Configuring battery to 650V - considerations

[Jacobsmess]

So working with the space I have allocated to battery storage, to get the capacity I want (around 90kWh) if I were to use the cells I plan to (Corsa E) I will end up with roughly 650V from memory. I'm pairing this with a lexus GS450H inverter and transmission so they can handle the voltage but are there other considerations? I guess charging will be an issue, contactors also? Anything else?

[bigmotherwhale]

its possible to use a contactor to split the pack into 2 and then use 2 separate chargers, you need to make sure your isolation clearance and cable rated voltages are enough.

[Jacobsmess]

its possible to use a contactor to split the pack into 2 and then use 2 separate chargers, you need to make sure your isolation clearance and cable rated voltages are enough.

That's a brilliant idea. Means I can go with lower capacity chargers and get faster charging as well I guess....

I'm not sure what you mean by Isolation clearance though. And yes I'll makes sure all my cable is ok with 650V although I thought cable was more concerned with high current than high voltage, or is it the case that when at high voltages the arc potential makes it more of a concern?

[bigmotherwhale]

Im talking bout creepage distance between two conductors or any bare metal case etc.. you don't want a breakdown between two conductors and you want a margin of safety.
The cable does matter, I would have thought you want minimum 1000v DC rating double insulated cable, if you are recycling parts from EVs it would likely already be rated for that anyway.
Another thing to consider is putting HV disconnects in the middle of each pack, that way your working with 150v (but should still be considered deadly of course)

[Bigpie]

You probably want to stick to 600v max, 650v doesn't leave any overhead for the capacitor rating. 600v has been done successfully though

[bigmotherwhale]

650v is used by the 450h so it must be rated for higher than that https://openinverter.org/wiki/Lexus_GS4 ... 20the%20GS.

[Bigpie]

Pay your money and take your chances, it's been run at 600v, as far as I'm aware no one running higher in a conversation. There's only one way to find out

[tom91]

Voltage when fully charged of 650V should be okay.

LS 600h report
https://www.osti.gov/servlets/purl/947393

I would strongly recommend you read into the subject of high voltage. The higher the voltage the more you need to pay attention to component ratings and design considerations.

There are very few and not really available second hand components for such high voltages. This means you will need to buy all auxiliary HV components new and they will be expensive due to being 650V.

[Bigpie]

Ahh, I thought it was a 650V cap, not massively familiar with it yet. Don't think zombie does anything with the buck boost, but on the Prius OI boards you could use it to buck down the voltage into the DCDC range.

If you got control of it, you could use 400v DCDC

[Jacobsmess]

Ahh, I thought it was a 650V cap, not massively familiar with it yet. Don't think zombie does anything with the buck boost, but on the Prius OI boards you could use it to buck down the voltage into the DCDC range.

If you got control of it, you could use 400v DCDC

Wouldn't I then fall into the issue of the max power output of the boost converter (30kw?) Limiting the system?
Or is it possible to use the buck/boost and inverter independently?

[Bigpie]

Use it in reverse so it's taking HV down to lower. 30kW would be plenty for heater/DCDC etc, but not for driving. Probably moot unless you're willing to workout how to control it though

[Jacobsmess]

Use it in reverse so it's taking HV down to lower. 30kW would be plenty for heater/DCDC etc, but not for driving. Probably moot unless you're willing to workout how to control it though

Ah I see, I thought you meant using the same GS450H inverter, yes I'd thought about using another Prius inverter. I think Johannes has already cracked this but I'm not sure how developed it is....

[Bigpie]

I did mean using the GS450h inverter, you connect the 650V to the higher voltage side, directly to the side the inverter uses for traction. Connect the 400v systems to the lower side and buck down the 650v to within range. All adds complexity and expense, I'd start with just 400v and tackle going to 650v if required after the learning experience of a 'simpler' conversion or stump up for 650v components if you're determined for 650v

[bigmotherwhale]

Forget about using the buck / boost for traction purposes, you would get more power and efficiency with a single 300v battery, you would be limited to 30kw max at around 80% eff...
is there any reason you need to use the 450h at 650v rather than 325v?
You should get a good amount of power even at that voltage, and it will make things a lot easier for charging etc.