Please explain the jump in reported AC power usage when plugged into shore power?

I have a 24Vdc/690Ah lithium batteries managed by a Quattro inverter/charger with a Lynx shunt and a Cerbo GX in my Ford Transit conversion van. The system is updated with the latest firmware.

I have an induction cooktop appliance powered by 120Vac. With every other AC breaker off except the one for the cooktop, the Cerbo GX shows 26W AC power draw when unplugged from shore power. But when I plug into shore power, it jumps to 340W. Though plugged in, the cooktop is off in both cases. Why the jump from 26W(unplugged to shore power) → 340W(plugged to shore power)?

Maybe your batteries being recharged?

Thanks, but that’s not it. Two things.

  1. This happens even if my batteries are at 100% and my Quattro is at “Float” state
  2. If I turn off the breaker for the cooktop, I read 0W, as expected.

My first suspicion would be the AC Out 2 …

What else have you connected to your system?
A small diagram would be great …

Thanks for taking the time to respond @Netrange. I don’t have anything connected to AC Out 2 since I want to be able to use ALL my AC appliances all the time.

I’ll try to post a simple diagram soon, but it’s nothing complicated. Maybe this simple text layout will help

Car alternator/battery → Renogy 3000 12Vdc/120VAc inverter → Quattro AC1 In (Primary)
Shore power → Quattro AC2 In (Secondary)

Quattro AC1 Out to AC breaker panel, which then feeds my AC circuits. NO connection to AC Out 2

Quattro 24V DC out to Lynx Distributor
Lynx Distributor connected to Victron Power In
Victron Lynx Power In connected to lithium batteries (which are fused at terminals)

Victron Lynx Distributor goes to DC panel, which then feeds my DC loads.

I don’t know how the Quattro works, but for the Multiplus, the AC IN 2 goes to AC OUT 2 circuit. So maybe it is looking for something that isn’t there? Wouldn’t explain the 0W is you turn off the cooktop.

I don’t think the Multiplus has 2 AC inputs, which is why I chose the Quattro.

Does it stay at 340W? Or just jump up and then settle down? I assume the latter?

If so, a few thoughts. Could be a grounding issue? Using the vehicles built in Inverter a second input to the Quattro is a cool idea I haven’t seen before. But, that alone makes me question the setup. Does this occur if the Vehicle inverter is disconnected? Not just off, but disconnected?

It stays at 340W.

I don’t use my Ford Transit (in USA) built-in inverter. Instead, I use a Renogy 3000 inverter, like this

12Vdc alternator/battery → Renogy 3000 12Vdc-to-12Vac → Quattro AC1 input

So it’s essentially a generator. It’s a common practice from what I gather, at least to the Ford Transit van conversion community.

My Quattro’s AC2 input is connected to shore power. I will soon switch the 2, so AC1 input will be shore power, and AC2 input will be the Renogy 3000.

When this happens, my AC1 input (currently the Renogy 3000) is not powered on. The Quattro is only receiving input from AC2, currently shore power.

Not an answer but observations/questions:

  1. I guess 12 vac is a typo and that should be 12vdc/120vac?
  2. Where are you reading the cooktop draw values: on the Cerbo, on VRM or both?
  3. What do you see when both AC in-1 and AC-in 2 are off, if you have that option?

Hmm Okay. I slightly strange wiring scheme, but it should work all things considered. Maybe next time look more into an Orion XS? You probably did, but that my thought.

Regarding the AC Loads changing after plugging into Shore, my thoughts still land on a grounding issue. I think @Fideri has the right idea to troubleshoot that. Turn off/disconnect both AC Inputs, then connect 1, then the other, then both, and record the Load draw. Also, knowing how you are recording this could be helpful too.