Battery Charging Control For RV based on AC input and SOC?

Q&A and troubleshooting
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1

We have an RV that we have been trying to implement a Node Red control on without real success. I had someone else set it up, and it has never functioned properly, and now I’m trying to learn this and just do it myself.

We have a Multiplus2 48/3000 inverter, 4 MPPTs for 4 solar arrays (app 3700 watts of PV), a Cerbo GX, 4 Pytes V5 batteries, a 30A 120vac shore power input and a 4kw onboard generator. The shore power and generator and run through a transfer switch.

My goal is to only have the batteries charge differently when plugged in to shore power. Currently shore power will charge the batteries to 100% SOC and then hod them there, which is causing issues.

I’d like to have the shore power only start charging the batteries when a low SOC is achieved-say 40%, then charge to a higher SOC, maybe 60%, then stop charging so that the batteries can cycle. I would even mind if we charge them to 100%, but I can’t hold them there indefinatly when the RV is in storage on shore power.

The current generator charging scheme is generator start at 20%, charge to 60%, then release and generator shut down and that works fine and needs to remain.

We installed a 120VAC coil relay that energizes when the transfer switch is powered by shore power, and use that to send a signal to digital input 1 on the cerbo so that we can tell which AC power source is active.

The node red logic that was created looks overly complex for what we are trying to do, and I feel I need to just start over.

I would love some pointers on how to build a flow to accomplish this! What nodes should I be using? Anyone else do something like this? When I searched, I didn’t come up with anything that seemed to apply to our scenario.

Thanks!

2

try to build a node red flow with ChatGPT. it´s amazing how KI could help for such tasks

3

The Solar and wind priority function is what we use for storage on shore. It doesn’t prevent solar charging, but we’re indoors. It holds the pack at a constant voltage, ~30% SOC in our case. NR can easily make the switch between storage hold & normal charge.

I use it on the road too. Solar keeps things topped off, but prevents campground power from always hitting the battery. It’s also useful for backup if our 24V A/C pulls down the battery down to that constant voltage point, the charger takes over. Gen always charges if your Cerbo knows it’s running.

4

This was my thought as well. It may not accomplish exactly what you want but is far simpler. Maybe at least it will work for you in the shorter term. You can use it to hold the batteries at a specified voltage and allow other sources to do the rest of the charging. It will automatically fully charge every 7 days if no other source has been sufficient to charge the batteries completely.

5

The auto full charge is something I have not seen happen on my coach, I’m okay with that.