Generator Not charging Batteries

[Mercadian]

Good evening all,

I have 2 x Deye 8KW inverters connected to 7 x 100Ah BSL Bull batteries and we cannot seem to get the batteries to charge with the generator. 
 

The generator is wired to a manual changeover switch so it would be seen as grid if I understand correctly. 

Basically what happens is that we can turn on the generator and flip the change over switch to Generator and after a few seconds the generator icon appears on the inverter, generator sounds like it’s labouring and then the inverter drops the connection and no longer shows the generator icon, a few seconds later the cycle repeats. It never seems to keep a stable link. 
 

The generator is a 7.5KVA Briggs and Stratton generator that is admittedly about 14 years old, maybe older. 
 

Our installer doesn’t seem to know why it’s doing that and has mentioned something about a frequency stabilizer as he thinks it’s the frequency of the generator not being stable. 
 

Battery Setting has the following settings:

 

Grid Charge and Grid Signal selected Gen Charge and Gen Signal are not, but this could be because the generator is not connected to the Gen Port

Gen Force is also not ticked. 
 

Gen is not ticked on Work Mode for 9AM to 5PM, so as I understand it generator won’t charge during that time. 
 

I’m pretty sure we did set gen charge and it didn’t work either. But happy to try it again if everything else checks out  

 

Hope that explains everything.  

 

 

 

[TaliaB]

14 minutes ago, Mercadian said:

generator sounds like it’s labouring and then the inverter drops the connection

As a general rule, the generator should be around 2 times the size of the inverter’s continuous output. For example, a 8,000-watt inverter should be paired with an 16,000-watt (20kva) generator.

This is because the generator needs to charge batteries while still powering the loads.

[Mercadian]

9 hours ago, TaliaB said:

As a general rule, the generator should be around 2 times the size of the inverter’s continuous output. For example, a 8,000-watt inverter should be paired with an 16,000-watt (20kva) generator.

This is because the generator needs to charge batteries while still powering the loads.

Good morning, surely though if it’s not double the size it should split the load still? As an example on average we draw just over 2kw when we don’t use kettles or geysers from the inverter, the generator is enough to run the house, which when the generator is running we don’t use anyway. I mean I understand that ideally you want as much power available to charge the batteries as quickly as possibly but surely with load first set the generator would power the house and take what it can to the inverters?

Edited March 28 by Mercadian

[Scorp007]

1 hour ago, Mercadian said:

Good morning, surely though if it’s not double the size it should split the load still? As an example on average we draw just over 2kw when we don’t use kettles or geysers from the inverter, the generator is enough to run the house, which when the generator is running we don’t use anyway. I mean I understand that ideally you want as much power available to charge the batteries as quickly as possibly but surely with load first set the generator would power the house and take what it can to the inverters?

While you want to charge the battery fast you can look at switching off load first. 

Further due to high load on the genny is the reason you can hear it is labouring. This could be the reason why the inverter disconnects as the speeds drops to low. Look at you grid volts and frequency and use wider settings on the lower side for both. 

You might also use grid peak shaving with a lower setting when on genny. 

Just a few pointers to keep genny connected. 

[Bobster.]

13 hours ago, Mercadian said:

Basically what happens is that we can turn on the generator and flip the change over switch to Generator and after a few seconds the generator icon appears on the inverter, generator sounds like it’s labouring and then the inverter drops the connection and no longer shows the generator icon, a few seconds later the cycle repeats. It never seems to keep a stable link. 

Most inverters will have some sort of safety code setting. Voltage must be higher than this, lower than that. There will similarly be a range of acceptable frequencies. SA is supposed to be 230V (give or take an allowed amount) at 50Hz (give or take an allowed, small amount). If your genny is labouring then it's output is probably not within those limits and so the inverter disconnects (as it would if your grid voltage drops too low). Your installer may be right.

When the inverter drops the connection, the genny will stop labouring. The inverter will still be monitoring the genny output and will reconnect after a minute or so with the voltage and frequency within limits. At which point the load on the genny goes up and it starts labouring again.

When was the generator last serviced?

I'm no electrician, but @TaliaB's rule of thumb looks a good one to me. You have 16kW of inverter trying to charge 35kWh of batteries (they will take 700A if they can get it). A 7.5kW generator (assuming a good power factor) seems a bit underpowerered for this task.

[Coulomb]

You could try the following trick; sorry if it's already been posted.

The generator will typically change speed (run slower) with any sort of load, but once it has some load, it may not change speed nearly as much. The inverter sees this initial speed change and decides that the grid is out of spec. So you can add a smallish load (I usually suggest 200 W, but for your larger generator, try something like 1000 W, like a toaster or similar). Add that to the inverter before you connect the generator to the inverter; many generators have spare outlets.  Now with this moderate load, connect to the inverter. Adding the battery charging load will hopefully not change the generator speed too much, and the inverter may keep going. Once the battery charging has started, you can disconnect the load (or leave it on till the toast ejects; enjoy you toast :-)). Hopefully the starter load (toaster, whatever)  coming off won't change the generator speed too much.

[Sc00bs]

There is a box to tick in the DEYE menu's for connecting a generator to the Grid port, I assume that this relaxes the restrictions on generator frequency & probably slows the speed at which the load is added to the generator when it starts connecting. 

I would also check the frequency that the generator is running at (you can see this on the inverter screen) and adjust the frequency on the generator to the max that it will allow but still connect, this will give you some space for the generator slowing down when load is applied without disconnecting. 

I did make a video some time ago so you may want to check that out as well. 

  

[TaliaB]

3 hours ago, Sc00bs said:

There is a box to tick in the DEYE menu's for connecting a generator to the Grid port, I assume that this relaxes the restrictions on generator frequency & probably slows the speed at which the load is added to the generator when it starts connecting. 

I would also check the frequency that the generator is running at (you can see this on the inverter screen) and adjust the frequency on the generator to the max that it will allow but still connect, this will give you some space for the generator slowing down when load is applied without disconnecting. 

I did make a video some time ago so you may want to check that out as well. 

  

 @Sc00bs Thanks for informative video

 

 

 

 

 

Edited March 29 by TaliaB

[Mercadian]

Hi guys, sorry for the delay in the responses. Things have been a bit crazy. 
 

Thank you all for the valuable input. @Sc00bs thanks for the video, very informative. 
 

i am currently not at home but will definitely look at these suggestions next week and will revert back. 
 

Have a great Easter guys for those that celebrate, but most important have a safe one and enjoy the time with loved ones. 

[Engel]

We only connect low revving gensets, 1200-1500rpm diesels to systems. Never seen a small generator working reliably. We would mostly install a changeover to run the house till the pv has sufficiently charged the batteries. Yes you do need a 20kva unit

[Mercadian]

3 hours ago, Engel said:

We only connect low revving gensets, 1200-1500rpm diesels to systems. Never seen a small generator working reliably. We would mostly install a changeover to run the house till the pv has sufficiently charged the batteries. Yes you do need a 20kva unit

Ours is a petrol and old. Change over switch is used and it can run the entire house. Was just hoping to get it to charge the batteries as well. But after trying some suggestions when I’m back next week it turns out it won’t work then it’s also cool. . 
 

Thank you for the input. I have had a suspicion the generator would be to old / small. 
 

 

 

 

[Sc00bs]

2 hours ago, Mercadian said:

Ours is a petrol and old. Change over switch is used and it can run the entire house. Was just hoping to get it to charge the batteries as well. But after trying some suggestions when I’m back next week it turns out it won’t work then it’s also cool. . 
 

Thank you for the input. I have had a suspicion the generator would be to old / small. 
 

 

 

 

As long as you set the max load on the generator to within it's limits it will work without a problem. 

I have a 5.5Kva petrol generator connected to my 16kw DEYE inverter. 

My Gen-Peak shaving is set for 3000w and it works without issue.  

 

[Scorp007]

1 hour ago, Sc00bs said:

As long as you set the max load on the generator to within it's limits it will work without a problem. 

I have a 5.5Kva petrol generator connected to my 16kw DEYE inverter. 

My Gen-Peak shaving is set for 3000w and it works without issue.  

 

Good to see the gen peak shaving works so well. I do think my suggestion on Thursday to set the grid peak shaving to a low level should work as well as @Mercadian is using the grid port.

I have seen guys testing the gen port with loads like 2.5-3.5kw loads instead of perhaps trying a lower load 1st and ramp it up to see up to what load the inverter is happy before the voltage or in most cases the frequency is too low. 

I know of a few guys that use a 2.2kW with success on a 8kW Deye/Sunsynk

Edited March 30 by Scorp007

[Mercadian]

Hi guys,

 

have not had a chance yet to test the charging. Just some additional info the Gen connect to Grid input is ticked. 
 

I also notice that the Geneator input was set to 7500W. If I look at the info plate in the generator it is a 7.5Kva but rather at 6KW. So im suspecting that could also be part of the problem. 

if I understand correctly the inverter will try pull the full 7500w from the generator which could cause weird things. 
 

If I change to 5000w would this be the max draw? Or would it pull more if needed?

[Scorp007]

29 minutes ago, Mercadian said:

Hi guys,

 

have not had a chance yet to test the charging. Just some additional info the Gen connect to Grid input is ticked. 
 

I also notice that the Geneator input was set to 7500W. If I look at the info plate in the generator it is a 7.5Kva but rather at 6KW. So im suspecting that could also be part of the problem. 

if I understand correctly the inverter will try pull the full 7500w from the generator which could cause weird things. 
 

If I change to 5000w would this be the max draw? Or would it pull more if needed?

It should only pull what is keyed in. I would however when testing if the ports etc work start with a low like 2500W setting. Once that works fine I would adjust it upwards to find the level where the gen power is stable enough for the inverter to be happy. 

[Mercadian]

3 hours ago, Scorp007 said:

It should only pull what is keyed in. I would however when testing if the ports etc work start with a low like 2500W setting. Once that works fine I would adjust it upwards to find the level where the gen power is stable enough for the inverter to be happy. 

Perfect will try it like that. 

[Mercadian]

Thanks all the for the input, I finally had an opportunity to test the generator today but alas, no luck. 
 

I did decrease the generator input to 2500w to start, flipped the change over switch to generator and inverter picked it up after a few minutes, tried to pull load and then disconnected again. 

generator input was increased and had it back to 6500w but to no avail. What I did notice though when looking at the power coming in from the grid the frequency jumped to 50 hz to 50.7 hz which is about the time the generator kicks out. 
 

so for now I’m writing off this idea and will use the generator just to run the house when we have issues and the inverter runs out of batteries.  
 

we are not off grid, so it doesn’t happen all to often.

 

 

 

[Sc00bs]

@Mercadian  Your inverter is dropping the connection to thew inverter when load is applied because the frequency is dropping below the permitted value (+- 49hz). 

Like I said in my first reply to your question "I would also check the frequency that the generator is running at (you can see this on the inverter screen) and adjust the frequency on the generator to the max that it will allow but still connect, this will give you some space for the generator slowing down when load is applied without disconnecting." 

If you follow this suggestion you should be able to apply more than 2500w comfortably without disconnecting. 

If you have a 7.5kva, that is 6kw. 

6kw @ 75% load =  4.5kw 

If you are @ Johannesburg altitude your generator will loose about 15% power over at the coast so I would say you will probably be able to pull about 4kw from it without an issue. 

You adjust the generators frequency by screwing in the screw on the throttle setting. 

Usually looks something like this. 

[TaliaB]

11 hours ago, Sc00bs said:

@Mercadian  Your inverter is dropping the connection to thew inverter when load is applied because the frequency is dropping below the permitted value (+- 49hz). 

Like I said in my first reply to your question "I would also check the frequency that the generator is running at (you can see this on the inverter screen) and adjust the frequency on the generator to the max that it will allow but still connect, this will give you some space for the generator slowing down when load is applied without disconnecting." 

If you follow this suggestion you should be able to apply more than 2500w comfortably without disconnecting. 

If you have a 7.5kva, that is 6kw. 

6kw @ 75% load =  4.5kw 

If you are @ Johannesburg altitude your generator will loose about 15% power over at the coast so I would say you will probably be able to pull about 4kw from it without an issue. 

You adjust the generators frequency by screwing in the screw on the throttle setting. 

Usually looks something like this. 

@Mercadian

Consider these facts before deciding to run the generator into your expensive inverter setup.

If a portable generator( normally tubular frame without or on wheels) is used the chances is very good that it is illegal to connect to the db board as these generators are V0V winding configuration. Even connecting these type generators through a transfer switch it is still illegal. The reason being you will always have a floating neutral even when using an earth spike.

SANS 10142-1 states in clause 7.12.2.7 that a 230 V generator with a V-O-V earth connection (centre tap on winding which is earthed) shall
not be connected to a fixed electrical installation. Such a generator may only be used as a free-standing unit to provide power to specific appliances.

Portable generators produce "dirty power" with THD of between 8-30% where the industry standard should be <5%.

It is not just voltage and frequency we should look at when deciding on generator connection to inverters but also the quality of the sine wave we push in.

As a rule i would not install any petrol generator to business premises or domestic environment unless it consist of TN-S earthing arrangement nor would i supply a COC.

I will however recommend diesel generators twice the output of the inverter to be installed.

 

 

Edited April 5 by TaliaB

[Mercadian]

1 hour ago, TaliaB said:

@Mercadian

Consider these facts before deciding to run the generator into your expensive inverter setup.

If a portable generator( normally tubular frame without or on wheels) is used the chances is very good that it is illegal to connect to the db board as these generators are V0V winding configuration. Even connecting these type generators through a transfer switch it is still illegal. The reason being you will always have a floating neutral even when using an earth spike.

SANS 10142-1 states in clause 7.12.2.7 that a 230 V generator with a V-O-V earth connection (centre tap on winding which is earthed) shall
not be connected to a fixed electrical installation. Such a generator may only be used as a free-standing unit to provide power to specific appliances.

Portable generators produce "dirty power" with THD of between 8-30% where the industry standard should be <5%.

It is not just voltage and frequency we should look at when deciding on generator connection to inverters but also the quality of the sine wave we push in.

As a rule i would not install any petrol generator to business premises or domestic environment unless it consist of TN-S earthing arrangement nor would i supply a COC.

I will however recommend diesel generators twice the output of the inverter to be installed.

 

 

Hi @TaliaB, thank you. And I hear you, I’m just going on what was done regarding the wiring on the house years ago, before my time on the property.

The dirty power is always a concern, even more so with the generator being how old it is. The AVR feature have come a long way, and yes sadly it is also a petrol generator. 

the idea is to move away from the generator and use the inverter. But there are times where it rains or threatens to rain and Eskom goes out for longer than the batteries hold for and we need to use the generator to get power. Which is works well, and at least hold until the batteries charge enough with solar. 

 

 

[Harmdor]

1 hour ago, TaliaB said:

 

I will however recommend diesel generators twice the output of the inverter to be installed.

 

 

You are free to think that.

I tested a 1 phase Deye 8kW and a 9,6kWh Pylon.

Disconnected the grid, set the "battery grid charge" at 5A, connected a 4kVA petrol generator (RPM controlled power, so no AVR) to the grid input, set the grid settings to 45Hz-55Hz and 180V-260V, started the gen and watched the inverter come to life. Then increased the grid charge to 10A. 

No problem at all, the gen will charge the battery's. (make the setting at 100% in time of use.)

There is no cleaner sine wave than a prehistoric stator/rotor generator.

 

 

 

Edited April 5 by Harmdor

[Scorp007]

I have to agree with @TaliaB We always hear of the bad sine wave from generators. From my experience moving a rotor through a magnetic fuel creates a sine wave. Not talking of intervention with other gadgets.

The generator can battle to keep the speed constant. For that reason we recommend a low load but as @Coulomb indicated you must put a load on.

Genny might have a bad QOS due to the frequency that changes when on/off load. 

I know of many guys running small like 2.5 kW generators at low power to charge their batteries on bad PV days... 

I agree on wide settings for frequency. 

[Mercadian]

11 minutes ago, Scorp007 said:

I have to agree with @TaliaB We always hear of the bad sine wave from generators. From my experience moving a rotor through a magnetic fuel creates a sine wave. Not talking of intervention with other gadgets.

The generator can battle to keep the speed constant. For that reason we recommend a low load but as @Coulomb indicated you must put a load on.

Genny might have a bad QOS due to the frequency that changes when on/off load. 

I know of many guys running small like 2.5 kW generators at low power to charge their batteries on bad PV days... 

I agree on wide settings for frequency. 

Low load itself could be interesting. Because it is tied into the db board and therefore grid port on the inverter it will try run the house, basically plugs about 7 fridges, tvs, desktop pc, network switch and I with POE devices. . 
 

I am still going to check the frequency screw if I can find it, also trying to find a manual for the generator.

[Sc00bs]

 @Mercadian You will get much cleaner power running in your house from the inverter than from the generator. 

First prize in my opinion is to run the generator on the Gen port and not have a transfer switch as opening up your permissable grid voltages/frequencies is not ideal.

Ideally you want your inverter running at 50hz when it is under load, adjust your throttle setting to get it there. The generator will then run at +-51hz when there is no load which is not a problem as long as the inverter will still connect to it. Load on the inverter is relatively stable if you are using grid shaving but I have noticed the load does increase momentarily on the generator when large loads are applied, if you are close to the edge with frequency your generator will be disconnected if it slows down too much. 

[Mercadian]

Sorry for the delay in responding. Been a little bit hectic. 
 

so some new developments, we have managed to get a Kipor kde12sta 9.5kw Diesel generator, still enough to power the house and run 4 geysers,  but inverter still doesn’t seem to what to charge from grid port. Which is strange. 
 

we have also added in an additional 12 x 565w JA solar panels on our current 18 x 400w panels. 
 

An additional question based on this thread is now how may kw should I expect from the 565w panels?

 

we have 30 panels in total and still have a shortfall of charging the batteries with have, I’m suspecting we are still about 10 solar panels short to charge the batteries and run the house loads of about 9kw that peaks during the day.