What causes voltage drop on other circuits, when using high amp draw electronics and how to eliminate it?

[Jonathan86]

I'm a total novice regarding this stiff. My question/title assumes that's what's happening. I've read many posts on "flickering led lights," but none have really helped me understand the issue.

I have a ~ten year old outback system, don't have the model number atm, if that matters. Two inverters that I believe are ~3.6kw each, 7.5kw solar, and ~70kw battery bank of rolls lead acid batteries at 48v. Off grid.

Randomly over the years, I would get the light flicker, sometimes when starting the AC or well pump, sometimes they wouldn't flicker when starting those, and sometimes the lights would flicker when minor draw things would run. Also, all of my uninterrupted power supplies in the house would also flip on sometimes, when certain electronics would start. A few years ago I purchased a Miller 252 mig welder, (a big transformer style welder), and whenever I would be in my shop, which is on a separate panel from the house, if that matters, welding, it would flip on all the uninterrupted power supplies in the house and make all the lights flicker. Everyone in the house would get quite annoyed, and you can probably imagine what it was like when doing dozens of tack or stitch welds, just a few seconds between each. I sold that welder and bought a smaller, inverter style welder, which got rid of that issue.

Running that big miller welder only drew about 2kw, so I had plenty of power, but I don't understand the issue it was causing. I have wanted to get other tool, that I know will draw even more power, but haven't because of this issue. I am now looking to replace my system to have greater output and with a lithium bank. I have been thinking Victron, It's basically going to be several of the Multiplus 2 5kva or 2-4 of the quattro 10kva units. However, I watched Adam De Lay's video on youtube of him setting up two multiplus 2 5kva units and tehn testing them, and when he started his AC, the lights flcikered.

Is there no way around this issue? There must be, because I've also watched videos on Victron's youtube channel where they're setting up massive systems for businesses, like a saw mill, and I can't imagine they're having those same issues and just dealing with them, after spending hundreds of thousands of dollars? If there is a definitive answer as to why this happens and how to eliminate it, I would be very happy to know, especially before spending tens of thousands on my new system. Thank you.

 

[hwy17]

Inverters have no inertia so it's not a problem that can really be solved in an inverter. The inverter will always have to see the drop in order to react to it.

On the grid the spinning turbines provide the inertia, imparting reactive power with zero reaction time.

It would be cool if we could develop a flywheel inertia motor for off grid systems that would do the same.

 

[12VoltInstalls]

The inverter will always have to see the drop in order to react to it

Right, and lead acid batteries are “slow to reply” when asked that question.

would be cool if we could develop a flywheel inertia motor for off grid systems that would do the same

You can do that inefficiently with a flywheel, a drive motor, and a big electric motor as a power generator. I’m not saying it’s a good idea….

and when he started his AC, the lights flcikered

this is not the typical flickering people refer to or complain about. Though maybe still undesirable.
The flicker issue has to do with, say, let’s call it alignment or misalignment- of the circuitry in the AC switching of the LED lights (they actually run on DC and without ‘weighting’ the rectifying circuits create spike reactions with some inverters) with the multi-stage switching within the inverter that creates the sine wave.

In your case, possibly more expensive or higher quality LED lighting fixtures may stop this (or running one incandescent or fluorescent bulb), or perhaps LiFePo batteries may eliminate it, or perhaps a low-frequency inverter may buffer away the pulsing.

I do not have this problem but nearly all my lighting is DC direct, and having read about this issue it has occurred to there is something I do not know: (@Hedges ) do electricity “rhythms” do the same thing that clocks do and align themselves to coordinate their motion? (Or cycling of the balance of the current/volts is probably more accurate). Because it’s a cycling self-perpetuating anomaly.

In your case, you are getting voltage sag most likely. So ‘faster’ batteries (or more capacity?) may be a component of a solution with all the potentially I’ll-advised assumptions I’ve incorporated here.

 

[Jonathan86]

In your case, possibly more expensive or higher quality LED lighting fixtures may stop this (or running one incandescent or fluorescent bulb), or perhaps LiFePo batteries may eliminate it, or perhaps a low-frequency inverter may buffer away the pulsing.

In your case, you are getting voltage sag most likely. So ‘faster’ batteries (or more capacity?) may be a component of a solution with all the potentially I’ll-advised assumptions I’ve incorporated here.

Are there differences in "speed" between different LiFePO4 batteries?

I believe the Victron inverters are low frequency.

What about when you don't have batteries, or you're not really using them, but instead pulling straight from the panels to the inverters to the house? (that is possible right?) Then would it be the type/quality of inverter that would either cause or prevent the issues with lights and other devices having power interruptions?

 

[Jonathan86]

Inverters have no inertia so it's not a problem that can really be solved in an inverter. The inverter will always have to see the drop in order to react to it.

Does the size of the transformer in the inverter have anything to do with it? I've watched videos where many people have commented on the "massive" size of the transformer in the Victron units, and I've seen teardowns of other brands' inverters that have very small or non existent copper coils in comparison.

 

[Zwy]

I think you need to define light flicker. This is light flicker.

If the lights blink when a large load is suddenly switched on, that is due to voltage dropping for a split second. The inverter can not react fast enough or the battery bank voltage drops.

 

[Zwy]

Does the size of the transformer in the inverter have anything to do with it? I've watched videos where many people have commented on the "massive" size of the transformer in the Victron units, and I've seen teardowns of other brands' inverters that have very small or non existent copper coils in comparison.

I'd look at your battery bank, how old are the Rolls?

Lead acid has voltage sag and as the plates deteriorate over time, the sag will become more pronounced. You can still get sag with LFP but that usually is corrected by larger battery bank and large cabling/busbars.

 

[hwy17]

Does the size of the transformer in the inverter have anything to do with it? I've watched videos where many people have commented on the "massive" size of the transformer in the Victron units, and I've seen teardowns of other brands' inverters that have very small or non existent copper coils in comparison.

It does and doesn't. Large transformers are known for their surge capability but I think that's more about handling them than being completely unaffected. I have an XW which has one of the largest transformers in an off grid inverter and LEDs will still flicker sometime when a clothes dryer motor starts. I don't have any UPS at home but I know those can be more sensitive than the devices they power, like the UPS will react to a voltage drop that would not have shut down the computer, because computer power supplies can operate down to like 90v.

Your Outback's are already in the low frequency legacy of design with the schneider and magnum so I'd be hesitant to assume that an inverter change will solve your symptoms. But it's possible.

 

[Checkthisout]

Welding has enormous current fluctuations.

Try running a welder off an inverter generator and witness how erratic the engine RPM is.

 

[12VoltInstalls]

Are there differences in "speed" between different LiFePO4 batteries

Not really
But LiFePo can output its full capacity near instantaneously while lead-based batteries are relaxed and slow to sudden loads and exhibit more voltage sag.

Maybe I was analogously being too simple by saying ‘speed’
Batteries aren’t really judged by speed Lol

 

[Steve_S]

Former Rolls Lead Acid guy here... Boy I do not miss those Big Red Beasts !
FLA is much lazier especially when aged and that will cause voltage sags that are slow to recover. I ran my MIG with them as well as my compressor, it worked but not terribly pretty. After switching to LFP life got So much better with those heavies.

I won't beat around the bush... BTDT and spend oodles learning lessons...
You absolutely want a Low-Frequency inverter system. Anything used that is heavy or dirty draw can be handled reasonably well with a good LF Inverter where a High Frequency is NOT GOOD for that kind of duty. HF is good for electronics & lighter loads but not motors or deep cycle devices.

Flicker:
Two part issue there...
1) Low cost LED lights etc do tend to flicker (regardless of power source) but ca be worse with invertered systems. Those $1 Wallymart specials are crap ! Good Quality name brands do not flicker - TIP when buying bulbs stick to "dimmables" they have a small rectified inside and it helps.
2) Also remember that even when on Grid Power, things like Well Pumps, AC Compressors etc will still cause a SAG in the household circuits and lights can & do flicker in such cases... Again partly depends on the device itself but also on the existing loads in the home and if you are in the higher consumption levels.
3) Undersized inverting can also result in flicker because if the inverters are delivering close to their max capacity, can also result in some lag & sag when responding to demand.

Your Equipment is Good Stuff - see what happens when you buy GOOD right from the get-go ! 10 years & still going strong. It is most likely that you can use what you have with little effort to switch over to LFP. They may need flash update (firmware) for extra features etc but even without, LFP is very close to FLA and so tweaking the settings is easy. Also note that LFP Charges considerably faster than FLA and takes it a lot better to boot.

You have 70kWh of FLA which translates into 35kWh useable (at best).
1x 48V/100AH = 5120Wh or 5.1kWh
1x 48V/280AH = 14,336Wj or 14.3kWh - Three packs replaces your functional FLA Capacity.
You can buy Prebuilt Battery Packs but above 200AH weight, S&H etc get tricky.
You can DIY your packs (not hard) but that will require extra tools & kit + patience & learning. Here is a Guide I wrote a while back that explains how to DIY which you may find interesting. Luyuan Tech Basic Lifepo4 Guide V1.0A

Something Different from FLA to LFP to get used to.
Unlike FLA where we have series/parallel combinations to make up a bank that can deliver XXX Amps, each LFP Packs does that in one small powerful package. Now I mention this because it often does not occur to people until they get 1 "hard lesson". My Bank is 45kWh LFP, it can output a "standard" 1200A (1C Rate discharge) all packs BUT it can do a Burst Discharge (5C) @ which is a full 8400A. A BMS will STOP the Burst Discharge Capability but it is there and if something goes horribly wrong... you get the idea. Believe me when I say "horrible" potential. The LFP Chemistry is conservative but can be pushed over the edge, the BMS is the guardian to keep all factions happy. *A Burst Discharge would only happen with a full short condition.

VICTRON is Grade-A Top Quality and has a great software management eco-system that's hard to beat. Proper planning can make it all go quite smoothly if you need/want to change over. Would be a shame to waste the goodies you got, maybe a secondary install or ?

 

[JRH]

Former Rolls Lead Acid guy here... Boy I do not miss those Big Red Beasts !
FLA is much lazier especially when aged and that will cause voltage sags that are slow to recover. I ran my MIG with them as well as my compressor, it worked but not terribly pretty. After switching to LFP life got So much better with those heavies.

I won't beat around the bush... BTDT and spend oodles learning lessons...
You absolutely want a Low-Frequency inverter system. Anything used that is heavy or dirty draw can be handled reasonably well with a good LF Inverter where a High Frequency is NOT GOOD for that kind of duty. HF is good for electronics & lighter loads but not motors or deep cycle devices.

Flicker:
Two part issue there...
1) Low cost LED lights etc do tend to flicker (regardless of power source) but ca be worse with invertered systems. Those $1 Wallymart specials are crap ! Good Quality name brands do not flicker - TIP when buying bulbs stick to "dimmables" they have a small rectified inside and it helps.
2) Also remember that even when on Grid Power, things like Well Pumps, AC Compressors etc will still cause a SAG in the household circuits and lights can & do flicker in such cases... Again partly depends on the device itself but also on the existing loads in the home and if you are in the higher consumption levels.
3) Undersized inverting can also result in flicker because if the inverters are delivering close to their max capacity, can also result in some lag & sag when responding to demand.

Your Equipment is Good Stuff - see what happens when you buy GOOD right from the get-go ! 10 years & still going strong. It is most likely that you can use what you have with little effort to switch over to LFP. They may need flash update (firmware) for extra features etc but even without, LFP is very close to FLA and so tweaking the settings is easy. Also note that LFP Charges considerably faster than FLA and takes it a lot better to boot.

You have 70kWh of FLA which translates into 35kWh useable (at best).
1x 48V/100AH = 5120Wh or 5.1kWh
1x 48V/280AH = 14,336Wj or 14.3kWh - Three packs replaces your functional FLA Capacity.
You can buy Prebuilt Battery Packs but above 200AH weight, S&H etc get tricky.
You can DIY your packs (not hard) but that will require extra tools & kit + patience & learning. Here is a Guide I wrote a while back that explains how to DIY which you may find interesting. Luyuan Tech Basic Lifepo4 Guide V1.0A

Something Different from FLA to LFP to get used to.
Unlike FLA where we have series/parallel combinations to make up a bank that can deliver XXX Amps, each LFP Packs does that in one small powerful package. Now I mention this because it often does not occur to people until they get 1 "hard lesson". My Bank is 45kWh LFP, it can output a "standard" 1200A (1C Rate discharge) all packs BUT it can do a Burst Discharge (5C) @ which is a full 8400A. A BMS will STOP the Burst Discharge Capability but it is there and if something goes horribly wrong... you get the idea. Believe me when I say "horrible" potential. The LFP Chemistry is conservative but can be pushed over the edge, the BMS is the guardian to keep all factions happy. *A Burst Discharge would only happen with a full short condition.

VICTRON is Grade-A Top Quality and has a great software management eco-system that's hard to beat. Proper planning can make it all go quite smoothly if you need/want to change over. Would be a shame to waste the goodies you got, maybe a secondary install or ?

I have had led lights for years …never have seen a flicker …last weekI l bought a pack of cheaper ones to put in a Mobil home I own and they now drive the people crazy blinking , flickering or what ever…same place ,same service and fixtures , and wiring ….
Only thing that changed was those cheap china lights…
Is there anything they cant figure out how to make cheap enough to fail.. wasted 20 bucks..

I broke my own rule of always buying good stuff , and ya see what I got in return…Im sick of cheap shit flooding this country…

Make Stuff Great Again…….USA USA USA USA USA ..