BLUETTI AC500 Vehicle charging through AC input - am I suicidal?

[dominoconsultant]

I am the proud new owner of a BLUETTI AC500 with two B300S battery banks for my electrical refit of a VW Crafter motorhome. I had a couple of issues straight outa the box with charging but the password enabled me to fix those default/factory settings.
What I'm looking at now is the DC charging options from the alternator.
I don't want to use the two PV/DC charging leads to do this. I'll be setting up two larger capacity solar arrays so I'll be dedicating those two (each max 1500W) for that purpose.
What I'm thinking of is running my 1500W Pure Sine-Wave Inverter straight from the alternator via a voltage activated relay that connects the circuit after the starter battery is fully charged. So once the voltage reaches 14.2V it would connect through the inverter.
The inverter would then provide 240V (Australia) through to the Grid charging port of the AC500.
Some questions:
1) Am I crazy;
2) Where should I put fuses in this feed;
3) Do I need to introduce a "buffer battery" in this circuit considering that the starter battery sits between the alternator and the voltage relay;
4) Are there alternatives besides a pair of victron (or other) DC-DC charge controllers pumping into the DC charging circuits. I really don't want to have to toggle the unit between "PV" & "other" every time I drive and want to charge.

 

[fratermus]

What I'm thinking of is running my 1500W Pure Sine-Wave Inverter straight from the alternator via a voltage activated relay that connects the circuit after the starter battery is fully charged. So once the voltage reaches 14.2V it would connect through the inverter.
The inverter would then provide 240V (Australia) through to the Grid charging port of the AC500.

Yes, that can work. Caveats below.

Some questions:
1) Am I crazy;

Maybe, but that won't affect the system. The important questions, IMO, are:

1. is the Crafter's alternator going to be happy with whatever the wall charger is pulling (plus inverter losses?)
2. is the alternator a plain single-voltage type or is it a variable voltage ("smart") alt? If the latter it could cause the VSR to connect/disconnect incessantly

 

[dominoconsultant]

Reporting back in on progress...

Here we have a photo of the rough-in for testing feasibility

My alternator is the older style (2014) so it doesn't "auto-adjust" output but runs at 140A-180A (best as I can tell)

Some results with various settings of input DC at 1A up through 7A with the engine just idling and also at higher (driving) revs:

NOTE: this is 240V inverter (because Australia)

Just Idling
1A charges at 236W
2A at 474W
3A at 709W <== inverter cuts out at idle above this
4A at 944W
higher revs
5A at 1184W
6A at 1305W <== Inverter appears to max out
7A at 1306W <== no apparent increase in wattage above 6A

For each of these DC input charging wattage input levels I can get in an additional 97W through the cigarette lighter socket connected to the DC1 input (set to other)

this indicates if I'm just idling the engine - what I'm going to call "in-camp generator mode" I can get around 800W input

at higher revs "driving/repositioning mode" I can get approx. 1,400W charging input

I do have to set the input voltage of the AC500 between 3A & 6A depending on what I'm doing - in reality I'll be having to change this infrequently.

for extra credit I could probably pump extra DC-DC charging into the B300S DC input ports

Next step is to work on the solar panel arrays

After that I'll look at charging from a crappy cheap generator via DC - it already craps out attempting to charge with the generator's built-in AC inverter

 

[RV8R]

I’m posting this, because I don’t know ,,, but ;



You have what appears to me as a “Smart Solenoid” or “Battery Combiner” that is typically on the positive side of “direct charging” rather than a DC2DC charger.

Further this looks like it is connected to an Inverter ?


If this “Isolator” is similar to a Victron Cyrix, I do not know it’s purpose in that positive line to your inverter.

 

[wpns]

I’m posting this, because I don’t know ,,, but ;

View attachment 207485

You have what appears to me as a “Smart Solenoid” or “Battery Combiner” that is typically on the positive side of “direct charging” rather than a DC2DC charger.

Further this looks like it is connected to an Inverter ?


If this “Isolator” is similar to a Victron Cyrix, I do not know it’s purpose in that positive line to your inverter.

I think what that is supposed to do is to connect the inverter DC power when the battery voltage is above the threshold (the battery is fully charged).

 

[RV8R]

I think what that is supposed to do is to connect the inverter DC power when the battery voltage is above the threshold (the battery is fully charged).

Right ;

But why is it “inline” on the positive cable to the inverter ?

My experience with these is a Starter Battery is on one end & the house battery is on the other ,,, not an Inverter.

Caveat, I have Victron Cyrix experience & do not know of the OP’s equipment;

 

[wpns]

But why is it “inline” on the positive cable to the inverter ?

Because you don’t want the inverter (think house battery) connected until the starter battery is fully charged. It took me a few minutes to wrap my head around using the isolator in this way (similar to dump load controller).

 

[dominoconsultant]

Right ;

But why is it “inline” on the positive cable to the inverter ?

My experience with these is a Starter Battery is on one end & the house battery is on the other ,,, not an Inverter.

Caveat, I have Victron Cyrix experience & do not know of the OP’s equipment;

View attachment 207495

You are correct in that it works like the Cyrix. As to what the equipment... right at the start of this thread you can see I mentioned it is a BLUETTI AC500 with two B300S battery banks.