Inverter Charger Transfer Switch Cycling

Robbutton

New Member
Joined
Sep 7, 2021
Messages
6
My father in law has a Renogy 2000w inverter charger hooked up to a battery bank and generator in his cabin. The inverter has an automatic transfer switch, which is controlled by software, to bypass and charge the batteries when it detects the generator is online. When I was there I noticed that when the generator is online the symbol indicating that the inverter detects the generator stays on but the transfer switch is cycling between battery/inverter mode and bypass/charge mode approximately every 10 seconds. Everything appears to be hooked up correctly and I checked through all the settings and couldn't see anything wrong so I'm assuming it's a software issue. Anybody ever have a similar issue and/or have any suggestions before I recommend sending the inverter back on warranty?
 

Bud Martin

Photon Sorcerer
Joined
Aug 27, 2020
Messages
3,244
Is there a battery Voltage setting for when it should go into the charging/xfer mode when the battery reaches low Voltage set point, and another Voltage set point when it should go back to battery mode? The value should be set to give it hysteresis so it will not be switching back and forth due to small change in battery Voltage.
 

Robbutton

New Member
Joined
Sep 7, 2021
Messages
6
Not for the battery setting which is selected. The batteries used are flooded batteries and the setting for these, which is what is currently selected, doesn't have min/max charge settings. Only lithium ion batteries allow for changing charge values, all other battery settings use automatic bulk/boost/float charge which is software controlled
 

Bud Martin

Photon Sorcerer
Joined
Aug 27, 2020
Messages
3,244
It is not the charge setting, it is the transfer point setting that you need to see if it has one, it should have one so you can set it when it should go into transfer mode when the battery gets too low, the value should be able to be adjusted.
What is the exact model of the inverter/charger?
 

Robbutton

New Member
Joined
Sep 7, 2021
Messages
6
On this particular inverter (renogy 2000w inverter charger) there is no such setting unless the battery setting is set to lithium ion. Since the batteries used are flooded, and the battery setting reflects that, the option to change the transfer switch setting is locked out. I'm not 100% sure why, but I am extremely confident that that's how the settings work with this particular inverter
 

Bud Martin

Photon Sorcerer
Joined
Aug 27, 2020
Messages
3,244
I do not know which exact model you have but the one in this user manual is setup #12 page 29

12 Low Battery Voltage Setpoint
The purpose of this setpoint is to protect the batteries from being over discharged. It assumes that Battery Priority is set on Program 01. If utility power is not available, the designated setpoint will cut of all working loads. Upon Utility power being detected, the Utility power/Generator will then power the loads.

What does Renogy say about the problem?
 

Robbutton

New Member
Joined
Sep 7, 2021
Messages
6
That's the same manual I've been looking at.

I guess I should have mentioned, the priority is set to utility not battery, so the low battery voltage setpoint also doesn't apply.

I reached out to renogy but haven't heard back yet. The more I think about this problem the more it seems to be a software malfunction...
 

RCinFLA

Photon Sorcerer
Joined
Jun 21, 2020
Messages
1,712
Not familar with that model but looks like an ACin synchronizing inverter. It must lock to phase of AC source.

For generators, if the rpm govenor control is the least bit unstable, inverter may not lock or stay locked to generator. Sometimes a load passthrough surge will bog down generator rpm causing freq drop and inverter will release from generator.

Inverter phase lock tracking is very slow rate adjustment and it cannot track much wobble in input AC freq/phase shift.

Listen to generator. It should be smooth and steady with no 'wah-wah' pitch change sound.

Inverter-generators do not have this problem but they may not stay locked if run in ECO mode since a surge load will momentary dip AC output voltage as engine rpm spins up to meet additional load.
 

Robbutton

New Member
Joined
Sep 7, 2021
Messages
6
I didn't think that frequency would be a problem. According to the manual the base setting for input frequency range is 55-65Hz and the generator output has been steady with a voltage of 119-120V so the frequency can't be varying all that much. But there is an alternate setting for "specail" input frequency which tolerates 40-70Hz so I'll try switching to that and see if I see any improvement.

It may be a few days before I get a chance to head up to the cabin and give it a try but I'll post my results when I eventually do.

Thanks a lot for your help!!
 

RCinFLA

Photon Sorcerer
Joined
Jun 21, 2020
Messages
1,712
Frequency range is different from frequency stability. Range may allow 40-70 Hz but within that range it must be stable at whatever the frequency actually is.

Many times the stability is not spec'd on inverter but the AC input typically needs to have less than a rate of change of +/- 0.3 Hz per second for an inverter to maintain lock on incoming AC phase. If the inverter cannot track the rate of change it just releases from generator and starts the reconnect process all over again. If gen freq initially wobbles too much the inverter will never connect to it.

The frequency counter on a DVM may not pick up that amount of frequency wobble as the meter's count period time window will average out the variation. Easiest way is to just listen to the generator sound for variations in pitch of sound.

A dirty air or fuel filter, or too rich or lean carborator needle value adjustment can cause the governor rpm control to 'hunt'. Sometimes it only shows up when there is a load change on the generator, then within a second or two it smooths out again. I am sure you have likely heard it before. A typical generator does this immediately after you start it up for a few seconds until it has time to settle down to an even engine speed.

Another common problem is when you put independent appliance loads plugged directly into generator and also plug in inverter for normal house loads. This may be something like a water pump or air conditioner that draws too much current to be put through inverter pass-thru. When air conditioner cycles on or off the generator load abruptly changes that varies generator engine speed and inverter releases from generator only to reconnect a few seconds later when AC becomes stable again.
 
Last edited:

Robbutton

New Member
Joined
Sep 7, 2021
Messages
6
Yeah that does make sense.

I'm not nearly as familiar with the generator itself as my father in law but I wouldn't be surprised at all to find out that fuel/air filters haven't been changed/cleaned in a while or that she might be overdue for a little tune up.

I'll take all of this into consideration and, between me and the in law, we'll see if we can get some stability into the system.

Thanks a lot for your help. This is my first time dealing with this type of system and a bit of outside experience goes a long way when it comes to troubleshooting. Greatly appreciated!!
 
Top