Hi all,
I’m looking for some advice on retrofitting a Victron BMV-712 and Victron Smart BatteryProtect into my existing 2006 Autotrail motorhome electrical setup.
The challenge is that the leisure battery compartment (located at the rear of the vehicle, ~5m from the main Sargent PSU 2005 unit) is served by a single wire, which acts as both the DC load and charge line—handling alternator and mains charging, as well as powering the 12V loads.
From what I understand, the Smart BatteryProtect is designed to be installed only on DC loads, not in a combined load/charge wire like this. So it doesn’t seem like I can use it in a conventional way here.
As a workaround, I was thinking of using a normally open high-current relay controlled by the BMV-712’s relay output, configured to disconnect the battery at a low voltage. But if I do this, it would cut off both the loads and the charging sources—which defeats the purpose, since the batteries could not recharge. Getting more ad-hoc, maybe I could add a VSR in parallel to the cut-off relay, this would allow voltage to pass back to the battery through the VSR when the charger kicks in (in time also triggering the relay to close once the BMV-712 detects a high voltage again).
Has anyone successfully implemented automatic low-voltage battery isolation on a similar 1-wire charging/load setup? Is there a clean way to automatically isolate just the loads without interfering with charging? Rewiring to split the charge and load paths would be a very involved solution as the looms are very well packaged, and I want to keep the main Sargent PSU 2005 unit.
Any suggestions or examples would be greatly appreciated.
Thanks in advance!