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diy solar

diy solar

DIY 'Chargenectifier'

Because I want to leave the units "open" without an addition enclosure, I've decided to 3D print some additional covers for the stud terminals to protect them from touching (originally, the copper lugs were touchable from the outside and in case a tool would drop on it...). Additionally I've added some "HOT surface" stickers. It's a bit like giving the thing a final touch and make it more safe.

20250114_182454_resized.jpg
 
I would like to share an observation about using SolarAssistant since I've disabled my AC-in's and using the rectifiers.

At first, now the grid usage in SA is always showing 0 - which is clear and was expected because AC-in's are disconnected (but I get the grid usage in my smart home system via MQTT from the CAN controller).

The power provided by the rectifiers will be distributed to the load and/or charging the batteries, depending on the current situation. My first assumption was that SA would not show the part of the rectifier energy which is used to charge the batteries. But it works and the SA total values for "Load", "Battery charged", "Battery discharged" are correct - with or without using the rectifier.

I don't know if it works because I've connected any battery via RS485 separately to SA - but I'm pretty happy about it and I can still use SA as my main solar monitoring tool (y)

Also, I don't know if it would also work in closed loop communication (which I don't use) where the battery status may be routed via master battery through the EG4-6500EX master AIO to provide the data to SA.
 
These Huawei R4875G1 units are really fantastic (y)

Even after many hours of using them with 40A each, the fans are running slow and the noise level is really low :)
After start charging with 40A, they heat up fast to 70-72°C (158-161°F) and stay constant at this temperature with an ambient temperature of 23°C (73°F). Still >97% conversion efficiency! Also they are very accurate balanced and throw out exactly the same amount of amps which is set as the limit. All four of the units are very close regarding their output power (within 0.4% difference) this is also a result of my equal length wiring, I guess.

The CAN bus communication is flawless and the units react very fast to requested changes.

A nice side effect is that my EG4-6500EX chargers are not longer used which were not very efficient when in use. I found that the 6500EX getting hotter when using the integrated chargers compared when using only the inverters (even it's the same H-bridge because it could either inverting or charging but not both at the same time). Now my EG4-6500EX running cooler and because of my fan modding even more quiet :)

For now, I've working with the following charging rules:
  • Leave the unit settings at 40A current limit with 51V output voltage. As long as the 51V are not hit or undercut, they are OFF (hibernate). If the battery voltage is <=51V the units switching ON and help to keep the voltage at 51V. If the voltage gets >=51.8V (a 0.8V hysteresis), because PV production may have charged the batteries in the meantime, the units go to hibernate again. I call this "auto" mode. This rule prevents the batteries SOC to fall below 15-20% SOC.
  • Every 3 days I want to charge the batteries to 100% to keep them balanced and to reset/recalibrate to SOC gauge of the batteries. To achieve this, the program stores the highest battery voltage every day. After the PV production ended for a day, the rule checks if the batteries have reached >=56.2V (100% SOC) in the last 3 days and if not, the program set the R4875G1 voltage to 56.3V with 40A each. It falls back to "auto" mode after the 56.3V has been reached. When the voltage reaches >=55V in this mode, the amps are reduced to 20A to stay longer in the balancing range.
All rules are implemented in the ESP32 and even when the smart home system will be down (where I'm doing all the complex monitoring stuff), the solar system will work just with the controller itself. This is more reliable compared to my previous smart home based controlling of the solar system.
 
I have temperature issues with my battery connection on my DIY Chargenectifier.

I've done some tests with a thermal camera and found the wires close to the connections on the battery switches are pretty (unusual?) hot, also the connections on the fuse holder (about 10°C less compared to the switch). Because of the very short length of the wires, I've chosen maybe too tight AWGs. From each unit to the studs I'm running #6 AWG (max. 75A) and after the join of the two units I'm using #4 AWG (150A). The #4 has a length of about 4 foot from the top of the battery racks to the busbars inside the racks (one connected on the top and one at the bottom end).

The following pictures are done with "only" 40A per unit (80A for the #4 AWG wire for the switch and fuse).

Xinf_250120_070320_055.jpg Xinf_250120_070330_908.jpg
Xinf_250120_070349_490.jpg Xinf_250120_070411_119.jpg

On the short wire between switch and fuse terminal (pic 1) I found my shrink tube a bit melted on one side of the wire - this is definitely NOT ok and a result from a short test with 120A (60A per unit).

I've tightened the screws on the switch as much as possible (which is not so easy because I fear to break the switch), but my feeling is not very good about these connections. The nuts look very dull (like zinc) and between nut and lug is a split lock washer. The copper lugs are straight and blank. The crimps are really good (I'm pretty sure - but not 100%) and tight so I think is more related to the (bad) screw connection contacts.

1737382954360.png

The situation on the other 2 rectifiers is only a little bit better (about 5°C less).

Any ideas how I may improve this?
Should I remove the split lock washer?
Maybe I should change the nuts in the switch to different ones from a hardware store?
Do you think my wire size is really too small even considering the short distances?

Until the situation improves, I definitively don't want to use the units above 40A each.
 
I have temperature issues with my battery connection on my DIY Chargenectifier.

I've done some tests with a thermal camera and found the wires close to the connections on the battery switches are pretty (unusual?) hot, also the connections on the fuse holder (about 10°C less compared to the switch). Because of the very short length of the wires, I've chosen maybe too tight AWGs. From each unit to the studs I'm running #6 AWG (max. 75A) and after the join of the two units I'm using #4 AWG (150A). The #4 has a length of about 4 foot from the top of the battery racks to the busbars inside the racks (one connected on the top and one at the bottom end).

The following pictures are done with "only" 40A per unit (80A for the #4 AWG wire for the switch and fuse).

View attachment 271497 View attachment 271499
View attachment 271500 View attachment 271501

On the short wire between switch and fuse terminal (pic 1) I found my shrink tube a bit melted on one side of the wire - this is definitely NOT ok and a result from a short test with 120A (60A per unit).

I've tightened the screws on the switch as much as possible (which is not so easy because I fear to break the switch), but my feeling is not very good about these connections. The nuts look very dull (like zinc) and between nut and lug is a split lock washer. The copper lugs are straight and blank. The crimps are really good (I'm pretty sure - but not 100%) and tight so I think is more related to the (bad) screw connection contacts.

View attachment 271502

The situation on the other 2 rectifiers is only a little bit better (about 5°C less).

Any ideas how I may improve this?
Should I remove the split lock washer?
Maybe I should change the nuts in the switch to different ones from a hardware store?
Do you think my wire size is really too small even considering the short distances?

Until the situation improves, I definitively don't want to use the units above 40A each.

This is the only one I would trust for 48V, Victron 275A:

 
If I was doing a solution I'd use a midnite quad mndc box and mnedc DC breakers of your choice (5 to 100A):


 
Because I have tight space on my boards I think I have two options (the MidNite will not fit).

Using the Victron switches and replace the no-name switches with it (same dimensions) 2x $35.
Or using these "Heschen" breakers to replace both the switch and the MEGA fuse with it (no space for both because it so long) 2x $30.

I think about going with the breaker which would also reduce the number of screw connections / crimps.

@upnorthandpersonal do you have experience with this breaker?
@Brucey do you have experience with this switch?
 
Because I have tight space on my boards I think I have two options (the MidNite will not fit).

Using the Victron switches and replace the no-name switches with it (same dimensions) 2x $35.
Or using these "Heschen" breakers to replace both the switch and the MEGA fuse with it (no space for both because it so long) 2x $30.

I think about going with the breaker which would also reduce the number of screw connections / crimps.

@upnorthandpersonal do you have experience with this breaker?
@Brucey do you have experience with this switch?
Yes I have that switch. Ended up going with an mnedc250 breaker in the end but seems like a quality unit.
 
Screenshot 2025-01-20 161445.png

I use this style, they are built into quite a few batery packs and I have seen overcurrent tests with these also. Come in different ratings, different brands, all the same factory? For the R4875G1s I use one 100A double-pole breaker for the pair.IMG_20250121_125249.jpg and... I use the terminals as mini "bus bars". 🫣
 
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I'm using the MNEDC 100A (Carling Tech) for my battery packs and rectifier.
They are nice. I didn't use the enclosure... Just bolted one side to the bus bar and the other to the cable. (I know they aren't designed for that but it's been working great).
 
I figured you guys may know this more than the average Chargeverter user.

How flexible really can the input voltage, amperage and specifically frequency be on these rectifier based chargers?

The spec sheet for the Chargeverter says 50/60Hz, is that a hard limit?
Presumably there's some leeway there by 10% or more either way?

I have some cockamamie idea that I want to run a diesel generator off of various types of used fuels.

and that theoretically it shouldn't matter that on any given "fuel" the generator doesn't put out properly AC.
If they can handle "normal" THD and square wave/modified sine wave input and "standard" generator fluctuation, how bad can it go before the rectifier says NOPE?

Sure, I would never want to plug an actual appliance into the output of that generator that I would be running in a way in which it was intentionally creating dirtier than normal AC power, but if it was solely for being used as input to the Chargeverter, how dirty is too dirty?
 
Very. It's intended for that. You can find some numbers in the datasheet, e.g. for the Emerson:


Permitted input voltage: 85V to 300V
Line Frequency: 45Hz to 65Hz

Current depends entirely on the load.
So that maybe our next goal up at our family cabin.

Get a diesel generator and just raw dog the fuel tank with a bunch of miscellaneous (but still filtered) used oils. 😂

It'll live a rough life.
 
So that maybe our next goal up at our family cabin.

Get a diesel generator and just raw dog the fuel tank with a bunch of miscellaneous (but still filtered) used oils. 😂

It'll live a rough life.
Make sure the engine starts and stops with diesel. After its warm, mix diesel with oil, make sure engine is working hard. If it's not working it will carbon up and you will have all kinds of problems...
Indirect injection should be more forgiving if eng I running hot and hard.
Use coolant to preheat the oil.
 
Make sure the engine starts and stops with diesel. After its warm, mix diesel with oil, make sure engine is working hard. If it's not working it will carbon up and you will have all kinds of problems...
Indirect injection should be more forgiving if eng I running hot and hard.
Use coolant to preheat the oil.
That makes sense.
Time will tell if that's how we end up doing it though.

I have feeling like most things that are communal use (we have a lot of people who use the property and we want things to just be plug and play without convoluted procedures for start and stop) it will get rode hard and put away wet.

Which I guess we could just keep the gas generator there available for use for the less involved people.

In order to keep the generator from wet stacking or other similar issues it probably wouldn't be a bad idea to run some sort of dump load and use it to heat up some hot water tanks or something like that.
 
Very. It's intended for that. You can find some numbers in the datasheet, e.g. for the Emerson:


Permitted input voltage: 85V to 300V
Line Frequency: 45Hz to 65Hz

Current depends entirely on the load.
Just noticed in my G4875G1 spec that it can handle DC input also, between 85-420Vdc. It's interesting that an AC input frequency is specified at all even if DC input is possible...

1737599691041.png

1737599636711.png
 
R4875G1: Question about device temperature / load / fan-speed / ambient temperature

Today I've used the units for a couple of hours and found the following situation (nearly the same on all 4 units with +/- 2° difference between each):
  • 40A load (~53% of max. current) with about 2,150W
  • Units heat up to 76°C (~169°F) - read via CAN bus
  • Ambient was 22°C (~72°F)
  • Fan speed setting is "auto" but fans did not speed up a lot (still nice quiet) - even with this relatively high device temperature.
  • No issues, they are working like Swiss watches.
The spec shows that the units have an operating temperature range between -40°C to +75°C (-40°F to 167°F).

The Output Power Vs Temperature curve from the spec:
1737601853180.png
I have no idea if the temperature is the device temperature or the ambient in this diagram (my guess is ambient, but not sure anymore).

Now I wonder
  • Is this device temperature "normal" for these units at "only" 53% load? For my feeling it's pretty hot, even though they are not installed in an enclosure... I know that these units are designed for harsh environmental conditions... but... really so hot?
  • Would the fan speed ramp up if they'll getting even hotter? (I don't want to test higher currents right now until I've changed the wiring to bigger AWG... hopefully next week). There is a possible setting for "fan full speed" which I've not tested yet because of the noise level.
  • I wonder how this units can continuously work in an ambient up to +75°C if I see how hot they are at my current (low) ambient. The diagram shows that the power will throttle down at higher temperatures and now I wonder if the units can really deliver full 4kW continuously with usual (25°C) ambient temperatures
  • How hot will the units get (inside) if used with full power continuous operation at moderate ambient (about 25°C)?
  • I'm impressed, they really have to use high quality components in the units to allow operation with such high temperatures!
What is your experience about load and temperature and fan speed?
 
The R4875G1 units were tested at 40°C ambient temperature and have their MTBF set at 500k hours under those conditions. This figure halves for every 10°C increase above that ambient temperature.

The units are hot-swappable, meaning they slide in and out of server racks that offer little to no additional cooling on the sides—certainly no thermal compound! (In fact, they are stacked right next to each other.) Their bottom plate also has a thick plastic insulator. In other words, the fan is all they have to stay cool.

As you observed, the fan responsible for cooling the internal components (some of which sit directly in the airstream, while others do not) operates very quietly at room temperature, even as the unit appears to get "hot." However, to effectively transfer heat via air cooling at 60°C ambient air temperature, the components need to reach around 85°C. The hotter the unit, the less air needs to be moved to achieve heat transfer.

I have conducted some limited testing of the R4875G1 at a 75A output. The units allow the "output temperature" to approach 80°C before the fan significantly increases its speed. I find that using the maximum fan setting (perhaps something to try when you're home alone) substantially reduces the output temperature, indicating that there is considerable margin built in for higher ambient temperatures. I suspect these units could reliably power a cell tower in the middle of the desert without additional cooling.

That said, many mobile operators control ambient temperature and air quality with air conditioning units and air filters to protect their radios and rectifiers from excessive dust and heat. This is why many used rectifiers appear so clean. In other words, as long as sandstorms are kept out, these units will likely last a lifetime without modifications. This is industrial-grade equipment—not the "designed-to-fail" consumer rubbish we’ve come to expect. I trust its quality.
 
Regarding DC-in support, fancy writing a "CAN ESP32 MPPT tracker" for the R4875G? Would make it one hell of a high efficiency universal component... How hard can it be...

Screenshot 2025-01-23 101733.png
 
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