Observations on 12v Battery SOC

[Aussi55]

Hi all,

I recently fitted my Bluetooth BM2 battery monitor to the ZS EV just to get an idea of what the SOC was over time as I am currently not using the car every day.

It had been sitting for a few days when I fitted it and I was surprised it was low at 47%. The car is just over a year old.

Anyway I can confirm that once charged it runs down to around 50% in 5 days. Either my battery is failing or there is a drain, which I will check into when time allows.

Possibly the car sat for some time before I bought it, lead acid batteries get sulphate build up if allowed to go below 50%.

Charging does occur when the traction battery is on charge.

Thought I'd share as the battery monitor gives good information and is relatively cheap.

 

[Deleted member 7171]

Could also be a poor quality 12v battery the manufacturer fits to reduce costs?

 

[Kithmo]

50% in 5 days does sound excessive.
If that battery was on an ICE car it wouldn't start, definitely something not right there.

 

[Alb]

Either my battery is failing or there is a drain, which I will check into when time allows.

Don't forget that some of that drain will be the monitor itself!

 

[Kithmo]

Don't forget that some of that drain will be the monitor itself!

Not much at 1.5mA (as shown in his picture), less than 0.2A in 5 days by my reckoning.

 

[Alb]

What it says it does and what it actually does aren't necessarily the same thing!

 

[Aussi55]

Hi,

Thanks for your replies. The monitor takes very little (measured to be sure). It was also on my previous car for sometime without issues, even during lockdown.

I suspect a combination of some drain, the colder weather and a tired battery.

As mentioned if it were ice it wouldn't start.

Glad I know.

I do like the monitor though!

Thanks again and keep you posted.