Generator kicked on

BoFuller

Wed night about 11:30, my backup propane generator kicked on. I went out to the solar shed and the SOC was 81%. The generator is programmed to come on when the batteries get down to 50%. After a half hour or so it turned off. I checked the batteries and they were now 80%, so it wasn't charging the system. The next day while flipping through my read outs, it said "last generator use - April 23". That's the day they tested it. Why did it come on? It has been getting down to 19-20 degrees at night. Does it come on occasionally to charge the generator battery?

BoFuller

I haven't been on for a few months. I use to have my equipment in a sig line. What happened to that? Can I redo it?

westbranch

Bo go to the top of the page, beside your name there is a little "gear", click on that to enter your sig line...

BoFuller

westbranch said:

Bo go to the top of the page, beside your name there is a little "gear", click on that to enter your sig line...

Thanks. I think I got it all.

BB.

Some controllers are programmed to cycle the genset every X days... Possibly you have a very large value that has never been set to something else?

Most gensets seem to assume that they are "backup" to AC main power, and use an AC battery charger or expect the genset to be exercised every 1-2 weeks to keep the genset starter battery charged. If your genset still started after 7 months of not running--Sure sounds like it is getting charged somehow.

-Bill

BoFuller

I'm mostly here on weekends (Thurs-Mon) and sometimes gone for 2 weeks. It might run weekly or monthly. I'm just saying I've never noticed it before. If I flip through the display on the genny, will it tell me the duration/frequency?

BoFuller

If I'm here on a cloudy day and it's only up to 80% at 3:00 in the afternoon, should I force the genny on?
Once while I was gone it got down to 69%. That's the lowest so far.

BB.

I would guess that there should be a a setup menu with the information.

I am a bit confused that even if this was a monthly exercise, that it did not appear to charge the battery bank during that time. You may have a fault somewhere.

A suggested, fuel efficient, running schedule would be to start the genset at 50% State of Charge and run it up to 80% SOC. That would be the most fuel efficient program and relatively easy on the batteries. Batteries are there to be used.

As always, you should measure the specific gravity once in a while to confirm your SOC estimates (from charge controllers, battery monitors, etc.). SOC readings from meters are not always accurate.

-Bill

stillchillin

Hi, check your AGS setup sometimes my generator will come on because I have reached an amperage setpoint say for instance 30A. Maybe your load had reached that setpoint. My guess, by the way you should exercise your generator every week or so you can set that up at your AGS or on the generator control. The battery gets charged by the feeders you have connected to the generator terminal strip, can't remember the #s now but can look it up. I don't think the generator will charge its own battery while running, it is charged from the house panel.

Still

stillchillin

Marked N1 N2 also T1 needs to be connected. Utility Sensing 240V and Load sensing 120V

BoFuller

Thanks, I'll try to check it tomorrow. I spent all day today hauling water.
We've had a few cloudy days and the SOC only got up to 69% today. I'll be surprised if the genny doesn't come on tonight.

BoFuller

Genny came on at 10:30 pm when batteries hit 52%. It ran all night and when I checked it at 8:00 am, and the gen was still running, the SOC had only increased from 52 to 54%. Not good. Upon playing around with the Mate, I found the culprit. It was set to charge at the rate of 2 amps. I increased it to 10 and starting seeing a decent charge immediately. It got up to 79% today. Hopefully it will hit a full charge tomorrow.

BB.

You can (and probably should) set the Bulk charging current to ~10% of your battery bank capacity (assuming charger/genset can support that level of current--Or at least 5%).

-Bill

BoFuller

How do I determine that? 

BB.

If you have 2x strings of 8x 6 volt @ 370 AH (20 hour rate), then your battery bank would be 48 volt @ 740 AH.

10% of 740 AH = 74 Amp charge rate
74 amps * 59 volts charging = 4,366 Watts -- fare amount of power (not including AC charger losses, generator deratings and such)

-Bill

Fix driver error with calculator...

mike95490

BoFuller said:

How do I determine that? 

What is the Ah size of your battery bank ?     16 Trojan L16 RE-B batteries   wired into a 48V config, 2 strings, would  be about 800Ah, so Capacity/10 (C/10) would be 80A charge (60*80=4800watts)  well within your 11Kw generator capacity.  So the inverter/charger would be your limiting factor

BoFuller

Thanks for the info!!! I'll experiment this weekend.

Dave Angelini

And keep in mind that even though you can charge at that rate of 80 A. Your batteries will last longer if you drop it to,say 60A.
You are balancing fuel cost and battery life. It is the reason a well designed solar system in a good location will have long battery life without a generator.