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VW ID.3 1st Edition & Tesla M3 LR
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Discussion Starter · #1 ·
I fitted a CTEK battery monitor to my ID.3 about 48 hours ago, just to see what was happening with the battery whilst the car is idle.

Nothing too exciting so far, SOC seems to have gone from 100% to 98% in that time, but I’ll see what happens in the next few days. The tiny voltage drop seems to coincide with when I’ve used the WeConnect ID App.

I need to use the car tomorrow morning, but I’ll update as it sits over Christmas.

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VW ID.3 1st Edition & Tesla M3 LR
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Discussion Starter · #3 ·
Tell us more about this monitor, sounds like a winner
It’s the CTEK 40-149 Vehicle Battery Monitor, which uses Bluetooth to communicate to an App on your phone.

There seem to be similar ones available by other manufacturers, but I like CTEK stuff.
 

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VW ID.3 1st Edition & Tesla M3 LR
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Discussion Starter · #5 ·
CTX BATTERY SENSE

About £45. It's a sad state of affairs that EVs seem to need these. I have a manual display visible from outside of my LEAF due to similar concerns.
I haven’t suffered any 12v failures yet, I don’t think the car sits long enough unused, but I was interested in identifying anything that might cause a sudden flat battery as reported by other owners.

I had to replace the 12v on my GTE, at 3 years old.

The ID.3 12v battery is 61Ah, not sure if that’s a typical size for an EV or not.
 

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Sounds typical. Ampera was 65 Ah I think. Swapped out my Bosch S5 after 3 years 'coz it went below 12.0 briefly, but battery is since doing well in wife's Citroen C1! Juuuust fits in! And has stopped her flat-battery-in-the-morning problems! :)
 
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2020 BMW i3S 120Ah BEV
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Actually a lot of EVs have had much smaller 12v batteries than that.. I suspect (hope?) that car manufacturers are watching these threads during lockdown, with so many of their client's cars sitting idle (not to mention their own staff), and that in future 12v battery state monitoring will not just be part of the car's system it will be exposed to the drivers with guidance about when (and how) to consider charging them. In an even less ridiculous world, they'll incorporate a more efficient method for drawing power from the HV pack in an EV to top up the 12v battery, but I'm not holding too much hope for that.
Cars should just have a 12v charge socket under the bonnet. "Plug one of <these> in <here>". Sorted. Like my 1995 Corrado has now.. :)
 

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Did pop bonnet and can see the neg charging stud, and presume the pos is under the plastic cover. So if dies at home can easily give it a charge

On fitting a battery monitor - was thinking a Victron one (have one to monitor small lithium off-grid house battery, so already using app). Question is around connecting - anyone got a youtube clip of attaching a monitor - concern is around attaching wiring securely without dropping the 12V supply, since I presume the car will moan/reset fully.


Is the monitor I use, comes with a sticky pad and fuse in wiring just in case.
 

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2020 BMW i3S 120Ah BEV
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I've done several now. Since you're essentially loosening the main clamp to attach the sensor you kinda have to hold the clamp against the battery post while it's not tight. Just be careful not to touch anything else at the same time. Yes it's a little risky that the car will lose power momentarily, but be careful. I've not broken anything yet ..
 

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VW ID.3 1st Edition & Tesla M3 LR
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Discussion Starter · #10 ·
Did pop bonnet and can see the neg charging stud, and presume the pos is under the plastic cover. So if dies at home can easily give it a charge

On fitting a battery monitor - was thinking a Victron one (have one to monitor small lithium off-grid house battery, so already using app). Question is around connecting - anyone got a youtube clip of attaching a monitor - concern is around attaching wiring securely without dropping the 12V supply, since I presume the car will moan/reset fully.


Is the monitor I use, comes with a sticky pad and fuse in wiring just in case.
You can slacken off the positive and negative battery stud nuts to slide a terminal in behind it (assuming your monitor has U shaped terminals?) without the main terminal clamp coming off the battery post.

I found bending the terminal 45 degrees made it easier to slide behind the nut.
 

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Nissan LEAF30
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In the LEAF there are a number of always on fuses so I just used a fuse holder tap to get a positive and a negative connection to the body. This suited me as I wanted the display inside but visible on the dash through one of the A pillar windows.
 

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I have too recently fitted a 12V Bluetooth monitor, probably the same as BatteryLife, since the app looks the same.
Rather than play with the 12 battery terminals, I found a more convenient and easily accessible place to fit it.
Under the +12V cover, mine had a spare terminal which I used for +12. For the –ve, I used the nearby headlight mounting point.
Yes, I tested it before fitting, both seemed like a reliable source for the 12V and less risk of disconnecting the battery inadvertently.
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Why is there a plastic bag stuffed in here? (Red Arrow)


Now the interesting bits…
During a home charge, the 12V is charged as well, monitor showing approx. 14.9V. Nothing new here. We all know both batteries get charged.
When HV finished charging, monitor shows 12.7V. I was hoping it would be higher, but that is what it is for mine.
I left the granny charger plugged in overnight to see if there was any ill effects. I can only say there was no significant 12V battery drain. Next day 12.69V.

The key fob proximity does affect the car! As I approach the car, the fob starts to blink, I guess forever (well at least 5 minutes). At this time the battery voltage drops to 12.1V. My take is that the car awakes and obviously draining the 12V somewhat. Unfortunately I don’t have a clamp meter to see how much current was being drawn. But I suspect it is not a trivial amount.
I hung around for another 5 mins and key fob still flashing and battery monitor still at 12.1V. Could this be the infamous battery drain? The key fob being too near the car???
I moved away until the fob led stopped flashing. About 3 minutes later the 12V started to creep back to 12.6V. Car must have gone back to sleep.
I repeated this, but put the fob into a metal biscuit tin, but near the car. Same effect; well, we know a metal tin cuts off the signal.

As already stated, the mains was still plugged in, but finished charging, so the charge port light was off.
I used the App to initiate preheating. The charge port light came on (green) and I could hear some fans coming on. The house meter was showing a draw of 3KW. Good, it was preheating from the mains and not the HV battery. The battery monitor showed it was charging at a measly 12.9V, if one could call it charging.
I gave it 5 mins and unlocked the car. BTW, mine is setup to unlock when I touch the door handle, not as I approach.
When it unlocked, the 12V battery was still charging at 12.9V. However when I sat down, the charging voltage jumped to 14.9V. Yay, it was charging properly. The fans were still belting out due to preheat. So I turned them off.
I sat in the car for 15 mins playing with the menus to see if I could fathom the headlight setting (to set it so we drive on the left)… For another episode.

To summarise:
Having the key fob too near the car, keeps the car awake and probably drains the key fob as well.
I suspect my battery is on the verge of dying. 12.6V locked and key fob far away is not high enough in my books.
A 15 minute charge/drive per day is not really enough to keep the 12V battery from dying since I lost 0.1V in this one off experiment and the 15min charge was not enough to replenish the 12V drain.
 

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If meter is showing 12.9V when car is also connected to the mains it is possible the 12V charging circuit is possibly just matching power requirements to such that there is no battery drain at that point. Thinking charger circuit may do this after it has seen the battery reach a 100% SOC state.
 

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@ElectricMadMan I like your connections, will see if I can do the same with the BM2 I've got lined up. I'd suggest that you find a way to stop the unit flapping around. It's going to get the wires stressed & flexed as you drive, so maybe put something like a double-sided sticky foam pad to fasten it to side of battery maybe? Or giant cable-tie(s) around battery?
 

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@ElectricMadMan I like your connections, will see if I can do the same with the BM2 I've got lined up. I'd suggest that you find a way to stop the unit flapping around. It's going to get the wires stressed & flexed as you drive, so maybe put something like a double-sided sticky foam pad to fasten it to side of battery maybe? Or giant cable-tie(s) around battery?
Is the BM2 the same as Hyundai branded units on the market?
Does anyone have a Hyundai unit, how good is the App?
 

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This looks like a very useful thread to me. Love our ID.3 of a few days, but it just died with the 12v battery at 3.85v when I checked (and photographed). Asked VW to fix and replace with a useable car, but seeing as I got it going again (spare key, 12v charger etc) and it is two days before Christmas during a pandemic, they seem not to have capacity to assist, unless it becomes completely unusable.

So I am keen to monitor the voltage and current and understand what is happening. ID.3 Life on 0564 software.

Please confirm the major suspects for overnight drain? My experience and reading suggests:

1. Keyless entry with keys close and activating car systems (should not be us, as Life is without this)
2. Regular phone app checks may be draining car 12v as car responds (seems the car has an active 4G, GPS, DAB aerial, so this may contribute)
3. Some heating/ventilation issue that occurs even when car is shutdown (anyone have further info?)
4. Central screen not closing down correctly (AA man theory on FB)
5. AC charger still plugged in, but finished, rumoured to cause 12v consumption issue
6. ACC radar using heater or staying live while car is off
7. Pre-damaged 12v battery after waiting a long time before shipping
8. Something else?

I think between us we can solve this, or at least explain it.

Evidence below of some current going to the active aerial.

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Is the BM2 the same as Hyundai branded units on the market?
Does anyone have a Hyundai unit, how good is the App?
AFAIK BKM2 not the same as the Hyundai branded item. Was a discussion a while back, sounded to me like the Hyundai one was only meant for doing an on-the-spot test, rather than long-term monitoring, or something like that. The poster decided to send the H one back & stay with BM2 IFIRC.
 

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The current going to the aerial makes sense, otherwise the app wouldn't be able to work at all. Not that it excuses the complete draining of the battery of course.

I have read a couple of accounts that mention the 2.0 (0783) software doesn't actually "fix" the battery drain issue, but allows the main HV battery to keep the 12v topped up when not plugged in. This should prevent the problem of having a dead car almost overnight as some have experienced, but still doesn't explain the real cause.
 

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@ElectricMadMan I like your connections, will see if I can do the same with the BM2 I've got lined up. I'd suggest that you find a way to stop the unit flapping around. It's going to get the wires stressed & flexed as you drive, so maybe put something like a double-sided sticky foam pad to fasten it to side of battery maybe? Or giant cable-tie(s) around battery?
The picture was taken excitedly before it was finished. There is a cable stress relief just behind the BM. I tie-wrapped it to that to stop it flapping. I didn’t want to stick it to the top of the fuse cover because inevitably means I will need to get in there and then have to unstick the BM.
 
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