diy solar

diy solar

I just bought a Ampeak 1200 Watt Pure sign wave inverter for $71 with a digital display. Who thinks it will be good or junk?

Mine is a great deal for the $71 discounted price I paid. It looks like the myvipon.com link is up again with a total cost of $86 with the coupon and $20 off.

Here's what I came up with so far. The no load power draw with AC output working but no load is about 10.8 Watts. USB puts out its rated 2.4 Amps measuring 5.09 Volts no problems and the fan stays off using it. I haven't done the efficiency tests yet but it should be just over 90% at full load. I need to get my flukes and oscope to see the waveform.

My fan only turns on if the watts are in the >50-70 Watt range. Under 50 or so Watts it turns off again. The unit build quality is good but the display calibration is off a little. I haven't opened mine up yet to see if there are any adjustments.

The battery Charge % indicator on the display of mine shows WAY too low. Even a Full Lifepo4 at 14 Volts does not show 100% charge. I pushed the unit to 1300 Watts for 30 seconds. I couldn't get it to trip with just a 1500 watt heater as that heater really draws 1380 Watts at 120 volts and at the 108 Volts the inverter was pushing at max load. The heater was drawing around 1150 Watts. I had to add in another >150 or so Watt load and the heater to get it to overload reset. The Wattage out display is lower than real watts out as the voltage INPUT about .2-.3 Volts low under max load and the Voltage shown for the OUTPUT shows lower than it really is by about 3 volts. 1200 Watts shown on the display is closer to 1300 Watts with about 120 Amps draw.

The display not being dead on accurate is not really a big deal for me but it would be nice if I could zero them out. Having an inverter that shows the displayed voltage a little low and the output wattage a little lower than it's really putting out. Is better than the more expensive inverters that don't have any display at all. So far it seems to pass all the advertised specs.



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I just checked, and this is now $151 how are you finding it for 89?
 
Go to myvipon.com and sign up for free. click to request the coupon. https://www.myvipon.com/product/9472510-Ampeak-1200W-Pure-Sine-Wave-Power-amazon-coupons

Go to Amazon. https://www.amazon.com/dp/B09SZCWM8R Make sure to click the $20 off coupon then when checking out add the Myvipon Coupon code. Mine came out to $71 but I think with the new coupon it comes out to $86 now. The double coupon math is hard for the sellers to figure out so they miss the exact price most of the time. Sometimes I end up with free items. They offer the coupons on Myvipon hoping you will leave a good review on Amazon.



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I have these fans coming today. Going to see if that tames the fan noise a bit, while hopefully proving adequate cooling

Crazy thing the fans in this inverter are 12v 0.35a = 4.2w each x 2fans 8.4w total
Yet these noctua's are only 0.6w each

EDIT: Well I should have measured, the fans in the inverter are 50mm, so these 40mm's not going to work so great LOL :)
 
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Back on Amazon at a higher price with a new coupon (20X4MVJU) - doesn't seem to be unique to each user.

According to the Vipon site it's supposed to be $87.40 after coupon, but it's coming up at $102 for me; not sure if it's because I previously already purchased it.

Price$151.99
Shipping & handling:$0.00
Your Coupon Savings:-$20.00
20X4MVJU:-$30.40

Total before tax:$101.59
 
Finally received my larger LiFePO4 battery to play around with this inverter.

it's noisy as hell. Loud fans kick on full speed even a low wattage under 100w.

Agreed, the fans are indeed loud, though what's worse than a constant fan noise? A fan that is constantly cycling on and off!

I had a load that was fluctuating around 90-105W (kitchen fridge after the inrush startup), and the Ampeak would rapidly cycle the fans on and off around the 100W mark. I had to put a dummy load to keep it above 100W so that the fans stayed on constantly.

Temp sensor is indeed off - unless it's measuring some internal temperature which is higher than ambient?
 
Finally received my larger LiFePO4 battery to play around with this inverter.



Agreed, the fans are indeed loud, though what's worse than a constant fan noise? A fan that is constantly cycling on and off!

I had a load that was fluctuating around 90-105W (kitchen fridge after the inrush startup), and the Ampeak would rapidly cycle the fans on and off around the 100W mark. I had to put a dummy load to keep it above 100W so that the fans stayed on constantly.

Temp sensor is indeed off - unless it's measuring some internal temperature which is higher than ambient?

I fixed that fan noise by wiring in a 5v zener reversed biased with each fan. This runs the fans at about 7v instead of the 12v
Soo much better. I only over heated it once in 105 degree ambient running 1100w, it ran 700w fine in 105 degree ambient.
I thought about adding a switch where I can bypass the zeners to run the fans at max if I need to push it hard in the heat.
 
Back on Amazon at a higher price with a new coupon (20X4MVJU) - doesn't seem to be unique to each user.

According to the Vipon site it's supposed to be $87.40 after coupon, but it's coming up at $102 for me; not sure if it's because I previously already purchased it.

Price$151.99
Shipping & handling:$0.00
Your Coupon Savings:-$20.00
20X4MVJU:-$30.40

Total before tax:$101.59
My first time purchasing and 102.00 for me too.
 
Alright I bought the inverter and I finally have it, things are not looking great.

With no load the fans are at full power, and the internal temperature display says 107F when the actual temperature is about 90F, maybe this is why the fans are at full blast all the time, I will wait for the temp to drop in the night to see if the fans stop.

Also sometimes when I turn on the inverter I get an Invlow error. Not sure what it is, might be related to the low battery voltage.
The performance is good though, it has no issues starting a 1/2hp water pump and I also tested it with a 5000 BTU AC, the inverter does work down to 9.5V, so it is great for my application since I'm using it with a 3S lithium pack (voltage range is from 12.6 to 9V), however the fans at full power all the time is an issue.

The input and output voltage readings are correct within 5%, haven't checked how precise the power output reading is though.

Also the USB ports only give 2A when the inverter is on, when it is off they give 0.5A max.

 
Alright I bought the inverter and I finally have it, things are not looking great.

With no load the fans are at full power, and the internal temperature display says 107F when the actual temperature is about 90F, maybe this is why the fans are at full blast all the time, I will wait for the temp to drop in the night to see if the fans stop.

Also sometimes when I turn on the inverter I get an Invlow error. Not sure what it is, might be related to the low battery voltage.
The performance is good though, it has no issues starting a 1/2hp water pump and I also tested it with a 5000 BTU AC, the inverter does work down to 9.5V, so it is great for my application since I'm using it with a 3S lithium pack (voltage range is from 12.6 to 9V), however the fans at full power all the time is an issue.

The input and output voltage readings are correct within 5%, haven't checked how precise the power output reading is though.

Also the USB ports only give 2A when the inverter is on, when it is off they give 0.5A max.


Yup, the fans are annoying. I modded the fans in mine to run slower, and it's much more tolerable.
 
I have two of the 1200Watt units. They work great. My fans stay off at idle and low power draw. They kick in around >100Watts draw. I haven’t tried this but if your temp sensor probe is registering 107 degrees when it’s really 90F. I wonder if you could open the unit and use a resister or variable resistor in the circuit so it registers the temp 10-15 degrees lower to keep the fan off at no and low loads. I’ve done this on my mini refrigerators to get the closer to 32 degrees as the themostat prevented anything lower than 38 degrees..
 
Alright I can confirm that the issue is the temp sensor, because now that it is cooler at night the fan does stop, however it still cycles on and off every now and then because the inverter warms up a bit when idling to trigger the fan threshold.

Kinda odd that the inverter doesn't a varible fan speed, it is either full blast or nothing.
 
Alright I decided to open the inverter to see what I could do with the temp sensor.

The terminals for the AC outlets of the inverter are super loose, they popped out of their place when I removed the front cover of the inverter.

Also the N and L cables are flipped around, the PCB says that the black cable is neutral and red is live, while they are backwards in the 3 outlets, now that really isn't a problem because this inverter is fully isolated from the DC side and behaves more like an isolation transformer.
The ground terminals are connected to nothing, again not a problem because of how the inverter is built, normally at the very least these should connect to the metal case of the inverter, but this inverter is built like a double insulated PSU, there's a insulation layer on the underside of the PCB even.

The inverter is easy to open, the fans have their own connectors each, I just had to disconnect each fan and also disconnect the cable for the display and the PCB was out.

There are two NTC termistors as temp sensors, both are read by the display which is surprising (Thought that one would feed into the display and the other would just be a overtemp protection that would shut the inverter off), the one that has the decalibration issue is the NTC for the AC side of the inverter, if removed the temperature display displays the temperature of the DC side NTC which at 88F ambient temperature reads 93F, not too far off.

Here is a video showing the temperature display with the AC side NTC (shows the temp of the DC side NTC instead), then with the AC side NTC connected (shows 99F) and finally with a 3K resistor in series with the NTC, which just drops the temperature from 99 to 97F, a higher value resistor will reduce it even further, however doing so will disable the NTC because the resistor doesn't lower its resistance by increasing the temperature, so lets say that at 50C the NTC drops to 5K Ohm, if I added a 4.7K resistor instead the AC side would not be able to read temperature above 50C.

Since I don't have other NTC what I just did was add a 3K Ohm resistor in series with the NTC, this isn't ideal however I tested to check if the fans turn on and they do, this really didn't fully fix the inverter, every 4 minutes it will still turn the fans on for about 2 minutes when idling, I will need to replace the termistor with one of a slightly higher value.

Vid after being partially fixed:

Also I tested the idle power draw, with fans off it is 9.59W and with the fans on it is 16.1W, the display reads 20W+ in both cases.

IMG_20220827_123255.jpgIMG_20220827_122931.jpg

More pics of the insides:
 
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