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You are referring to a battery equipped hybrid inverter that accepts AC input from grid or generator. Hybrid inverter has inverter permanently connected to AC output. There is a connect relay between AC input and inverter. Relay is normally open. When an AC input voltage is detected and...

Compression of cells is probably second in controversy to LFP battery longevity. There is not full agreement from LFP battery engineers on topic. Here is some general info on topic. Tried to avoid my own opinions, only present fairly well verified info. I attached the recent EVA 280AH spec...

It is about lithium-ion migration rate which gets more sluggish the colder the temperature. Lithium ions become vulnerable when they get close to and enter the negative electrode graphite granules during charging. They need to quickly find a safe parking spot in the graphite lattice...

Most low cost high freq inverters do not have isolation between PV and AC H-bridge. The PV panels pos and neg input lines are riding on top of a high voltage squarewave when AC neutral is grounded. This is why you need two pole breakers to cut both pos and neg legs of PV panels. The AC...

When a LFP cell is fully charged up to 3.65v with charge current tapering off to low levels, overpotential charge voltage is traded for surface capacitance charge. For LFP cell, the capacity stored in this surface charge capacitance is small, only amounting to about 0.01% of cell's AH rating...

A very critical process step in the fabrication of lithum Ion chemistry batteries, including LiFePO4 battery, is the initial formation of the Solid Electrolyte Interface (SEI) layer. It is crucial in protecting electrolyte from chemical decomposition facilitating long cycle life of battery...

Using just about any Li-Ion battery at lower temps is going to have significantly reduced performance. Charging damage is a combination of temperature, charge current, and cell state of charge. Most manufacturers do not provide specific relationships on these three variables. It is a lot...

In attached diagram, note the path from PV inputs to HV DC bus and AC generating H-bridge PWM switching. The AC PWM H-bridge effectively flips the floating HV DC supply polarity at the line frequency rate. When AC output neutral is grounded, this HV DC polarity relative to neutral-ground will...

A surge spec with no time duration specified is a useless spec. A one msecs surge spec is not really good for much of anything, maybe the initial surge current of a cold incandescent light bulb or a power supply with simple rectifier/filter cap with no inrush current limiter to initially charge...

Assume you know the EasyStart has to be given five startup sequences to optimize for given air conditioner load. It saves the best startup of five sequence cycles. The first training sequence is conservative with less voltage ramping to ensure there is not a stall and it progressively...

The voltage slump during top-off tail charge is not normal. It is caused by high overpotential voltage vs cell current and possibly high cell leakage rate due to lithium metal shorts. You can check for leakage by just checking how much voltage drop cells get after a few weeks of open circuit...

The effects of shading is very much dependent on where the shading is relative the string arrangement to the bypass diodes. A smaller area can be more damaging then a larger area if it encompasses multiple bypass groups. Panel long row pairs (down and back) go into one bypass diode in the...

If this is a HF Growatt it requires inverter battery to HV DC converter to be active to charge battery from PV. This draws 40-50 watts. The tech quoting 2 watt is not even standby strobing average. It is the power required to run display and microcontroller with everything else shut down...

Most of the heat comes from ionic migration energy losses. What you measure on a battery impedance meter is primarily only cell conduction loss which is copper foil/terminal connections and electrode particles conduction resistance through carbon black interconnect powder. It takes DC current...

To all planning to do top balancing, repeat this three times before beginning. "I will not set unloaded power supply above 3.65v". "I will not use small gauge power supply cables havng more than 50 mV voltage drop between power supply and cell(s)." "I will be patient and expect to wait more...

The thickness of lug metal is very important. Cheap lugs are formed from thin copper. Think about the hollow tube from where the inserted wire ends inside the tube to where the lug flattens out for the terminal surface connection. The quarter to half inch or so of hollow tube is pure extra...

I can recommend a relatively inexpense buck converter to triple your output current from a typical 30v 5 amp power supply for LFP top balancing. You can even use an old computer power supply 12v output to feed the buck converter. The buck converter is SZBK07 based on LM25116 synchronous buck...

Looking for a mini-split service contract.

All modern inverters using PWM digital sinewave creation have an output L-C filter to smooth out the PWM chopping to a pure sinewave. The L-C filter has a typical cutoff corner frequency between 2 kHz to 4 kHz. When inverter is lightly loaded the L-C filter becomes very undamped which makes it...

If you connect panels directly to battery the panel voltage will drop to that of battery. You also have no charge managment so may overcharge batteries. Using a BMS for charge cutoff is not a good solution. When you have panels facing different directions you really should have each group on...

Noticed each one of the five transformers have two 20 amp auto type fuses. First thing to check. Any blown fuses point to MOSFET's on that transformer.

An AC induction motor rpm is fixed/related to excitation frequency. Just reducing applied effective voltage via PWM'g or conduction angle changing sinewave via SCR's or Triac's only reduces it maximum torque capability. This may be okay if motor load doesn't need the maximum capable torque and...

First issue is both battery arrays are not balanced. Pack 2 is significantly out of balance. Set start of balance between 3.40v and 3.45v. Balancing below 3.40v can actually misbalance cells due to random inverter load current upsetting BMS cell voltage measurements for balancing cell...

Lot of people here want to break the laws of thermodynamics. You did not measure the electric power until it was warmed up when it dropped back to heat pump only mode. (had already shut off supplemental electric heating elements. Top electric heater assist will initially come on for quick...

It could be worse. They could require you to be union member in each construction discipline. I had construction with a piece of equipment that needed to be taken to equipment room on roof of building. It took 15 months to get required permits to install equipment. I had to pay $800 to have a...

The 304 AH cells have some doping to the electrodes. There are a couple of possible candidates for doping. One is lithium added to graphite negative electrode. This is to provide self charge forming of the Solid Electrolyte Interface (SEI) layer around graphite. Its primary benefit is to...

HV DC is more dangerous than HV AC. AC gives your muscles a chance to relax and let go. DC locks up your muscles causing you to clamp on and be unable to let go.

LFP cell cathode material is much more rugged than other Li-Ion battery chemistries. It is due to the iron providing vertical lattice structure support when most of lithium is removed from positive cathode at full state of charge. It is reason why LFP cells have long cycle life. Downside for...

Compression is intended to suppress delamination, primarily the aluminum and copper foil from their respective LFP and graphite screen printed material. Electrode delamination from metal foil is more likely to happen when there is more temp cycling of cell due to temp expansion coefficient...

Electrolyte is fairly stable to 4.3v. LFP positive cathode electrode has strong lattice so it can take some overcharging. Graphite negative anode electrode is stuffed with lithium-ions at maximum graphite negative electrode expansion (about 11% in graphite volume). There will be a bit more...