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Surge spec without time duration specification is meaningless. For A/C compressor you need about 0.5 seconds of duration for the surge load. Power factor is another issue. HF inverters don't like poor power factor loads. During startup surge on A/C compressor the power factor can be in the...

Maximum Voc has little to do with illumination shortcomings. As long as there is enough illumination to overcome panel self-leakage shunt current the panel will go to Voc.

You should be able to treat each compressor as its own independent unit tied to the compressor contactors. It would require two Easystarts. Easystart is only engaged during compressor startup and is bypassed during Run mode. You probably want to remove startup delay at least to larger...

Reason for Columb counter use is to judge SoC under cell current loading and charging conditions where there is overpotential voltage slump or bump screwing up OCV vs SoC relationship. OCV is determined by electrode chemistry. Only thing that will effect OCV is internal leakage current that...

Most hybrid inverter do. - Pass-through relay open, grid forming. - Pass-through relay closed, grid following. Closing pass-through relay is based on first detecting AC voltage present on AC input then aligning inverter's voltage/freq/phase (becoming a slave) before closing pass-through relay...

10 foot cable length pair (pos and neg) 20' total path length. fine strand copper welding cable 300 amps continuous current. 00 = 1.68 milliohms = 0.505v total voltage drop @ 300A, 151 watts of cable loss heating 000 = 1.34 milliohms = 0.401v total voltage drop @ 300A, 120 watts of cable loss...

There is a limit on voltage between the data line twisted pair and any reference ground. There is basically three grades of quality for USB to RS485 converters. 1) lowest, shares USB +5v to power RS485 converter chip. No ESD protection. 2) medium - shares USB +5v to power RS485, has ESD...

Primary wear on pass-through relays is grid-glitches and collapse. Inverter pass-through relay releases its parallel grid connection when grid drops out and inverter momentarily gets overloaded trying to power the collapsed grid causing pass-through relay to release contact connection under...

The difference is just whom is in charge of being AC phase master and who is AC phase following slave. A battery powered hybrid inverter can switch between being a slave to grid phase or standalone master for off grid AC coupled PV GT inverters. For hybrid battery powered inverter, when AC...

EG4 uses a standard PV boost SCC taken from a 230vac AIO HF inverter that uses a 500vdc internal HV DC bus for 230 vac PWM sinewave switching. For 120vac EG4 which has a 250vdc HV DC bus, it follows the 500 vdc boosted SCC output with a push-pull down converter DC to DC converter that has a...

SCC is a boost only converter. Output of SCC must not exceed 500vdc. If array exceeds 500vdc it will just pass through boost diode of boost converter and overvoltage 500 vdc internal bus of inverter. Vmp is typically 0.81 to 0.85 of Voc for silicon panels with good illumination level. If max...

It may be because of array Vmp.. There is a maximum array current to each SCC input. When that current is reached it will self limit. Max power will be that limit current times whatever the Vmp is. Lower Vmp (<200 vdc) arrays will not max out the inverter's PV power generation capability.

You must design for Voc max at coldest temperature. Usually in the morning after a cold night. Without any load on panel, the panel will approach Voc when illumination level generates current that exceeds the inherent shunt leakage current of panel. This is common in morning sunlight levels...

If your boat runs on gasoline you have another consideration of wanting to avoid sparks setting off gasoline vapors trapped under floorboards.

In several months, yes. Not significant in a few weeks. LFP cells have between 0.2% total capacity/month to about 6%/mo. worse case for self leakage rate. Leakage is greater when ambient temperature is higher and when cells get older . All cells will unlikely have the same leakage rate. Over...

Q41 and Q42 are operating in parallel to double their current capability. Check the pin to pin continuity. The isolation A, B toroid transformer is likely only the 60 Hz of PWM H-bridge switching. The high frequency PWM comes from the HCT244 circuit. The 60 Hz HV DC polarity flipping is via...

Time period is wrong. Shape is not correct. Marketeers have gotten creative again. Diagram from Copeland with little interconnect wiring resistance resulting in shorter start periods. Curve of Emerson SecureStart softstarter. Again, with little wiring resistance that increases start period...

What Easystart document says normal startup time is 0.1 seconds? That is just plain wrong. Easystart targets about 0.5 seconds of start time during the training process by backing down the voltage level during ramp up, which yields lower starting surge current. It requires the hard start cap...

Battery monitor with Columb counter has to measure positive and negative current accurately. A common issue with cheap monitors is DC offset for current shunt op amp. If zero current point is skewed off to one side, it causes polarity sense of current to be incorrect at low current levels...

I would say the typical AC service personnel I have seen work has a much higher probability of causing premature failure of compressor than an Easystart softstarter does.

Cheap low freq inverters only provide L1, L2 inputs with no input neutral connection. Because of the output transformer 240/120vac arrangement with center tapped neutral, if AC input neutral is connected and there is imbalance in AC input L1-N-L2 voltage, there can be excessive transformer...

What are the 6 pin TSSOP's part #'s on top of board. They look like the opto isolators to IGBT gate drive.

I keep forgetting we are talking about a PV GT inverter. With a combined module PWM IGBT H-bridge. I don't see any floating drivers in the IGBT Module so there must be something on the main PCB. Follow the gate inputs back from module you should find them. The TX1 toroid may be the isolating...

A 120vac unit of at least 12k btu likely has power supply filter inductor between rectifier and filter capacitor, giving it a reduced (but still high) peak current and a power factor of about 0.8. Without the inductor a 12kbtu 120vac unit will likely trip a 15 amp circuit breaker. In U.S...

Existing hybrid inverters that can do load shaving can do what you want. You are more likely to find a LF inverter that does this properly. Preventing back feed is easy. Load shaving requires instant supplementing by inverter which is easier to achieve with LF inverters that are inherently...

The gates, and emitters of IGBT are jacked way up voltage, 15vdc above HV DC level. This absolutely requires isolated gate 12-15 volt gate drivers. Some gate driver circuits have high voltage processing design and use a boot-strapped supply capacitor to power the upper driver. The supply...

Dont't set start of balancing below 3.40v. Doing so increases the chance of balancer actually misbalancing cells due to discharge current overpotential voltage slump causing voltage sampling of cells to report cell voltages that do not represent which cell has greater SoC. The cell's...

It is almost impossible for a DIY'er to get truly matched cells. Matching is more than just capacity matching. Very important to have similar overpotential voltage versus cell current. Ohmic series resistance needs to be matched. There will be significantly different load current sharing...

You should use #10 or #8 gauge wire and keep length as short as possible to reduce voltage drop through cables. When you approach voltage limit on power supply the voltage drop in cables will greatly increase the time to finish off current taper down. Many voltage/current limited power...

Assuming you have overvoltage set properly and you are talking about a cell exceeding the overvoltage trigger voltage, there is a known issue that will allow this condition to happen. It has to do with MOSFET charge path shut down when overvoltage on a cell is exceeded. The MOSFET arrangement...

When output IGBT's get blown out they often present high AC voltage to gate drive circuitry to IGBT's. This often blows out the opto-isolated driver that drive the IGBT gate. Look for 8-pin IC's on backside of PCB. The series resistor to IGBT gate is also often smoked. Sometimes it damages...

Pretty much is maximum inverter rated power. Charging power delivered is AC input power divided by inverter efficiency. You get a little more battery charging amps when battery voltage is low. Because of the synchronous rectification and PWM'd near sinewave AC load current draw profile, the...

When LV6548 is charging battery from AC input the battery to HV DC converter is being used in reverse power mode to charge battery so it cannot supply HV DC for AC output PWM sinewave output generation. Any AC output has to come from AC input pass-through. It also sends PV power to HV DC bus...

Back to the original post question. You have to be very careful of AC input transfer switching to a single AC input hybrid inverter. You must always ensure the inverter's pass-through relay has released open before connecting/reconnecting or changing AC sources. This can take up to a couple...

When grid drops, the L1 side is immediately picked up by inverter at L1 grid original phase. L2 previously on 240vac split-phase grid gets its 120vac to neutral L2 side phase flipped 180 degrees to L1 side phase by cross-strapping relay. If the cross-strapping delays engagement, allowing any...