Will it stall if the 12V batt dies?

It says "12V battery low. Charge by driving". It did NOT charge by driving half an hour. Will the car stall if the 12V battery dies while driving?

Answer from later in this thread: it CAN, depending on the failure mode. From my 12/9 reply:

"It seems to me there are just two 12V-failure modes, which are identical for ICE or EV, & would answer my original subject line:

1) 12V batt goes bad (usually gradual, over the course of several years) & the car won't start, but it won't stall while running, because after starting, everything will run off the charging system.
2) Charging system suddenly goes bad (usually after a great many years/miles) & the car will still start & run, but only until the 12V is drained, at which time it can stall while running."

Since the battery was under a year old, the cause was clearly the charging system, in which case it could stall while driving, contrary to what Timmons VW in Long Beach assured us.

TomHoulden said:

It says "12V battery low. Charge by driving". It did NOT charge by driving half an hour. Will the car stall if the 12V battery dies while driving?

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If the car is on and driving, the DC/DC converter should be charging the battery. If it is still low, either the 12V battery or the DC/DC is faulty. Take it to the dealer to find out which. If you have a battery charger and a volt meter, you can do some troubleshooting, but something is definitely wrong and it can strand you on the road.

Thanks miimura! Unfortunately none of the 3 local VW dealers will take it since their only EV techs are gone for the weekend, & my friend has the car, so I can't do any testing. Personally I would just start it, disconnect the 12V, & see if it dies.

Here's some history on this issue:

After about 10 months of 25-mile round-trip commutes (nearly all without heat needed here in Southern California), one morning without warning the 12V was completely dead, after fully charging at work the night before (9 bars on the HV battery guage, 7/8 on the analog guage). The dealer jump-started it to get the parking brake off, then towed it to service, where it later started for them to move it. They could not find any problem, so they just replaced the 12V battery!

Now just about a month later the warning came on after fully charging the HV batt, & has stayed on ever since (half-hour drive, then parked overnight). One dealer said that even if the battery goes dead while driving it won't stall, which I'd bet is an FAQ they're taught for ICEs, & is incorrect for EVs as confirmed by miimura.

Since your friend is borrowing the car, why don't you let them be the guinea pig and find out for us what happens. Send them the bill if any electrical parts get fried due to low voltage and excessive current being drawn on the 12v electrical system.

There will be no bill, since it's fully warrantied.

She understandably doesn't want to be a guinea pig, stranded stalled in the carpool lane.

For her Monday commute I plan to loan her my 2013 Fiat 500e. It's also still under warranty, but since its 4 recalls have been completed, maybe all of ITS bugs are now worked out! Maybe before I take the eGolf (on surface streets!) for service I'll disconnect the 12V after starting the motor, & see if it dies. If so, it would eventually stall while driving, so it would be the second occurrence of a safety issue (since it clearly says "charge by driving"). That qualifies it as a "lemon" they have to take back, hopefully with the higher-range 2017 being the only thing they have to replace it with. :twisted:

Here are two scary things that can happen when an EV's 12V battery goes low. There is a contactor in the HV battery that is powered by the 12V. When the voltage drops too low, that contactor cannot be held closed. So, you will lose motive power and anything else that is powered by the HV battery. I don't know if the power steering assist is on 12V or HV in the e-Golf though. It is on the RAV4 EV. Also, the e-Golf is relatively unique in that the main brake booster is run completely off the 12V battery. There is no vacuum assist like on an ICE vehicle. So, if the 12V drops too low, the brake boost will be gone too. If you've ever tried to stop an ICE car with disc brakes when the vacuum assist is out, you will know it's not fun.

So, if you're planning to drive the car to the dealer, make sure you charge the 12V with an external charger. It will greatly increase your odds of making it there without incident.

Thanks again Miimura,

My current issue is a faulty 12V charging system. In the more likely event of a battery that dies after several years, a properly-functioning 12V charging system should keep everything running until you shut it off, & then should drive fine after a jump-start.

So an EV's 12V battery dying at speed due to a faulty 12V charger is actually even a bit scarier than a stalled-at-speed ICE, where the power steering goes out but at least the power brakes have a couple applications available (I think 3 is the legal requirement) due to the legally-required vacuum reservoir. I wasn't sure if the HV contactor would be held closed by the HV battery itself, but even if it was, that would most likely only keep the motor running & not the power steering or power brakes.

The 500e has a manual handbrake which would help at least a little, & a 12V fuse for the power steering, so it would be gone, although it steers fine without it, except at parking speeds. I know that because the stock assist makes it a lot lighter than I prefer, so I pulled the fuse to test it without.

We took it back to Timmons VW (Long Beach) Sunday without any external 12V charging, since that might have turned off the warning light. Driving my 500e there (to bring my friend back) I realized how if an 8-month-old battery dies, it's because the 12V charging system is faulty & needs to be fixed. Just replacing the 12V battery like they did last time is a VERY temporary "fix". Stupid of me not to realize that then, but that's not MY job.

On arrival I plugged in to their unlisted ChargePoint charger to top up a bit while waiting, & then found that they're charging $2.00/kW!!! At its 6.6kW spec, that's $13.20/hour, 62 TIMES the local average power cost, & roughly equivalent to $13/gallon gas in a 29mpg car!!! I quickly unplugged. At Pacific VW in Hawthorne the ChargePoint is free, as well as the no-card-needed chargers at McKenna VW in Cerritos, & also at Orange Coast Fiat.

At 5pm Monday they wanted until noon Tuesday before giving us a loaner, since they "can't find the problem yet"! The problem is the 12 charging system isn't working. Period. If they can't figure out which part of that system is bad, they should be able to just replace each part one-by-one until it works.

I would definitely hold out and not take the car back until they do a believable repair. Not giving a loaner until they find the problem is a bit ridiculous. I would call VW Customer Service at 800-822-8987 and open a case with them indicating the problem you've had, what has been done previously, and which dealer is currently working on the car. I had very good service from an e-Golf specialist at corporate. They coordinated resources behind the scenes to make sure the techs could find the problem and that warranty parts were approved quickly. They also communicated with me regularly when the dealer did not.

If you need your car charged at a VW dealer with a ChargePoint charger, you need to ask them to do it so they use their card to start the charger. Their intention is to keep it for dealership use, so they crank up the fees for others who use it.

Thanks again Miimura,

12:33 today they called to say they "don't know how long it will take", & to refuse to deliver a loaner (like they did last time), but only offer a ride there to pick one up.

ChargePoint: Admittedly I was in a Fiat, but before I even found the charger I asked to plug in while awaiting eGolf service, & complained to FOUR employees about the high fee, but NONE of them mentioned using their card. I will certainly ask for that next time though!

TomHoulden said:

On arrival I plugged in to their unlisted ChargePoint charger to top up a bit while waiting, & then found that they're charging $2.00/kW!!! At its 6.6kW spec, that's $13.20/hour, 62 TIMES the local average power cost, & roughly equivalent to $13/gallon gas in a 29mpg car!!! I quickly unplugged. At Pacific VW in Hawthorne the ChargePoint is free, as well as the no-card-needed chargers at McKenna VW in Cerritos, & also at Orange Coast Fiat.

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OC Fiat will only let you charge a fiat and only in the daytime (thanks to someone suing them because their car got damaged overnight)

McKenna charges for Free? I didn't know that, I asked around and the person in the front couldn't help me. I found their 'other charger' around the side and it was $10 Min...wow

Back closer to the topic first: Timmons called to say it was ready Wednesday afternoon, the day before Thanksgiving, which was rather late to rent a gas car for the long weekend's road trip, so they said the loaner didn't have to be back until Tuesday. Apparently they installed a new "module" in the Golf. I'll see what the invoice says & report back.

I have only been at OC Fiat in the daytime, charging a Fiat, but by comparison to Timmons, the service was infinitely better.
OC Fiat: Ask, plug, free.
Timmons VW: Ask, plug, complain to 4 employees, $12/hr.

I have only been at McKenna to order, & then to pick up, an eGolf, & they let me charge my Fiat 500e free from a no-card-needed charger near the service bay. Their new(?) high fee seems to agree with Miimuras note: "If you need your car charged at a VW dealer ... ask them to do it so they use their card to start the charger... they crank up the fees for others who use it.".

I suppose in an emergency that's still better than if they had it set up so that ONLY their own ChargePoint card works, & nobody else can ever charge there.

TomHoulden said:

Back closer to the topic first: Timmons called to say it was ready Wednesday afternoon, the day before Thanksgiving, which was rather late to rent a gas car for the long weekend's road trip, so they said the loaner didn't have to be back until Tuesday. Apparently they installed a new "module" in the Golf. I'll see what the invoice says & report back.

I have only been at OC Fiat in the daytime, charging a Fiat, but by comparison to Timmons, the service was infinitely better.
OC Fiat: Ask, plug, free.
Timmons VW: Ask, plug, complain to 4 employees, $12/hr.

I have only been at McKenna to order, & then to pick up, an eGolf, & they let me charge my Fiat 500e free from a no-card-needed charger near the service bay. Their new(?) high fee seems to agree with Miimuras note: "If you need your car charged at a VW dealer ... ask them to do it so they use their card to start the charger... they crank up the fees for others who use it.".

I suppose in an emergency that's still better than if they had it set up so that ONLY their own ChargePoint card works, & nobody else can ever charge there.

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Or do like most of us and adopt a charge at home mentality at night. Open up a ChargePoint account, put $25 on it, and use an app to find Charge Point EVSE units. Even Tesla is putting an end to free charging, mooching electrons should be painful. It creates bad habits like you are owed something, when they owe you nothing, you should be buying your electricity like everyone else pays for a utility. Time to grow up and stop sucking the hind tit for free recharges, and driving for free. As it is already, without buying fuel, you aren't paying any road taxes to support the infrastructure you are driving on. It's just bad manners to assume so much from VW dealerships, they are already reeling financially from cleandieselgate. Giving you a charge doesn't in any way help their bottom line. Since action is usually taken as a reaction to abuse, Timmons decided to nip the problem in the bud and make you pay dearly for it. Go try to get a 24kwh quick charge at VW of The Peoples Republic of Santa Monica, and see what it costs.

BTW, I bought my 2015 SEL from Timmons, Long Beach. My gauge read almost 2 clicks off of full when I picked it up. It was not washed up, cleaned up or detailed at all. It still had a bunch of plastic protection inside it on panels and seats when I bought it... I doubt any pre delivery inspection ever took place. I will never go back to Timmons as a result. If they were to charge 0.30 to $0.35 per kwh, that would still be pretty expensive for what you are getting.

The problems I see with free EVSE's and free charging consist mainly of abuse of equipment by thoughtless users that don't take care of the cords, or twisting them up, or storing them properly, or theft of the charger handle from locked charge ports. Many is the VW that's had a charger handle locked on it and ripped off by some other selfish person that thought they had a right that doesn't exist. This almost never happens at pay to charge locations, the fee involved almost always ends of causing them to be underultilized, under abused, and vacant.

Wow, I can hardly believe it, but I happen to agree with a few things JT wrote on the topic of free charging. I do think it encourages people to abuse their time at EVSEs.

That being said, I am ok with businesses offering limited free charging to customers as it is a perk, like free coffee or a car wash, that may make those customers come back. To make people not hog the station, a parking fee should be applied after a reasonable amount of time. When I take my trip from the Peninsula to Salinas, I stop at the Holiday Inn Express in Morgan Hill where they have two 24 kW DCFC stations, charge $0.25 per kWh and after 30 minutes, tack on $0.10 a minute - this sort of pricing is fair and yet encourages me to stick around for no more than 30 minutes (and I don't want to stay longer anyway). And I always walk up to the front desk to thank them for installing the stations.

If VW dealers want to recover from the diesel mess, they should be nice to their customers (see above). I did read that VW is compensating dealers, so that should help a little.

The 12V lead acid battery gets charged via a DC-to-DC unit from the traction battery. So, once the car is turned on, it will keep going, even if the 12V battery "totally" fails. So, the e-Golf is like ANY car - the 12V battery is used to start up the car, and if it does that, then you are fine until you shut the car off. If the 12V battery is too weak, then the car will not start.

NeilBlanchard said:

The 12V lead acid battery gets charged via a DC-to-DC unit from the traction battery. So, once the car is turned on, it will keep going, even if the 12V battery "totally" fails. So, the e-Golf is like ANY car - the 12V battery is used to start up the car, and if it does that, then you are fine until you shut the car off. If the 12V battery is too weak, then the car will not start.

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If the 12V battery fails with an internal short it can still suddenly pull down the 12V system such that the car will die. This happened to my friend's Honda Accord on the road too. However, I admit that is rare, especially for the AGM type battery in the e-Golf. However, the DC-DC converter can fail too, then the car will eventually die when the 12V battery runs out of energy. This failure mode is like your alternator (or the voltage regulator on the alternator) failing on an ICE car. It's not an immediate failure, but it eventually fails because the 12V battery is not being charged properly while driving. The voltage regulator is another $400 repair cost that I incurred on my Passat Wagon that led me to replace it with the e-Golf.

Right, but we are getting away from the OP's question. A lot of people don't understand how the 12V battery is set up in an EV, and I think the question comes from that.

Sorry for getting everybody off-topic (I don't mind paying for charging, just not an outrageous amount) & glad we're back now.

It seems to me there are just two 12V-failure modes, which are identical for ICE or EV, & would answer my original subject line:

1) 12V batt goes bad (usually gradual, over the course of several years) & the car won't start, but it won't stall while running, because after starting, everything will run off the charging system.
2) Charging system suddenly goes bad (usually after a great many years/miles) & the car will still start & run, but only until the 12V is drained, at which time it can stall while running.

The situation at hand which prompted the subject line is: A nearly-new 12V batt drained to the point of failure to start the EV (without warning). Timmons replaced the battery, but of course it also drained (this time with an on-screen warning) since it's a very safe bet that it wasn't charging. That's failure #2 above, so it could have stalled while driving, contrary to what Timmons told us.

We asked Timmons to highlight the relevant part of their otherwise cryptic invoice, & here's that text.:

"replaced battery and BDM/negative 12 volt battery cable"

Battery D____ Module?

The prior page of the invoice says, among lots of other code:
"CAUSE: REPLACED BATTERY AN CONTROL UNIT" (I assume it's supposed to be "AND", but why the word "cause" in front of their ACTIONS?)
1 5Q0-915-181-G CONT. UNIT
1 000-915-105-CB BATTERY"

The bottom of that page repeats the batt #, but not the cont. unit. (?!)

Hopefully that all brings the original subject up to date, so can I digress again?

The day before pickup at Timmons we called to ask if they could top off the drive batt about 1.2 hours (it was at 70%) & they agreed. Two hours prior to pickup we called to remind them & they said okay. When we got there it had not been charged since drop-off, "because 2 other cars were ahead of it". At one point they had told us they have a 3rd charger in the back. No cars were charging at the 2 front plugs. I guess at Timmons 3 minus 1 is zero.

The invoice specifies "THE CUSTOMER WANTS THE OLD PARTS", yet they were never offered.

Not charging an EV when specifically asked is one of my pet peeves of EV servicing. This happens a lot.

I would not expect to get the old parts if I didn't pay for the new parts. I would expect any replaced parts to be the manufacturer's property when they pay for a warranty repair. Not only did you not pay for it, but the manufacturer (or their supplier) should be doing failure analysis on those parts.

miimura said:

Not charging an EV when specifically asked is one of my pet peeves of EV servicing. This happens a lot.

I would not expect to get the old parts if I didn't pay for the new parts. I would expect any replaced parts to be the manufacturer's property when they pay for a warranty repair. Not only did you not pay for it, but the manufacturer (or their supplier) should be doing failure analysis on those parts.

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Do they fill up your car with fuel when you take it in for service too, top off the tank? Unrealistic expectation. Fill it up yourself, on your dime, on your time. The only time itś full from a dealership is when you buy a new car.