How to make use of 9.5kW generator to charge LiFePO4 DIY bank off-grid

[pralinebuckets]

Hi all,
I'm new to the forum and am learning a lot here. I'm designing an off-grid system that will not include solar for the foreseeable future mainly due to lack of appropriate clearings in the forest. I do however, have a 9.5kW generator on the site, but have no grid access. I would like to run the generator for the least amount of time possible to charge my batteries, so my goal is to design a system that will take advantage of the relatively high output.

My generator can provide 240V @ 50A peak, or steady at 9500W through the one cable, or a combo of multiple 120V 50A & 30A outputs. My hope is that I can run the generator at or close to the max capacity of 9500W. I believe the Victron Skylla TG Charger 24/48V will get me the closest to success here. It would allow for charging @ 240V 50A.

I'm not sure what the best inverter to choose is. I don't see a good 48VDC to 120VAC inverter w/ CANbus support from the usual suspects. Victron only has 240VAC units or low wattage 120VAC, and the rest seem to only offer inverter/chargers, which I don't need half of.

For batteries, I'll be building my own LiFePO4s of somewhere in the range of 10-14kWh in a 48V series setup. I want to be at or above 9.5kWh in my bank so that I can arbitrarily charge it from the generator in roughly 1 hour.

I believe that the REQ and Orion BMSs will allow charging the cells at a high enough amperage, but I'm finding conflicting information on the cells themselves. Can a single LiFePO4 cell handle upwards of 100A even? I see some BMSs support that rate and higher, but I'm having a hard time finding out the limitations of the cells themselves. Will I need to hook up multiple 48V banks in parallel to charge at or around the ~200A required at 48VDC?

Thanks for any advice or help you can offer!

 

[Ampster]

I believe that the REQ and Orion BMSs will allow charging the cells at high enough amperage.

The Orion has adjustable current limits and because of its EV heritage it can measure up to 1000 Amps. It has several ways to control Amperage depending on the charger.The only sucessful CANBUS connections to chargers that I know of are several EV chargers and a Victron implementation discussed here.
Some LFPcells can be charged at 1C which for 100 Ahr cells could be 100 Amps of current but Iwould check the specs of your particular cells. I charge mine at 60 Amps but i have two 280 Ahr cells in parallel to that is 560 Ahrs or a little over .1C.

 

[pralinebuckets]

Oh interesting. Do you meant to say that the Orion BMS will not hook into the CANBUS network if I use Victron products elsewhere in my setup? It implies in the user manual that it will work, but obviously I've never tried.

 

[Ampster]

Do you meant to say that the Orion BMS will not hook into the CANBUS network if I use Victron products elsewhere in my setup.

No, @cinergi is doing that with some isssues. The Victon uses a proprietary protocol but one additional Victron device is needed which does translate CANBUS to the Victron Protocol. I think it is documented on the Orion site.

 

[pralinebuckets]

Hm.I think I read the Victron charger manual incorrectly ( https://www.victronenergy.com/upload/documents/Datasheet-Skylla-Charger-EN.pdf ). It looks like even the 240VAC 48VDC charger can only charge at a max of 50A @ 48VDC ( 2400W). Does anyone know of any other 240VAC to 24VDC or 48VDC chargers that can supply a decent amount of current?

 

[Rocketman]

Batrium is another bms that has Can-bus for Victron. I just got it(don’t have batteries yet) so I can’t say anything about it except what it should do.
For charging you can set your own charge rate to match your batteries. Then when it is almost full it will go into limited charging as it balances the cells. The Bms tells the GX device (in my case CCGX) the charging rate and the GX passes that to any chargers.

Same with Discharging.

I don’t know the charge only line, I have the Multiplus 12/3000. I know you can have a setting for charge only with the inverter off. That way you have the inverter draws - until you want them and turn it on.

 

[Ampster]

Will I need to hook up multiple 48V banks in parallel to charge at or around the ~200A required at 48VDC?

It depends on your use case and whether you want redundant packs but it does not matter whether it is two 100 Amphour Packs in parallel or one 200 Ahr pack as far as charging Amps. It is the same cell Amperage.

 

[Ampster]

How many kWhrs do you expect to use in a day? That is where i would start. My limited experience with chargers is the the price starts going up exponentially as the Amps go up. It might worth looking at the trade off of less Amps and the cost to move the generator out of earshot or invest in soundproofing.

 

[toms]

I use the SMA Sunny Island to charge my batteries at 100A 48V DC. I use a REC BMS, and my batteries are rated at 1C charge, which is 400A at 48V.
The Sunny Island 8.0 will allow charging up to 6kw (125A at 48V)

The Sunny Island 6048 is a 120V version, and will charge from a generator at 110A.

 

[cinergi]

You can connect multiple Victron equipment together to increase the charge rate (e.g. parallel the 120v multi's).

As far as the BMS "allowing" high charge rate -- it's more about the physical limits of the equipment. Current doesn't flow through the Orion. It flows through a relay that the Orion controls. So the sky is the limit as far as current is concerned (well, up to the maximum current the measuring device can handle; in Orion's case, 1000 amps).

 

[pralinebuckets]

Thank you all, this is very helpful!
I'm wondering if it's possible to use the Quattro 15kW 230V inverter to do what I want. It would allow the single 230V input from my generator @ 50A, and I should be able to use the 230V outputs as 115V AC for my North American devices.

 

[pralinebuckets]

Replying to my own post, Victron even has a wiring diagram that would work for me https://www.victronenergy.com/uploa...-phase-240V-to-120-240V-with-Quattro-240V.pdf