Even though the maximum charge current spec for the 48/10000 is 140A I never see this even from a cold start, typically I get 110A or so – and this falls over time as the unit heats up, to as low as 70A even though the incoming air temperature is no higher than 40C which should derate it to 80% current (110A). Power source is a 9kVA generator which is perfectly capable of supporting this, I’ve seen power levels this high when an AC load is applied while charging. It’s not the maximum charge current from the BMS limiting this, which is set to several hundred amps.
Any ideas? This is meaning much longer generator running times than I expected…
Did you adjust the maximum charge current of the Quattro up to 140? Usually the charge current is set to around 2/3 the maximum from factory.
It’s also worth considering that generators don’t usually like being run at 100% output; 140A at 57.6vDC = 8064 watts being pulled, not counting any circuit inefficiencies or the Quattro itself, so on a 9kVA generator, figuring the typical adjustment for power factor, the maximum realistic output in watts would be 7200 under ideal conditions. With zero losses, that would result in about 125A of charging, but factoring in a very optimistic 10% loss to account for device and circuit inefficiencies, would result in a realistic maximum charge current of 112A which is in line with what you’re seeing.
I measure typically 12% loss between generator output and DC charging power to the battery, this appears as an AC load in VRM – for example with 5000W into the battery, generator power will be 5600W, with 600W spurious “AC power” which must be the Quattro losses.
Battery voltage with the generator running/charging is typically about 55V, so 140A would be 7700W into the battery, with 900W Quattro dissipation this would be 8600w at the generator output – which I’ve seen with added AC loads, and it seems happy with – generator spec sheet gives about 5% continuous derating at 40C which is 8550W.
Even if I can’t get to 140A, something well above 100A should be possible rather than dropping right down to 70A or so when hot which is what happens now.
I’ll check on the Quattro charge current limit settings, but AFAIK this was set to the maximum 140A. Anyway it runs under BMS (“External Control”) so shouldn’t this set the limits? (set to 210A minimum IIRC)
Input current limit may also have something to do with it.
If weak ac is also selected it will derate the charger.
Is the generator 9kVa derated for altitude. FYI normally they want to be run at 80% load even at sea level. So really you do have a 7200W generator at sea level.
Does it also limit when switched to charger only?
Input current limit is set to 40A.
Weak AC is not selected.
The generator is at about 200’ above sea level.
Yes it might be preferable to run at lower loads for extended periods of time, but typically it’s nly run for an hour or two once or twice a day, so I expect closer to 100% load would be fine.
The charging current is the same whether in “on” mode or “charger only” mode.
Charge current limit is set by the external BMS to 420A, or 210A above 95% SoC (700Ah LFP), so the Quattro should be putting out as much current as it allows (and the generator supports).
I checked the Quattro settings using VEconfigure (boat is 150 miles away in marina) and the Quattro had charge current set to 110A. I thought this would be over-ridden by the external BMS control but maybe it uses the lower of the two, so I’ve changed it to 140A.
@iand
Beware that ambient and air temperature are not the same thing. Ambient is temperature around the device which tends to be higher than air temperature.
Quoted temperature (40C max) is measured by a Ruuvi tag at the Quattro air intake. That should be what Victron specify as “ambient temperature” in the derating curves, surely?
