XW6848 charge rate limited

[jtvt]

Hi,

I'm trying to figure out why my charge rate seems to be capped at ~7000w. It's a Kohler 12 res. The AC 2 breaker is at 50a. AC 1 at 60 (but I'm off grid). Setting Maximum Charge Rate from 75% to 85% makes no difference. I see ~28a on both A2 L1 and AC2 L2. ~90a at the BMS. I haven't tried a low value yet. I use a custom Battery type, but it is LFP.

At one point, I switched over from using the Conext battery monitor to BMS, but then switched back. I'm wondering if my battery type got toggled to li-ion in doing that and maybe the Maximum charge current settings that are only available in li-ion some how are the problem.

Trying to figure out if I missed a setting or something else. Ideas?

edit to add : This is with a 400w house load. And changing AC2 breaker to 60a makes no difference.

 

[BentleyJ]

If its the XW+ or the XW Pro, the built in battery charger is limited to 140A. If you have set maximum charge rate to 85% then the max Amperage is limited to 119A. If the charging voltage is say 56V then charging watts is going to be 56V x 119A = 6,664W.

 

[400bird]

Hi,

I'm trying to figure out why my charge rate seems to be capped at ~7000w. It's a Kohler 12 res. The AC 2 breaker is at 50a. AC 1 at 60 (but I'm off grid). Setting Maximum Charge Rate from 75% to 85% makes no difference. I see ~28a on both A2 L1 and AC2 L2. ~90a at the BMS. I haven't tried a low value yet. I use a custom Battery type, but it is LFP.

At one point, I switched over from using the Conext battery monitor to BMS, but then switched back. I'm wondering if my battery type got toggled to li-ion in doing that and maybe the Maximum charge current settings that are only available in li-ion some how are the problem.

Trying to figure out if I missed a setting or something else. Ideas?

edit to add : This is with a 400w house load. And changing AC2 breaker to 60a makes no difference.

"Limited" to 7000 watts on a 6800 watt inverter?
Maybe I'm slow, but that's sounds pretty ok.

Something seems off because you say 90 amps at the BMS. 7000 watts at 90 amps is 78 volts, that's not possible.

Maybe you meant 5,000 watts?

You could post all your settings we can look them over. If you still have the max charge rate set to 85%, that would be causing some (15%) limitation.

 

[jtvt]

Here's more data:

20% .2*140=28a
XW AC side 2085w 8a/leg .5kw into house
batt mon 52.9v 28.7a 1518w
bms 52.65v 29a 1529w
whizbang 52.9v 28.7a 1518w

75% .75*140=105
XW AC side 6885w 28.5a/leg .5 into house
batt mon 53.6v 108a 5789w
bms 91a 53.47v 4850w
whizbang 107a 53.7v 5746w

85% 119a
XW AC side 6910w 28.5a/leg .5 into house
batt mon 53.8v 108a 5810w
bms 53.68v 91a 4870w
whizbang 107.1a 53.8v 5762w

100% 140a
Same as 85% which is same as 75%

So part of the issue is the Batrium BMS shunt is a pos. The XW pro specs are 140a at 40-64v, 48v nominal. 140*48=6720w. Charging seems to be capped at 5800w.

Generator AC in on the XW is supposed to be pass through. I'm expecting AC side wattage to represent charging wattage plus house loads so potentially greater than 6800w. But maybe that's not how it works.

IIRC, I was previously able to get more wattage at the battery, but it's been a while since I've been in those settings.

 

[jtvt]

The batrium shunt issue is likely

Batrium Shunt inaccurate current measurment

My batrium shunt is reading inaccurate current. Both my charger and clamp on meter will show 100A charge current, the batrium reports 85A. This of course throws off the SoC counter. Is there a calibration procedure for this? Googling doesn't reveal any.

secondlifestorage.com

I don't recall it happening with the solar charging. It seems to be only when charging via the XW.

 

[jtvt]

Seem to be stuck at DC Power = ~5500 . Maybe that is all I should expect with derating. Specs say 140a at 40-64v, 48v nominal. 140*48=6720w. but I get ~5500 or ~80%

 

[hwy17]

Your charging voltage is 56.45? The battery may just not be taking any more than 108 amps at that voltage. The inverter can only lead the horse to water.

 

[jtvt]

That's absorb voltage. It was charging at ~54v at the time of the screen shots.

 

[hwy17]

So it's in a 56.45 charge mode but only at 54, does seem like it should be pushing volts higher to get more amps in then.

 

[BentleyJ]

According to your posted screen shots, the inverter is in Bulk Charge mode which is set at 56.45V so the Volts should get pushed up until the Amps limit setting is reached. That's why bulk is also called Constant Current charging.

 

[hwy17]

What's the ambient temp in the inverter room during this.

 

[jtvt]

Temp usually 65-75.

I'm just trying to figure out why bulk wattage is as low as it is. 140a and 48 nominal is 6720w which jives with the inverter being a 6800w inverter. But I only see ~5500w of charging max...which is probably fine since why run the inverter at it's max. But I'm trying to figure out what the limiting factor is. Maybe it's just AC-DC conversion loss or some internal derating like with the input breaker. But having said that, the specs say 140a at 48 nominal.

 

[hwy17]

It shouldn't matter but I would wonder if you set bulk up to 57 or 58v if it acts differently. Maybe some kind of hysteresis equation is holding it back from raising the voltage.

 

[400bird]

If you increase or decrease your AC load does the charge current/wattage change? I'm wondering if the 50 amp breaker setting was written wrong or something and is causing the issue...

If not, would put the inverter into standby and make very small changes to every charging related setting. Make sure to apply them. You can even change back immediately and apply the old values again. Schneider recommends only making changes with the inverter in standby, maybe if you've made any changes love, the data was corrupted.

Do you have the battery temp sensor connected? If so, try disconnecting it.

 

[Rossman]

Maybe that is all I should expect with derating

Not sure about that? Our XW6048 says it can charge at 100A and it does in fact charge at 100A, it doesn't derate anything.

 

[jtvt]

Interesting behavior with more house load.

Before toaster oven:

After toaster oven:




Adding gen support:



There are also two midnite classics providing some power to the battery which is why battery wattage is higher than the XW DC + the MPPT.

Turning on the load (toaster), the generator provided another 0.6KW on the AC side, but XW DC battery out dropped 0.8KW. Kinda like gen support, but I don't use gen support.

My firmware is back level two versions. I'm off grid and recent updates didn't really have anything much for off grid users so risk/reward wasn't that good, but maybe I'll need to update.

I don't have a battery temp sensor.

 

[400bird]

800 watts less battery charging and 700 watts more from the generator is pretty close to the 1700 watt toaster.

You've got 40 amps on L1, what is your breaker setting?

Where do I get a 1700 watt toaster oven? I want one of those we use the toaster oven vs the big slow 240 volt wall oven nearly every day.

 

[400bird]

Oh, it's probably got to do with putting 1700 watts (14 amps) on just one leg and the imbalance that caused.

 

[jtvt]

Breaker is 50a. 40a actual with built in derating. So that makes sense. Toaster oven is a Breville which specs out at 1800w but I think it only pulls that in pre heat mode.

 

[hogback]

When my resa 14 charges my 14kWh bank, it dumps 115A in the pack at ~53V, so 25A at 240V. Breaker is 60A.