’t matter if I have the proper outlet capable of supplying up to 15A on a dedicated line.
Porsche still strongly suggests to never charge for more than 12 hours and only in emergencies.
I will likely put a temperature probe on the 120v 15A plug to see how hot it gets after 2 hours, 8 hours, 12 hours, 16 hours, 20 hours & 24 hours to determine once and for all if there is any risk to the charger, the cables, the plug or the outlet itself.
Porsche does not make it clear the exact reason they issued the service bulletin back in early 2022 where they stated you should never charge at 120V for more than 12 hours.
No sense in trying to get them to tell me why they were compelled to issue this warning. Was it because of idiots plugging into improper wiring, outlets, etc., or is the Porsche charging system at risk of failure when charging for days & days. Temperature rise over 24 hours should show what the peak temperature of the plug/outlet is and I expect it will reach the max temperature within an hour or two. The big question will be what that max temperature turns out to be.
I will also get an adapter so I can use Tesla destination chargers to give me more options outside of EA.
Thanks everybody for your suggestions…

 

[mikelevitt]

after Porsche fixed the horrible no good 12V battery death problem while plugged in - I had no further problems with 12V drain - and the big battery charges the little battery when it needs to - even when the car is left alone.

why are you concerned about this - Porsche's instructions to leave the vehicle plugged in should maintain both the 12V battery and big battery.

I'm not sure what problem you're trying to avoid?

of all the problems with the Taycan the 12V battery dying is not the one I'd be focusing on.

Porsche has not fixed the problem. We first had the 12v battery die in our 2022 in the winter of 2024. Porsche towed it in, replaced the battery and assured us that the problem was permanently fixed and that we did not have to start up the car during the winter, as long as the main battery was charged (it was left on a charger all winter.) We went to get the car out of the garage for the first nice days and had the exact same problem.

So I think you should proceed with caution, and use a 12v battery trickle charger. I will never park it without one again.

 

[anonymouse]

Porsche has not fixed the problem. […]
use a 12v battery trickle charger. I will never park it without one again.

I had a Porsche specialist put a Ctek socket just below the windscreen wipers so there is no messing about with connecting to the battery and no cables trapped in doors or hood.

However it does seem that there has been a recent speed of 12V batteries going flat after just a few days (mine was nine days) and there is a suspicion that there is a software problem causing this.

My dealer has literally no clue what is going on, and also does not know whether a recent ”WRW1” update fixed the problem or not. So sadly I’m still plugging mine into the battery tender.

 

[Gino]

I had a Porsche specialist put a Ctek socket just below the windscreen wipers so there is no messing about with connecting to the battery and no cables trapped in doors or hood.

However it does seem that there has been a recent speed of 12V batteries going flat after just a few days (mine was nine days) and there is a suspicion that there is a software problem causing this.

My dealer has literally no clue what is going on, and also does not know whether a recent ”WRW1” update fixed the problem or not. So sadly I’m still plugging mine into the battery tender.

I was warned by a few people to be careful using a trickle charger through the OBDII port so I have been using my 120V Porsche charger instead now that my Porsche dealer told me the campaign to not use the 120V charger for more than 12 hours and only for emergencies no longer applies to my VIN.
I typically keep the vehicle in the garage above 50% on the main battery up to about 85% just to be safe.
I plug in the 120V charger when it gets close to 50% or below and it adds about 20% to 25% capacity back each night charging from 9pm to 4pm.
We rarely use the Taycan for long trips since the range is no more than 200 miles. When we do plan a longer trip we charge it to 100% on the 120V charger.
My only issue now is even though I set the charging to stop at 85%, sometimes it stops at 85% but then starts charging again after a few hours later and goes to 100% & stops.
It doesn’t do this all the time but my dealer has told me not worry about charging to 100% occasionally. Worst case when I check the battery status on the app and I see it going past 85% I can resend the charging profile to the car and it will stop.
I may also add a remote wireless outlet in the garage so once it is at 85% I can also cut off the power to the charger completely so it will not blow past 85% when I don’t want it to.
So far zero 12V battery issues. Keeping my fingers crossed…

 

[anonymouse]

I was warned by a few people to be careful using a trickle charger through the OBDII port so I have been using my 120V Porsche charger instead now that my Porsche dealer told me the campaign to not use the 120V charger for more than 12 hours and only for emergencies no longer applies to my VIN.
I typically keep the vehicle in the garage above 50% on the main battery up to about 85% just to be safe.
I plug in the 120V charger when it gets close to 50% or below and it adds about 20% to 25% capacity back each night charging from 9pm to 4pm.
We rarely use the Taycan for long trips since the range is no more than 200 miles. When we do plan a longer trip we charge it to 100% on the 120V charger.
My only issue now is even though I set the charging to stop at 85%, sometimes it stops at 85% but then starts charging again after a few hours later and goes to 100% & stops.
It doesn’t do this all the time but my dealer has told me not worry about charging to 100% occasionally. Worst case when I check the battery status on the app and I see it going past 85% I can resend the charging profile to the car and it will stop.
I may also add a remote wireless outlet in the garage so once it is at 85% I can also cut off the power to the charger completely so it will not blow past 85% when I don’t want it to.
So far zero 12V battery issues. Keeping my fingers crossed…

Your message mixes up 12V and HV (high voltage, ie the big battery). Let's see if I can help:

1. Trickle chargers (for 12V) are best connected directly to the battery rather than OBD port (and cigarette lighter socket won't work either).

2. Your HV battery issue of running to 100% is fixed by setting BOTH a profile (which tells it you want to go to 85%) AND a timer for (say) 0500 which also says 85%. This is a particularly peculiar part of Porsche's misunderstanding of how humans think. You can read more by searching the group for many posts on this. You don't need a wireless outlet.

3. There is no reason not to use your wonderful Taycan for long drives. I take mine all over Europe on road trips. You just need to stop every 2 hours or so for 15-20 minutes to recharge, which is consistent with the breaks that safety experts say drivers should take anyway. However this requires decent charging infrastructure and I know it is still a bit primitive in some parts of the US.

 

[Gino]

Your message mixes up 12V and HV (high voltage, ie the big battery). Let's see if I can help:

1. Trickle chargers (for 12V) are best connected directly to the battery rather than OBD port (and cigarette lighter socket won't work either).

2. Your HV battery issue of running to 100% is fixed by setting BOTH a profile (which tells it you want to go to 85%) AND a timer for (say) 0500 which also says 85%. This is a particularly peculiar part of Porsche's misunderstanding of how humans think. You can read more by searching the group for many posts on this. You don't need a wireless outlet.

3. There is no reason not to use your wonderful Taycan for long drives. I take mine all over Europe on road trips. You just need to stop every 2 hours or so for 15-20 minutes to recharge, which is consistent with the breaks that safety experts say drivers should take anyway. However this requires decent charging infrastructure and I know it is still a bit primitive in some parts of the US.

Thanks for the info on setting both the profile & a timer. Definitely not intuitive…
We don’t take it on long drives very often. Maybe 1 or 2 times a year. Living in Southern California we have 4 different vehicles for different uses.
In the winter when we drive to Lake Tahoe or Deer Valley, Utah we take the Hummer H2 since we can carry all our ski stuff and drive in heavy snow where I would never choose the Taycan unless it was my only vehicle. For long trips we use our Porsche Boxster and if we need more luggage space for long cross country trips we take the Airstream Interstate (Mercedes Sprinter). For the most part the Taycan only gets driven from just north of LA down to San Diego so we never have to charge anywhere but in our garage.
After the 3 year free EA charging I just have an issue with the 64 cents/kwh EA charges when they only pay 5-7 cents/kwh. I would rather keep an ICE Porsche in my garage for longer drives anyway. I usualy like to drive 5-6 hours before I make a quick stop to fill up and make a bathroom break. Stopping every 2 to 3 hours would annoy me to no end. Long trips in California involve zero interesting roads. All highway, 70-80mph speed limits meaning 80-90mph on dead straight, extremely boring highways. Also, once I get outside of California gas is 2.25 to 2.75/gallon which makes the H2 & the Airstream diesel almost as economical as my Taycan but they both have 500+ mile range.
Even the Boxster has a 450+ mile range.
If I could upgrade the HV battery to get me at least 400 mile range I would consider taking it on long trips but since that’s not close to possible I’m planning to buy another ICE Porsche in the next year like a 911 convertible (ICE) or hoping they decide to make a Taycan (ICE or Hybrid) or the perfect car I would jump on would be a Taycan convertible (ICE or hybrid). I can only dream at this point…
The Taycan is my favorite vehicle to drive but since all the fun roads to drive in Southern California are within an 85 mile radius at most I don’t bother to take it further unless we’re going to Las Vegas 2 or 3 times a year.
I’d likely drive it more if I lived in Europe where larger vehicles are a pain in the ass and the roads are much more fun to drive.

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