Weird scenario with Magnum 2812 and low voltage at the campground

[newmarokie]

I had a new experience this weekend. We were camping at a RV park at the lake for the weekend. The voltage was terrible. I saw as low as 103v on one leg. My surge guard kicked us off of the pedestal. The AGS kicked in and handled (I thought) everything. Last night, the voltage had got better so I turned the generator off. What I did not know was that the Magnum system got kicked out of auto connect. The ACs operated and everything else worked as well. This morning the twelve volt systems all went down. Deader than a hammer. I eventually found the disabled problem and reset the auto connect in the Magnum system and everything is functioning correctly now. Just a little warning if you encounter this.

 

[Neal]

I suggest checking your Low Battery Cut Off (LBCO) as the 12V should cut off around 11.9 or whatever you need for your batteries.

Whatever turns the GEN on i.e. AGS needs to turn the GEN off, otherwise you can have a fault and possibly other issues. I don't think I ever saw my magnum change settings in this situation but it's a rule of thumb for GEN use.

 

[newmarokie]

I agree Neal. I haven't ever seen the AC input disabled like this. I turned the generator off with the dash switch and it probably threw a fault light, but I didn't see it until the next morning. I have already experienced the AGS getting throw out of AGS with the manual stop. It was bedtime when all this happened. My brain might have went to sleep before the rest of me did. I posted as much to let others know if something funky started happening, this could be a possibility. My LBCO was set at 11.2. I just bumped it up. The bright side is the BMK is acknowledging 100% SOC, as are the batteries and their apps. SOK acknowledges that the SOC reading on the app will drift and become inaccurate unless the batteries are run down to cmos (low voltage BMS shut down) periodically.

 

[Neal]

With my lead acid I used 11.0 as LBCO as spikes would kill me such as using the keurig on battery. You mention SOK, what type of batteries are you using? LBCO needs to be set based on battery type, and other settings.

 

[newmarokie]

They are the 206Ah heated, bluetooth batteries. I have three. They have been very good for me. The only complaint I have is that the SOC on the app drifts off. The support people put out a paper explaining that the battery (or the app) uses the new charge floor for zero. So as the batteries cycle the SOC gets further off. I think if you treated them like "dumb" batteries and just let them do their job it would be better. It's kind of like complaining about the heat going down the road with the windows down. If you never had AC in a car you just think it is normal. The batteries cycle every 6-7 days and they do great.

 

[Neal]

SES didn't speak highly of Magnum with LiFePO4's which is why I went all Victron. Regardless, with LiFePO4's your LBCO can probably go closer to the 10.0 range.

 

[newmarokie]

Everything has been functioning fine until this kerfluffle. When something adverse happens, it is nearly always a series of events. The BMS had locked down all three batteries at about 10.4 volts. The LBCO was set at 11. I am sure the Magnum shut down like it should. I can only assume the 12 volt system that doesn't go through the inverter drug the system down to BMS shut off.

 

[Neal]

The electrical aspects of these modern way too technical coaches is baffling at times. LiFePO4's are the new monster to me, had to put in a call to SES on my last boondocking adventure (HH stay). Complex to say the least. I like them, recommend LiFePO4's and can't think of ever using anything else, but it's a steep learning curve.

 

[newmarokie]

Totally agree. And I am respectable at understanding flow charts, amps, voltage, and wattage relationships. I grew up on a dairy farm and had to learn a little about everything. BUT, we never had motorcoach when we were milking.