A question for Xantrex XW4024 XW4548 XW6048 owners about charging

NorthGuy

When you charge batteries with your XW, you can specify charging current (as a percentage of max).

When you charge, obviously XW doesn't hold the set current exactly. It goes a little bit down, then a little bit up.

How much are typical deviations from the specified current?

Blackcherry04

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Since no one answered you, I'll give you one. I don't have a XW4024 XW4548 XW6048, but I do have a Xantrex SW 3000 that has the same SCP and probably 99 % of the same parts and programing they have. You have to be looking at the SCP display, it's all over the place, mine jumps up and down as much as 15 amps at times. Someone once posted in here it the way they measure it and where they measure it at in the inverter. I have to keep mine at 94 % or it will overshoot the max and kicks the charger out at times. It will also do it when it transfers and drop back into the Invert mode.

If this doesn't fit, I tried.

Sun Dog

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Yes, it is possible to specify charging current as mentioned above with the SCP. It is a percentage of the 100A max for your XW6048. Mine always hits the max set value when the generator firsts starts, stays very close to that value through most of the bulk phase and then consistently lowers during absorb. I have mine setup to go to float once the charging current reaches 1% of my batteries capacity.

RCinFLA

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Also if charging from grid, short period variations in grid voltage will cause short term variations in charge current. It takes a moment to react to a change in ACin voltage.

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Thank you for the answers.

Mine doing sort of both. At times, it's very steady at 98-99A (should be 100), but other times the charging current drops down to 90, 80, or even 70, and start jumping up and down more, say 5 to 10A. It can last for few minutes, or for a long time. I though that was somehow related to AC loads or other charging sources during the charge. I tried disconnecting all loads and all solar chargers but it does this anyway.

I'm trying to figure out if this is just a sloppy firmware that doesn't regulate well, or some more serious problem.

Sun Dog

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Afraid it is not a solution but I can confirm that mine never moves up or down by that much. It might move 2 or 3A when the current is higher but at lower levels it is within an amp or so.

inetdog

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

NorthGuy wrote: »

Thank you for the answers.

Mine doing sort of both. At times, it's very steady at 98-99A (should be 100), but other times the charging current drops down to 90, 80, or even 70, and start jumping up and down more, say 5 to 10A. It can last for few minutes, or for a long time. I though that was somehow related to AC loads or other charging sources during the charge. I tried disconnecting all loads and all solar chargers but it does this anyway.

I'm trying to figure out if this is just a sloppy firmware that doesn't regulate well, or some more serious problem.

If you look at the battery voltage with a sensitive meter at the times that it is doing this, it might give you a clue as to what it causing it and whether it is a condition that you should be concerned about. It is acting similarly to what I would expect if the battery voltage is very close to the transition from Bulk to Absorb and the apparent battery resistance is changing, possibly because of gas bubbles on the plates or intermittent cable connections or something similar.
Does that status continue to show Bulk charging during the whole time?

mike95490

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

I see mine twitching +-5A as the batteries get close to the end of bulk and into absorb. When the generator gets qualified, it loads it down to nearly 40A, before the AC2 breaker limit pulls it back to 30A. Very strange, but the breakers never pop, and while the genset is really grunting, it never drops off.
Just goofy software is my bet.

Blackcherry04

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

mike95490 wrote: »

I see mine twitching +-5A as the batteries get close to the end of bulk and into absorb. When the generator gets qualified, it loads it down to nearly 40A, before the AC2 breaker limit pulls it back to 30A. Very strange, but the breakers never pop, and while the genset is really grunting, it never drops off.
Just goofy software is my bet.

Yeah, it's software and weird design issues that don't always work together well, one is telling it to go and the other telling it stop. Stuff like having two inputs and two outputs and only measuring one of them and causing a imbalance. Temperature sensors without enough differential in a couple locations. Oh well, stuff we live with, you just get where you ignore it.

I think they display a lot of raw data an not some kind of a few cycles average on the display.

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

mike95490 wrote: »

I see mine twitching +-5A as the batteries get close to the end of bulk and into absorb. When the generator gets qualified, it loads it down to nearly 40A, before the AC2 breaker limit pulls it back to 30A. Very strange, but the breakers never pop, and while the genset is really grunting, it never drops off.
Just goofy software is my bet.

Mine was doing the same thing. I had to widen tolerances to avoid generator drop-out during overload.

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Looks like some people have very stable behaviour, but others get variations.

I only concerned about bulk. As the absorption begins there's some variation in charging current at the beginning, but then it diminishes, and when current gets below 50 it's always very stable.

In the bulk though, it would be nice to have a constant current of 100A, and it's supposed to output the maximum it can. And often it does, but frequently it drifts to 90A or 80A (in rare cases even to 70A) and start varying around these numbers. Even though it often comes back soon, it can stay at this decreased level for hours. The downside is that generator would need to run 20% longer at these reduced levels.

This is not a generator problem because the same thing happens with the grid. The grid voltage is stable.

As I understand from what people posted here, similar things happen to others, this is not a sign of any problem with the inverter, and nothing can be done to improve this.

Blackcherry04

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

I hear you, well I cut the percentage back ( a unit of measurement thats not real ) in thoughts that I'd be better off with a lower constant amperage then one that was all over the the place, but that was no joy either. So I ended up with 134 amps, but that slips to 123 at times and a low of 108. There no consistent time it will stay at any of them. It has stopped most of the total drop-outs though.

Again, I don't have the same Inverter, just the same problem. My wife always reminds me that we never had the problems when we had displays with idiot lights....lol

ChrisOlson

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

It might not apply, but for what it's worth our previous generation SW Plus 5548 does the same thing during bulk charging. The SW Plus shows AC amps to the charger instead of percentage of max to the batteries, and I have it set to the max that the generator can deliver continuous. But it varies constantly by 2-4 amps, which is 5-10 amps variation on the DC side going to the bank. Once it gets to absorb and starts tapering off it's rock steady. If I back the maximum charging amps down to 80% or so of what the generator can deliver, then it don't vary.

My guess is automatic de-rate of the inverter/charger when the windings in the transformers get hot so they vary the charging amps to control internal temperatures in the bi-directional inverter/charger. The reason I think that is because when it's really cold in the utility room (close to freezing) it will deliver the max amps longer before it starts to vary.
--
Chris

Blackcherry04

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Chris, I agree with you, I have several Magnums that do it and that's their tech tells me. " Charger Cut-Back Mode " non-documented and non adjustable. There just not as twitchy in how they do it.

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Blackcherry04 wrote: »

Again, I don't have the same Inverter, just the same problem.

It goes through the models and ages ...

ChrisOlson wrote: »

My guess is automatic de-rate of the inverter/charger when the windings in the transformers get hot so they vary the charging amps to control internal temperatures in the bi-directional inverter/charger. The reason I think that is because when it's really cold in the utility room (close to freezing) it will deliver the max amps longer before it starts to vary.

Yes, that is actually documented for mine. I also noticed that at 100A the inverter gets much warmer than when I limit the charging current to 90A. Assuming 90% efficiency, it's 500-600W of heat at 100A. That's a lot of heat. Higher temperatures can decrease efficiency, which will produce more heat. This can create a termal run-away if they don't watch it. May cause more problems in summer time.

However, it often starts outputing lower current right form the beginning of the charge cycle. At this point, the heat cannot be a problem. My guess is that it just doesn't quite have the rated power.

ChrisOlson

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

NorthGuy wrote: »

However, it often starts outputing lower current right form the beginning of the charge cycle. At this point, the heat cannot be a problem. My guess is that it just doesn't quite have the rated power.

The charger and inverter in the SW's and XW's are the same thing - the inverter just works in reverse for charging. But the charging is not quite as efficient as the inverter for whatever reason. In the manual for the SW Plus they give a ratio of 2.5x AC current for DC draw from the batteries (Ex: 10 amps AC load = 25 amps DC draw @ nominal voltage of 50.4), and 2x AC current for DC charging amps (Ex: 10 amps input will deliver 20 amps to the batteries @ 50.4 nominal).

Since the inverter and charger is bi-directional you should be able to load test the inverter at overload (the manual should show overload capacity vs time), and rated continuous load) to see how it holds up delivering power to loads. It takes a healthy battery bank to do that. We have 1,200 ah and the bank will deliver 150% rated load for a few minutes and maintain the nominal voltage if it's fully charged. And it will go about a half hour at rated load (5,500 watts) before the voltage drops below 50.4 nominal. But that should tell you if the inverter/section has a problem.

I see you have a Generac, and my wild guess is that it's more related to your generator not maintaining freq and voltage under load than anything wrong with the inverter. The Generac 10 kW (Guardian series, I'm guessing) is really a 5 kW generator with a duty cycle over 5 kW where it will maintain a reasonable range of output up to 10 kW - but that may not be sufficient for your inverter/charger to operate at peak efficiency so the inverter adjusts accordingly, based on other pass-thru loads that are present at the time and how well the generator is maintaining "clean" power to the loads.

Just a guess. And that guess is based on what our Honda does and how I observe the inverter/charger perform - our Honda is a "4000 watt" unit but it has a duty cycle of 30 minutes on, 30 minutes off at 4 kVA. It's continuous, or prime rating, is 3.6 kVA and that is the power output level where it will maintain perfect voltage and freq continuous at up to 114 degrees F ambient temp. At 4.0 kVA it will maintain 60 Hz (the Honda's governor is awesome) but the voltage drops from 120 to 115 gradually over 30 minutes and if required to continue delivering 4.0 kVA it will drop to 108 and the inverter will "spit" it off due to under-voltage. This is due to winding heat that builds up and causes a gradual voltage drop on the output because the Honda does not have an exciter winding in it. It uses rectified main winding output to the field (thru the iAVR) and when it gets to critical temp the voltage is not there to maintain it.

The Generac has an exciter winding with a conventional AVR, which is not nearly as accurate as Honda's system for maintaining proper field current at output levels above 50% of the generator's "rating". So if the input to the charger is not what the charger needs for peak performance, you aren't going to get out more than you put in, minus the heat losses in the circuitry. And the same could be true for your grid power input to the inverter/charger. If you don't have minimum 120% of the rated required service to the inverter you will also get voltage drop as wiring and breakers heat up on grid power.
--
Chris

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

ChrisOlson wrote: »

Since the inverter and charger is bi-directional you should be able to load test the inverter at overload (the manual should show overload capacity vs time), and rated continuous load) to see how it holds up delivering power to loads. It takes a healthy battery bank to do that. We have 1,200 ah and the bank will deliver 150% rated load for a few minutes and maintain the nominal voltage if it's fully charged. And it will go about a half hour at rated load (5,500 watts) before the voltage drops below 50.4 nominal. But that should tell you if the inverter/section has a problem.

I did a lot of load testing before, when we had an electric range and electric dryer. Everything worked fine. I do not even have such heavy loads to test.

ChrisOlson wrote: »

I see you have a Generac, and my wild guess is that it's more related to your generator not maintaining freq and voltage under load than anything wrong with the inverter. The Generac 10 kW (Guardian series, I'm guessing) is really a 5 kW generator with a duty cycle over 5 kW where it will maintain a reasonable range of output up to 10 kW - but that may not be sufficient for your inverter/charger to operate at peak efficiency so the inverter adjusts accordingly, based on other pass-thru loads that are present at the time and how well the generator is maintaining "clean" power to the loads..

It actually works well up to about 7.5kW. I tried it at this load for 3-4 hours several times. I haven't found any problem. However, when it runs above this, it starts losing frequency very quickly, especially when it's warm. I haven't tried these loads for more than couple minutes though. So, it runs better that you would think. I still think I would be better off with 17kW generator that I would run at 1/2 load even at the expense of higher fuel consumption.

ChrisOlson wrote: »

And the same could be true for your grid power input to the inverter/charger. If you don't have minimum 120% of the rated required service to the inverter you will also get voltage drop as wiring and breakers heat up on grid power.

The grid has always been ok. Electric dryer was 5kW right there, almost the same as Xantrex.

I think if I see it with both generator and the grid, it must be related to inverter. If you see it, and BlackCherry sees it, even though your inverters are different models, that must be a common occurence.

ChrisOlson

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

NorthGuy wrote: »

I think if I see it with both generator and the grid, it must be related to inverter. If you see it, and BlackCherry sees it, even though your inverters are different models, that must be a common occurence.

That could very well be. I've never had any grid power to test the charger to see how it works with it. But I've always felt that if the freq and voltage from the generator are the same as grid, that the inverter shouldn't know the difference.

The Generac Guardian series generators are designed for only 50% rated load continuous. And they are designed for limited run time - exercise every once in awhile, and a power outage once in a blue moon. They are not designed for the rigors of off-grid and battery charging duty at continuous high loads. You may want to consider a more robust generator when you make the move to cut the wires to the grid.
--
Chris

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

ChrisOlson wrote: »

The Generac Guardian series generators are designed for only 50% rated load continuous. And they are designed for limited run time - exercise every once in awhile, and a power outage once in a blue moon. They are not designed for the rigors of off-grid and battery charging duty at continuous high loads.

These outages may be quite long, especially when hurricane hits, sometimes a week or even longer. So they're disigned to run non-stop for a long time. And they do. If you look up on the Internet, you may find stories about Generacs running several weeks during outages. You may need to stop it for an oil change. This is actually not what I need. I need short runs at high power. But there has to be some durability built into the design to withstand these long outages. Three weeks is 500 hours - 3 to 4 years of operation for me.

When I bought mine, screws around breather were not tightened up. So, once I ran it it made an oily mess. I had to disassemble half of the generator to get access to the screws, which took me two days. It has worked without problem afterwards.

ChrisOlson wrote: »

You may want to consider a more robust generator when you make the move to cut the wires to the grid.

I didn't really wanted to buy Generac because of its bad reputation, but there's not much else for NG.

ChrisOlson

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

NorthGuy wrote: »

These outages may be quite long, especially when hurricane hits, sometimes a week or even longer. So they're disigned to run non-stop for a long time.

Indeed, but not at continuous high load over 50% of rated power. The average load in the typical home is less than 2 kW with the heavy loads being very intermittent.

NorthGuy wrote: »

I didn't really wanted to buy Generac because of its bad reputation, but there's not much else for NG.

Generac builds the EcoGen for off-grid duty, however, it is LPG only:
http://www.generac.com/Residential/EcoGen_Series/EcoGen_Series/

They will refuse to honor the warranty on a Guardian series generator used for off-grid power because of the continuous high load imposed by inverter/chargers on a generator. The Guardian is a cheaply built box store generator designed to compete in the market at a price point. It was never designed to be a prime power generator.

Cummins/Onan makes several nice NG fueled generators suitable for off-grid duty. But you will pay 3x for a Cummins what you paid for the Generac.
--
Chris

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

ChrisOlson wrote: »

Cummins/Onan makes several nice NG fueled generators suitable for off-grid duty. But you will pay 3x for a Cummins what you paid for the Generac.

I tried to buy Cummins first They had an air cooled model, but they warned me that it wouldn't last. They said "The 13AC is a 500-1000 hour generator set as it is a standby generator, and its use is intended to be limited to that."

Kohler had a small liquid cooled model but it was $11K!

That's pretty much were all my choices. Of which Generac was the only viable option.

ChrisOlson

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

NorthGuy wrote: »

I tried to buy Cummins first They had an air cooled model, but they warned me that it wouldn't last. They said "The 13AC is a 500-1000 hour generator set as it is a standby generator, and its use is intended to be limited to that."

Yes, the residential standby units with the Onan engine are the same as the Guardian series. I was talking about the commercial/industrial Power Command sets:
http://cumminspower.com/en/products/generators/sparkignited/

The smallest one has an entry price of around $18,000. The diesel Power Command sets are generally a little cheaper entry price because they're more common and more of them are built than the spark ignition sets. But if you absolutely need natural gas instead of diesel they are a very robust option - generally 50,000 hours between overhauls, and they are designed from the ground up for prime power applications.

Not too many off-grid folks have access to natural gas.
--
Chris

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

ChrisOlson wrote: »

The smallest one has an entry price of around $18,000.

That would buy 5 Generacs

ChrisOlson wrote: »

Not too many off-grid folks have access to natural gas.

True. When you need something unusual, it's often hard to find.

inetdog

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

ChrisOlson wrote: »

Not too many off-grid folks have access to natural gas.
--Chris

Pretty much only someone with their own gas well on the property.
Or living next to a pipeline, which would not be very comfortable. :-)

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Xantrex tech support found the problem. The grid voltage was sometimes dropping below 115. This caused Xantrex to derate and decrease charging current. So, it was, seemingly radom, dropping down now and then. I would never guess that such a small drop in voltage could affect charging current so dramatically.

When charging from generator, there also was similar derating, but for completely different reasons - because of the loads.

I saw the same thing happening with both grid and generator, and thought that there must've been something wrong with XW. However, XW was perfectly perfect and worked as expected.

westbranch

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

OK so this explains what is happening , but does it solve the problem? Gettin old, forgot what the issue was...

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

westbranch wrote: »

OK so this explains what is happening , but does it solve the problem? Gettin old, forgot what the issue was...

The issue was that the charging current didn't stay at 100A and often dropped to 70-80A, sometimes for the long time.

This happened to be because of low voltage from electric company, which happens now and then quite often.

There was no workaround.

Doesn't concern me because I'll be off-grid really soon. The important thing is that everything's ok with the XW.

YehoshuaAgapao

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

I like Outback Radian better for transition to off-grid or mini-grid use. Mini-grid says off grid as much as possible, powergrid replaces generator when batteries get too low unless it is down then ATS will use the generator instead. The Radian's configuration settings lend you towards minimizing grid use. Xantrex prefers to be grid-tie. It is a best of both worlds inverter It grew out of the trace inverters that were built around the California power crisis. It is common in 3rd world banana republic countries - currency debasement, high rates, and rolling blackouts (caused by hyperinflation and/or draconian/incompetent government regulations).

For those who more want backup power for storm outages or the once in a long while power company malfunction (blown up transformer, open grid block circuit braker), they are better off with AC-coupled battery backup systems.

Outback Radian (DC-coupled) - Bi-Modal, as off-grid as possible, favors off-grid. Favors battery cycling over grid draw.
Xantrex XW (DC-coupled) - Bi-Modal, best of both worlds, handles rolling blackouts well. Favors grid-draw over battery cycling but supports peak load shave.
AC-Coupled battery backup system bolt-on to grid-tie solar - Bi-modal, strongly prefers grid-tie, better for infrequent storm outages / power company malfunctions.



My grid voltages are high. 124.5-125V.

YehoshuaAgapao

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

Also if charging from grid, short period variations in grid voltage will cause short term variations in charge current. It takes a moment to react to a change in ACin voltage.

If your voltage is borderline, using larger wire to your service panel may help. If you L1/L2 amperage is highly unbalanced, then balancing your subpanel will help a lot more, especially if the wiring to the main panel is undersized. This is especially true when charging off the generator (vs grid) as the generator has a hard limit of 80% of breaker rating on either leg - unbalanced L1/L2 can greatly bottleneck charge rate. The wiring to the main service panel should be rated to the full capacity of the inverter's automatic transfer switch, which is the breaker size in the PDP also - 60A. This is because the inverter needs to charge the batteries and passthrough to the subpanel at the same time. This applies to both Xantrex XW and Outback Radian. Borderline voltage can also cause anti-islanding false alarms and poor grid-selling performance.

NorthGuy

Re: A question for Xantrex XW4024 XW4548 XW6048 owners about charging

YehoshuaAgapao wrote: »

Xantrex prefers to be grid-tie.

While connected to a grid, they have lots of features that more suitable for backup system. If you have a grid power, you cannot really tell XW not to use it. The only way is to disconnect.

However, once you go off-grid, you do not need all these numerous features, you need charging and inverting. And it does this well.