lights flicker when on battery

dBeau · January 2012

Slowly, I'm getting my system online. I have an XW6048 with 800AH of forklift battery set up as a backup for when the grid goes down (panels to come later). I ran a test the other night an noticed my LED lights flicker a bit when the fridge kicks on. The fridge is about 10 years old. It draws between 150-200watts when the compressor is running (I cant measure the start-up surge). The LEDs are fairly sensitive but dont usually flicker when powered from the grid. At the time of the test the inverter load was about 1500watts, well within what the XW6048 can handle. The battery connections are all tight with about 10' of 4/0 cable between the battery and XW6048. I cant really say that this bothers me all that much but I am curious if this should be considered "normal". My expansion plans include adding another XW6048 to the same battery bank, would this be likely to help, make this problem worse, or not change a thing (assuming similar load)?

waynefromnscanada · January 2012

Re: lights flicker when on battery

One way around it is to have a small inverter to run lights and other small loads, and reserve the big bruiser for big loads like the fridge. Assuming the small inverter is good quality and regulates well, it should greatly reduce the flickering when heavy loads start, assuming the battery is in good enough shape to handle the heavy loads.

BB. · January 2012

Re: lights flicker when on battery

CFL and LED fixtures/ballasts tend to not have any "local energy storage" (capacitors, etc.). So, any variation in the AC input voltage can affect their output (flicker).

I had installed CFL's both in the house and outside for security lighting. The outside fixture had the motion/photo sensor pointing to close to the white all and the CFL starting up would trip the daylight sensor.

The outside fixture flickering at something like 10Hz--And inside the home, the CFL kitchen lights are flickering at ~10 Hz too--due to the starting loads (I guess) of the outdoor CFL's... And this is on a utility connected home (with 125 amp 120/240 VAC main service).

Short of double checking the wiring and home running the refrigerator back to the main panel separate from the lighting circuits, and double checking that you have a solid neutral connection (bad neutral connections back at the main panel can make for lights brightening (or dimming) with current changes on Line A or Line B 120 VAC lines.

-Bill

RCinFLA · January 2012

Re: lights flicker when on battery

Probably due to the compressor startup surge which may be over 1500 watts for an older refrig. XW will take a few cycles to react and settle out where as grid is much lower impedance.

With 10' of battery cable it is important to strap the positive and negative lines together in parallel as much as possible to cut down on cable inductance. Doesn't take much inductance on battery lines to make inverter battery supply 'twang' due to a sudden load change. Hopefully your battery connections are arranged so you don't have a long distance between your battery array positive and negative take off feeds.

solarvic · January 2012

Re: lights flicker when on battery

I have a question about putting 2 XW 6048 inverters on the 800 ah fork lift battery. I,m not trying to be smart, I just don,t know the answer. Will 2 of them inverters discharge the battery too quickly? I have 1 magnum 4000 watt 24 volt inverter and a 630 ah forktruck battery and that inverter can draw down the battery preety fast if I am not careful. :Dsolarvic:D

dBeau · January 2012

Re: lights flicker when on battery

BB. wrote: »

Short of double checking the wiring and home running the refrigerator back to the main panel separate from the lighting circuits, and double checking that you have a solid neutral connection (bad neutral connections back at the main panel can make for lights brightening (or dimming) with current changes on Line A or Line B 120 VAC lines.

I am pretty sure the wiring is in good shape, though it never hurts to double check. But now that you mention it, I do think the lighting and the fridge are on the same circuit. I can think of a couple of other reason why I'd like to separate them.

Cariboocoot · January 2012

Re: lights flicker when on battery

solarvic wrote: »

I have a question about putting 2 XW 6048 inverters on the 800 ah fork lift battery. I,m not trying to be smart, I just don,t know the answer. Will 2 of them inverters discharge the battery too quickly? I have 1 magnum 4000 watt 24 volt inverter and a 630 ah forktruck battery and that inverter can draw down the battery preety fast if I am not careful. :Dsolarvic:D

Certainly the potential for problems is there. Each XW is capable of 12 kW surge. Together that would be a maximum current of 500 Amps (24 kW / 48 Volts). An 800 Amp hour battery would not take that kindly. Even at their constant 6 kW rate it is a potential 250 Amps combined, and again that's a very heavy load for one such battery.

But the OP indicates there is one XW, not two. A peak 125 Amps for 6 kW, although heavy, should not kill an 800 Amp hour battery. He probably does not come close to 6 kW in power-outage use.

mike95490 · January 2012

Re: lights flicker when on battery

Cariboocoot wrote: »

...Even at their constant 6 kW rate it is a potential 250 Amps combined, and again that's a very heavy load for one such battery.

So you need to balance your "potential" loads, vs your realistic loads, and remember, 2 inverters have twice the idle current of one, but it would split up your loads to prevent blinking/flicker.

Is it worth it, for a 2nd inverter, to prevent blinky lights ?

dBeau · January 2012

Re: lights flicker when on battery

RCinFLA wrote: »

With 10' of battery cable it is important to strap the positive and negative lines together in parallel as much as possible to cut down on cable inductance. Doesn't take much inductance on battery lines to make inverter battery supply 'twang' due to a sudden load change. Hopefully your battery connections are arranged so you don't have a long distance between your battery array positive and negative take off feeds.

Admittedly, I am still a newb at all of this. Tips like yours are great to come by. If I knew it was really going to matter that much, I could rotate the battery bank by 90 degrees and trim the cables by a couple of feet. I do have nearly 2 feet between the positive and negative terminals. My other choice would have had the terminals within "screwdriver" distance of each other (6" or so). I didnt feel comfortable with them that close. But again, if I knew it mattered I may have put more thought into it. So each cable is on it's own for only about a foot. The rest of the way to the inverter they run together.

Cariboocoot · January 2012

Re: lights flicker when on battery

I think the confusion comes from Wayne's suggestion of a second, smaller inverter for maintaining lights. Something like the Morningstar 300 wired to dedicated lighting circuits. They draw 450 mA, but in this case there is a system Voltage difference that would need to be dealt with. I don't know of any small 48 Volt inverters, so it would be a second battery bank and some extra equipment to keep it charged.

That is not still not as bad as spending another $3,000 for another XW just to keep the lights stable.

dBeau · January 2012

Re: lights flicker when on battery

Cariboocoot wrote: »

But the OP indicates there is one XW, not two. A peak 125 Amps for 6 kW, although heavy, should not kill an 800 Amp hour battery. He probably does not come close to 6 kW in power-outage use.

I did hint that another XW could be on the way. A question in this direction was going to be a topic for another post. My typical loads average under 2kw for any two hour period, but I would like to be able to handle a somewhat seamless transition to battery/generator when the grid goes out. My peak loads over a five minute average period rarely top 8kw. Also, I am hoping to get close to 8kw of PV on the roof. I've gathered that 400ah is absolute minimum for a single XW6048, so it seemed that 800ah would cover two (in my situation) even if only long enough to get the generator running. So, if it would be stupid to stack two XW6048's with only 800ah, there might be another 2100lbs delivery in my future! Of course I could simply scale back my goals, but the point of my original question was to try to get a feel for what it's like to live off an inverter and to determine if stacked XW's would be more or less prone to flicker than a single.

Cariboocoot · January 2012

Re: lights flicker when on battery

Actually 600 Amp hours is the minimum for a single XW 6048. And whenever you run anything close to the minimum or maximum limit, expect problems. In this case you not only need the minimum battery capacity to deal with the ripple current when selling back to the grid, but also enough to handle the over-all Amp hours needed by loads between charge periods and enough to take the current spikes from heavy loads coming on.

An 8 kW array looks like more than one 6 kW inverter can handle for GT, until you take the inevitable efficiency losses into account. 8 kW @ 77% = 6160 Watts which should keep the XW "maxed" for most of the good daylight hours.

Your 800 Amp hour battery really only needs about 4 kW of array to recharge from. An 8 kW array could support about 50% more battery capacity.

I could be wrong here, but two XW stacked on the AC side would probably be two XW inverters allowing the lights to flicker because they'd both be trying to stabilize when the 'frige comes on.

Maybe the most practical solution here is to buy a new 'frige, which costs a lot less than a XW 6048.

dBeau · January 2012

Re: lights flicker when on battery

Cariboocoot wrote: »

Maybe the most practical solution here is to buy a new 'frige, which costs a lot less than a XW 6048.

Nah, not by a long shot... the most practical solution would be to find something else to obsess over

But yeah, a new refrigerator would make a lot of sense. Then I could set off to replacing the next appliance that makes the lights blink. What I am hearing though is that "grid quality" power is difficult or impossible to make yourself and that short of spreading the loads across a "clean" and "dirty" inverter, I should expect some flicker.

Cariboocoot · January 2012

Re: lights flicker when on battery

dBeau wrote: »

Nah, not by a long shot... the most practical solution would be to find something else to obsess over But yeah, a new refrigerator would make a lot of sense. Then I could set off to replacing the next appliance that makes the lights blink. What I am hearing though is that "grid quality" power is difficult or impossible to make yourself and that short of spreading the loads across a "clean" and "dirty" inverter, I should expect some flicker.

Well mine doesn't flicker. Even when the waterpump comes on. Hmm. Maybe that's another sign of Outback quality.

But I do not have LED lights (too expensive here) only CFL.

Mostly it's a matter of not being able to match the electrical inertia of grid power, which is huge. But I have known many on-grid houses whose lights would dim momentarily whenever a big load was switched on.

So it comes down to your choice of how annoying the flicker is and how much you're willing to spend to stop it.

solarvic · January 2012

Re: lights flicker when on battery

dbeau. I thought that having 2 of those big inverters on the one 800ah battery was too much inverter for the battery. Maybe all you need is the 1 60/48 inverter and a smaller exeltech 1100 watt, 48 volt inverterif you can find one. . The exeltech is suposed to be able to operate a few hundred watts over its advertized limit. You could get an energystar fridge and probably a small freezer and dedicate it to the exeltech and let your other big inverter power your house. I am guessing your 800 ah battery could do it. solarvic

dBeau · January 2012

Re: lights flicker when on battery

Cariboocoot wrote: »

Well mine doesn't flicker. Even when the waterpump comes on. Hmm. Maybe that's another sign of Outback quality.

I was really tempted by the GS8048 but couldnt find enough information on it (too new?). I read through the manual and really liked what it had to offer. But, there was so much out there and generally positive about the XW that I didnt think it would be a mistake.

Cariboocoot wrote: »

But I do not have LED lights (too expensive here) only CFL.

The LEDs I have are 8w (40w equivalent) and only $10/ea. Even on grid it's obvious they are quite sensitive as they flash when adjusting the dimmer. But they dont flicker on grid when the motors start up. I've tried a few LEDs at this point. Cost, color, buzz, flicker, slow start, can't dim, they each have had one or more of these problems. For the price these are hard to beat but I wont be replacing all my bulbs with them.

Cariboocoot wrote: »

Mostly it's a matter of not being able to match the electrical inertia of grid power, which is huge. But I have known many on-grid houses whose lights would dim momentarily whenever a big load was switched on.

So it comes down to your choice of how annoying the flicker is and how much you're willing to spend to stop it.

It's almost never as easy as just spending money. Figuring out where to spend it is the real trick!

mike95490 · January 2012

Re: lights flicker when on battery

My florescent shop lights are on the same sub panel (but I don't know if they are on the same phase) as my fridge, and I've never seen a blink at fridge startup. I do get a glitch when the pump starts, but I expect that's pretty universal.

westbranch · January 2012

Re: lights flicker when on battery

quickest and cheapest test would be buy a CFL and replace that LED, if no flicker, you can 'upgrade' to CFLs ,
after that the next cheapest would be as Vic suggested, a second smaller inverter...

hth

techntrek · January 2012

Re: lights flicker when on battery

I have my well pump, electric water heater, microwave, and nearly every light in my house on one 50 amp subpanel. The lights are mostly CFLs, and two four-foot fluorescent fixtures in my kitchen. The CFLs don't flicker for anything, they don't even appear to dim when we get brownouts. The tube fluorescents flicker for everything, even noticably dimming with as little as a 5 volt voltage drop.

So the flicker is probably just the nature of the beast, and CFLs would probably solve your problem as westbranch suggested. LEDs don't need much power supply circuitry - no need for capacitors like CFLs, and those capacitors are partially why the CFLs can weather a brief voltage sag. Plus poorly designed LED power supplies will just drive them at 30 Hz (half of the supply cycles), not bothering to fully rectify the AC. That will amplify voltage sags, visually, since they aren't lit half the time to begin with.

waynefromnscanada · January 2012

Re: lights flicker when on battery

The "Lights of America" LED lights I have, thankfully don't flicker in my situation.
Thing I wanted to mention though - - those 4 foot fluorescent fixtures in the kitchen - - you'll find that CFL's can be added as needed, to give the same light output, for far less wattage consumed. I threw out all my 4 foot fixtures long ago because of this, and now the CFL's have been replaced with LED.

sub3marathonman · January 2012

Re: lights flicker when on battery

techntrek wrote: »

So the flicker is probably just the nature of the beast, and CFLs would probably solve your problem as westbranch suggested.

It is one of those things that would just bother me too, because it really shouldn't be happening in a perfect situation.

This may not even exist, but is there a "hard start" setup that could be installed for the refrigerator?

They do it with A/C units. On the webpage http://flagshipmarine.com/do's-don'ts.html (about 80% down the page) they say that the surge is reduced from 150% to 120% with the hard start capacitors for a new rotary compressor, and is just 110% (even without the capacitors) for a scroll compressor. They say it is about 350% for an older piston compressor.

So as others have suggested, a new refrigerator might work if the right one is chosen, or a hard start system for the current refrigerator might reduce it enough. I have actually experienced the difference when, during a prolonged power outage from a hurricane, I had to run a refrigerator from an APC 750xl Smart UPS. For the first refrigerator, at my mom's house, which was an older one, the UPS couldn't do it because of the power surge. On my newer refrigerator, at my house, it worked just fine. (I would have to take the UPS over to my in-law's house, that still had electricity, to recharge it after running awhile. But we got by for several days.)

techntrek · January 2012

Re: lights flicker when on battery

waynefromnscanada wrote: »

...those 4 foot fluorescent fixtures in the kitchen - - you'll find that CFL's can be added as needed, to give the same light output, for far less wattage consumed.

Fully agree, they are on the list when we redo the entire kitchen. Since we aren't sure of our overall design it doesn't make sense to upgrade the lighting yet. They are only on for an hour or two each day and we are very dilligent in turning them off when not in use (unlike our hall light that the kids leave on then I don't notice it until 3 hours later). So for now they'll stay. Funny how at one time they were considered the low-power-cheap-to-run option. 95% of the rest of the house is CFL (has been for 4 years), not ready for LED yet, I may start that conversion in another year or two as the CFLs burn out.

lights flicker when on battery

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