Keep track of your 12V battery with the Ancel BM200

[Dee]

A very handy battery monitoring device, the Ancel BM200.
It connects by Bluetooth and you can monitor your battery voltage live.
I installed it on my Microlino cuz it doesn't have any remote services.
I thought I'd share it here, it may come in handy for the Taycan to install it in too.
At least I will.

Loads of features, really great stuff.

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[Scandinavian]

Willbe interesting to hear if that works with a Lithium 12 volt battery?

 

[Shug]

Slightly off topic.

I receive a recall from Porsche this week, turns out it is something to do with my J1.1 12V battery that is being reprogrammed.

 

[Dee]

Willbe interesting to hear if that works with a Lithium 12 volt battery?

Why not?
With a LiFePO battery, the voltage is a very good indication of SoC.
With a Pb one (AGM), like in my Microlino, it's just a wild guess.
Right now, it says it's 39% SoC while it was full yesterday so this doesn't work properly on a Pb battery (you can select different kinds of batteries).
I've ordered another Ancel BM200 (it's only €18) for my Taycan, it's on it's way so it'll be here probably next week.
I'll report back of course.

 

[Dee]

Today I installed my Ancel BM200.
Easy to install, under the nut of the both terminals.

The white part in the front is the Ancel BM200.

Now I can check my both batteries.

Nice.

 

[69Mach390]

Interesting.

Something like this may reduce anxiety for some, but it would just create extra anxiety for me.

Other than testing/replacing the 12v when it fails (hopefully after 8+ years), I plan on having zero interaction with it until then.

 

[Dee]

I plan on having zero interaction with it until then.

I'm just adding another consumer, nothing else.
Some add a dashcam, others a BT monitoring device.

 

[Scandinavian]

Why not?
With a LiFePO battery, the voltage is a very good indication of SoC.
With a Pb one (AGM), like in my Microlino, it's just a wild guess.
Right now, it says it's 39% SoC while it was full yesterday so this doesn't work properly on a Pb battery (you can select different kinds of batteries).
I've ordered another Ancel BM200 (it's only €18) for my Taycan, it's on it's way so it'll be here probably next week.
I'll report back of course.

Would like to hear more about you experience of this after some time.

From what I have seen the voltage curve for a LiFePO battery is very flat. Thus it will be difficult to determine the SoC from voltage alone. Some good monitoring devices (probably more expensive) will instead monitor the input and draw from batteries, Coloumb meter. And I hope that is whatPorsche has installed in the Taycan.

Your ANCEL monitoring device will of course register very well the voltage over time and it would be interesting to see such a diagram over a week or a month. I am not saying it would not work to measure voltage, but that it would be difficult to determine the SoC.

I am surprised at your Microlino results, given the diagrams below, but I am not a battery expert. Maybe @Dr Bob can clarify?

 

[Dee]

Would like to hear more about you experience of this after some time.

From what I have seen the voltage curve for a LiFePO battery is very flat. Thus it will be difficult to determine the SoC from voltage alone. Some good monitoring devices (probably more expensive) will instead monitor the input and draw from batteries, Coloumb meter. And I hope that is whatPorsche has installed in the Taycan.

Your ANCEL monitoring device will of course register very well the voltage over time and it would be interesting to see such a diagram over a week or a month. I am not saying it would not work to measure voltage, but that it would be difficult to determine the SoC.

I am surprised at your Microlino results, given the diagrams below, but I am not a battery expert. Maybe @Dr Bob can clarify?

Taycan: you can't monitor SoC to 0% as the 12V battery is automatically being charged by the car as you probably know.
13.2V for a LiFePo is a reliable indication it's healthy and the charging is on par.
14.4V means it's charging which is good, <13V means the car isn't charging which is very very bad!
With Li-ion batteries, the voltage is an excellent indication about SoC, with AGM/Lead-acid not so much.
There's the difference.

Microlino: it has a small 12V Pb AGM battery and it's not automatically being charged by the car when it's off, that's why I have to monitor it.
When it gets below 10-11V it needs charging, that's mostly after a week, just to be sure.
Today I discovered the battery is being charged as soon as I open the door so no need to actually turn the car on, I didn't know that, thanks to my Ancel.

 

[69Mach390]

Taycan: you can't monitor SoC to 0% as the 12V battery is automatically being charged by the car as you probably know.
13.2V for a LiFePo is a reliable indication it's healthy and the charging is on par.
14.4V means it's charging which is good, <13V means the car isn't charging which is very very bad!
With Li-ion batteries, the voltage is an excellent indication about SoC, with AGM/Lead-acid not so much.
There's the difference.

Microlino: it has a small 12V Pb AGM battery and it's not automatically being charged by the car when it's off, that's why I have to monitor it.
When it gets below 10-11V it needs charging, that's mostly after a week, just to be sure.
Today I discovered the battery is being charged as soon as I open the door so no need to actually turn the car on, I didn't know that, thanks to my Ancel.

Oh my that thing is ADORABLE!

 

[Dee]

Oh my that thing is ADORABLE!

Thanks!
Indeed, it's brilliant.
It does 90 km/h and has around 100 km of range.
I had a custom interior installed with the original BMW Isetta fabric.

My little grocery getter.

 

[Dr Bob]

Would like to hear more about you experience of this after some time.

From what I have seen the voltage curve for a LiFePO battery is very flat. Thus it will be difficult to determine the SoC from voltage alone. Some good monitoring devices (probably more expensive) will instead monitor the input and draw from batteries, Coloumb meter. And I hope that is whatPorsche has installed in the Taycan.

Your ANCEL monitoring device will of course register very well the voltage over time and it would be interesting to see such a diagram over a week or a month. I am not saying it would not work to measure voltage, but that it would be difficult to determine the SoC.

I am surprised at your Microlino results, given the diagrams below, but I am not a battery expert. Maybe @Dr Bob can clarify?

Good note Peter.

Dee said - "With a LiFePO battery, the voltage is a very good indication of SoC."
No it is not. It is a poor indication of SoC.

LiFePO's and Li ion are both similar in the voltage v SOC curve as indicated in your diagrams Peter. They are principally the same shape but the curve is shifted down to lower voltage for the LiFePO. The curves are essentially flat between 20% and 85% so the voltage hardly changes. My experience is 'knees' at 90% and 20% are more significant than these diagrams ie big changes at the ends but almost flat in the middle. For both types, you cannot estimate SOC between 80 and 20%. When you are in the knees, you can. This is why examining the performance of the Taycan main battery is usually done by measuring voltage at a very low SOC.

Just some other comments on the thread.
Why put a battery monitor on the 12V battery? You can see the voltage in the battery already on the information display. I keep my voltage displayed at all times. You have to know what you are looking at however - as it only displays when the car is 'on' and so the 12 V battery will be charging. Normally when driving, my 12V is at 13.5V. This is likely 0.2v above the 'rested' voltage of the battery, ie with no drain or charge on the battery. It is slightly above the rested voltage as the main battery is trickle charging the 12V. This says to me the 12V is fully charged.
If you start the car after a week or so of non use, you will see the voltage rise to 14.1V or higher voltage. This is the car identifying the 12V is low SOC and is charging it at a fast rate. That voltage could rise to 14.3 or 14.4V. I've never seen it go higher. The higher the voltage, the higher the rate of charge and the lower the SOC. After 30 mins of driving or external charging, the 12V will be fully charged and the voltage returning to 13.5V.
To know how charged the 12V battery is, just look at the voltage the car reports. 13.5V is fine. over 14V means it is charging and needs more.

These battery monitors cant measure SOC without measuring current flow in and out of the battery which likely then needs a shunt to do the measurement and is more complex to fit - you cant do it with just 2 connectors.

I am not sure why the thread keep mentioning LiFePO's. Maximum charging voltage on a LiFePO is usually less than 14.2V and I am seeing higher than this on my Taycan (J 1.1). I guess my 12V is an Li ion ??? Not sure. Happy to be put right.

I guess the only reason for a battery monitor is to keep a track of 12V charge when the car is not in use. Mine has only lost its charge once in my 3 years of ownership and if it does it again then I will get Porsche to sort it. It only took Porsche assist 30 mins to turn up to sort it when it failed a few weeks ago. Fitting a battery monitor in the UK with the excellent Porsche assist (The AA give us Taycan owners priority over everyone) just seem like more hassle.

 

[Gru]

Oh my that thing is ADORABLE!

it is ! sat in one recently: entering/exiting is an adventure

but the price 🫣... oh my....

 

[Dee]

Why put a battery monitor on the 12V battery? You can see the voltage in the battery already on the information display.

I don't want to start the car for just reading the state of the battery.
Besides, it'll jump to charging right away (14,4V).
Like I said: 13.2V is good, 14.4V is very good (the car is indeed charging the battery), <13V is very very bad.
For my Microlino: just to see when it has to be charged again (@10-11V), mostly after a week or so.
But I think I'm repeating myself here.
I want to read the batteries from my home.
Wasn't that clear?
You guys are going way too deep into this matter.

 

[jkoya]

The ancel website (for US) does state the BM200 is "compatible with 12V Lead-acid & Lithium battery" while the BM200 Pro is for Lead Acid Batteries.

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