Mini review of Xindun Power Low Frequency Inverter

AussieSim

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Following my 48V Foshan SNADI All-in-one review, I also purchased a 24V low frequency pure sine wave inverter from Guangdong Xindun Power Technology Co.,Ltd. My sales representative Cindy Lee was extremely helpful and a pleasure to deal with.


The unit price was USD$401 EXW for :
24V / 4000W Inverter 240V 50Hz output
MPPT 60A charging
AC input screw terminals
1 * universal AC output socket
Screw terminals for DC output and AC output
Resettable button fuses for input/output.
6269468632885543840.jpg

Like my 48V All-in-one, this unit allows PV solar charging while the inverter is off.

The unit is quite sizeable, 580mm x 315mm x 290mm and weights approx 20kg.
Screenshot_20210112-210733_Adobe Acrobat.jpg

(The Xindun inverter is the white unit in the middle)
20210112_161016.jpg

The internals look well made and brand new. There is a larger fan for the inverter board on the right, and a smaller fan for the MPPT on the left.
20210109_123942.jpg.

Mine actually had some transport damage where 4 of the Toroidal transformer leads had disconnected off their respective spade connectors.
1610448262638.png
Xindun were able to diagnose the problem from the photos I sent them and sent instructions on how to reattach the leads.

Pros :
- works as advertised, no problems with my DIY EVE 280Ah 8s battery packs.
- menu allows you to configure Float and Constant charge limits, LVD, Crossover voltage from Battery -> AC Grid and vice versa.
- Main priority / Eco mode / Battery Priority
- PV charges my EVE 280Ah 8s pack while simultaneously powering the inverter output.
- Well made, sturdy powder coated steel construction
- $401 price
- Custom built (other suppliers could only provide 220V AC) Voltage, Hz, optional PV charging / MPTT / PWM, you can choose the PV max Amps and the Inverter output up to 7kW.

Cons :
- Mine came with some shipping damage, the glued foam padding on one side had delaminated and the metal wing base of one corner was slightly bent. The toroidal transformer leads had slid off their spade tabs.
- The unit gets surprisingly hot - 39 degrees C reported by the display when PV charging. Up to 50 degrees C when PV charging and the inverter running. Even the white metal shell became quite warm.
- The small left side fan comes on intermittently from 40 deg C and is a bit whiney.
- The larger right sided fan never came on.
- the PV output in watts is incorrect. I am using an external PV combiner box to combine 2 series strings of different voltages. This isn't a problem for the Foshan Snadi, but this unit report an incorrect PV power (W).
- Horrible loud beep every time you press any button, I put kapton tape over the speaker.
- Fairly small battery terminal screws, approx M6.
- Only one AC output socket, therefore you will need to cut and strip an extension cord to connect to the AC input / AC output screw terminals
- When PV charging I noticed the inverter's displayed battery voltage was between 0.2v - 0.4v lower than my BMS/multimeter recorded. Set your inverter HV cutoff accordingly (they as also set as for 12v, like Renogy, so 14.4 = 28.8)
- No grounding attachment on the case, I don't know if this is an issue, but other inverters include a ground terminal.

Caution :
- Like my All-in-one, these units can run in Battery or Mains priority mode. Imagine you are drawing 4000W AC output from the inverter in Battery priority mode, and your battery discharges down to the low voltage switchover to grid.
- neither an Australian 10A 240V socket nor 15A 240V socket can provide 4000W.
- hence it is recommended that you have an electrician wire the AC input to your house's electrical system.
- in my case I will use a 15A powerblock with included safety switch/RCD


Edit : May be I've posted this review in the wrong sub forum, but with this inverter you obviously can't feed back into grid excess solar power.
 
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Bud Martin

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Did you check the sine wave to see if it maintains pure sine wave through out light load to full load?
 

AussieSim

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Did you check the sine wave to see if it maintains pure sine wave through out light load to full load?

I don't have an oscilloscope to check that.

One issue I'm working through with Xindun at the moment is yesterday in my testing of PV charging, it did not stop at the constant charge V set limit in Battery Priority.

Cindy asked me to make a video, as it wasn't too sunny today, I used AC charging in Mains Priority Mode (this and my Snadi AIO won't AC charge in Battery Priority) and today the set constant charge limit worked correctly.

I'll have to wait for a sunny day to try a PV charging test again.

All of the set limits are in 0.1v increments as per 12V, so you can only set 14.4, 14.5, etc +/- 0.2v steps for 24v.

The inverter displayed voltage was also 0.25v below my multimeter reading whilst AC charging, on appears to increment in 0.2v steps, set your limits accordingly.

The large fan does come on when the internal temp reads 55 degrees (whereas the smaller fan is next to the MPPT). Both fans are 2 pin, so they only operate at a single speed/noise level intermittently, unlike the Snadi which has a baseline constant low speed large fan, with adjustable speed.

Internally there is an earth lead screwed to the case, but no corresponding earth terminal on the outside.
20210113_104759.jpg

Edit : speaking to Cindy she says the inverter voltage error margin is the industry standard +/- 0.5v

Testing in Mains Eco Mode A0d2 The AC charging behaviour was different (than A0d1 = AC mains priority).

My multimeter recording was between 0.2 - 0.4v above the inverter screen voltage (which steps in 0 2v steps).

Once the multimeter hit +0.39v above the set limit, the inverter ticked over to 27.6 (the set limit was 13.7 = 27.4) and then the AC input current tapered down - dropping the inverter's display back to 27.4 and keeping the multimeter voltage between 0.35 - 0.39v above the displayed 27.4.

After around 10 mins tapering current, the charge the charging stopped and the LiFePO4 voltages came down.

The behaviour maybe the same the PV charging such that I will need to set the limit to at least 0.4v lower than intended.....

Edit 2: one nice feature of this inverter is that in Battery Priority Mode you can set a Low Voltage switch to Mains threshold and a switch back to Battery Priorty level. In that way it would act like a powerwall.

One downside in comparison to the Snadi is the noise level, both fans are 2 pin single speed, they only come on intermittently but at full speed (around the noise of microwave).

When the Inverter is on it makes a soft "electrical substation" buzzing. So in Eco mode the noise comes on and off every 15 seconds. The SNADI is nearer to silent, there is no inverter buzz day I can hear, and the large fan runs at low speed/noise.
 
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Barbar0ssa

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Thanks for this review! I ended up going with a model from this company over the SNADI based on the configurability. I'll get my own review up when the parts all come in!
 

Barbar0ssa

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@AussieSim, could you please measure the output voltage across all the pins?

I picked up a split-phase unit and L to N is 110V (good), L to PE is 75V (?!?) and N to PE is 30v (?!?)

Cindy Lee is ghosting me.
 

smoothJoey

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@AussieSim, could you please measure the output voltage across all the pins?

I picked up a split-phase unit and L to N is 110V (good), L to PE is 75V (?!?) and N to PE is 30v (?!?)

Cindy Lee is ghosting me.
This is confusing.
When you mention split phase I would expect to hear about line 1, line 2, neutral and ground.
I would also expect 120/240VAC@60hz.

When you mention PE=protective earth I wonder if you expecting 220-240VAC@50hz.

Are you expecting 120/240VAC@60hz?
 

Barbar0ssa

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Sorry that was confusing. I bet it is more accurate to say "Low Voltage" than "Split Phase." My inverter is only capable of outputting 120 (actually 110) @60hz. I measured (as described above) 110v, 75v, and 30v but I expected 110v, 0v, and 0v.
 

smoothJoey

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Sorry that was confusing. I bet it is more accurate to say "Low Voltage" than "Split Phase." My inverter is only capable of outputting 120 (actually 110) @60hz. I measured (as described above) 110v, 75v, and 30v but I expected 110v, 0v, and 0v.
I think your system may be floating.
@FilterGuy
 

FilterGuy

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Sorry that was confusing. I bet it is more accurate to say "Low Voltage" than "Split Phase." My inverter is only capable of outputting 120 (actually 110) @60hz. I measured (as described above) 110v, 75v, and 30v but I expected 110v, 0v, and 0v.
Can you point us to a manual for the inverter you have?
 

FilterGuy

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Interesting.
1635967326376.png
I had not seen a system that had a DC loads output before. Is that battery voltage? (I did not see it specified).

Anyway.... to your question>>>
I agree with @smoothJoey that it appears the 120V circuit is floating. When you measured the voltages, was the system hooked up to the Utility or was it stand alone?
 

Barbar0ssa

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Interesting.
View attachment 71214
I had not seen a system that had a DC loads output before. Is that battery voltage? (I did not see it specified).

Anyway.... to your question>>>
I agree with @smoothJoey that it appears the 120V circuit is floating. When you measured the voltages, was the system hooked up to the Utility or was it stand alone?
There is no documentation of the DC Loads but the voltage I measure on it makes it seem like it is the battery charging circuit. It is hot when the inverter is off (battery voltage) and the voltage goes up when the unit is on and charging. It's weird, I will never use it, and there is no capacity documentation.

When I plug the inverter in to the wall it switches to AC mode and the ground fault disappears. The voltages look normal. As soon as I unplug it, the car charger complains about ground again, and the voltages misbehave.

Definitely seems like the circuit is floating.
 

FilterGuy

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As a test, is it possible to force the inverter to go into battery mode while the inverter is still plugged into the wall? Perhaps the inverter has a battery-priority setting? If you can do that, let me what happens to the fault.
 

Barbar0ssa

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I set it into battery priority mode so it only uses mains power when the battery gets down to 10% and everything is working great. As long as it is plugged in, the circuit is not floating.
 

Barbar0ssa

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OK... Will the system be permanently plugged in or is this a mobile system?
It can be permanently plugged in. My goal is to use no mains power but I can manage that by not draining the batteries below 10%.
 

FilterGuy

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It can be permanently plugged in. My goal is to use no mains power but I can manage that by not draining the batteries below 10%.
OK.... is the problem solved then?
I am not very familiar with that inverter, but it appears to be intended to be permanently connected to mains. If you want to use it when off mains, there are a few options:

1) Set up a normally closed relay that creates a neutral - ground bond when mains goes away.
2) Set up a switch that can be thrown and create the bond when not on mains. I really don't like this because of the possibility of the switch being 'on' while on mains. This would create 2 N-G bonds and that is a no-no.
3) Create a 'dummy' receptacle that you plug the cord into when not plugged into mains. Inside the dummy receptical, there would be nothing but a connection between Neutral and Ground.
 
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