In Australia, plenty of houses were catching on fire because of those polarized breakers. As Roland said, they are prohibited from using in certain circumstances where there is any likelihood of current being bi-directional, such as between battery bank and inverter hybrid charger or parallel strings of PVs. As a precaution, it is recommended to only use non-polarized DC breakers (or correct type of rated fuses) for everything.
I just bought 5 of these ABB brand fir a 125 vdc NON photovoltaic application... I really got confused when I saw the - and + pole sides in get reversed to + and - sides out... I checked continuity to be CERTAIN and yes, the + plus side in goes to minus side out, as is the - minus side in has continuity to the + plus side out... Again, this is for a DC NON🚫 PHOTOVOLTAIC application for industrial purposes... The other thing, as an electrician there is no line or load side indicated in the breakers, but I'M ASSUMING that viewing the breaker's texted / inked info as you're seeing this texted message that the TOP or line side is at the situated top, again, the same as you'd read THIS.
The reversal of +/- on each side just considers which way you use as In/Out. So there shouldn't technically be a Line or Load side as long you connect the right polarity at your chosen In. You are right, totally confusing, these DC breakers.
Thank you Roland, for the explanation. As a child I watched my father replacing the contact points and condensor under the distributor cap of previous generation vehicles ignition system. (before electronic ignition) The condensor (capacitor) absorbed excessive energy to prolong the life of the contact points. I am not sure if the spark extinguishing chamber in the dc contactor serves the same purpose. In my opinion a capacitor of sufficient capacity can be of great help to absorb excessive energy across a dc circuit breaker when switching off. to make it safer. When switching on a bleeding resistor may be incorporated to pre charge the capacitor. Maybe it is a matter of production cost, but in my opinion such a capacitor should be incorporated to make switching dc on and off safer.
Thanks for the video. I am very reluctant to utilize these type of breakers. For me, I am still trusting Midnite Solar DC circuit breakers the most. It helps me sleep better at night.
@@RolandW_DIYEnergyandMore Thx. Much appreciated. I trust your correct wiring tutorial over other online sources. Funds ready to deposit once video is uploaded and explains proper connection of AC and DC SPDs.
@@Matthew_Australia the video is already finished. I am planning it to release on 2nd. Before nobody will look it anyways because of the holidays. OK with you?
Roland, regarding your setup; the polarized breaker DC breaker has not tripped with reverse current due to not exceeding the current rating of the bimetal thermal strip within the breaker itself. However, if the current exceeds the bimetal strip (i.e. to heat it where it will deform) this will disengage the breaker under load causing a likely catastrophic failure of the device, due to the arc not being directed into the arc chute chamber. So, it is in your best interest to replace the polarized DC breakers used in battery bank with either non-polarized breakers or Class T fuses (or any fast blowing fuse that will extinguish the arc within the fuse).
Yes. I will surely replace the set of breaker there. You have the fortune to live in a country where manufacturers where already forced to switch their products. Here I just cannot find any! non-polarized breakers, not even on AliExpress. The selection of fuses are thin as well. Non is really made for such battery-bank distributions. So, yeah. I am trying to find the best solution. Will get what I need eventually.
@@RolandW_DIYEnergyandMore Roland, regarding your setup in the resort; the way you had wired the polarized breakers to offer fault protection is correct, so long as you do not disconnect (i.e. manually trip) those breakers under normal load and operation. The plastic case of the polarized DC breakers will deform and break down internally due to excessive heat whenever they are manually tripped, until eventually the device will have a catastrophic failure.
@@RolandW_DIYEnergyandMore I bought most of my non-polarized DC MCB breakers from EBAY, even though Australia has some local suppliers and retailers of the device. Trusted brands are NOARK (number one pick), ZJ Beny (sometimes marketed as just "Beny"), Suntree (sometimes rebadged as "Renogy").
For my chargers; what would you say to RT18, DC fuses, 14x51? They are available in 40-63A. I would use 40A for ech of the chargers. Because that have DIN rail holders
This video has made me inspect breakers that I installed long ago, and found some with "incorrect" polarity. I did use several old-fashioned knife switches disconnecting components. In a situation where a fault might arrive from either side of a breaker, would 2 polarized breakers in line be protective if wired backwards to one another? In other words one having + towards the solar array and the next one having + towards the solar controller? Probably a poor idea.....
Roland, I thoroughly listened to the entire video. There is no fault with your logic and understanding with how to correctly use a polarized DC breaker. You you have correctly wired up the polarized DC breakers as a protection device and NOT as a convenient switch. Another thing to consider though is a third party (such as the FIre Department) needs to understand the polarized DC breaker can NOT be used as a switch. So, my suggestion is to clearly label the polarized DC breakers with something like "DO NOT USE AS A SWITCH UNDER LOAD" to ensure a third party avoids doing so.
Thank you Roland for making this important video. Just one little correction I would like to mention. At 22:00 you say that the solar charger, with the maximum 20 amps it can deliver, cannot trigger the 25A breaker, which in this case is flowed through with incorrect polarity. However, such circuit breakers are designed for a maximum of 40 degrees ambient temperature, which is all too often exceeded in Thailand, and at 20 amps the bimetal in the circuit breaker heats up considerably, so that tripping is over time also possible well below the ampere value on the circuit breaker. I have used a 63A AC Breaker for my additional 60A MPPT, which is not a propper solution too, but I thought its better to have no magnet to push the arc in the wrong direction and cause i have only 24 Volts, which is 20 times less than the rateted voltage of the AC-Breaker, it will work. Matthew will not agree, I guess. In addition i have built in a fan into my small breaker box with a 40 degree temperature switch to activate the fan.
Correct. Well said. Temperature does affect the bimetal thermal strips within breakers. I partly agree with the edited post of yours, regarding AC breakers can be safely used for low voltage DC applications.
Where I live in Australia, it is typical for the outside ambient air temp to be over 40°C for a few weeks each year, with the highest so far being 48.5°C.
I agree with you, that you can use an AC breaker, but only if it has an adequete arc chute chamber to extinguish the DC arc. In your scenario, you are better off using an actual polarized DC breaker (if used between a solar string and a charge controller). If the breaker does not have any rating for DC, then it is not rated for DC. Derating is a fallacy, as it does not matter if the DC voltage is low, damage still occurs on the arc contacts and bimetal strip and internal housing if the arc chute is inadequete in dissipating the heat from the DC arc. An arc is formed when you pull the contacts away from each other, regardless of DC voltage, and this needs to be thoroughly directed into the arc chute chamber to avoid internal damage. Just because most AC breakers do have a bi-directional electromagnet to direct AC arcs (that self extinguishes anyway), this of itself is not the only requirement for a DC breaker. The DC arc needs to dissipate the heat over a larger surface area within the splitter plates of the arc chute. DC breakers have larger arc chutes that can effectively reduce the internal heat to reduce damage and failure. If the marketed AC breaker does not have any DC rating (such as detailed in spec sheets), then nobody should be derating as a solution. There are sound reasons why MCCB DC breakers are larger and heavier than common household AC breakers.
@@Matthew_Australia I have used a branded quality AC-breaker (ABB, the Company I've learned mechatronics). The main reason for fires are wrong connected polarized DC-breakers when comming with the source from below, cause then the + must be connected on the side where a - symbol is printed on top of the breaker. This is not pointed out enough, drown in all the other expert stuff, unfortunately.
I put a 20 amp DC MCB breaker with a 450v single string in my attic. It was a low cost Chinese item. Could be good, could be not. I've decided I'm not happy with this and have just replaced it with fuses on both poles with yet another DC isolator. I need to sleep well also.
@@kpxoda1 there are only a couple of specialized brands which make non-polarized MCBs, and they explicitly state that their products are so. Every other DC MCB will be polarized, especially if it is marked with pole symbols.
Well, did you have the courage to switch off the breakers? Because if you have a switch and that switch will trigger a fire, that's probably a really bad design. There is also a huge question what the right polarity is! These TOMZN breakers for example, I am not at all sure the +/- marking is meant for the source above and load below. I think it's the opposite.
Power coming and going makes these circuits way too convoluted for using breakers. Also you probably have insulation on wires getting very hot out in the sun which can cause insulation to fail and wires to dead short. I would never use breakers on the battery, only class T fuses on both wires. Really seriously, you can EXPECT crap to happen with these systems and fuses are the only safe way at the time to control events. There are even some events with insulation failure where it is impossible to fuse for because power will arc from both directions!
Dear Roland, I have a suggestion for another topic I came accross: Additional capacitors. The short cirquit protection of my JK BMS was triggered by the Inverter during the night. I have increased the delay from 1500 micro seconds up to 2500 and it solved the problem. But I'm going to add some capacitors at the battery Input of the Inverter (4pcs 47'000 uF 35V) to bolster short big current draws of the Inverter, in the hope it will enhance the efficiency of the Inverter. With 24 volts of my system I have anyway not the most efficient system (yes I regret not choosed a 48V system, but its too late) but never the less if the voltage ripple with additional capacitors will be less, same amount of power can be transfered with less current, right, or will it overload the MOSFETs of the BMS when it turns on? I will add a 100A Fuse at the capacitor connection to limit the charge current a little bit. Others claim additional capacitors at solar input will improve efficiency of the solar panels. There I think additional capacitors will help even more, cause solar panels like to deliver constant current and especially PWM solar controllers draw with pulses and MPPTs maybe too. What you think about it?
If fluctuating current inrush is really an issue, than more caps can of course help to stabilize the voltage. But usually the battery is a very powerful source and should keep DC bus voltage quite constant. Do you have such long cabling on the battery side? or is the battery bank relatively small? or are you pulling so huge power changes on the AC output? The only problem big capacitors are making, is the initial charging when they are depleted. That inrush or pre-charging should be done via a resistor. But once the caps are at charge it shouldn't make any problems to the BMS. I do not think that additional caps are required on the PV input. The inverter or charge controller should be designed in a way to manage the PV array for which they are designed for. I have never heard of someone adding caps anywhere. Would be really interesting if you share your experiences if you decide to give it a try...
@@RolandW_DIYEnergyandMore The battery I have is with 560Ah (16x280Ah 2p 8s) strong enought and the cabling is just one meter with 32sq.mm, but as I mentioned the SCP of BMS was triggered. I have some peaks on the AC consumption, i guess they come from a inverter fridge or the Inverter it self need some spikes to keep the waveform smooth with force, which he does really good. The seccond issue I try to eliminate with the additional caps is, cause I have beside the hybride Inverter a additional MPPT which is feeding into the same battery, so the hybrid Inverter switch into floating charge even the Battery is not fully charged. Short voltage spikes comming from the MPPT are maybe enough for the Inverter to think the battery is already full. The BMS (200A) seems to have too much resistance, so the battery is not able to iron the voltage on the other side of the BMS. By the way the cheap good lookin PowMr hybride inverter performs quite good. The efficiency is surprisingly good, he dont produce a lot of heat and delivers the rated 4500Watts constantly. The cooling is made quite good with the three fans on top and cause its a slim costruction the airstream inside is quite fast. I ordered a second one, so I can easy swap and have time for service or repair in case. The App they have is rubbish and it allways works like a UPS if mains are connected, even the priorities can be changed in menu (at this time they are not able to solve this issue, the lady from the surprisingly good customer service said). I just let it run without Mains backup now, thats no problem at all and the fast ATS will switch over, when the battery is empty. For monitoring the grid consumption if have added a small kilowatt hour meter anyway in my main distribution box. They gave me a 10% voucher... for 240 € I cant complain 💁
@@RolandW_DIYEnergyandMore Now I came to the conclusion the shorts came from the H-bridge and i've found a study where they add a capacitor too, to improve the system: quote: The performance of converters has improved considerably using high switching frequency, which leads to a significant improvement in a power converter’s performance. However, the high dv/dt through a fast-switching transient of the MOSFET is associated with parasitic components generating oscillations and voltage spikes having adverse effects on the operation of complementary switches, thereby affecting the safe operation of the power devices. In this paper, the MOSFET gate-driver circuit performance is improved to suppress the H-Bridge inverter’s voltage spikes. The proposed technique is a simple improvement to the gate driver based on the IR2112 driver (IC) by adding a capacitor to attenuate the effect of parasitic components and the freewheeling current, suppressing the negative voltage spikes. end of quote Maybe my capacitors will help too, even its not directly connected to the gate driver. The tiny voltmeter i have at the battery input of the inverter is constantly fluctuating up and down while the voltmeter at the battery is absolutely stable. The capacitors will calm down the whole system of the complex (maybe cascaded multilevel-) H-bridge and will help to make it more stable and smooth I hope. Now I mesured the ripple, its nearly 3 Volts! , looks like rectified 50Hz AC voltage without smooting cap, a wavy jagged round hill every 10 ms. I didn't expect such a blockage through the BMS : /
@@topeye4202 how old is your inverter? maybe the internal caps are not good anymore? I have to change my power supply caps on the MUST inverter again soon. The AC output is becoming irregular again. Changed them 4 years ago last time. But must say that I never had to change a cap on the power lines yet. But here in Thailand, electrolytic capacitors are aging and dying very quickly due to the climate.
So Roland at the end you didnt show a non polarised breaker or explain what these mythical devices are ? You know when an event occurs you have seconds to respond, you dont have time to think about getting your switch order right. Last ditch , always have some profesional cable cutters to hand
@@RobinRastle well, if you look and into my playlist you will find how I struggle with real non-polarized breakers, and that in the meantime I do not trust ANY DC MCB. From your statement about having a wire cutter ready, I do read that you are using DC MCBs as switches, which i do oppose.
Wow. Who knew these things could be so much trouble? Nice, but confusing video and explaination, very tricky these are. I am currently using ordinary ac breakers in my 48v system. Not legal i know but i have disassembled checked and calibrated them exactly to my needs. I have a parallel bank of breakers of different values on the input side of the inverter tailored precicly to my intended loads that will trip when ovetloaded. You cant be too careful with this stuff.
@@uncontrollabledogs3791 some good AC breakers do nave DC ratings too but they can only achieve this if the DV voltage is far lower then the rated AC voltage. I will soon replace every breaker on any of my bi-directional circuits with fuses...
@RolandW_DIYEnergyandMore yes. I was very concerned about breaking the dc arc. Two panels in series can arc about 1 inch when the short is separated. The opening in my breakers is about half an inch but 10 years on, no problems.
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In Australia, plenty of houses were catching on fire because of those polarized breakers. As Roland said, they are prohibited from using in certain circumstances where there is any likelihood of current being bi-directional, such as between battery bank and inverter hybrid charger or parallel strings of PVs. As a precaution, it is recommended to only use non-polarized DC breakers (or correct type of rated fuses) for everything.
Thanks I now understand why all combiner boxes use fuse in the look alike breaker.
This is an excellent amount of detail, thank you for producing this video!
I just bought 5 of these ABB brand fir a 125 vdc NON photovoltaic application... I really got confused when I saw the - and + pole sides in get reversed to + and - sides out... I checked continuity to be CERTAIN and yes, the + plus side in goes to minus side out, as is the - minus side in has continuity to the + plus side out...
Again, this is for a DC NON🚫 PHOTOVOLTAIC application for industrial purposes...
The other thing, as an electrician there is no line or load side indicated in the breakers, but I'M ASSUMING that viewing the breaker's texted / inked info as you're seeing this texted message that the TOP or line side is at the situated top, again, the same as you'd read THIS.
The reversal of +/- on each side just considers which way you use as In/Out. So there shouldn't technically be a Line or Load side as long you connect the right polarity at your chosen In.
You are right, totally confusing, these DC breakers.
Nice video.. I made sure to used non-polarized mcb for my pv panels
Thank you Roland, for the explanation. As a child I watched my father replacing the contact points and condensor under the distributor cap of previous generation vehicles ignition system. (before electronic ignition) The condensor (capacitor) absorbed excessive energy to prolong the life of the contact points. I am not sure if the spark extinguishing chamber in the dc contactor serves the same purpose. In my opinion a capacitor of sufficient capacity can be of great help to absorb excessive energy across a dc circuit breaker when switching off. to make it safer. When switching on a bleeding resistor may be incorporated to pre charge the capacitor. Maybe it is a matter of production cost, but in my opinion such a capacitor should be incorporated to make switching dc on and off safer.
Thanks for the video. I am very reluctant to utilize these type of breakers. For me, I am still trusting Midnite Solar DC circuit breakers the most. It helps me sleep better at night.
Roland, I sent you 20 Euro for this very important safety video about polarized DC breakers. Well explained.
Thanks Mate. It will be invested in a new fuse/breaker solution for the battery bank
Matthew, I know you are still waiting for the SPD video. Will be next ;)
@@RolandW_DIYEnergyandMore Thx. Much appreciated. I trust your correct wiring tutorial over other online sources. Funds ready to deposit once video is uploaded and explains proper connection of AC and DC SPDs.
@@Matthew_Australia the video is already finished. I am planning it to release on 2nd. Before nobody will look it anyways because of the holidays. OK with you?
@@RolandW_DIYEnergyandMore Okay with me. :)
Thanks for sharing my video in the description. That was a surprise 😂
Roland, regarding your setup; the polarized breaker DC breaker has not tripped with reverse current due to not exceeding the current rating of the bimetal thermal strip within the breaker itself. However, if the current exceeds the bimetal strip (i.e. to heat it where it will deform) this will disengage the breaker under load causing a likely catastrophic failure of the device, due to the arc not being directed into the arc chute chamber. So, it is in your best interest to replace the polarized DC breakers used in battery bank with either non-polarized breakers or Class T fuses (or any fast blowing fuse that will extinguish the arc within the fuse).
Yes. I will surely replace the set of breaker there. You have the fortune to live in a country where manufacturers where already forced to switch their products. Here I just cannot find any! non-polarized breakers, not even on AliExpress. The selection of fuses are thin as well. Non is really made for such battery-bank distributions. So, yeah. I am trying to find the best solution. Will get what I need eventually.
@@RolandW_DIYEnergyandMore Roland, regarding your setup in the resort; the way you had wired the polarized breakers to offer fault protection is correct, so long as you do not disconnect (i.e. manually trip) those breakers under normal load and operation. The plastic case of the polarized DC breakers will deform and break down internally due to excessive heat whenever they are manually tripped, until eventually the device will have a catastrophic failure.
@@RolandW_DIYEnergyandMore I bought most of my non-polarized DC MCB breakers from EBAY, even though Australia has some local suppliers and retailers of the device. Trusted brands are NOARK (number one pick), ZJ Beny (sometimes marketed as just "Beny"), Suntree (sometimes rebadged as "Renogy").
OK, will try to find something
For my chargers; what would you say to RT18, DC fuses, 14x51? They are available in 40-63A. I would use 40A for ech of the chargers. Because that have DIN rail holders
This video has made me inspect breakers that I installed long ago, and found some with "incorrect" polarity. I did use several old-fashioned knife switches disconnecting components. In a situation where a fault might arrive from either side of a breaker, would 2 polarized breakers in line be protective if wired backwards to one another? In other words one having + towards the solar array and the next one having + towards the solar controller? Probably a poor idea.....
@@jeffreykropp7664 the breaker which is installed the wrong way would still be able to catch on fire, even when backed up by a second one in series.
Roland, I thoroughly listened to the entire video. There is no fault with your logic and understanding with how to correctly use a polarized DC breaker. You you have correctly wired up the polarized DC breakers as a protection device and NOT as a convenient switch. Another thing to consider though is a third party (such as the FIre Department) needs to understand the polarized DC breaker can NOT be used as a switch. So, my suggestion is to clearly label the polarized DC breakers with something like "DO NOT USE AS A SWITCH UNDER LOAD" to ensure a third party avoids doing so.
Agree simply do not use Polirised breakers, use Non Polarity breakers. Lots of confusion around it. Love the magnet test
Happy New Year Roland and family.
Happy new Year to you and your family as well!
Hi Ronald, what are those SSR installed up there for? Are they AC or DC?
@@taiwanese002 hi, those are switching my high power AC chargers. using 12v DC to switch 230V AC
Perfect . You should write a book .
Thank you Roland for making this important video. Just one little correction I would like to mention. At 22:00 you say that the solar charger, with the maximum 20 amps it can deliver, cannot trigger the 25A breaker, which in this case is flowed through with incorrect polarity. However, such circuit breakers are designed for a maximum of 40 degrees ambient temperature, which is all too often exceeded in Thailand, and at 20 amps the bimetal in the circuit breaker heats up considerably, so that tripping is over time also possible well below the ampere value on the circuit breaker.
I have used a 63A AC Breaker for my additional 60A MPPT, which is not a propper solution too, but I thought its better to have no magnet to push the arc in the wrong direction and cause i have only 24 Volts, which is 20 times less than the rateted voltage of the AC-Breaker, it will work. Matthew will not agree, I guess. In addition i have built in a fan into my small breaker box with a 40 degree temperature switch to activate the fan.
Correct. Well said. Temperature does affect the bimetal thermal strips within breakers. I partly agree with the edited post of yours, regarding AC breakers can be safely used for low voltage DC applications.
Where I live in Australia, it is typical for the outside ambient air temp to be over 40°C for a few weeks each year, with the highest so far being 48.5°C.
I agree with you, that you can use an AC breaker, but only if it has an adequete arc chute chamber to extinguish the DC arc. In your scenario, you are better off using an actual polarized DC breaker (if used between a solar string and a charge controller). If the breaker does not have any rating for DC, then it is not rated for DC. Derating is a fallacy, as it does not matter if the DC voltage is low, damage still occurs on the arc contacts and bimetal strip and internal housing if the arc chute is inadequete in dissipating the heat from the DC arc. An arc is formed when you pull the contacts away from each other, regardless of DC voltage, and this needs to be thoroughly directed into the arc chute chamber to avoid internal damage. Just because most AC breakers do have a bi-directional electromagnet to direct AC arcs (that self extinguishes anyway), this of itself is not the only requirement for a DC breaker. The DC arc needs to dissipate the heat over a larger surface area within the splitter plates of the arc chute. DC breakers have larger arc chutes that can effectively reduce the internal heat to reduce damage and failure. If the marketed AC breaker does not have any DC rating (such as detailed in spec sheets), then nobody should be derating as a solution. There are sound reasons why MCCB DC breakers are larger and heavier than common household AC breakers.
@@Matthew_Australia I have used a branded quality AC-breaker (ABB, the Company I've learned mechatronics). The main reason for fires are wrong connected polarized DC-breakers when comming with the source from below, cause then the + must be connected on the side where a - symbol is printed on top of the breaker. This is not pointed out enough, drown in all the other expert stuff, unfortunately.
@@topeye4202 That is because those types of breakers are polarized (i.e. they only offer protection for current going in one direction).
I put a 20 amp DC MCB breaker with a 450v single string in my attic. It was a low cost Chinese item. Could be good, could be not. I've decided I'm not happy with this and have just replaced it with fuses on both poles with yet another DC isolator. I need to sleep well also.
Great video, only thing is I am still not sure how to tell for SURE if what I am buying /using is polarized or not. Thoughts?
@@kpxoda1 there are only a couple of specialized brands which make non-polarized MCBs, and they explicitly state that their products are so.
Every other DC MCB will be polarized, especially if it is marked with pole symbols.
yep that i call interesting thanks mate.
Great video
Correct me if im wrong but when polarity is shown in breakers it indicates polarity of the "source" incoming side 🤔
@@tjmooney4181 correct
Wow this is such a good explanation!! Subbed
Well, did you have the courage to switch off the breakers? Because if you have a switch and that switch will trigger a fire, that's probably a really bad design. There is also a huge question what the right polarity is! These TOMZN breakers for example, I am not at all sure the +/- marking is meant for the source above and load below. I think it's the opposite.
Power coming and going makes these circuits way too convoluted for using breakers. Also you probably have insulation on wires getting very hot out in the sun which can cause insulation to fail and wires to dead short. I would never use breakers on the battery, only class T fuses on both wires. Really seriously, you can EXPECT crap to happen with these systems and fuses are the only safe way at the time to control events. There are even some events with insulation failure where it is impossible to fuse for because power will arc from both directions!
Dear Roland, I have a suggestion for another topic I came accross: Additional capacitors.
The short cirquit protection of my JK BMS was triggered by the Inverter during the night. I have increased the delay from 1500 micro seconds up to 2500 and it solved the problem. But I'm going to add some capacitors at the battery Input of the Inverter (4pcs 47'000 uF 35V) to bolster short big current draws of the Inverter, in the hope it will enhance the efficiency of the Inverter. With 24 volts of my system I have anyway not the most efficient system (yes I regret not choosed a 48V system, but its too late) but never the less if the voltage ripple with additional capacitors will be less, same amount of power can be transfered with less current, right, or will it overload the MOSFETs of the BMS when it turns on? I will add a 100A Fuse at the capacitor connection to limit the charge current a little bit.
Others claim additional capacitors at solar input will improve efficiency of the solar panels. There I think additional capacitors will help even more, cause solar panels like to deliver constant current and especially PWM solar controllers draw with pulses and MPPTs maybe too.
What you think about it?
If fluctuating current inrush is really an issue, than more caps can of course help to stabilize the voltage. But usually the battery is a very powerful source and should keep DC bus voltage quite constant. Do you have such long cabling on the battery side? or is the battery bank relatively small? or are you pulling so huge power changes on the AC output?
The only problem big capacitors are making, is the initial charging when they are depleted. That inrush or pre-charging should be done via a resistor. But once the caps are at charge it shouldn't make any problems to the BMS.
I do not think that additional caps are required on the PV input. The inverter or charge controller should be designed in a way to manage the PV array for which they are designed for.
I have never heard of someone adding caps anywhere. Would be really interesting if you share your experiences if you decide to give it a try...
@@RolandW_DIYEnergyandMore The battery I have is with 560Ah (16x280Ah 2p 8s) strong enought and the cabling is just one meter with 32sq.mm, but as I mentioned the SCP of BMS was triggered. I have some peaks on the AC consumption, i guess they come from a inverter fridge or the Inverter it self need some spikes to keep the waveform smooth with force, which he does really good. The seccond issue I try to eliminate with the additional caps is, cause I have beside the hybride Inverter a additional MPPT which is feeding into the same battery, so the hybrid Inverter switch into floating charge even the Battery is not fully charged. Short voltage spikes comming from the MPPT are maybe enough for the Inverter to think the battery is already full. The BMS (200A) seems to have too much resistance, so the battery is not able to iron the voltage on the other side of the BMS.
By the way the cheap good lookin PowMr hybride inverter performs quite good. The efficiency is surprisingly good, he dont produce a lot of heat and delivers the rated 4500Watts constantly. The cooling is made quite good with the three fans on top and cause its a slim costruction the airstream inside is quite fast. I ordered a second one, so I can easy swap and have time for service or repair in case. The App they have is rubbish and it allways works like a UPS if mains are connected, even the priorities can be changed in menu (at this time they are not able to solve this issue, the lady from the surprisingly good customer service said). I just let it run without Mains backup now, thats no problem at all and the fast ATS will switch over, when the battery is empty. For monitoring the grid consumption if have added a small kilowatt hour meter anyway in my main distribution box. They gave me a 10% voucher... for 240 € I cant complain 💁
This topic is above my pay grade, but I am interested.
@@RolandW_DIYEnergyandMore Now I came to the conclusion the shorts came from the H-bridge and i've found a study where they add a capacitor too, to improve the system: quote:
The performance of converters has improved considerably using high switching frequency, which leads to a significant improvement in a power converter’s performance. However, the high dv/dt through a fast-switching transient of the MOSFET is associated with parasitic components generating oscillations and voltage spikes having adverse effects on the operation of complementary switches, thereby affecting the safe operation of the power devices. In this paper, the MOSFET gate-driver circuit performance is improved to suppress the H-Bridge inverter’s voltage spikes. The proposed technique is a simple improvement to the gate driver based on the IR2112 driver (IC) by adding a capacitor to attenuate the effect of parasitic components and the freewheeling current, suppressing the negative voltage spikes.
end of quote
Maybe my capacitors will help too, even its not directly connected to the gate driver. The tiny voltmeter i have at the battery input of the inverter is constantly fluctuating up and down while the voltmeter at the battery is absolutely stable.
The capacitors will calm down the whole system of the complex (maybe cascaded multilevel-) H-bridge and will help to make it more stable and smooth I hope.
Now I mesured the ripple, its nearly 3 Volts! , looks like rectified 50Hz AC voltage without smooting cap, a wavy jagged round hill every 10 ms. I didn't expect such a blockage through the BMS : /
@@topeye4202 how old is your inverter? maybe the internal caps are not good anymore? I have to change my power supply caps on the MUST inverter again soon. The AC output is becoming irregular again. Changed them 4 years ago last time. But must say that I never had to change a cap on the power lines yet. But here in Thailand, electrolytic capacitors are aging and dying very quickly due to the climate.
So Roland at the end you didnt show a non polarised breaker or explain what these mythical devices are ? You know when an event occurs you have seconds to respond, you dont have time to think about getting your switch order right. Last ditch , always have some profesional cable cutters to hand
@@RobinRastle well, if you look and into my playlist you will find how I struggle with real non-polarized breakers, and that in the meantime I do not trust ANY DC MCB. From your statement about having a wire cutter ready, I do read that you are using DC MCBs as switches, which i do oppose.
Wow. Who knew these things could be so much trouble? Nice, but confusing video and explaination, very tricky these are. I am currently using ordinary ac breakers in my 48v system. Not legal i know but i have disassembled checked and calibrated them exactly to my needs. I have a parallel bank of breakers of different values on the input side of the inverter tailored precicly to my intended loads that will trip when ovetloaded. You cant be too careful with this stuff.
@@uncontrollabledogs3791 some good AC breakers do nave DC ratings too but they can only achieve this if the DV voltage is far lower then the rated AC voltage. I will soon replace every breaker on any of my bi-directional circuits with fuses...
@RolandW_DIYEnergyandMore yes. I was very concerned about breaking the dc arc. Two panels in series can arc about 1 inch when the short is separated. The opening in my breakers is about half an inch but 10 years on, no problems.