question

Hi @ivo

Where is the DC shunt installed, if there is any, or your SOC metering device?

In order to have an accurate SOC you should also meter the current consumed by the battery heating system.

Also, you should activate "Has DC system" and provide a constant current power supply on DC bus equal with your heating system consumption

Kind regards,

Mihai

Hi @MihaiR

thanks for your prompt reply.

> Where is the DC shunt installed, if there is any, or your SOC metering device?

There is no external shunt. The BMS does all the measurements (SOC, current, voltage etc.) and provides them to Venus. It also controls the heating. There is no external control for that.

I have activated "Has DC system" but cannot see any effect. If I understand the manual correctly, what this does is add an additional "box" to visually indicate the difference between the DC current measured by Venus (VE.bus) and the one measured by the BMS. This would indeed be handy to quickly check the power consumed by the heaters. However I cannot find said box.
In any case, this presumably wouldn't solve our problem.

> provide a constant current power supply on DC bus equal with your heating system consumption

This is not practical.
The heating is variable, it depends on ambient temperature and on battery usage patterns, so it would be problematic to use a constant-power charger.

Since we already have a controllable charger (a Quattro), it guess it should be involved in a solution to our problem with ESS.

This -of course- if the problem we experience is indeed caused by self-discharge.
Can you, or somebody else, confirm or reject that hypothesis?

regards

Ivo

Hint for building a suitable CCS for Victron ESS:

Use a high quality bench power supply capable to limit both current and voltage and supply the output to a Bluesolar MPPT controller connected to DC bus. Set the bench power supply current limit accordingly with the max heater consumption and voltage below max MPPT input voltage

Obviously, you must connect the MPPT to Venus device :-)

It looks like indeed; the BatteryLife option is not suitable with that battery type.

To then conclude that all of ESS doesn’t work is premature.

Sustain will do it; it works on voltage. See ESS manual for how sustain works.

To answer the more software developer question;

The 5A parameter is probably in the hub4control source code; which is closed source, and C or Cpp. I’ll send you an email about it; Ivo.

Hi Mathijs,

> Sustain will do it; it works on voltage. See ESS manual for how sustain works.

Thanks, I will look into this and report back.

> To then conclude that all of ESS doesn’t work is premature.

Well, I admit the title chosen is click-baity.
But it got your attention, right :)
cf. Betteridge's law.

Sincerely
Ivo