Newbie needs some education

[zarathust]

I have recently put together an off grid system comprised of 48 volt battery bank, dual xw 6000w inverters and 10.5 kw generator. Everything seems to be functioning but not sure I'm getting the most of the system. Generator runs too frequently (in my opinion), batteries drain down faster than I think they should with rather small loads put on her, but again I'm fairly new at this so I'm not totally sure what too expect nor how to insure that the system is performing as efficient as it should. Any useful information would be greatly appreciated. Thanks, Brian G 

[Robin]

We know what is draining your batteries. The inverters. We do not know what you are charging them with or what the batteries are or what your loads are?
Need a full description of the system. Since you have two large inverters, I would expect to see a very large PV array and numerous chargers and a good sized battery bank. Also we need to know more about what voltages you are seeing on the batteries. Do you have any data logging? Do you have a battery status monitor. Tell us more!

[SolarMusher]

Take a look first at your batteries specific gravity when your system shows 100% SOC, new flooded batteries could be sulfated with low SG if not equalized correctly at the begining. Also your generator may be a bit undersized for a dual 6Kw inverters system when charging according to your battery capacity and loads. As Robin said, tell us more.

[zarathust]

As of this moment the generator serves as the only charger. Planning to add panels at a later date, house still under construction. The loads tend to be small: lights, small power tools and such. Larger systems such as HVAC, when occasionally turned on, won't stay running. I have a dual ac coupled schneider xw inverter panels, 6000w each, (16) L-16's (380 ah) batteries in two parallels of 8. I was told that such systems would only run efficiently with bank at a SOC of 53 volts. Generator starts auto when bank is below 48 volts, bulk charges, and shuts off but battery bank never seems to read better than 51 volts after charge. I know the generator isn't the most efficient but I needed it for the construction, wanted it for back up and a solar/off grid company screwed me out of money on a system I purchased but never received so I am forced to live with the system as is until I can recoup those funds and add the panels. Just trying to get the most of my system in the current state its in. I am new to these kind of systems and understand there will be a learning curve pertaining to all this. Just trying to get everything running as best as it can so I move my family into this house.

[Westbranch]

what are the charging parameters set on the XW? That is where your problem is in all likely hood from what you have posted so far.

[zarathust]

Its all default settings from the factory but I don't have an extensive knowledge of the best way to change them to fit my applications. The generator runs steady at 1800 rpm delivering 120 volts and about 80 amps, roughly at 40% discharge rate of the inverters (dual 100 amp chargers). Its default set for 3 stage charging with absorption time set at 180 minutes. The generator starts every few hours, runs shortly and stops auto. It seems its bulk charging and nothing else. After charge batteries are reading no higher than 51 volts.  I assume that the system should be able to run a lot more efficiently if I can get the parameters set properly to fit the system and my needs.

[boB]

Aha, Zarathust !   The reason your batteries are running out fast is because, as you have
pointed out, your batteries are not getting charged.... hardly at all.

You need to find out why that generator is turning off too soon and then get the system
to get to absorb and stay there for that 180 minutes (3 hours or so).

Also, you will need to make sure the absorb voltage is set correctly for your L-16 batteries.

Seems like your system should be able to charge it though, unless for some reason the
generator is being over-loaded and that might be the reason it is stopping.  If not, it is
most likely just a setting in your generator start-stop programming.

L-16s ~can~ take as much as 60 volts (or higher ?) for absorption voltage but check with
the manufacturer first and also check the water level to make sure they don't boil away the
electrolyte/water so they still cover the plates.

Your voltage should be getting up to at least around 57 to 58 volts absorb and staying
there for at least a couple of hours.  The batteries will gas and bubble some but that's
OK...  Just check the water level.

Are you using the XW gen start system ?  Maybe run time is set too short ?

With 380 * 2 = 760 amp hours of battery, you should be seeing at least
around 75 amps into the batteries from both chargers and the generator.

You said you saw 80 amps but I'm not sure if that was one or both XWs or
AC or DC current.

If the charging was just completing the bulk cycle, you would see the maximum voltage
rise to whatever your absorb voltage setting is.

Maybe some more information is required but that's the gist of it I think.

Please let us know what you find about that generator and/or we may think of
something else to try.

boB

[zarathust]

Thanks for all the usefull info. bob, what you said makes sense, I'll check the settings see whats going on and make some changes. Also, would that be an HAM radio call sign there on the bottom of the page? Ive been learning a bit about HAM's and an interested in testing for my license. As soon as this whole project is completed.

[Halfcrazy]

Also realize the battery voltage will drop down to around 51 pretty much as soon as the generator shuts off. A full battery at rest (No charging or discharging) is 50.4 volts DC.

My system is comprised of a single XW6048 and 16 Trojan L16RE-B batteries. I have the single inverter set to charge at 75% or about 75 amps into the battery. With two inverters you will probably want that set around 35%. Verify it is charging at around 65-75 amps DC.

I also have my set points set for 61v Equalize, 58.8v Bulk/Absorb and 53.6v Float. These are the values Trojan recommended for my battery bank. I also have an absorb time of 4 hrs.

So with the inverters set at default and the charge rate possibly to high I think what is happening is the generator starts and hits the battery to hard and the voltage spikes to the absorb voltage that is to low and then shuts off.

PM me or Email me and I will give you a contact at Schneider, She is super knowledgeable and a pleasure to work with.

Ryan