[Ovmsdev] MS_V_BAT_SOH
Michael Balzer
dexter at expeedo.de
Sat May 26 04:42:56 HKT 2018
I suggest to build upon the Twizy storage structure for this, extending it if necessary.
That way I can also easily make the Twizy battery history chart in the Android App available for other vehicles. Here's a screenshot:
https://dexters-web.de/g/custom/ovms/fn/Battery-Monitoring.png
The Twizy battery records are explained in the V2 Twizy manual, page 23/24:
https://github.com/openvehicles/Open-Vehicle-Monitoring-System/blob/master/docs/Renault-Twizy/OVMS-UserGuide-RenaultTwizy.pdf
When deriving a "*-BAT-…" definition from these, I would change some value types from int to float and output all values using their default units (i.e. V, kW).
I removed the cell count from the pack record some years ago to save space, that should again be added for the "*" records.
Please have a look and tell me if you think something else is missing.
Regards,
Michael
Am 25.05.2018 um 21:15 schrieb Geir Øyvind Vælidalo:
> Really nice, Michael! 🙂
>
> On the Kia Soul we get all 96 to 100 cell voltages, but the resolution is not that good: 0.02 V.
> We get the voltage and cell number for the two cells with the highest and lowest voltage, also with the lousy 0.02V resolution.
> At least we get the cell number and deterioration (%) for the best cell and worst cell, and that is what I actually use.
> On mykiasoulev.com <http://mykiasoulev.com> there is a group of people that created the SOH calculation I’ve implemented i OVMS. It matches the printouts from
> different car service reports quite well, so it is currently the best SOH number we have.
>
> A common way to store (and display) the battery cell voltages would be great ;-)
>
> Geir
>
>
>> 25. mai 2018 kl. 15:55 skrev Michael Balzer <dexter at expeedo.de <mailto:dexter at expeedo.de>>:
>>
>>
>> Am 25.05.2018 um 03:55 schrieb Mark Webb-Johnson:
>>> We definitely need some way to make these available in a standard way. I’m not sure that vehicle metrics is the correct way for that, though. Just too many numbers (99 for Tesla Roadster, for example) and maybe not available real-time (need to poll for them). Perhaps a standardised command would be a better approach for this?
>>
>> Yes, lots of metrics. I know that ;)
>>
>> OVMS# me li xrt.b.
>> xrt.b.cell.01.volt.act 3.995V
>> xrt.b.cell.01.volt.max 4.12V
>> xrt.b.cell.01.volt.maxdev 0.01V
>> xrt.b.cell.01.volt.min 3.795V
>> xrt.b.cell.02.volt.act 3.985V
>> xrt.b.cell.02.volt.max 4.11V
>> xrt.b.cell.02.volt.maxdev -0.01V
>> xrt.b.cell.02.volt.min 3.785V
>> xrt.b.cell.03.volt.act 3.985V
>> xrt.b.cell.03.volt.max 4.11V
>> xrt.b.cell.03.volt.maxdev -0.005V
>> xrt.b.cell.03.volt.min 3.785V
>> xrt.b.cell.04.volt.act 3.98V
>> xrt.b.cell.04.volt.max 4.105V
>> xrt.b.cell.04.volt.maxdev -0.01V
>> xrt.b.cell.04.volt.min 3.78V
>> xrt.b.cell.05.volt.act 3.985V
>> xrt.b.cell.05.volt.max 4.11V
>> xrt.b.cell.05.volt.maxdev -0.01V
>> xrt.b.cell.05.volt.min 3.78V
>> xrt.b.cell.06.volt.act 3.98V
>> xrt.b.cell.06.volt.max 4.105V
>> xrt.b.cell.06.volt.maxdev -0.01V
>> xrt.b.cell.06.volt.min 3.78V
>> xrt.b.cell.07.volt.act 3.985V
>> xrt.b.cell.07.volt.max 4.105V
>> xrt.b.cell.07.volt.maxdev -0.01V
>> xrt.b.cell.07.volt.min 3.78V
>> xrt.b.cell.08.volt.act 3.985V
>> xrt.b.cell.08.volt.max 4.115V
>> xrt.b.cell.08.volt.maxdev -0.005V
>> xrt.b.cell.08.volt.min 3.785V
>> xrt.b.cell.09.volt.act 3.985V
>> xrt.b.cell.09.volt.max 4.12V
>> xrt.b.cell.09.volt.maxdev 0.005V
>> xrt.b.cell.09.volt.min 3.785V
>> xrt.b.cell.10.volt.act 3.99V
>> xrt.b.cell.10.volt.max 4.12V
>> xrt.b.cell.10.volt.maxdev 0.005V
>> xrt.b.cell.10.volt.min 3.785V
>> xrt.b.cell.11.volt.act 3.99V
>> xrt.b.cell.11.volt.max 4.12V
>> xrt.b.cell.11.volt.maxdev 0.01V
>> xrt.b.cell.11.volt.min 3.79V
>> xrt.b.cell.12.volt.act 3.99V
>> xrt.b.cell.12.volt.max 4.12V
>> xrt.b.cell.12.volt.maxdev 0.01V
>> xrt.b.cell.12.volt.min 3.785V
>> xrt.b.cell.13.volt.act 3.985V
>> xrt.b.cell.13.volt.max 4.115V
>> xrt.b.cell.13.volt.maxdev 0.005V
>> xrt.b.cell.13.volt.min 3.785V
>> xrt.b.cell.14.volt.act 3.995V
>> xrt.b.cell.14.volt.max 4.125V
>> xrt.b.cell.14.volt.maxdev 0.015V
>> xrt.b.cell.14.volt.min 3.795V
>> xrt.b.cell.15.volt.act 0V
>> xrt.b.cell.15.volt.max 0V
>> xrt.b.cell.15.volt.maxdev 0V
>> xrt.b.cell.15.volt.min 0V
>> xrt.b.cell.16.volt.act 0V
>> xrt.b.cell.16.volt.max 0V
>> xrt.b.cell.16.volt.maxdev 0V
>> xrt.b.cell.16.volt.min 0V
>> xrt.b.cell.cnt 14
>> xrt.b.cmod.01.temp.act 17°C
>> xrt.b.cmod.01.temp.max 23°C
>> xrt.b.cmod.01.temp.maxdev 1°C
>> xrt.b.cmod.01.temp.min 16°C
>> xrt.b.cmod.02.temp.act 16°C
>> xrt.b.cmod.02.temp.max 23°C
>> xrt.b.cmod.02.temp.maxdev 1°C
>> xrt.b.cmod.02.temp.min 16°C
>> xrt.b.cmod.03.temp.act 17°C
>> xrt.b.cmod.03.temp.max 23°C
>> xrt.b.cmod.03.temp.maxdev 1°C
>> xrt.b.cmod.03.temp.min 16°C
>> xrt.b.cmod.04.temp.act 16°C
>> xrt.b.cmod.04.temp.max 23°C
>> xrt.b.cmod.04.temp.maxdev -1°C
>> xrt.b.cmod.04.temp.min 16°C
>> xrt.b.cmod.05.temp.act 17°C
>> xrt.b.cmod.05.temp.max 23°C
>> xrt.b.cmod.05.temp.maxdev 1°C
>> xrt.b.cmod.05.temp.min 16°C
>> xrt.b.cmod.06.temp.act 16°C
>> xrt.b.cmod.06.temp.max 23°C
>> xrt.b.cmod.06.temp.maxdev -1°C
>> xrt.b.cmod.06.temp.min 16°C
>> xrt.b.cmod.07.temp.act 16°C
>> xrt.b.cmod.07.temp.max 23°C
>> xrt.b.cmod.07.temp.maxdev -1°C
>> xrt.b.cmod.07.temp.min 16°C
>> xrt.b.cmod.08.temp.act -40°C
>> xrt.b.cmod.08.temp.max -40°C
>> xrt.b.cmod.08.temp.maxdev 0°C
>> xrt.b.cmod.08.temp.min -40°C
>> xrt.b.cmod.cnt 7
>> xrt.b.pack.1.temp.alerts
>> xrt.b.pack.1.temp.max 23°C
>> xrt.b.pack.1.temp.min 16°C
>> xrt.b.pack.1.temp.stddev.max 1°C
>> xrt.b.pack.1.temp.watches
>> xrt.b.pack.1.volt.alerts
>> xrt.b.pack.1.volt.max 57.6V
>> xrt.b.pack.1.volt.min 52.8V
>> xrt.b.pack.1.volt.stddev.max 0.005V
>> xrt.b.pack.1.volt.watches 1,2,4,5,6,7,11,12,14
>> xrt.b.pack.cnt 1
>> xrt.b.soc.max 100%
>> xrt.b.soc.min 69.78%
>>
>>
>> But if they are available in real time, they provide a very cool battery monitor, that displays per cell voltage breakdowns during driving:
>>
>> <kefminlpnpehmipb.png>
>>
>>
>> If metrics can use extram, 100 cells would be no problem.
>>
>> Regards,
>> Michael
>>
>>
>>> Regards, Mark.
>>>
>>>> On 24 May 2018, at 10:28 PM, Robin O'Leary <ovmsdev at caederus.org> wrote:
>>>>
>>>> On Wed, May 23, 2018 at 10:42:32PM +0800, Mark Webb-Johnson wrote:
>>>>> What is MS_V_BAT_SOH used for?
>>>> ...
>>>>> Which is it?
>>>>> An overall indication of battery health? 100% being perfect, and 0% a brick?
>>>>> Or battery capacity (100% being a new car, and 50% being one who’s range is only half that of a new car)?
>>>> If the car provides its own SOH value, then we should report it, even if
>>>> we don't know exactly what it means. In some cases, it may be important
>>>> for warranty claims.
>>>>
>>>> For the Leaf, the BMS-reported SOH seems more complicated than just a
>>>> percentage of new capacity; e.g. increased internal resistance and cell
>>>> imbalance are also factors.
>>>>
>>>> If the car does not provides its own SOH value directly, then maybe
>>>> it's better not to fake it; just show whatever values are available.
>>>> Or perhaps it could be user preference which value best serves their
>>>> particular purpose: total capacity depletion, cell imbalance ...
>>>> or some combination.
>>>>
>>>> ...
>>>>> Nissan Leaf uses:
>>>>> StandardMetrics.ms_v_bat_soh->SetValue(ah / newCarAh * 100);
>>>> You may recall, we had a recent discussion in favour of changing the
>>>> Leaf's ms_v_bat_soc and ms_v_bat_soh to report the values directly from
>>>> the BMS.
>>>>
>>>> We do now report SOC as both direct-from-car and scaled-to-new values
>>>> in Leaf-specific metrics ("m_soc_instrument" and "m_soc_new_car")
>>>> and we have a config preference for which one to copy to ms_v_bat_soc
>>>> (defaulting to the instrument value).
>>>>
>>>> We have not yet done that for SOH, but hopefully will do so soon, adding
>>>> "m_soh_instrument" for the BMS value and moving the above calculation to
>>>> "m_soh_new_car" .
>>>> ...
>>>>> Find out the difference between SOC LIM MIN and LIM MAX, and use that as an indication of imbalance in the pack.
>>>>>
>>>>> Or should we just add SOC_MIN and SOC_MAX if these are used in many cars? Or an imbalance percentage?
>>>> Having a way to report cell imbalance is a good idea, but trying to
>>>> express it as two percentage values seems rather crude. The Leaf can
>>>> report voltage for every cell, but (as far as I know) does not indicate
>>>> the nominal voltage value (and I wouldn't be surprised if these differ
>>>> between the three(?) generations of chemistry already in circulation), so
>>>> converting each one to a % would be arbitrary. Also, the distribution of
>>>> voltage values for the modules is often tightly grouped, with just a few
>>>> outliers, so just picking the lowest and highest is a bit too simplistic.
>>>> A better way would be to report all the cell voltage measurements
>>>> directly, or at least some basic statistics (n, average, stddev).
>>>>
>>>> How widely are such detailed values available for other vehicles?
>>>> _______________________________________________
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>>
>> --
>> Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
>> Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
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Michael Balzer * Helkenberger Weg 9 * D-58256 Ennepetal
Fon 02333 / 833 5735 * Handy 0176 / 206 989 26
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