NeilBlanchard
Posts: 298
Joined: Sat Feb 21, 2015 12:19 pm

Re: Charging the 12V battery if car is not driven much

Fri Mar 13, 2015 9:54 am

IF there is an alternator, it would be physically driven by the electric motor. Have you looked under the hood, and/or looked at technical images of the e-Golf drivetrain?

When / if you find the alternator, please inform us.

Do you see a power takeoff on the e-Golf motor that would spin an alternator?

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GadgetGav
Posts: 243
Joined: Wed Dec 24, 2014 7:42 pm

Re: Charging the 12V battery if car is not driven much

Sat Mar 14, 2015 7:01 pm

From a Green Car Congress report written after a visit to the Wolfsburg plant ahead of the US launch:

"The power electronics module controls the high-voltage energy flow between the e-motor and the lithium-ion battery (between 250 and 430 V depending on the battery voltage). The power electronics converts the direct current (DC) stored in the battery to alternating current (AC). The primary interfaces of the power electronics are its traction network connection to the battery; 3-phase connection to the electric motor; connector from the DC/DC converter to the 12-V electrical system; and a connection for the high-voltage power distributor."

Source: http://www.greencarcongress.com/2014/07 ... egolf.html

From that it seems that the 12V system is charge from a DC-DC converter from the main battery pack, but it's still not clear if the power electronics module is awake enough to trigger that DC-DC conversion if the car isn't in use. Maybe the 12V system could run down if the car is 'off' because the main power electronics module may only come on when you press that 'Engine Start' button...

Kosta
Posts: 83
Joined: Fri May 26, 2017 1:50 pm

Re: Charging the 12V battery if car is not driven much

Sat Jul 22, 2017 5:33 am

cove3 wrote:After replacing my BMW 528E and 525I 12V batteries every few years, I was told by BMW to use a trickle charger to the cigar lighter if a car is not driven much, which was the case my being retired. The battery life is reduced if they are undercharged from lack of driving. The batteries draw some current constantly even if the car isn't used, and I found myself charging them from dead with a charger..

I'm wondering about the e-golf battery when the car isn't driven much. With the snow I haven't used it for over a month:
1. The manual says the battery will drain if not driven for long periods, the doors are unlocked, or lights left on
2. It appears the 12V battery is charged from an alternator while driving
3. The battery capacity is small as it's not needed for starting like an ice, so the safety margin is less
4. The manual says only the dealer should charge it and that the dealer has to reset things when changing a battery
5. There doesn't seem to be an indicator for the 12V battery state of charge

This leaves 3 questions:
1. Is it really necessary for the dealer to charge the battery.
2. How to tell if it's in the danger zone of discharge?
3. Is it safe to use a trickle charger through the cigar lighter as with my ICE to to be on the safe side?

Ron
I would say the easy fix is to take it for a drive once a week for giggles , you have time , the vehicle depreciates regardless if you use it or not , and no special actions are needed then to quell your worry on a 12 v battery :-)
2017 black eGolf
2009 2.5 Jetta
2013Honda Pilot
1976 MGB
maintain nanas 2013 VW jetta

RonDawg
Posts: 835
Joined: Sat Jul 25, 2015 2:24 am
Location: SoCal

Re: Charging the 12V battery if car is not driven much

Sat Jul 22, 2017 5:04 pm

cove3 wrote:While it's true there's no start load as with an ICE, this also allowed VW to use a small battery so concerns still exist
Comparing the batteries of my eGolf and my gasoline-powered Alltrack, the eGolf's battery isn't a whole lot smaller. It appears to use the same battery tray as the ICEV versions so when the eGolf's battery dies you can put in a standard size replacement; there's even a third bolt hole for it. It's also bigger than the battery I remember from my Leaf, which is quite small, but appeared to be the same size as the battery on my 1982 Honda Accord.
There's nothing in the manual as to how long the car can be sitting idle before the 12V battery drains below a safe thresh hold. 3 weeks, 2 months?
I've left my car at an offsite airport parking structure for 3 weeks, and had no problem turning on the car upon my return.
Nor is there any easy way to test the capacity or state of charge to know whether to use a trickle charger.
If it makes you feel better, use the trickle charger. If it's a true trickle charger and it is working properly, it won't overcharge your battery.
Does the 12V battery get charged when you charge the main battery? If so, and the main battery is at 50% for storage puroses, I could charge it to 80% in order to top up the 12V battery
Not sure on the eGolf, but that was NOT the case on the Leaf. In fact, leaving a Leaf plugged in for far too long actually drains the 12 volt battery.
Looking in the engine compartment, there don't seem to be any openings in the grill to run a trickle charger through, so the hood would have to be up
On my Alltrack (which I rarely use) I just leave the hood down but not fully shut; it's the same state if you pull on the inside hood release lever but don't open the hood. That also serves as a reminder that I need to unplug the trickle charger.
If the 12V battery is charged by the car main battery, couldn't I just turn on the electric motor for a couple of hours?
You could, but I would think it's easier to attach a trickle charger if it will not be used for some time.
I called my dealer service and they said the 12V system is just like an ICE and is independent of the main battery system, and I could charge it with either a trickle charger or battery charger without loosening any battery connections
Again if it makes you feel better, use the trickle charger.

EDIT: I just realized I'm replying to a 2+ year old thread but I'll leave my answers up anyway should someone's search take them here.
2015 eGolf SEL (originally leased, bought out lease)
former EV: 2012 Nissan Leaf SV (lease returned)
Range Extender: 2017 VW Golf Alltrack S 4Motion

miimura
Posts: 1317
Joined: Fri Mar 27, 2015 4:13 pm
Location: Los Altos, CA

Re: Charging the 12V battery if car is not driven much

Tue Aug 22, 2017 10:18 pm

Rorence wrote:Thanks for you nice post. To charge battery with DC 12v to AC 110v 400w power inverter is easy to me. Since I have used this car charger for a long time. Simply to connect it with car cigarette lighter charger outlet. The advantage that I know about this tool is soft and convenient to take away. If you want to catch more information about it, you can click here to get. Best regards.
Please stop spamming us with your Bestekmall links.
2015 e-Golf LE (returned) | 2018 Tesla Model 3 LR | 2012 RAV4 EV Shoreline w/JdeMO | Leviton EVB40 & Jesla Home Charging | 4.32kW Motech/Enphase PV + 2x Powerwall 2 AC

Mena
Posts: 5
Joined: Tue Dec 12, 2017 12:53 am

Re: Charging the 12V battery if car is not driven much

Mon Dec 18, 2017 11:26 pm

tigger19687 wrote:There must be something wrong if you are going through 12v batteries like candy !?

If you are going to leave a car unused for more then or about a month I would disconnect it.

My trucks don't go through batteries unless I leave a light on or don't drive it for 4 months straight.

Not sure if you have Electronics in the car (navigator etc) that are not turned off ?
Or, like my son, who leaves things plugged in the lighter of the truck.
Yes, you're right. Car batteries can be drained if you leave electronics on when the car is parked or even when the car is unused for months. I often forget unplugging out my bestek 300w power inverter and just think that it doesn't matter if my phones or other connected things are plug out. While, after I do that for a long time, just found that I can't jump my car on the road. So, finally, I used a jump starter. The 4S store told me my car battery was damaged. But not so bad. So I have to remember to turn off the head lights and all my devices charged in car.

Nick
Posts: 8
Joined: Fri Dec 23, 2016 2:50 pm

Re: Charging the 12V battery if car is not driven much

Sun Dec 24, 2017 10:00 am

The 12v battery on my 2016 SEL is an AGM (applied glass mat). It has very low internal resistance and will not self-discharge substantially over several months. My car was in the garage for 7 weeks this summer, and started up normally when I got home.
_________________
2016 e-Golf SEL
2017 Golf SportWagen
2009 Jetta TDI

JoulesThief
Posts: 2576
Joined: Mon Oct 05, 2015 2:01 pm

Re: Charging the 12V battery if car is not driven much

Sun Dec 24, 2017 5:58 pm

Nick wrote:The 12v battery on my 2016 SEL is an AGM (applied glass mat). It has very low internal resistance and will not self-discharge substantially over several months. My car was in the garage for 7 weeks this summer, and started up normally when I got home.
AGM is Absorbent Glass Mat. The Fiber Glass Mat absorbs the sulfuric acid in between the lead plates.

http://batteryuniversity.com/learn/arti ... ss_mat_agm
2015 e-Golf SEL
2015 Passat TDI SEL
2014 Touareg TDI LUX

Full spectrum VW owner, life is too short to wait to drive for a recharge.

BomBoi
Posts: 68
Joined: Sun Apr 23, 2017 1:45 am
Location: Daly City, CA
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Re: Charging the 12V battery if car is not driven much

Wed Jun 30, 2021 1:04 pm

Bumping up for a positive answer to see if i can trickle charge the 12v battery through the cigarette lighter.


EDIT: i will just try it and report back .
17 e-Golf SE Urano Grey

flyboy320
Posts: 65
Joined: Sat May 13, 2017 8:38 am
Location: Toronto, Canada

Re: Charging the 12V battery if car is not driven much

Sat Jul 10, 2021 12:48 pm

BomBoi wrote:
Wed Jun 30, 2021 1:04 pm
Bumping up for a positive answer to see if i can trickle charge the 12v battery through the cigarette lighter.


EDIT: i will just try it and report back .
Did it work?

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