Troubleshooting generator issues

Deckard · October 2010

I have recently purchased 4 crown 24 volt 12-85s-13. 510 ah that were used for approximately 5 years together in a string in what may have been a "well maintained system" total I have 2040 ah and I am running dual sw4024 inverters And two trace 30amp charge controllers. I am getting approximately 230 ah a day from the solar panels and I am running a 13KW northstar trifuel generator using the 240 volt connection. The inverters are both hooked to the batteries on either end of the bank. But when I try to equalize the bank the inverter kicks out the ac2 in past 14amps on each inverter. Then I tried my miller 22KW welder/gen set and was able to get 23 amps on each before it kicked the ac2 out. I am wondering if I maybe setting the inverter up wrong or if I am in need of a bigger genset. (I would love to get more panels but that would cost a pretty penny)
Thanks for any input on this.

I apoligize for spelling errors, I am stuck using my phone for internet.

techntrek · October 2010

Re: Troubleshooting generator issues

You say "The inverters are both hooked to the batteries on either end of the bank." Do you mean that the batteries are hooked up in parallel, and it looks something like this?

inverter = battery = battery = battery = battery = inverter

I see problems with the wiring of the batteries and the inverter/chargers. But I must run to a meeting so hopefully someone else can explain. For starters the batteries need to be wired up in a "star" pattern so the wiring resistance is equal - assuming only one charger is operating, the battery on the far end must go through 3 times as much wiring as the first one.

techntrek · October 2010

Re: Troubleshooting generator issues

Another quick note, off topic. We only can get cell-based internet at home so I understand your problem. If your phone is Windows-based look up WMWifiRouter as one of several options for turning your phone into a router that you can use with any laptop or desktop. You can also get cell modems that plug into your computer, you just need to transfer your sim chip (or get a 2nd cell line).

RCinFLA · October 2010

Re: Troubleshooting generator issues

I interpret "the inverter kicks out the ac2 in past 14amps on each inverter" as the inverters disconnect from generator when generator is loaded past 14 amps.

What is your 'AC2 Max Amps' and 'AC Chgr Max Amps' settings on the two inverters?

You may have a problem with generators dropping out of frequency range when loaded too much causing the inverter to disconnect.

Check generator frequency and voltage with DVM that has freq counter.

SW inverter freq and voltage reading only work when locked on generator. (solid green LED)

Deckard · November 2010

Re: Troubleshooting generator issues

I am using both inverters to charge. And I have them in parallel inverter-battery-battery-battery-battery-inverter.

I and I let the gen sync with the inverter and then I ramp up the amps to 14amps each. I will have to check the max ac amps.

And these are 24volt batteries and I. Don't know of any other way to connect them except positive to positive and negative to negative.

When the generator is running and I ramp it up to bring the batteries to float it takes between 1-3hours to bring to float with the absorbtion time set at 2 hours. I cannot hear the genset drop underload.

The problem is when I try to equalize the batteries. With full sun and the generator I can only bring the batteries to 30.2volts and I need it to be 32 volts. And if I try to bring the 13kw generator up to a combined 28amps(14on each inverter) then it plataues out at 30.2 volts, if I try to go above 28amps they drop out of frequency and I need to take it down let it re sync and then I am back to 28amps. With the larger genset(its a welder generator) I can take it to 50amps (combined inverters) but then they drop out of frequency and I have to bring it back down. I get to 31.4volts this way. Should I just run the generator for a longer time or should I invest in a heavier duty gen set.

I did also add two more 170watt panels so I hope they will assist. I just want these forklift batteries to last a few years.

RCinFLA · November 2010

Re: Troubleshooting generator issues

Sounds like you have older generators without electronic regulators that are dropping in speed as more load is applied to generator.

I also suspect the wiring arrangement on the batteries and SW's. You should have a wiring arrangement such that everything see the same total wire length and connectors. For example, if you connect two 24v batteries in parallel, the inverter would be connected to positive terminal on first battery and negative terminal on second battery. (not positive and negative from same battery).

With SW's connected to each end, the end batteries will get more of the discharge load, and charging current, resulting in end batteries getting slightly more cycling then center batteries. This is due to the progressive wiring voltage drop across the parallel string.

Attached is a drawing of my setup with four SW inverters. The 500 amp current sense shunt is in the 4" negative central junction box in middle of drawing. The blue Anderson connectors allow each battery pack to be individually unplugged and rolled out for servicing. Each battery pack cart weights about 450 lbs.

Deckard · November 2010

Re: Troubleshooting generator issues

All the wire lengths are the same for the jumpers to the batteries and the wires coming from the inverters are the same length. So what I should do is have the negative on each side coming to the center batteries?

And the generators are new generators one is a miller 250 bobcat welder and the other is a northstar 13000watt that is 3years old. But I did look at the miller and it clearly is labeled for power generation at 120/240 that it will put out 46 amps. So I just need to double my solar panels and then I will be getting a better charge during the day and will not be so dependent on the genset at night.

I really appreciate all the help with this.

Troubleshooting generator issues

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