Inverter Mystery

Lucas61

Active member
Jun 13, 2014
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retired English teacher (30 years)
Hello All,

I hope everyone is happy and safe.

Before I bought an inverter, I had questions. Now that I bought an inverter, I have questions. LOL!

Really, there's only one that completely stumps me and that I can't figure out AT ALL.

My machine is a Powertek with indicator lights and LED panels with a 12vdc gel battery.

Here's what I can't figure out:

When the mains power is ON and the battery is 100% charged (and not charging), sometimes the machine runs, draws 400 watts, fans spinning up, etc.

What the hell is the machine doing? It seems to me that it has only two things to do: 1. Charge the battery, 2. Convert AC to DC when the mains power goes out.
However, there is a #3 that the machine is doing and I have no idea what that is . . .
 

josh2203

Bronze
Dec 5, 2013
1,147
282
83
Hello All,

I hope everyone is happy and safe.

Before I bought an inverter, I had questions. Now that I bought an inverter, I have questions. LOL!

Really, there's only one that completely stumps me and that I can't figure out AT ALL.

My machine is a Powertek with indicator lights and LED panels with a 12vdc gel battery.

Here's what I can't figure out:

When the mains power is ON and the battery is 100% charged (and not charging), sometimes the machine runs, draws 400 watts, fans spinning up, etc.

What the hell is the machine doing? It seems to me that it has only two things to do: 1. Charge the battery, 2. Convert AC to DC when the mains power goes out.
However, there is a #3 that the machine is doing and I have no idea what that is . . .
Maintaining the charge? I'm really no expert here but when we had an inverter, it did just that, but our batteries were really bad...

Same as with car battery charger, once the battery is full, it goes into maintaining the charge mode. Could that be it?
 

cavok

Silver
Jun 16, 2014
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Are you talking about the fan on the inverter? it's running to keep it cool.
 

cavok

Silver
Jun 16, 2014
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The only thing I can think of is, like you said, maintaining the charge(?).
 

Lucas61

Active member
Jun 13, 2014
598
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retired English teacher (30 years)
Yeah, but the indicator says the battery is at 100% and the battery is not being used, so what is there to maintain? It's like if you load a device, say, with AA batteries, and you never turn on the device, they have not lost charge because they have never been used, although batteries do have an expiration date but that is months if not years away . . .
 

cavok

Silver
Jun 16, 2014
6,049
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I'm just guessing, but maybe there's a small internal short in the battery. The voltage drops just enough for the inverter to start "topping it off". but not enough for the indicator light to come on.
 

XTraveller

Active member
Aug 21, 2010
362
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43
Not Sure but what about load connect to the AC thru the inverter? Where are you measuring the 400 watts?
 

NanSanPedro

Nickel with tin plating
Apr 12, 2019
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I can't imagine a fan drawing 400Watts. That sounds incredibly inefficient. If the electronics add 5W I would be shocked. I agree, something is wrong.

Are there hot spots on the inverter? I
 

josh2203

Bronze
Dec 5, 2013
1,147
282
83
Yeah, but the indicator says the battery is at 100% and the battery is not being used, so what is there to maintain? It's like if you load a device, say, with AA batteries, and you never turn on the device, they have not lost charge because they have never been used, although batteries do have an expiration date but that is months if not years away . . .
I might continue being wrong, but:



So first of all, you cannot compare inverter batteries and AA batteries, as the structure is different (please refer to the table in the Wikipedia article).

For gel batteries, found the below, so it should draw less than with lead-acid one:


As said, we don't have an inverter at this time, but when we had, as far as I recall, even with new batteries, it behaved exactly like you're describing... Of course, that was years ago so technology might have changed...
 

JD Jones

Moderator - Covid 19 in DR & North Coast
Jan 7, 2016
4,653
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Mine does the same, but I've always thought it's a precautionary feature that happens every time there is a momentary glitch in street power.
I say this because if the power goes for a few minutes when it comes back the charger kicks in for a few seconds and the fan runs for a few seconds.
 

windeguy

Platinum
Jul 10, 2004
36,542
2,856
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Not Sure but what about load connect to the AC thru the inverter? Where are you measuring the 400 watts?
That was my question as well. Is the measurement being made of the actual power being used in the house?

If the batteries are fully charge, there should be no need for the fan, which draws probably about 10 watts, to run.

When the inverter is in float mode (maintaining the full the charge) when the batteries are fully charged , it should be nowhere near 400 watts.
 

Cdn_Gringo

Gold
Apr 29, 2014
8,447
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I'm not an expert but this is what I think may be happening. As someone said above, if there is a momentary loss of power and the inverter kicks in there is an initial and significant hit to the battery charge that should be evident on the inverter display. Otherwise, these inverters automatically cycle themselves to adjust or maintain a floating charge in the batteries. Your inverter manual should tell you how often and for how long this float charge cycle will run. My inverter is installed in a somewhat hot location so whenever it charges (even briefly) the fan runs. You are correctly surmising that when your inverter fan is running the inverter is probably doing something. You just need to figure out what it is doing and the manual should answer that question. If you have a multi-meter you can check the output voltage/amps. If the street power is on and the inverter display indicates it is not supplying backup power to the house, then it has to be charging related. Determine the best recharge amp setting for your batteries and adjust the inverter as required. Less amps to the batteries means it takes longer to recharge but causes less wear and tear on the batteries and produces less heat in the inverter/batteries. Let us know if you figure this mystery out. It's possible that the ambient temperature near the inverter is high so your inverter might just be trying to cool itself a bit.
 

Lucas61

Active member
Jun 13, 2014
598
23
38
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retired English teacher (30 years)
I'm just guessing, but maybe there's a small internal short in the battery. The voltage drops just enough for the inverter to start "topping it off". but not enough for the indicator light to come on.
That's a logical explanation. I just don't know if it's true. Really, I should speak to the installer or call the company and speak to tech support. They can tell if this is normal or not and why it happens. Principally, I want to know if my new inverter has a problem or if this is a normal occurrence. At DR1 there are many who own inverters and have knowledge of them and experience with them. I thought that someone who had an inverter could tell me if this is a normal expectation.
 

Lucas61

Active member
Jun 13, 2014
598
23
38
68
retired English teacher (30 years)
I can't imagine a fan drawing 400Watts. That sounds incredibly inefficient. If the electronics add 5W I would be shocked. I agree, something is wrong.

Are there hot spots on the inverter? I
It's not the fans drawiing 400 watts; it's the running of the entire inverter, including fans, that draws 400 watts. You can hear a humming from the machine. There's more going on than just the fans spinning up. Exactly what components are "running" and what their functions are, I don't know.
 

Lucas61

Active member
Jun 13, 2014
598
23
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retired English teacher (30 years)
Not Sure but what about load connect to the AC thru the inverter? Where are you measuring the 400 wattI
I'm taking the measure of the 400 watts through one of the LED panel displays. There are many displays that I can cycle through to look at various values. I have reason to believe that the 400 watts measure is accurate because I have tested many electrical devices in the house. For example, if a fan is on medium power and the inverter display shows 350 watts load and I turn off the fan and it then shows 310 watts load, then I know that the medium power function is utilizing 40 watts. I have toggled many devices in the house the check their load in watts.

There's a reason for this. Where I live, when the electricity goes off, it doesn't go off for minutes or hours, it goes off for days, generally around two days. So I need to understand how each appliance contributes to total load so I can economize and know which devices to turn off during a power outage to save the battery charge. For example, I might turn off a computer and monitor and use a laptop instead.
 

Lucas61

Active member
Jun 13, 2014
598
23
38
68
retired English teacher (30 years)
I'm not an expert but this is what I think may be happening. As someone said above, if there is a momentary loss of power and the inverter kicks in there is an initial and significant hit to the battery charge that should be evident on the inverter display. Otherwise, these inverters automatically cycle themselves to adjust or maintain a floating charge in the batteries. Your inverter manual should tell you how often and for how long this float charge cycle will run. My inverter is installed in a somewhat hot location so whenever it charges (even briefly) the fan runs. You are correctly surmising that when your inverter fan is running the inverter is probably doing something. You just need to figure out what it is doing and the manual should answer that question. If you have a multi-meter you can check the output voltage/amps. If the street power is on and the inverter display indicates it is not supplying backup power to the house, then it has to be charging related. Determine the best recharge amp setting for your batteries and adjust the inverter as required. Less amps to the batteries means it takes longer to recharge but causes less wear and tear on the batteries and produces less heat in the inverter/batteries. Let us know if you figure this mystery out. It's possible that the ambient temperature near the inverter is high so your inverter might just be trying to cool itself a bit.
You may not be an expert but you know a lot and I do not understand everything that you have explained. However, if it is true what you say here, this is the best explanation that I have heard in this thread: " . . . these inverters automatically cycle themselves to adjust or maintain a floating charge in the batteries." I'm not sure what is meant by "floating" charge. Really, I need to know if my new inverter has a problem or whether what I have described is a normal function. According to your explanation, it is a normal function. Staff at the Powertek office are very helpful and they have tech support. I will call them. Meanwhile, I thought that with the experience of everyone here at the forum, that someone would be able to explain this. I think that your explanation comes closes to what may be happening.

The manual is in English and supplies no information on this topic. Re: recharge amp setting, etc. this is a little beyond my understanding. I kind of get it but not enough to act on it. Still the question remains: If mains power is on and the battery is 100% charged, what work is the inverter doing. Your answer is that it is maintaining a floating charge in the batteries. I need to confirm if this is the case or if it is something else.
 

Lucas61

Active member
Jun 13, 2014
598
23
38
68
retired English teacher (30 years)
That was my question as well. Is the measurement being made of the actual power being used in the house?

If the batteries are fully charge, there should be no need for the fan, which draws probably about 10 watts, to run.

When the inverter is in float mode (maintaining the full the charge) when the batteries are fully charged , it should be nowhere near 400 watts.
@ windeguy, see @ Cdn_Gringo. You both are in agreement on the float mode function and you (plural) are the only ones in this thread who have indicated
this function. The 400 watts load of the inverter, I calculated from one of the LED information display panels. During the day we were running 250 watts load. When the inverter kicked in it was indicated 650 watts load. Therefore, the inverter was drawing 400 watts.

There is a lot more that is working in the inverter than just the fans but what is working, that is the mystery.