Henry's Blog

[Rok_Dr]

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You can always fit a cheap BLE battery monitor to both batteries and take a closer look at what is going on. I have some screen captures from the BLE in my review of the rooftop solar panel here.

On my car, the BLE battery monitors and the Grenadiers SOC are broadly similar - both are estimating SOC anyway. I use the amps being charged to give me a good idea of where the SOC really is, 1 amp strongly suggests the batteries are close to 100% SOC (assuming the battery is working properly).

Thanks Michael

Yes getting some monitoring fitted is on my radar.... along with some sump guards, x-spec window mounts etc and getting my tax return in . I may go upmarket with Victron or Redarc shunts, only because I have their products and apps installed. Battery was tested as OK so my thinking is its either lazy alternator or more likely the BMW module has been programmed for city use.

My battery SOC generally hovers around the 80% mark. never above 82 unless I use an external charger and even then , only high 80s for a while.
I was reassured by this recent forum post:
"Maintaining the battery at approximately 80% SOC is by design. It's not a fault.
I discussed this with a senior BMW tech recently and he confirmed this is how BMW manage their batteries to reduce fuel consumption and extend battery life. In newer BMWs the target SOC is configurable to allow for the owner's usage pattern. For a city driver the alternator can be set to charge more aggressively during short trips and maintain the battery charge and ensure vehicle operation at the expense of higher fuel consumption.
This intelligent battery management is why we're seeing fluctuations in the charge rates during a drive cycle. Setting aside that there has been some reports of faulty batteries, my suggestion to the forum is to understand this is normal operation so stop fixating on less than 100% battery SOC."

Thanks Tazzieman

In my digging around the internet and forum that's my understanding as well, which is why I'm not too stressed and around 80% SOC may also extend battery life. But I would like to know why some cars like the loan vehicle I had, charge to 99% with higher amps coming from the alternator than a lot of our cars. Also it would be nice for the battery to fully charge so I have an extra 20-25 amp/hrs capacity when off grid. Still with a jump starter and a solar panel the worst that can happen is being parked up for an hour or so to recharge.

Finally talking with Paul Hennig last week he alluded to a forthcoming TSB that could also address this variability.

Cheers
Steve