Redarc 40 amp DC to DC Charger issue

Teleman wrote:
Using the battery isolator didn't work. It didn't shut down so we connected the ignition wire and now it turns off with the ignition. Don't worry, even if there wasn't a warning beep when the ignition is on until starting the motor it's not something I'd forget.

Did you happen to check voltage at the battery isolator with the engine not running? If the BI didn't shutdown the dc to dc charger that suggests your BI was defective or it was receiving >13.3v when the alternator was off-line. A fully charged automotive, lead-cell battery can only produce a max voltage of 12.7v-12.8v when the alternator is off-line (even with the ignition on). Not enough voltage to keep the contacts on a BI closed. In any event, if you're ok having your dc to dc charger active with the ignition on and the engine not running, that's certainly your call. Good luck with everything.