[Archived]

After looking at this again quickly, I think that both inverters are active in the charging process. I know that there is one functional group which is isolated to only one inverter and if my memory serves me, that is generator auto start control

That is correct. The number one inverter on my bus is the only one that is supposed to be set for generator auto start control. That begets more questions…

The single air conditioner we leave on if we are gone during the day runs through inverter #2. IF the power at the pole goes out, the air continues to run trough inverter #2. As it draws down the voltage does inverter #1 start the generator even though it has no load but the refrigerator?

Is inverter #1 monitoring what’s going on with inverter #2 as well? Are they both drawing down all eight batteries as a unit or is each one tied to four batteries effectively dividing the batteries into two separate banks?

DKO

[David]

The inverters and the design are just not that smart. You are giving them way to much credit.

Keep your thinking about this simple.

You have 1 large 24VDC battery

You have 2, 24VDC appliances (inverters #1 and #2)

Anything these inverters see is at the level of the big 24VDC battery.

I sent you the Vantare’ wiring diagrams and you should be able to see that from those drawings.

If the auto start sequence doesn’t see the shift in load, it will see the drop in voltage, either way it will trigger the start gen process. I the batteries are good and have been on shore power, I suspect that you will get several hours of run time before you hit a voltage trigger.

I don’t know your air conditioners. I know that for me, a single cruise air will not trigger a gen start, if the batteries are good and have been charged. I believe that the load trigger is 20 amps and the cruise airs fall in below that at 15 amps.

You probably need to learn to use the “meters” function on these inverters. Lots of good information coming through there.

Also, refresh my memory, don’t your have a pair of sw4024’s but only one is at software update 41?

[Ed]

Just to stir the pot and perhaps irritate the inverter contingent, if you are going to have to leave an AC on is there any reason why you wouldn’t just fire up the generator?

I have to believe that would extend the life of batteries and put less of a load on the inverter.

As a rule we don’t run our generators hard enough or often enough. That is a good opportunity to set the temperatures on all AC units and the generator runs them to keep the entire coach cool and comfortable. There is no way any single AC is going to keep the whole coach cool so it makes no sense to spend serious money for a coach and its generator and then not have the total coach comfortable.

[Archived]

I called my rep on my generator as I was worried about the hours on it when I first entered the bus world. He asked me how many hours it had on it and I replied, 1600 hrs. He said that a Kobota would generally run about 32,000 hours in its life time and he said they “loved it when you loaded ’em up and ran the ______ out of ’em!”

We ran ours nine days straight 24X7 on our last trip … I don’t care what diesel costs, I am not sweating.

Later,

BCO

Note: Oh yeah Jon, got my battery compartment done, you can see it here. Battery Workover

[Davy]

Jon, no issue with that appraoch, but another question was being asked/answered. We were wacking away at the scenario where:

1. In a campground with power.

2 Leave one AC and other nominal loads on.

3. Campground power fails.

WHAT HAPPENS? What do the inverters do and how do they know how to do that.

I love these coaches. Because we own one. we have lots of right answers and we all look good being right!

[Davy]

I keep telling myself that one of these days I have to learn to read. Obviously I keep putting it off.

[David]

That’s right Sawdust. Thanks for clearing that up. I run the generator often and load it up when I do. However, concerning that subject, isn’t the opposite true as well?

Haven’t we paid big money for batteries and big money for the best inverters? Why run the generator ALL the time when we have spent all that money? If I am going to replace the batteries every five years at a huge cost, shouldn’t I use them? Two sides to every coin…

I have studied the documents you sent me, Sawdust and I do not understand as I ought but I am making progress. On your question about my inverters, both have the software update you mentioned but one of the inverters is original and the other was replaced in 2004 if my memory serves me correctly. Since they are different ages some of their default settings are different but software is the same.

DKO

[Archived]

DKO,

With batteries there is a risk versus reward ratio. The harder you use them (deep discharge) the shorter the life.

The reality is this. Our coaches tend to be compromises. The typical coach can go from shore power to shore power, or rely on the generator or be used to dry camp. However unless designed specifically for a single purpose it doesn’t do any of the three exceptionally well. We draw a lot of power so we have to manage it on shore power. We have big generators and if we prefer to use the generator in stead of batteries or shore power we can save a lot of weight and space by eliminating batteries and inverters, only carrying the bare minimum. If we do a lot of dry camping we need to give a critical view towards power consumption and energy efficiency, something our coaches are not very good at.

But you are right. If we have it, we should use it. I straddle the fence. In hot weather without shore power my generator is running all the time and loaded to the maximum extent. In cooler weather such as when overnighting without shore power, I let the batteries do their job and don’t run the generator at all except maybe before we go to bed to use the cooktop or run the ACs before it gets cool enough to open the windows.

I have the battery power the coach came equipped with and for about 5 years I can go through the night and the batteries still have capacity left. But at 5 years of age I pull them out because I don’t want to deal with the problems a failing set of batteries can create. So I tend to not use them up because i am looking for a specific lifespan with no issues. Your choice may be competely different and neither of us is wrong.

[Ken]

O.K. So we are getting what we paid for. How many other things in this life do you get to passionately debate from a position of strength, “Who is Righter”?

Dang, Good for us!!

[Archived]

I would like to offer some insite as to the inverter/power system, but the very important question I have first is: “From the Trace Inverter – Menu 3”, scroll down to the version of software, and let me know if it is MC 41 option 2.2. The original version 41 OPTION 1 had the voltage parameters for the generator start set TOO LOW for discharge cycle and TOO HIGH for charge values. The second revision, 2.2, was released after the Trace engineers worked extensively with Marathon, Vantare and Lifeline Battery, and is actually the best setup for the longest battery life and performance for your coach.

The settings are not merely just for voltage, but a function of different voltage values per specific time intervals, which compensates for how much load is applied to the battery bank. ANY autostart that just utilizes one set voltage value to initiate recharge from the generator CANNOT give optimum performance because voltage alone without account for discharge rate is not accurate. Due to inherent battery characteristics, the RATE of discharge is required to really know what the state of discharge actually IS.

For most lead-acid batteries, 12.9v is fully charged and 12.1v is considered discharged to 50% (i.e. ready to be recharged), but these values are for an OPEN-CIRCUIT battery, at equilibrium, with nothing connected. In real life, these numbers mean very little. Batteries have internal resistance which makes the actual voltages for “full” or “empty” much higher or lower as indicated by your specific coach monitoring systems, and is dependent upon temperature and amount of load on the battery bank.

Hope this information is helpful.

[Bob]

Thanks Ben, as usual, you always help clear things up…