Home battery discharges during planned/smart charging in v0.314.x

[mietoome]

Description

I noticed a possible change in behavior after updating to v0.314.x regarding home battery protection.

Previously, setting the buffer helped prevent my home battery from discharging into the EV. In the newer version, the revised battery settings (Priority and Buffer) seem to apply strictly to PV mode. When a Target / Smart Cost charging plan activates, the system pulls full power, which leads my AC-coupled home battery (Marstek Venus E) to discharge at full capacity into the car.

I was able to mitigate this by utilizing the Hold Mode Script setting to call a Home Assistant script (script.battery_hold) that sets the battery discharge power to 0 W during planned charging slots.

Is this intended behavior with the new battery logic, or could this be an edge case?

If intended, would it be possible to consider adding a native toggle in the UI (e.g. "Hold battery discharge during planned/smart charging") so users don't necessarily need external scripts to keep their home battery reserved for household use during grid charging sessions?

Steps to Reproduce

1. Configure a home battery in evcc with buffer settings set to preserve battery capacity (e.g. Buffer set to 100%).
2. Set up dynamic grid pricing and configure a target/smart charging plan for the EV (e.g. cheapest slots or continuous target charge).
3. Connect the vehicle and wait for the planned charging slot to start.
4. Observe the home battery during the planned grid charging session: the battery discharges at maximum power to cover the vehicle load instead of remaining untouched/held for household consumption.

Configuration (YAML)

no yaml configuration

Configuration (UI)

{
  "charger": [
    {"id":14,"name":"db:14","type":"template","config":{"id":"9260ce11-902a-449e-9a37-eb2baade3813","template":"zaptec","passive":false,"password":"***","user":"***"},"deviceProduct":"Zaptec Go 2"}
  ],
  "experimental": true,
  "influx": {"database":"","insecure":false,"org":"","password":"","token":"","url":"","user":""},
  "interval": 30,
  "loadpoints": [
    {"id":15,"name":"db:15","batteryBoostLimit":100,"charger":"db:14","defaultMode":"pv","limitEnergy":0,"limitSoc":0,"maxCurrent":16,"minCurrent":6,"minSoc":0,"phasesConfigured":0,"planEnergy":0,"planPrecondition":0,"planStrategy":{"continuous":true,"precondition":0},"planTime":"0001-01-01T00:00:00Z","priority":0,"smartCostLimit":null,"smartFeedInPriorityLimit":null,"soc":{"estimate":true,"poll":{"interval":3600000000000,"mode":"charging"}},"thresholds":{"disable":{"delay":180000000000,"threshold":0},"enable":{"delay":60000000000,"threshold":0}},"title":"Zaptec","ui":{"maxTemp":100,"minTemp":0},"vehicle":"db:17"}
  ],
  "meter": [
    {"id":16,"name":"db:16","type":"template","config":{"template":"homeassistant","capacity":5.12,"energy":"sensor.marstek_venus_e_thuisbatterij_marstek_total_charging_energy","insecure":false,"maxacpower":"0","maxsoc":100,"minsoc":11,"modeHold":"script.battery_hold","modeNormal":"script.battery_release","power":"sensor.marstek_venus_e_thuisbatterij_marstek_ac_power","returnEnergy":"sensor.marstek_venus_e_thuisbatterij_marstek_total_discharging_energy","soc":"sensor.marstek_venus_e_thuisbatterij_marstek_battery_state_of_charge","uri":"***","usage":"battery"},"deviceProduct":"Home Assistant","deviceTitle":"Marstek"},
    {"id":11,"name":"db:11","type":"template","config":{"template":"homeassistant","insecure":false,"maxacpower":"0","power":"sensor.stadswarmte_actueel","uri":"***","usage":"charge"},"deviceIcon":"meter","deviceProduct":"Home Assistant","deviceTitle":"stadswarmte"},
    {"id":13,"name":"db:13","type":"template","config":{"template":"homeassistant","energy":"sensor.inverter_total_yield","insecure":false,"maxacpower":"0","power":"sensor.inverter_active_power","returnEnergy":"sensor.huawei_solar_inverter_day_peak_power","uri":"***","usage":"pv"},"deviceProduct":"Home Assistant","deviceTitle":"Zon actueel"},
    {"id":3,"name":"db:3","type":"template","config":{"template":"homewizard","host":"192.168.1.235","usage":"grid"},"deviceProduct":"HomeWizard Wi-Fi P1 Meter"}
  ],
  "mqtt": {"broker":"","caCert":"","clientCert":"","clientID":"","clientKey":"","insecure":false,"password":"","topic":"evcc","user":""},
  "residualPower": 0,
  "shm": {"deviceId":"","deviceSerial":"","vendorId":""},
  "site": {"aux":null,"battery":["db:16"],"consumer":null,"ext":["db:11"],"grid":"db:3","pv":["db:13"],"title":""},
  "tariff": [
    {"id":9,"name":"db:9","type":"template","config":{"template":"tibber","token":"***"},"deviceProduct":"Tibber"},
    {"id":10,"name":"db:10","type":"template","config":{"template":"tibber","token":"***"},"deviceProduct":"Tibber"}
  ],
  "tariffRefs": {"co2":"","feedIn":"db:10","grid":"db:9","planner":"","solar":[],"temperature":""},
  "vehicle": [
    {"id":17,"name":"db:17","type":"template","config":{"template":"cardata","autodetectdisabled":false,"clientid":"ebc41a9a-ef96-4663-a716-acc704a3edeb","climaterdisabled":false,"coarsecurrent":false,"icon":"car","phases":"3","priority":0,"streaming":true,"title":"ix3","vin":"***","wakeupdisabled":false,"welcomecharge":true},"deviceProduct":"BMW CarData"}
  ]
}

Logs

[lp-1  ] DEBUG 2026/08/22 08:46:52 set charge mode: pv
[site  ] DEBUG 2026/08/22 08:46:52 ----
[lp-1  ] DEBUG 2026/08/22 08:46:52 charge power: 0W
[lp-1  ] DEBUG 2026/08/22 08:46:52 charge currents: [0.026 0.025 0.024]A
[homeassistant] DEBUG 2026/08/22 08:46:52 loading token for http://192.168.1.195:7070-ede8f545 from database
[site  ] DEBUG 2026/08/22 08:46:52 ext 1 power: 90W
[site  ] DEBUG 2026/08/22 08:46:52 battery 1 power: 0W
[site  ] DEBUG 2026/08/22 08:46:52 pv 1 power: 403W
[site  ] DEBUG 2026/08/22 08:46:52 battery 1 soc: 11%
[site  ] DEBUG 2026/08/22 08:46:52 grid power: -117W
[site  ] DEBUG 2026/08/22 08:46:52 grid powers: [26 -122 -19]W
[site  ] DEBUG 2026/08/22 08:46:52 grid currents: [0.113 -0.529 -0.083]A
[site  ] DEBUG 2026/08/22 08:46:52 site power: -17W
[lp-1  ] DEBUG 2026/08/22 08:46:53 vehicle odometer: 822km
[lp-1  ] DEBUG 2026/08/22 08:46:53 charger status: B
[lp-1  ] INFO 2026/08/22 08:46:53 car connected
[lp-1  ] DEBUG 2026/08/22 08:46:53 set charge mode: pv
[lp-1  ] DEBUG 2026/08/22 08:46:53 pv timer elapse
[lp-1  ] DEBUG 2026/08/22 08:46:53 pv timer inactive
[lp-1  ] DEBUG 2026/08/22 08:46:53 vehicle soc: 80%
[lp-1  ] DEBUG 2026/08/22 08:46:53 vehicle range: 216km
[lp-1  ] DEBUG 2026/08/22 08:46:53 !! plan: plan time zero
[lp-1  ] DEBUG 2026/08/22 08:46:53 limitSoc reached: 80.0% > 80%
[cardata] DEBUG 2026/08/22 08:46:53 connect streaming (using gcid cb0b55eb-5f71-4a97-9927-46282ec7344b, id_token eyJ0eXAiOiJKV1QiLCJraWQiOiJiMDZEZXIvYndra04reFNHMVFKQ0puQ1djK0k9IiwiYWxnIjoiUlMyNTYifQ.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.BTVbeVqoJ-cwg2Wfpl2g50yrKbZWbM1RMgldLZfoQFYGaJ_4XgTceV2FbwJne-9QRyloLXGboyTFS3LgpRB0VQBNltT8Wf-aXSiEgrv_cepxHLjjZHOV6JzmfV5K9_uVYVBuGt2isyGtB3eqd7dwEtx7tI0g--ww0_vYTx8UYoInTcXMICIM16RrOfSjNyIAD697F1X_lNyTUjI3i7ymckp9NL-qeUgYHg1TEpEp-LCncBVcmywZ5Y0MZsG6wmof3Qb3R2u7JV1PR_J1EIl0_eIH_WZsrplj6BUQBWILyJJ7BZ6Saxv5mwHhgOsz93QD_67iQr_h7PnoWduNaBPmOA, valid: 2026-08-22 08:51:12 +0200 CEST)
[cardata] DEBUG 2026/08/22 08:46:53 connected streaming

[mfuchs1984]

the newer version, the revised battery settings (Priority and Buffer) seem to apply strictly to PV mode

That has always been the case. For fast mode, there is the battery hold mode. If you have enabled this in the battery settings, you need to find out why it doesn't work through your home assistant battery meter.

[mietoome]

Thanks for the clarification!
I have configured the Hold Mode Script (script.battery_hold) to explicitly set the Marstek battery's discharge power to 0 W via Home Assistant during fast/planned charging.
I will monitor the upcoming charging sessions to verify that everything triggers as expected and report back if I encounter any issues.