House power dipping low, causing problems

[DeepFrz]

So, it sounds like your inverter/charger is not the type that will automatically boost the output from the generator to compensate for surge loads like you AC compressor turning on. I think you need a pure sine wave inverter to do that, an inverter designed for that specific purpose. However as you haven't identified your equipment you leave us guessing. If your inverter isn't designed to boost the AC output of the generator then the two frequency outputs wont be synced. The inverter should not be "transferring load" from the generator, it should be adding to the generator output to keep everything on the load side happy.

You wouldn't see short term voltage changes with an ordinary meter so you are just guessing at what the output voltage of the generator actually is when the inverter kicks in.

[smac999]

If it's only dropping to 110v and changing 2hz it's probably an issue with the inverter /charger cutting out too easy. And it's probably time to replace

The only time I have seen this problem was when a gen was going way out of spec. Like I think it was 140v. And 5+hz out. So the inverter / charger was doing its thing and properly shutting off . But bad gen. your gen sounds fine.

[smac999]

Originally Posted by DeepFrz

So, it sounds like your inverter/charger is not the type that will automatically boost the output from the generator to compensate for surge loads like you AC compressor turning on. I think you need a pure sine wave inverter to do that, an inverter designed for that specific purpose. However as you haven't identified your equipment you leave us guessing. If your inverter isn't designed to boost the AC output of the generator then the two frequency outputs wont be synced. The inverter should not be "transferring load" from the generator, it should be adding to the generator output to keep everything on the load side happy.

You wouldn't see short term voltage changes with an ordinary meter so you are just guessing at what the output voltage of the generator actually is when the inverter kicks in.

It's a 22kw gen. it doesn't need boosting from a 2-3kw inverter. Only the victron does that (properly) that I know of. And it certainly won't pass through and boost a gen that big. . Don't confuse the issue by bringing up new ones unrelated.

[haveaday]

Another data point. I am seeing voltage dip what seems like pretty low under load. With a 40amp load on the house bank (8 GC2s) the voltage is dipping to about 11.6v. When the load drops to about 15a the voltage recovers to around 12.05v. This is with about 170ah drawn out of the batteries over five and a half hours or so.

Also, in terms of models, the generator is a Kohler 23eozd. The inverter is a Charles IQC-2600. It's actually made by Vanner and both are original to the boat made in 2003.

Thanks
Ben

[ranger58sb]

Originally Posted by haveaday

I'm wondering if this is an issue with the inverter being too sensitive and transferring load too easily. If it appears there's an issue with the inverter it wouldn't be the end of the world to replace it. It's a modified sine wave inverter and some of my loads don't love the power it produces. On the other hand if it's healthy I'd hate to replace just for the sake of replacing it.

Is there a way to mostly bypass the inverter altogether, let everything else happen (genset on, AC compressor kicks in, etc.) to see if anything else is affected? Not sure that'd be a legit test, though...

-Chris

[DeepFrz]

Originally Posted by ranger42c

Is there a way to mostly bypass the inverter altogether, let everything else happen (genset on, AC compressor kicks in, etc.) to see if anything else is affected? Not sure that'd be a legit test, though...

-Chris

Yes, of course it would be a legit test. It sounds like the inverter is kicking in when the generator is running. If its not designed to do so then the frequency wont be synced and it could be causing the problem. Turn the inverter off and let the generator run and see what happens.

[haveaday]

I will test with the inverter bypassed.

One more data point. This morning after about 11 hours on battery and 281 AH discharged I tested the specific gravity of each cell in the string. They all averaged between 1200 and 1210. This seems to point towards the batteries being between 50 and 75% charged, which is in line with what I'd expect to see having used 281 ah of a roughly 860ah string.

I'll go bypass the inverter now and report back on those results.

Thanks
Ben

[boatbod]

It sounds to me like the air cond startup load is causing the genset power to dip both in voltage and frequency and the inverter believes the power is going out of spec so it disconnects the transfer switch and flips into invert mode. The corresponding load on the dc system causes the 12vdc voltage to drop which is giving the mfd's problems.

There are multiple aspects to this:
1. Boost the genset governor speed so it puts out about 62Hz no load. This will allow for some dip in frequency when the load congress on.
2. Load test your dc battery bank because if the voltage is sagging hugely when subjected to a decent inverter draw your batteries may be old and tired.
3. Consider replacing the start/run capacitors in the air conditioners, or install a soft start kit to reduce the startup amperage.
4. Review your inverter/charger settings to see what the minimums are for incoming power to be considered "good". Often you can tweak the threshold for both voltage and frequency.
5. Try the test over again, but with the water heater pulling 10-15A resistive load. Sometimes pre-loading the genset helps a lot.

[haveaday]

The problem is getting worse. It appears there must be an issue in the house bank. The house bank is composed of 8 GC2 batteries in series and parallel. It is right at a year old and my BMS shows about 40 full cycles on the batteries.

Currently under load the voltage is dipping very low on the house bank. With an 860ah bank I'm seeing voltage dip below 12v on a fully charged bank with a 30a load. With about 150ah depleted over six or more hours the voltage is dipping to 11.25v with a 40a load. In part I believe the amperage of the loads is increasing because voltage is decreasing.

So this points to me towards a bad battery in the bank. I've checked the specific gravity of the batteries and they test out similarly. They all appear to be pretty good. I've called for an equalization from my inverter/charger but it appears that isn't working as described in the manual so I may need to do that again (it says in the manual flip a dip switch momentarily and it will run an equalization cycle, but the indicator lights show it only runs the equalization when the dip switch is on.) Short of that the only thing I can think to do is start changing the wiring to drop one pair out at a time and see if I can find a bad pair.

Any other thoughts or better tests?

Thanks
Ben

[zeehag]

have you load tested your batteries???


nothing has an open ground???

[ranger58sb]

Originally Posted by haveaday

I've called for an equalization from my inverter/charger but it appears that isn't working as described in the manual so I may need to do that again (it says in the manual flip a dip switch momentarily and it will run an equalization cycle, but the indicator lights show it only runs the equalization when the dip switch is on.)

Seems to me some thread around here recently mentioned some obscure instruction in an inverter/charger to get the rascal to actually do the equalization. Can't remember what brand, only that it was an instruction not well presented in the manual. May have been something Maine Sail posted, to help somebody else...

I haven't found it again, but you might have a rummage for that in case it's germane.

Wouldn't have thought equalization necessary after only 40 cycles, but then I dunno much about all that... and it probably depends on your usage and circumstances anyway...

Edit: Found it. Maybe only useful if your inverter/charger is Sterling or Promariner, though. If useful, see Post 9.

http://www.cruisersforum.com/forums/...ze-182221.html


-Chris

[haveaday]

Originally Posted by zeehag

have you load tested your batteries???


nothing has an open ground???

Doing that tonight. I don't believe anything has an open ground.

Here's another thing I noticed today. We were underway for quite a few hours. The house bank was showing voltage of about 14.7v and taking around 5a of charge. This implies to me that there isn't a charge regulator on the alternator. I didn't check the factory setup from Carver when I replaced the batteries. Seems as though that might have been a mistake. How likely is it that overcharging the batteries would have killed them?

We are doing the great loop and have logged about 600 hours underway in the last year. I wonder if the combination of high hours and unregulated charging could have killed the house bank.

Ben

[haveaday]

Can someone help sanity check me? After drawing down 22ah at a discharge rate of about 50a I'm seeing 11.82v. That's 22ah drawn down from an 860ah battery bank. I'm thinking this is lower voltage than I should be seeing with a fairly limited amount of draw down. Though admittedly drawn down at a reasonably aggressive rate (C/15)

Thanks
Ben

[haveaday]

Originally Posted by ranger42c

Seems to me some thread around here recently mentioned some obscure instruction in an inverter/charger to get the rascal to actually do the equalization. Can't remember what brand, only that it was an instruction not well presented in the manual. May have been something Maine Sail posted, to help somebody else...

I haven't found it again, but you might have a rummage for that in case it's germane.

Wouldn't have thought equalization necessary after only 40 cycles, but then I dunno much about all that... and it probably depends on your usage and circumstances anyway...

Edit: Found it. Maybe only useful if your inverter/charger is Sterling or Promariner, though. If useful, see Post 9.

http://www.cruisersforum.com/forums/...ze-182221.html


-Chris

Oh, and another thought. Given that it appears the alternator on the engine has been charging unregulated I'm thinking that I've basically been equalizing / over-equalizing continuously so that just dropped down the list of things to try.

Thanks
Ben

[haveaday]

I've done a load test on the batteries. Here's what I'm seeing:

The test was done after the batteries were fully charged. The boat ran most of the day today with mains and generator up and charging.

Pretest is before applying any load.
Load is the reading at the conclusion of a 10 second load test
Settled is what the battery came back to about 15 seconds after the test was completed.

Battery Pretest Load Settled
1 6.65 5.84 6.50
2 6.60 6.37 6.49
3 6.65 6.38 6.52
4 6.65 6.39 6.53
5 6.49 6.20 6.35
6 6.51 6.24 6.37
7 6.52 6.10 6.39
8 6.55 6.23 6.40

It looks to me like battery number one is toast. I can't tell about 5,6,7 and 8. Any thoughts?

Thanks
Ben