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SOLVED Generator overload when connecting to charge/inverter

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glamsland

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Jan 13, 2022
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Hi.

I have this all-in-one inverter/charger in my solar system. Works great.
Ifs a Epever 3000-hm10022. 3000watt/230v max 100A charge 24v battery.



But now, when i connect the generator, a loncin(predator) 3500i , to the grid (generator) input , the generator goes into overload mode. I'v found some simular threads here about some having the same issues, the generator goes into overload when charger goes into float mode. Wierd...

Seems like i'm in the same situation.

Tried some load (1200watt)direct into the generator, then it works fine, but
when connected into grid port and the battery is full it goes straight into overload..

But when i set charger/inverter in bypass mode, the generator don't stop! It giving power to (thru) the inverter and into the cabin..

Whats going on here? Is there a setting wrong? I also tryed to lower the charge current for the generator to 5A , still overloading..
 
Back down the inverter bulk charge current to keep inverter charging AC draw from overloading generator.

2800 watts AC input power with 90% inverter efficiency translates to 2520 watts/27vdc battery = 93 amps into battery. This varies based on state of charge voltage on battery.

If you have any AC output loads on inverter it must be subtracted from max generator AC input used for charging.

Some of the cheaper HF inverters do not use synchronous rectification for AC charging. They use passive rectifiers/capacitor filter which makes their charging AC loading have a higher peak current with poor power factor, further limiting how much charging power can be pulled from a given power level generator.
 
Last edited:
Is the generator hooked to anything else? Is the generator neutral-ground bonded? Is the inverter grounded to something?

If the symptom (overload) occurs only when battery goes to float, that makes me wonder if it might be related to differing neutral-ground bonding in a 230v inverter vs a 'US split phase' generator, and whether perhaps a difference there, combined with an internal transfer switch switching the inverter itself between 'bonded' and 'unbonded' whenever it starts or stops 'using the ac input', could be causing an actual short circuit through mismatched bonding practices, only when the internal transfer switch is in one position, but not when it's in the other position.

I can't get my head around this whole issue without visual aids but i feel like a possibility is there.
 
Tested some more .. connected a 2800watt heater direct to the generator. It run the heater with no problem?. So.. the generator is ok.
Then i connected the heater to the inverter and decharged the battery to about 50%. Then connected the generator and tryed again.. now the gen started charging the battery! With 25 amp.
It must be something with the inverter/charger when it goes into float mode, cuz when its in float mlde, the gen goes overloading. Asked inverter support about a new firmware update? It might solve the problem.. at least, good its not the generator. ?
 
glamsland said:
Tested some more .. connected a 2800watt heater direct to the generator. It run the heater with no problem?. So.. the generator is ok.
Then i connected the heater to the inverter and decharged the battery to about 50%. Then connected the generator and tryed again.. now the gen started charging the battery! With 25 amp.
It must be something with the inverter/charger when it goes into float mode, cuz when its in float mlde, the gen goes overloading. Asked inverter support about a new firmware update? It might solve the problem.. at least, good its not the generator. ?
Click to expand...
It seems really strange that the overload would happen on a float. (The charge current should be nearly zero when on float) What are your charge and float voltages set to?
 
Check all your charger settings again. Voltages, times, end amps, bulk/absorb amps and volts etc.
Depending on what batteries you have everything has to be just right. Float volts should be lower than absorb for lithium.

You can set the charge curve to 2 stage for lifepo4 and 3 stage for lead acid
 
I don't think it's any wrong with the settings , i agree that the amp is realy low in float, so it cant be the amp draw thad overload the generator. I think its something with the inverter/charger in the moment it goes from bulk to float. Some strange voltage peak, power peak or something that trip the overload protection in the generator. I don't know, ..
 
glamsland said:
I don't think it's any wrong with the settings , i agree that the amp is realy low in float, so it cant be the amp draw thad overload the generator. I think its something with the inverter/charger in the moment it goes from bulk to float. Some strange voltage peak, power peak or something that trip the overload protection in the generator. I don't know, ..
Click to expand...
For now eliminate float and set it to 2 stage charging, bulk then absorb. It should be done by float anyways.
 
FilterGuy said:
It seems really strange that the overload would happen on a float. (The charge current should be nearly zero when on float) What are your charge and float voltages set to?
Click to expand...
I have a nmc lithium 24v ev battery pack. The bulk charge is set to 28.7v(4.015v/cell) and float is set to 28.5. Bulk reconnect is set to 28v.
 
glamsland said:
I have a nmc lithium 24v ev battery pack. The bulk charge is set to 28.7v(4.015v/cell) and float is set to 28.5. Bulk reconnect is set to 28v.
Click to expand...
Seems really high. I would not go over 93% charge. You are pushing it to 99.9. The batteries last the longest if charged between 20-90%
Set charger to 28v bulk and absorb should both be 28v with float at 27.5 but turn off float for now.

Sorry is that lithium ion or lifepo4?

If its lithium ion forget what I said about volts and amps. But I would try to turn off float.
 
glamsland said:
I have a nmc lithium 24v ev battery pack. The bulk charge is set to 28.7v(4.015v/cell) and float is set to 28.5. Bulk reconnect is set to 28v.
Click to expand...
Hmmmm I have no experience with the NMC chemistry so I am not sure if I can help much..... but here are my thoughts:

Even with NMC, float should be nearly no current at all times..... even with NMC.
A float of 28.5 seems too high for a bulk of 28.7..... but like I said, I have no experience with NMC so maybe this is normal
In general, you don't really need float at all for most (all?) lithium chemistries. If you can, turn it off. If you can't turn it off, try a much lower value. Try 28.0 or even 27.5V.
 
My theory is that when you switch from bulk/absorption to float, you actually have NO charge current initially because the battery doesn't instantly drop to the float voltage. If that's the case, the inverter depending on settings might immediately deactivate it's transfer switch. This is supported by the statement about putting the inverter in 'bypass mode' stopping the overload symptom.


Since generator is happy when transfer switch is active and not happy when transfer switch is 'off' aka open, and open circuits don't overload generators, we have to look for what else a transfer switch might do when it goes open. In some inverters, it switches the neutral-ground bond on and off. Keeping in mind, a 230v single phase inverter would be 'bonding' the same neutral that your split phase generator considers a line, L1 or L2.

This is why I had the idea that, depending on whether your inverter and gen were grounded to the same grounding system, if the inverter's NG bond was shorting L1 or L2 of the generator through the ground circuit in a way that was enough to overload but not enough to instantly trip the breaker.
 
Seems the generator does not like the how the inverter is regulating the charge current. The inverter's IGBT switching regulation of charge current is likely creating a poor power factor that has a high, short time period peak AC input current. It is similar to a simple triac based light dimmer, just operating at a much higher power level.

It will show up as a power factor degradation on AC input when it regulates down to float current levels. If you have a meter, like a Kill-A-Watt meter, you can put on AC input, and measure power factor.

I agree they need to at least change the firmware on how they are doing the PWM switching regulation. Hopefully the hardware design is not a limiting factor.

This is a good example of why you need an inverter-charger that maintains a good AC input loading power factor for charging. Generators are rated for VA, not watts, so a poor power factor eats up ability of generator to produce its full output power capability.

Inverter-generator will start to complain of overload when their rectified three phase alternator output HV DC begins to have too much voltage ripple due to a high peak current demand. This causes some voltage dips in the peaks of the sinewave AC output.

When the inverter-charger is expecting a sinewave input, the voltage dips in AC input sinewave peaks can drive the inverter-charger PWM regulation feedback control into instability.

It is normal for inverter-generator to have AC output sinewave peak voltage dips when in eco-mode where engine rpm is running at reduced level then there is a sudden increase in AC load demand. The sinewave AC output peaks of inverter-generator will be clipped until generator engine rpm come up to speed to meet the heavier load demand. You usually see a momentary generator overload LED light until engine achieves required higher rpm to meet the additional AC load demand.
 
RCinFLA said:
Seems the generator does not like the how the inverter is regulating the charge current. The inverter's IGBT switching regulation of charge current is likely creating a poor power factor that has a high, short time period peak AC input current. It is similar to a simple triac based light dimmer, just operating at a much higher power level.

It will show up as a power factor degradation on AC input when it regulates down to float current levels. If you have a meter, like a Kill-A-Watt meter, you can put on AC input, and measure power factor.

I agree they need to at least change the firmware on how they are doing the PWM switching regulation. Hopefully the hardware design is not a limiting factor.

This is a good example of why you need an inverter-charger that maintains a good AC input loading power factor for charging. Generators are rated for VA, not watts, so a poor power factor eats up ability of generator to produce its full output power capability.

Inverter-generator will start to complain of overload when their rectified three phase alternator output HV DC begins to have too much voltage ripple due to a high peak current demand. This causes some voltage dips in the peaks of the sinewave AC output.

When the inverter-charger is expecting a sinewave input, the voltage dips in AC input sinewave peaks can drive the inverter-charger PWM regulation feedback control into instability.

It is normal for inverter-generator to have AC output sinewave peak voltage dips when in eco-mode where engine rpm is running at reduced level then there is a sudden increase in AC load demand. The sinewave AC output peaks of inverter-generator will be clipped until generator engine rpm come up to speed to meet the heavier load demand. You usually see a momentary generator overload LED light until engine achieves required higher rpm to meet the additional AC load demand.
Click to expand...
Thanks, i think you are on to something here.. ? i have sendt all my mesurements and all info to rhe epever support. Recomending to test it themselves, and update the firmware if possible.
Is there anthing i can do to trick the inverter or the generator to think it's all right?
 
glamsland said:
i have sendt all my mesurements and all info to rhe epever support
Click to expand...
Hmmmm..... I just realized you are talking about EPever. (You mentioned it in the original post but I did not pick up on it). This is yet another issue with EPEver. It seems like a lot of people have oddball issues with EPever. The problem I have seen the most is that they just stop working for no discernable reason and have to be totally un-hooked and reconnected to get them going again.

I hope they come through for you with a fix, but if history is any indication you probably won't get satisfaction from them.

(Sorry to be such a downer)
 
SOLVED. the firmware upgrade in the inverter/charger dud not fix it . Replaced the invertermodule in the generator, that fixed it. Working fine now.
 
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