RCT: add battery control

[andig]

Depends on mlnoga/rct#18

[andig]

@Maschga could you give this PR a try? I'm not sure I'm calling the right functions for hold/normal. Would be great if you could test this with an actual device.

[Maschga]

Normal looks good. 👍

Why do you use SOCTargetConstant for Hold?
According to do-gooder it should be SOCTargetExternal. Is SOCTargetConstant better? What is the effect?
Source:

evcc/meter/rct.go

Line 202 in dc00b24

return m.conn.Write(rct.PowerMngSocStrategy, []byte{rct.SOCTargetConstant})

[andig]

What is the effect?

I wouldn't know. It sounded as if the RCT would then hold the soc constant. However, that's also not what we want. Hold should prevent discharge, but still allow charge. Not sure how to best do this. I guess SOCTargetExternal with given Soc would still have the same problem.

[Maschga]

Is it evcc possible to calculate how much surplus is available in addition to charging the e-car and how many kw could still charge the battery? Then this could be added using power_mng.battery_power_extern.

[andig]

much surplus is available in addition to charging the e-car and how many kw could still charge the battery? Then this could be added using power_mng.battery_power_extern.

Why? Battery does that itself?!

[Maschga]

I have set power_mng.soc_strategy to Constant. This results in the target Soc of the battery being set to 50%. RCT then wanted to discharge the battery, which is currently full.

[andig]

So: what to use for hold (but still charge surplus)? You'll need to tell me- I can't test this...

[TobiasHuber1980]

Keine Ahnung, aber vielleicht hilft es euch ja...

External battery control is possible when the SoC target selection is set to "Extern":

Parameter: 0xF168B748 // power_mng.soc_strategy | t_enum (uint8_t) | SoC target selection

The following six values are possible:

0 – SoC target = SoC

1 – Const

2 – Extern

3 – Average Battery voltage

4 – Intern (default)

5 – Timetable

The power_mng.battery_power_extern parameter allows external control of the desired battery power:

0xBD008E29 // power_mng.battery_power_extern | t_float | Battery target power [W] (positive = discharge)

[Maschga]

You could set power_mng.soc_min to the current SOC value of the battery. This will prevent the battery from discharging, but the battery can still charge if there is excess power available.

[andig]

Welches Datenformat braucht da der Parameter? 1 Byte? Float32?

[Maschga]

Laut rctclient ist das ein float.
So sieht der Code im PR aus:

// SetSocMin sets the minimum SOC target (power_mng.soc_min) with the given value
func (c *Connection) SetSocMin(min float32) error {
	if min < 0.00 || min > 1.00 {
		return fmt.Errorf("invalid SOC min value: %.2f, valid range is 0.00 to 1.00", min)
	}

	// Round to 2 decimal places
	min = float32(math.Round(float64(min)*100) / 100)

	data := make([]byte, 4)
	binary.BigEndian.PutUint32(data, math.Float32bits(min))

	if err := c.Write(PowerMngSocMin, data); err != nil {
		return fmt.Errorf("failed to set SOC min: %w", err)
	}

	return nil
}

[Maschga]

Das Runden der Zahl kannst du weglassen. Das ändere ich noch im PR.

[andig]

Du kannst nochmal probieren. Wenn das nicht funzt gerne nach Bedarf anpassen.

[Maschga]

Kannst du für minsoc einen Default von 7% (also 0.07) und für maxsoc einen Default von 97% (also 0.97) angeben?

[andig]

Das kannst du im Template ändern.

[andig]

Braucht man für charge überhaupt external? Sonst könnte man da auch einfach nur den minsoc setzen und müsste gar nicht mit dem Modus rumfrickeln...

[Maschga]

@andig Kannst du mir für diesen PR Schreibzugriff geben? Würde gerne eine Implementierung committen.

[Maschga]

Hab's mit einem separaten PR gelöst.

[Maschga]

Super, das muss dann nur noch endgültig getestet werden.

[andig]

Kannst du das testen?

[andig]

Argh. Warum brauchts diese ganzen Werte? Ich möchte die nicht setzen falls es nicht absolut notwendig ist. Ich würde das gerne rückgängig machen, es sei denn es gäbe einen zwingenden Grund dafür.