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Author Topic: battery isolator  (Read 5113 times)
gumpy
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« Reply #15 on: September 06, 2006, 06:56:27 AM »

I don't think that's so unusual, from what I've heard. I have no personal experience with wrico, but I have to say I haven't been overly impressed with some of the things I've heard about them. I have a good friend who bought a bunch of stuff there also. He ended up with all sorts of parts and pieces, and not a single instruction about how to hook it all up. They sold him a generator and an SW4024 and an IOTA transfer switch. They told him to connect the shore line and generator to the IOTA inputs, and then connect the single transfer switch output to the AC input of the SW4024. You just can't do this on an SW4024 or you run the risk of voltage spikes. Now he's got pieces that he can't use and we're having to reengineer his electrical system and educate him via email and phone conversations so he can get it working. The whole idea of going there in the first place was to get a complete solution, but what he ended up with was far from that.

I do hear good things about their gensets, though, but again, I have no personal experience.

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Craig Shepard
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« Reply #16 on: September 06, 2006, 07:22:33 AM »

David,

After re-reading back through this thread, I guess I don't fully understand what's going on here.

The SW series has a transfer switch in it. When AC is sensed on the inputs, the inverter syncs it's output waveform and swtiches the transfer switch, which effectively passes the AC input directly to the output. Along with that, the charger kicks in and starts charging the batteries.

If your charger settings are lower than your alternator output, the charger will not put out anything becasue it thinks the batteries are already charged.

The draw you feel on your alternator is simply the alternator charging up your batteries. Yes, if your float setting is lower than your alternator, you might feel the alternator kick in when your inverter switches from bulk to float, and your charger will stop putting out anything because the voltage it senses will be higher. But this is just battery charging. Your inverter is not taking power off the alternator to supplement the AC going through the transfer switch, unless your 120v load is higher than your AC input limit setting, in which case the SW series will supplement off the batteries.

If you think the SW is supplementing the AC, you should probably check you AC input limit settings. Possibly they are too low for the loads you are running and the generator output capability.

Also, is your generator connected into the SW AC2 input?


BTW, it seems that your alternator output might be set too high. I seem to recall that the MCI alternator output is set to 27.2, which would translate to 13.6 on a 12 volt system. I seem to recall that batteries start boiling at about 14 volts. Maybe I'm mistaken on this, though.
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Craig Shepard
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« Reply #17 on: September 06, 2006, 07:39:00 AM »

Gumpy,

I too bought a generator,  SW4024 and an Iota transfer switch ( among other things) from Dick Wright.  He did tell me to hook it up as you described in your post.  I have hooked it up that way and have  no issues at all, it works great.  I hooked up the ouput from the Iota to the AC2 input on the SW4024.

Why would this be suseptible to voltage spikes?  The Iota switches slow enough, and does not allow both sources to be connected.

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Jim Stewart
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« Reply #18 on: September 06, 2006, 09:56:21 AM »

Why would this be suseptible to voltage spikes?  The Iota switches slow enough, ...


Are you sure?  In order for the SW4024 to resync it's wave form, the AC inputs must be disconnected for a minimum of 100 ms. I looked at the specs on the IOTA transfer switches and it says nothing about transfer time or break before make period. There's no guarantees of a center off position or a transfer time greater than 100 ms.  Typical switching times for a mechanical relay are on the order of 30 ms (e.g. http://rocky.digikey.com/WebLib/Omron%20Web%20Data/MGN.pdf).

That's the reason Trace has two separate inputs; one for shore power and one for generator power; so it can prioritize one over the other and smoothly switch between the two. When it detects the higher priority input while the lower priority input is active (SW4024 prioritizes shore over gen, SW4024MC prioritizes gen over shore), it reverts to inverter mode and resyncs it's output waveform to the high priority input, and then switches in the high priority input when it is synched.

That's why on page 20 of the User's Manual (http://www.xantrex.com/web/id/602/docserve.asp) you will find the following statements (my highlighting):

IMPORTANT PRECAUTION
The AC output of the inverter must at no time be connected directly to utility power or a generator.
This condition can be far worse than a short circuit. If the inverter survives this condition, it will shut down
until corrections are made. Connection to a utility or generator must be only done internally by the
inverters built-in relays. This allows the inverter to first synchronize to the other AC sources waveform,
preventing damage. Connect the utility or generator to the provided input terminals AC HOT IN 1 or AC
HOT IN 2 respectively.
When the inverter output is connected directly to an external source, the inverter will shut down and
indicate an error on the control panel. Checking the ERROR CAUSES menu heading will show a YES for
the AC SOURCE WIRED TO OUTPUT menu item. Either determine the source of the AC or call a
qualified electrician to correct the situation.

EXTERNAL TRANSFER RELAYS
It is not acceptable to switch the AC input from one AC source to another while the inverter is
connected.
This applies whether the inverter is in battery charging mode or inverter mode. Switching the
AC input from one source to another can result in a loss of synchronization that can cause a severe
overcurrent condition
that is far worse than short circuiting the inverter. Two separate AC inputs are
provided to eliminate the need for use of external transfer relays. If a transfer relay is used, it must provide
a center “OFF” position (“break before make”) that causes a loss of input power to the inverter for a period
of at least 100 milliseconds.
This will allow the inverter to disconnect from the original AC input and then
re-synchronize to the new AC source although the same AC input terminal is being used. During the
transition period, the inverter will have to operate the load while it re-synchronizes to the new AC source
(about a thirty-second period at the minimum). Most transfer relays will switch too fast for the inverter to
detect - and will cause the inverter to lose synchronization with the AC source.
This is indicated by the
inverter shutting down upon transfer and the red overcurrent LED indicator flashing or turning on.
Manually, hand operated transfer switches may be acceptable since the transfer time can be slow enough
for the inverter to detect. The switch must go through a center “off” position. They are often used to switch
from one generator to another. Since the inverter has a separate AC input for a utility grid, a transfer
switch is not required to switch from the utility grid to a back-up generator. The inverter will not allow the
generator to be connected to the utility - if both are available, the generator will be disconnected and the
inverter will connect to the utility on AC HOT IN 1.



That being said, you will only run into this issue if you switch to one input while the other one is active, and this will depend on the priority of the transfer switch.
If I remember correctly, the IOTA prioritizes generator over shoreline? If so, then you would probably see this problem only if you started your generator while plugged into shore power. This is probably not something you typically do but you should be aware of the potential danger. If you unplug from shore power first, and then start the generator, you will never see the problem as the inverter will take over in between and will resync when the generator comes online.

BTW, why do you have your feed going into AC2 as opposed to AC1?
« Last Edit: September 06, 2006, 10:15:57 AM by gumpy » Logged

Craig Shepard
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« Reply #19 on: September 06, 2006, 10:42:58 AM »

All you say and quote is true. 

When I was installing, I read the manuals, and was concerned, so I asked Dick about it, sent schematics etc to insure I was doing it correctly.  He said that the Iota's switching is not a problem for the inverter.  I have started my generator when connected to shore power, no issues.  I did not, however, have a large load on it at the time.

I connected the ouptut of the Iota to AC2, the generator input, so the auto generator start feature would work.  Also per Dick's directions.
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Jim Stewart
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« Reply #20 on: September 06, 2006, 11:12:08 AM »

David,

After re-reading back through this thread, I guess I don't fully understand what's going on here.

The SW series has a transfer switch in it. When AC is sensed on the inputs, the inverter syncs it's output waveform and swtiches the transfer switch, which effectively passes the AC input directly to the output. Along with that, the charger kicks in and starts charging the batteries.

If your charger settings are lower than your alternator output, the charger will not put out anything becasue it thinks the batteries are already charged.

The draw you feel on your alternator is simply the alternator charging up your batteries. Yes, if your float setting is lower than your alternator, you might feel the alternator kick in when your inverter switches from bulk to float, and your charger will stop putting out anything because the voltage it senses will be higher. But this is just battery charging. Your inverter is not taking power off the alternator to supplement the AC going through the transfer switch, unless your 120v load is higher than your AC input limit setting, in which case the SW series will supplement off the batteries.

With my model  when the genny is providing say 15 amps input voltage to run the roof air and 0 amps charger voltage to charge a topped off battery bank, as soon as I start the bus, the 15 amps drops to 0 and the charger amps go to -15 and the battery bank stays topped off.  With this situation the SW2512 is inverting and giving priority to the 12 volt input.   The Trace thinks it is selling power back to the grid or in other words, it thinks it's saving my money by using the DC source and backing off the AC input to the charger.   It senses the batteries are "over full" and the charger goes negative, thus sucking the power from the alternator to bring the voltage down to the float setting.

  This is unacceptable to me.  Dick verified this with Trace.  That is the design of the software to do that, and he didn't know about it before I purchased it.  There is no programmable setting in Menu 9 "inverter settings" to change float or sell mode.   I don't want to load my alternator and engine with this when I'm running my generator.  I need all the power I can get to the wheels, and I can tell a difference.  That is how I found out something was awry.  The bus wouln't go but 70 on a flat.  Turn off the Trace and it went 80 on the same piece of asphalt.  That is a lot of load on that Neihoff alternator.  I never would have dreamed it took that much power off the engine, but it does.  

If you think the SW is supplementing the AC, you should probably check you AC input limit settings. Possibly they are too low for the loads you are running and the generator output capability.

Dick and I went through this.  It made no changes in the system.  My AC input is set to 50 amps. 

Also, is your generator connected into the SW AC2 input?

Yes, it is.


BTW, it seems that your alternator output might be set too high. I seem to recall that the MCI alternator output is set to 27.2, which would translate to 13.6 on a 12 volt system. I seem to recall that batteries start boiling at about 14 volts. Maybe I'm mistaken on this, though.

The eagle manual specifies 14.2 volts output from the alternator.  My house bank require a float of 13.4.

David
« Last Edit: September 12, 2006, 07:34:35 AM by David Anderson » Logged
gumpy
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« Reply #21 on: September 06, 2006, 11:25:12 AM »

Is your Grid Usage Setup (menu 9) set to FLT or SELL?


This may be what you're seeing:

FLT - Float will try to maintain the batteries at the float voltage level. This can be used when the
source of power is a utility grid or a generator. When AC power is available, the inverter will complete
a full three stage charge cycle and then hold the battery at the float level until the source of utility
power is no longer available. This is the default setting and is appropriate for use with stand-alone
systems with back-up generators or utility back-up systems. FLT mode does not sell excess power
into the utility grid. If a DC power source is available and the battery is full, its power will be used to
directly power the AC loads connected to the inverter output even though the AC power is also
connected to the loads. If more power is available from the DC source than is required to power the
AC loads, the battery voltage will increase above the float level.
An external charge control device –
such as the Trace™ C40 Load/Charge controller - is therefore required to prevent over charging of the
battery.



This is interesting. I never realized it would do this.

Of course, this does make some sense, now that I think about it. This inverter was designed for the off-grid and alternative energy market, not the RV market. It was designed for an environment that uses solar panels, wind generators, micro hydro, etc for DC generation. In that environment, you would not want to purchase grid power (or run your generator) if you have enough DC power available (panels, hydro, etc) to support your needs. You want that power to be used for your needs up until the point where your needs exceed the DC source available and then you'd want to AC source to be tapped.

It's not trying to SELL power. It's trying to save you money  Smiley 


What are you using for house batteries? You could probably push the float voltage up to 13.6 if wet cell lead acid. You could drop the alternator back to that level also. I suspect you're boiling your start batteries at 14.2. How much water do you have to add to the start batteries each year?

Otherwise, you'll need to put a crossover relay between the coach and house batteries and turn it off when you're running the generator. I guess that's where you started.

« Last Edit: September 06, 2006, 12:06:27 PM by gumpy » Logged

Craig Shepard
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« Reply #22 on: September 06, 2006, 01:33:26 PM »

I bought the inverter from Dick.  I've spent over $16,000 with him buying stuff for my conversion.  He didn't know it would prioritze the DC input over the AC input even though he has sold 100's of them.  That is why I'm willing to pay extra $$$ and buy these parts from him.  I expect him to know the nuances of them.  I guess I was wrong this time and got screwed on this one. 
I'm still stinging.  Ouch!!

David

I stand corrected and you have a valid point.  I too would be dissapointed as service is a primary reason to buy from such a business.
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Craig MC7 - Oregon USA
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« Reply #23 on: September 08, 2006, 06:51:47 PM »

I sent a message to IOTA engineering and asked about the transfer time of the internal relay. They confirmed what I had indicated, that it is about 30 ms.  As indicated before, this does not follow the requirements of the Trace SW series inverters.

I find it interesting that Wrico is basically saying they know more about how these inverters work than the people who designed them do. And I find it more interesting that people who buy them trust the seller's word over the facts provided by the manufacturers.

I also find it interesting more things are not being fried with these combinations. I suppose it's all predictable with odds and statistics. I just don't like playing the odds with equipment that costs several thousand dollars.

But then again, I knew a fellow once who placed a bullet into a revolver, spun the chamber, and well, you can guess the rest.

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Craig Shepard
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« Reply #24 on: September 08, 2006, 08:35:03 PM »

Well, dang, I guess that means me, but now we will have to wait until next week when both Wrico and Xantrex(Trace)  are open. 

I just had faith in a guy with a lot of experience.  Good question, and yes I want it right, and we don't always make the best, most informed decisions.  I can't understand why more folks did not invest in apartment houses 12 years ago.

It appears as if my argument for the connections of the transfer switch and the inverter so far is analgous to the following - "I intend to live forever - so far, so good"  But maybe there is a real world practical reason why its ok.  or not.  That's partly what this forum is about.  Or maybe I should start calling you names and thumping my chest...Shocked

Let me get back to you, and my apologies for hijacking this thread.
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Jim Stewart
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« Reply #25 on: September 09, 2006, 07:07:04 AM »

Jim,

I hope I didn't come off as trying to demean you or call you names.

You are not the first person I've heard say that after selling them all this equipment, that Wrico told them it was ok, so it must be so. I just can't figure out why they think it's ok when the manufacturer of the inverter says it's not. I know he has a lot of experience, and from what I hear, they make a fine generator. But this issue has me puzzled.

And I've been wondering why I didn't invest in rental houses 12 years ago, too.  Only thing I can figure is cause I didn't have any money  Wink

craig
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Craig Shepard
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« Reply #26 on: September 11, 2006, 08:25:25 AM »

I did not take offense at all, its one of the downsides of written communication, you can't see the wink.  I appreciate your thoroughness and getting in to the details.

I just talked to Dick.  He said when the SW4024 inverter first came out in the mid 90's, there were some issues regarding auto transfer switches.  The issues were not a voltage spike, but a failure of the inverter to sync properly. Failure to sync properly means the load sharing feature of the inverter won't function.  Dick worked with the programmer at Xantrex and they changed their internal software, and it has not been an issue since then.  Dick said that they are not good about updating their manuals, and that while those paragraphs are still in the manual, they do not apply to the current units.  Dick says he has been wiring them this way for many years and never had an issue with them.   Once a thing like that is documented, even if its only on the first units, they are loath to remove the warning.   Dick says he has the blessing of Xantrex to do it this way.  Iota auto transfer switch feeding the AC input of the inverter.

He further said that most issues are caused by improper setup of neutral or ground wires. 

Although the big dollar coaches use two inverters and no transfer switch, he said they have having sync issues, and may start using transfer switches to alleviate.  In the meantime the poor rich guys are having to reboot. I imagine its irritating to have spend $1 or $2 mill and have to reboot your inverters.

I have always found Dicks advice and recommendations to be spot on.
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Jim Stewart
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« Reply #27 on: September 11, 2006, 10:23:11 AM »

OK, well, I just got off the phone with a tech at Xantrex. I've talked to this particular tech before, if I recall correctly, and he's very knowledgable about the SW series. Here's the scoop.

He says that while he can't give it an official approval, the 30 ms switching time of the IOTA transfer switch should be enough time for the SW series inverter to detect the break in source, which will cause it to revert to inverting mode, and when it detects the new input source, it will go through the normal sync and transfer on that. So, the unofficial word is that it should work just fine. They put the 100 ms requirement in the manual to ensure that there is a break-before-make in the sources when switching between two sources. However, if there were a case where the relays in the IOTA switch somehow allowed both sources to be connected at the same time (unlikely), or no break between the two sources, then bad things could happen, and ultimately, the warranty would not cover the damage resulting because it was not installed according to the specifications.

So, yes, you probably won't see a problem hooking it up this way. No, it does not meet Xantrex's official installation requirements.

And one other note that came up, which David might be interested in...

I mentioned the original problem that David had regarding the prioritization of DC power over the generator power. He was familiar with this, and said there's a way to get around this. Now, assuming you have a standard SW series inverter, and not an MC inverter, then go to menu heading 17, Battery Selling, and reduce the Max Sell Amps AC setting to as low as it will go. He thinks it won't go to 0, but should go to 1. This should inhibit the inverter from pushing the DC power back up the AC line, and therefore it will take the AC off the generator.  MC series inverters do not have access to this menu heading.

Give that a shot, and let us know if that has any effect.

craig

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« Reply #28 on: September 11, 2006, 10:37:55 AM »

Dick did say that the guy he worked with, who changed the internal code to accomodate it, was no longer at Xantrex, and the new guys night not even be aware of the history of what was done.
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Jim Stewart
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« Reply #29 on: September 11, 2006, 10:51:27 AM »

First off let me remind everyone that I only have experience with seated charter coaches, so I have zero experience on the topic of this thread! But I read each and every new post on this board when I have time ! Having that said I'll admit this thread has been and still is all GREEK (no offense meant, just a way of saying HUH?) to me! I still don't understand much more about it, than before I read the first post (I sometimes actually have to get hands on experience to grasp a feeling of things such as this!)! But that is exactly why I'm repling to it! I love this board and all the members on it, even though it still is confusing to me I think it's great the way everybody goes out of their way to search & research for solutions for one another and this thread proves that!   BK  Grin

Keep up the great teamwork guys! [/color]


TN FALL BUS BASH OCTOBER 26th thru 31st at Knuckle's place outside of Union City, TN! [/size] Hey Folks come on out and have a good time, we're gonna have at least 1 bus up from Miami, FL, and another who's been on an awesome journey to Alaska and back plus Bob and Jackie from NC by way of Timmonsville! Hopefully El Sonador will make it down from Canada also (even though he's extremely busy with his new biz aquistion these days!), he hasn't been able to confirm as of yet! (but this all started at his suggestion, and we're counting on him!)

Smiley Wink Cheesy Grin So everyone get off the couch (and into the COACH) & come on to the TN FALL BUS BASH! And meet these folks who are doing what we all dream of doing! Using their coaches to TRAVEL!  (and long distances I might add!) Shocked Cool Roll Eyes Undecided[/size][/color][/b]

Think of the great stories and travel tips and suggestions you'll be able to get in person from these " World Travelers! " be here or or well just be somewhere less fun!
« Last Edit: September 11, 2006, 11:03:24 AM by Busted Knuckle » Logged

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