BM2 Battery Monitor

Faults and Technical chat for the Honda E
kbjpick
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Post by kbjpick » Mon Feb 28, 2022 12:28 pm

Having recently viewed the Mr EV Monitoring the IONIQ 5's 12- Volt battery using the BM2 Battery Monitor which conclusively proves that Hyundai's housekeeping routines DO charge the 12 v battery from the Traction Battery as and when required and, having had a BM2 monitor on my Honda e Advance for a few weeks now - it would appear that the Honda DOES NOT charge the 12 v battery UNLESS you are charging the Traction Battery or using the car.

Therefore. if the car is sat in the garage and not being used - eventually it will deplete it's charge through normal parasitic usage, i.e. alarm system use or watching for proximity of owner's key etc. and thus requires a Maintenance routing to ensure a healthy battery in such low use situation.

Has anyone else formed similar conclusions?

Haaploos
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Location: Oslo - Norway

Post by Haaploos » Mon Feb 28, 2022 12:45 pm

IIRC the car wont charge the 12V battery if the car is over 80% charge.

Check out these threads for more info:
Charging of 12V Battery

12 volt battery
Modern steel advance 17"

kbjpick
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Post by kbjpick » Mon Feb 28, 2022 3:02 pm

For clarification - if I understand you correctly - if the traction battery is more than 80% charge, the assertion is that the 12v battery will deplete until it is no longer functional and unable to operate the 80% charged car !!

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londiniumperson
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Post by londiniumperson » Mon Feb 28, 2022 5:04 pm

Can you post some screenshots of the BM2 data?

Here’s are screenshots of my car using the CTEK battery monitor whilst I was not using it between 18-25 Feb (the spike on the far left was the last traction battery charge), the main battery had a SoC of >90% . Make your own assumptions.

Voltage:

Voltage.png

SoC:

SoC.png

Temperature:

Temp.png

Last edited by londiniumperson on Tue Mar 01, 2022 4:44 pm, edited 1 time in total.
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kbjpick
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Post by kbjpick » Tue Mar 01, 2022 4:33 pm

ref Londinium post - see screenshot of period

IMG_4896 copy.jpg

when there were no charging periods of the traction battery. Not SOC was <70% and NO evidence of a 'maintenance' routine for the 12v battery. For comparison I have also included a screenshot of a charging period indicating degradation post charging

IMG_4895.jpeg


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HausO
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Post by HausO » Tue Mar 01, 2022 8:00 pm

@kbjpick: The 12V battery will NOT be charged when you are charging the HV battery. The DC-DC converter is active while charging the HV battery but only at 13,3V. It's a kind of trickle charging. This will stop at 100% SoC.

Only while driving the DC-DC converter goes up to 14,6-14,8V and the 12V battery is really charged with the restrictions I wrote in the mentioned posts. Because of this I disconnect the current sensor (the data communication cable from the sensor to the car) at the minus connector of my 12V battery. Result: Orange battery warning light is on but my 12V battery every time independend from the SoC of the HV battery.

I my opinion your 12V battery is no fully charged because the voltage falls below 12V. Try a external charger to recharge it to 100%.

Regards

Henning
Last edited by HausO on Tue Mar 01, 2022 9:23 pm, edited 1 time in total.

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londiniumperson
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Post by londiniumperson » Tue Mar 01, 2022 8:45 pm

HausO wrote:
Tue Mar 01, 2022 8:00 pm
@kbjpick: The 12V battery will NOT be charged when you are charging the HV battery. The DC-DC converter is active while charging the HV battery but only at 13,3V. It's a kind of trickle charging. This will stop at 100% SoC.

Only while driving the DC-DC converter goes up to 14,6-14,8V and the 12V battery is really charged with the restrictions I wrote in the mentioned posts. Because of this I disconnect the current sensor (the data communication cable from the sensor to the car) at the minus connector of my 12V battery. Result: Orange battery warning light is on but my 12V battery every time independend from the SoC of the HV battery.

I my opinion your 12V battery is no fully charged because the voltage fall below 12V. Try a external charger to recharge it to 100%.

Regards

Henning
I can confirm, as proven by the image below:
  • Whilst driving the 12V battery is being charged as described to just below 15V as seen whilst I was driving home between 18:25 & 19:05 (no idea why there's 2 spikes because I didn't stop for more than a few seconds at junctions).
  • Whilst charging the HV battery, it is around 13V, again as described, seen between 20:30 & 23:30 (charged to 90%).

Voltage whilst driving and charging (Small).jpg

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kbjpick
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Post by kbjpick » Wed Mar 02, 2022 3:42 pm

Thanks to Henning and Londiniumperson - I will reflect on comments whilst familiarising myself with Ioniq 5 Ultimate AWD being stablemate to Honda e

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londiniumperson
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Post by londiniumperson » Sat Mar 05, 2022 12:31 pm

kbjpick wrote:
Wed Mar 02, 2022 3:42 pm
Thanks to Henning and Londiniumperson - I will reflect on comments whilst familiarising myself with Ioniq 5 Ultimate AWD being stablemate to Honda e
How are you finding the Ioniq 5, especially in comparison to the Honda, I’ve had a short test drive in one and really liked it, both from a driver’s perspective as well as visually. If you get an opportunity please could you add your thoughts to the existing thread:
IONIQ 5
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londiniumperson
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Post by londiniumperson » Sat Mar 05, 2022 12:41 pm

I’ve just had another look at the battery monitor and can confirm that the 12V battery is charged whilst the preheat function is running (the car was not drawing power from the wall charger during this time frame) this can be seen as the lower voltage before I was driving:

Preheat and drive .png

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