[Archived]

Chiming in – liberty auto start. Yeah atrocious. You need an op amp or some sort of resistive up pull to scale the voltage read from 11.8 to whatever you want to kick it off. I haven’t gotten around to it but may look at bypassing the watch dog and use a Victron generator auto start (tied to an generator auto start relay). Haven’t seen what is involved with that just yet. Personally I would look at triggering around 12.2 to 12.5 for lithium batteries – but hopefully you won’t get there.

But for me is I want to know when the inverter goes offline or when the generator actually auto started or what the situation on the coach is. Because if I leave dogs inside unattended while I’m gone, I don’t want to rely on that if something goes wrong. So having that information available online at all times is really helpful. But the only safe way is knowing what the temperature of the coach or the status of the power (is generator running or not) and have associated “alarms” that notify you via sms or email. You could use a sensor push to send temperature alarms/updates but that only alerts you to the temperature inside the coach vs the actual inverter/generator/power situation. On a Victron inverter – if I can interface it’s generator start to the power tech generator start – then I can remotely flip the inverter to start the generatoe as well

But having all that data fed in to the cloud and having access to it – takes a lot of the concern out of leaving it. Some example VRM screen shots of the data I always have available – updated every minute all the time.

[Archived]

Anthem, you are more up to speed on this than I am but I am leaning toward a voltage monitor that is adjustable and opens a load circuit when voltage drops to a programmed level. That offers an opportunity to play with different settings, but opening the circuit from the sense wire to the Watchdog is seen by the Watchdog as the trigger voltage.

I could use a resistor, but I don’t know enough to determine yet what an ideal start voltage will be or how ambient temps will impact my output voltages.

Are we starting to agree a little? Weird.

[Ronald]

I use the BMV712 battery monitor. it comes with a battery shunt that needs to be connected on the negative side. It measures SOC after you input some parameters.. . but it works in tandem with the rest of their bus/network. It does have a relay – that can be programmed a myriad of ways. I currently use mine for alternator cutoff – as in I enable the alternator when SOC falls below 60% and stop at 90%. . . You can also use it for generator start/stop as well, but you need to bypass the watchdog and just control it directly rather than using the liberty voltage meter. that being said – most large inverter companies have automatic generator start capability. the question is – after getting the generator auto start to interface with your generatore – whether you want to rely on the liberty one or the inverter one ? I know magnum, outback, victron, mastervolt all have auto generator start capability, but we seem to be tied to the watchdog that liberty provided.

Here is the 712 settings for relay control – as you can see the options that it has to control something via relay. I havent looked deeply in to the generator watchdog, but my thought process was to bypass it and control it from the inverter control.

Ha – i dont think we disagree on the overall thing. I think we just disagree on some conceptual methods of going about it. lol