12v battery monitor

[tongsli]

I just wanted to share this, sorry if this has already been posted. I did a search first but didn't see anything.

https://a.co/d/ihZ1fe8

 

[alohart]

I just wanted to share this, sorry if this has already been posted. I did a search first but didn't see anything.

https://a.co/d/ihZ1fe8

I installed one of these several years ago first on our former 2014 i3 and now on our 2019 i3. There's no better way to monitor the 12 V battery's health. This monitor logs the 12 V system voltage very frequently so that the 12 V battery's voltage is logged when the DC-DC converter is off.

However, several vendors sell the same monitor on Amazon at different prices and with different shipping charges. Just buy the least expensive Bluetooth BM2 monitor available.

 

[tongsli]

I installed one of these several years ago first on our former 2014 i3 and now on our 2019 i3. There's no better way to monitor the 12 V battery's health. This monitor logs the 12 V system voltage very frequently so that the 12 V battery's voltage is logged when the DC-DC converter is off.

However, several vendors sell the same monitor on Amazon at different prices and with different shipping charges. Just buy the least expensive Bluetooth BM2 monitor available.

I really like this product

 

[tongsli]

I'm noticing an intermittent anomalous dip every so often. Does anyone think this is a bluetooth connection issue? or something happening with the 12v battery or the monitoring unit itself.

TIA,

Lito

 

[tongsli]

Here's another one

 

[EvanstonI3]

I'm noticing an intermittent anomalous dip every so often. Does anyone think this is a bluetooth connection issue? or something happening with the 12v battery or the monitoring unit itself.

I've had my monitor for 2 years now and I've noticed that occasionally. For me, it appears if I send a command to the car from the app, like LOCK the doors or UNLOCK the doors. There have always been people that think sending a Lock/Unlock command to the car will somehow wake the car and "charge" the 12v battery, but it does not. Instead it does just what you see in your pic.

 

[tongsli]

I've had my monitor for 2 years now and I've noticed that occasionally. For me, it appears if I send a command to the car from the app, like LOCK the doors or UNLOCK the doors. There have always been people that think sending a Lock/Unlock command to the car will somehow wake the car and "charge" the 12v battery, but it does not. Instead it does just what you see in your pic.

So get this...a few weird things

1. my App will no longer tell me what time the car will be fully charged. Have no idea why.
2. I have my charging set to off peak, to start at 9:00pm. If I plug in beforehand, when 9pm hits the car won't start charging. If I ping the car with the app, like lock, it will immediately start charging. weird.

 

[Chrism88]

So get this...a few weird things

1. my App will no longer tell me what time the car will be fully charged. Have no idea why.
2. I have my charging set to off peak, to start at 9:00pm. If I plug in beforehand, when 9pm hits the car won't start charging. If I ping the car with the app, like lock, it will immediately start charging. weird.

Same issue. I think bmw updated the charging logic and it charges at the last minute, right before departure. It’s annoying

 

[alohart]

I'm noticing an intermittent anomalous dip every so often. Does anyone think this is a bluetooth connection issue? or something happening with the 12v battery or the monitoring unit itself.

I see similar dips occasionally as well. The monitor measures and records voltages directly and uses Bluetooth only to connect to the Battery Monitor app, so I doubt that Bluetooth connectivity is to blame. I doubt that the 12 V system voltage could plunge briefly unless a battery clamp, screw-on battery post, or a monitor connection is loose and loses full connection briefly. However, that doesn't make much sense when an i3 is parked, so I think there must be an occasional logging glitch.

The BM2 monitor developer told me how often the monitor measures the voltage. I can't recall exactly what he told me. Something like once every 5 minutes when the Battery Monitor app isn't connected and more frequently when it is connected. It appears that a single measurement is too low periodically.

 

[tongsli]

I see similar dips occasionally as well. The monitor measures and records voltages directly and uses Bluetooth only to connect to the Battery Monitor app, so I doubt that Bluetooth connectivity is to blame. I doubt that the 12 V system voltage could plunge briefly unless a battery clamp, screw-on battery post, or a monitor connection is loose and loses full connection briefly. However, that doesn't make much sense when an i3 is parked, so I think there must be an occasional logging glitch.

The BM2 monitor developer told me how often the monitor measures the voltage. I can't recall exactly what he told me. Something like once every 5 minutes when the Battery Monitor app isn't connected and more frequently when it is connected. It appears that a single measurement is too low periodically.

its a matter of sampling, I guess. Good to know others are having the same issue and it's just not me. It happens most often when I am not connected to the battery monitor.

thanks all

 

[808Pants]

I just got one of these Bluetooth monitors, and thinking I'd rather install it at some location more convenient than digging all the way in to the battery. Where can I find an always-hot and ground that are more easily accessed? (I take it these are strictly high-impedance voltage monitors, despite the #10-ish gauge wire they come with?)

 

[mojo]

At the fuse panel. IIRC I put a bolt in the alloy frame for the fuse panel to get a ground connection.

 

[808Pants]

Just realized I've never paid a moment's attention to cigarette lighters...are those always-hot items? If so, then maybe I should get a cig lighter variant of the Bluetooth voltage monitor (that I presume exists): plug/play installation?

 

[EvanstonI3]

Just realized I've never paid a moment's attention to cigarette lighters...are those always-hot items? If so, then maybe I should get a cig lighter variant of the Bluetooth voltage monitor (that I presume exists): plug/play installation?

No they are not always on. They shut down around 15 minutes after you leave the car. Also- getting to the 12v battery terminals to install is not that difficult. You just need to remove the Frunk Tray, then loosen the 10mm nuts on the battery terminals. You never have to go back to it after the install.

 

[tongsli]

Just realized I've never paid a moment's attention to cigarette lighters...are those always-hot items? If so, then maybe I should get a cig lighter variant of the Bluetooth voltage monitor (that I presume exists): plug/play installatio

No they are not always on. They shut down around 15 minutes after you leave the car. Also- getting to the 12v battery terminals to install is not that difficult. You just need to remove the Frunk Tray, then loosen the 10mm nuts on the battery terminals. You never have to go back to it after the install.

I initially tried this type of voltage monitor and could never get accurate readings. Much better at the battery itself. I also like being able to see the logs and to visually see if it is failing.

 

[808Pants]

Got this done after work yesterday. The only sketchy part of the process was the retightening of the + terminal (and the unexpectedly-large arcing, from each chance contact as I maneuvered it into place.) I actually removed that terminal again because it didn't seem that a safe level of torque applied to the little 10mm bolt through the split terminal was producing a rigid, tight connection. The plastic terminal housing obscures what's going on when tightening, but even after pulling it all the way out to inspect, then repeating it and paying particular attention to pressing downwards on the lug while tightening, at the max torque I felt comfortable applying, it felt like the terminal could still pivot slightly on the battery lug. I don't think this can be right. Comments?

The other thing I've not run into, coming from my last-millenium mechanical history, is the extra little horn sticking up from that battery lug. WTF? It's a BMW battery, but I won't speculate as to whether it's the original (2017.) Car was originally leased to someone who returned it, then dealer sold it to the guy I bought it from, and he drove it very seldom and never had any service work done.

 

[robthebold]

The only sketchy part of the process was the retightening of the + terminal (and the unexpectedly-large arcing, from each chance contact as I maneuvered it into place.)

Yikes!!!

 

[alohart]

The plastic terminal housing obscures what's going on when tightening, but even after pulling it all the way out to inspect, then repeating it and paying particular attention to pressing downwards on the lug while tightening, at the max torque I felt comfortable applying, it felt like the terminal could still pivot slightly on the battery lug. I don't think this can be right. Comments?

The connections to the battery terminals can be loose for 2 different reasons: the screws that attach the SAE posts to the battery terminals could be too loose and the screws that tighten the battery cable clamps could be too loose. Either could result in a poor or intermittent connection, so all screws should be tightened quite tight.

 

[EvanstonI3]

it felt like the terminal could still pivot slightly on the battery lug. I don't think this can be right. Comments?

The other thing I've not run into, coming from my last-millenium mechanical history, is the extra little horn sticking up from that battery lug. WTF? It's a BMW battery, but I won't speculate as to whether it's the original (2017.)

Mine have always pivoted slightly with some effort. Never been an issue yet.
Not sure what this "horn" is you refer to.
If you want to check to see if the battery is Original to the car, see this pic on what to look for:

If the 4-digit stamp is not there, it is a replacement battery and there will be a round date sticker someplace else.
If the 4-digit stamp IS there, you need to get rid of that battery ASAP

 

[Simoni3]

Yeh not easy to tighten the connection, lost a couple of torx bits