EV battery in a Victron system

I have an electric motorcycle that I am currently not using which had the battery replaced under warranty and is essentially brand new not having been used.

I am curious if there is a high voltage inverter that would play nicely in the Victron eco system or if there was a way to use the battery perhaps with a DC to DC converter.

The battery voltage is around 100V DC and I could step the voltage down to 48V.

Any idea how I could make use of this battery in a Victron system?

100v DC, and AH?

Cause it sounds complicated … the question is, is it worth the effort and extra costs, and risks?

Context: I once had 12v and 24v batts and inverters… the twain did not mix very well. One moment of inattention and I let the smoke out of a 12v Victorn inverter on a 24v battery.

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It’s 100V DC and a 14.4kWh battery. So ALOT of energy.

It could be a stand alone system but I would prefer if it could integrate some how.

Sure, it isn’t practical but its intriguing.

I’m sure you could feed this voltage directly in on your PV input to your inverter…
@plonkster Wat sê jy??

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Yeah, you could feed it into a 150V MPPT and convert it to 48V. Just fuse it properly. I think you could probably also feed some PV inverters with it, although 100V is a tad low for those. And I know Fronius inverters have a hard time finding a power point if it doesn’t have the characteristic PV bend in the curve.

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Fronius would need about 30pV min, so no go. MPPT would likely be the best way to do this.

Groetnis

Many PV inverters start up around 120V. The ABB model I’ve got will start up as low as 100V, but you are limited on power. To get full power out of it, you need at least 150V.

The Fronius Galvo (not manufactured anymore) will start as low as 70V. The small Primos will actually start at 80V according to their spec sheet.

The small Solis models start at 60V (up to 1.5kW), and 90V (from 2kW on).

The reason I am barking up the PV-inverter tree: One of the earliest ways that a high voltage battery was used in this manner, a proof of concept, was with a SolarEdge inverter. These use boost modules (aka optimisers) on the roof, so everything downstairs is already high voltage. Integrating a high voltage battery is easy, and the overall setup is really efficient too (typically 97% to grid).

The only issue, as mentioned, is the MPPTs in some PV inverters get REALLY confused if they cannot find the elbow point in the I/V curve. The Primo on my test bench is like that. So I wouldn’t go out and BUY a PV-inverter to do this, but if I already had one or two to test with, I might try it.

My bad, it was a typo on my side there :frowning:

GroetnisinError

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How would it be able to charge like that? Would you need another MPPT on some solar panels outputting onto the batteries then?

Indeed, you’d need to put it on the original charger (which I assume came with the scooter) during the day :slight_smile: A bit makeshift I admit.

Ah, but the original charger would probably want to plug into AC, meaning that your inverter would be “working” to charge it and there’s a lot of conversion losses?

So something like this perhaps:

  1. Battery connect to PV input of 150V MPPT, 150V MPPT output unto Multi’s DC Bus.
  2. PV Inverter (sommer a Solis or something) gets input from some PV panels, output to house’s circuits.
  3. Plug original EV charger into plug socket, put a relay (like Sonoff) on the socket to be able to run a time based charging schedule, and potentially automate by turning off when available PV is too low in a Home Assistant type setup.

Only problem I see is that the original charger might demand like 2kW or something and the PV might not always be able to deliver. So you lack the ability to charge with anything that you can generate on the roof, only charging while there is 2kW or more available on the roof?

Would there not be a “safe” way to charge the battery directly from an MPPT?

Yes. But you’d need a 100V MPPT. And I assume some kind of BMS is already present in that setup.

But basically, what you said in point 3 was the overall idea. When there is enough PV (or excess, batteries are full, etc), turn on the AC charger and store the excess.

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And rely on the battery’s BMS to shut it off from the MPPT once voltage is too low? Haha seems like a finicky setup, but 15kWh is a lot!

Yeah, that’s not “intriguing” … that changes EVERYTHING … get that MPPT and make it work! :rofl:

Also, this is another reason I’d want to look into the possibility of (ab)using a PV inverter. If you go from PV (using a PV-inverter) to AC, that’s typically 97% efficient, and then using an SMPS style charger to the battery, another 97%, and then with an MPPT back to 48VDC (95%), and then back up to AC (around 88%), you’re at 78% efficient overall. Maybe. You can get that to around 90% if you use a PV-inverter in the last step.

I had considered the round trip losses but I could easily charge from excess PV with the included charger.

I really like the MPPT option. This could also be used as a SHTF plug in extra capacity type of solution instead of running a generator.

I’m not sure if its worth cycling the battery daily, I think its an NMC battery. Very high discharge and charge rate, the motorcycle has a 660A speed controller, 60kW motor and is good for 0 - 100 in 2.9 seconds so the battery is no slouch.

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Can the battery not be broken down to drop its voltage to something that a 3rd party BMS could deal with? Or maybe multiple batteries.

What cells is it made up of?

Unfortunately not, the battery bank is a monolith and is fully potted inside to protect the cells from vibration and water ingress

The battery chemistry used is NMC or Lithium Nickel Manganese Cobalt: LiNiMnCoO2

Best case scenario would be to still be able to use the motorcycle but have an EV discharge port built in.

Fusing and cabling sizes will be key though.

That is par for the course… how to cost-effectively tap into that power, is the first question to get an answer for.