Morningstar MPPT 60 Battery Sense

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Ok guys, spent the morning getting this thing talking to my laptop. Bad crossover cable cost me an hour or two, but got it going. I'll post some of the state shots as has been done, but we have scattered clouds here today. Therefore, a lot of moving around in the current out, etc. It is very interesting to watch in real time the changing values. For instance, when a cloud comes by the current obviously drops, but the battery sense voltage is very reactive to that. The actual battery voltage isn't changing, but the sense output is obviously coupled in somewhere to the charge current. I can't obviously graph the actual battery voltage, but when taking a screenshot of the status screen I am simultaneously recording the true battery voltage. I have the dvm connected to the battery and record the actual reading when taking the screenshot.

The one below as I approached transition to absorption the actual battery voltage was 13.81 and it was trying to kick into/out of absorption because it thought it was at 14.22. It had just previously kicked into absorption for a few seconds because it went over 14.22 on the sense line. (this is the temp compensated target of the 14.4 V set in the dip switch) So the unit actually changed modes .32V early. We don't yet have enough sun to lock into absorption mode and stay but I'll post when I get it.


Actual battery voltage at time this was taken was 13.81 V.
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svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Below another shot as it went into and stayed into absorption. The battery sense was 14.22 V and the actual battery voltage (dvm) on the battery sense terminals and battery terminals was 13.88 V. This means the controller is now backing down the current to maintain 14.22V it believes is on the battery. A difference here at 20.63 A current flow of .34V.

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svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Below another shot as it went into and stayed into absorption. The battery sense was 14.22 V and the actual battery voltage (dvm) on the battery sense terminals and battery terminals was 13.88 V. This means the controller is now backing down the current to maintain 14.22V it believes is on the battery. A difference here of .34V at 20.63 amps of current flow.

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Cariboocoot

Re: Morningstar MPPT 60 Battery Sense

Let me try this again.
Your DVM doesn't compensate for temperature. Your charge controller does. The 0.34 Volt higher reading on the controller may well be mainly a matter of battery temperature being above 25C.

Depending on the wire size, I wouldn't expect a very accurate Voltage reading on any lines that have 20 Amps going through them either.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

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This one is at 60 min t_abs. The batteries are coming up slowly to meet the 14.22V setpoint. As the current is decreasing, so is the discrepency in the actual V/batt sense reading the unit measures. At the time of this shot, current is flowing at 15.31A and the actual batt voltage is 14.04V, batt sense still 14.22V. Slowly but surely these two readings look like they are going to converge. Maybe tomorrow we'll have a clear day where I can see max output from the panels early on before the batteries are almost charged. I think that will be the max divergence. I'm thinking about raising the setpoint from 14.4 to 14.6 for absorption. Any thoughts? Remember, I charging Lifeline AGM's here. Not particularly tolerant of overcharging I'm told. Any opinions from the guru's?

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Now this is at 114 mins of absorption. The batt sense now is 14.22V and actual battery voltage is at 14.1 V. Wow, been in absorption for almost two hours and am finally getting close to the actual absorption voltage. Current flow now down to 12.54A and deviation is .12V batt sense to actual batt voltage.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

I believe that Muskoka explained this earlier. If you look at all the numbers, the target V is 14.22. That is the temp compensated Target voltage that the unit is going for. It doesn't matter that the DVM is not temp compensated. The unit adjusts the target down from the 14.4V setting from the dip switch to the 14.22V compensated target. I would agree that if the the Target V remained at 14.4 as set then you'd have to either have a compensated DVM, (which doesn't exist that I know of) or you'd have to do the math and apply the adjustment. The unit does it for you and appears to be doing that part correctly.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Any of the admins tell me why the charts I posted are shrunk down in size when I view the thread? Seems like the first one I did was full size, but now even that one scaled back to thumbnail. I was proud of myself for figuring out how to post it at all. Is something in the way I posted it, or is that just because I'm viewing my post or what?

Thanks

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Well, never made it to float and starting to lose the sun. Logged 153 mins at absorption, obviously actually only spent a few truly at absorption voltage. Now back to MPPT and the deviation between sense and true batt voltage are basically gone. Now at 5.98 amps current, the batt sense is 13.55V and the true batt voltage is 13.51V. Maybe tomorrow we won't have this high overcast and we'll be able to see it go through all the phases with plenty of power.

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Anybody got any suggestions on where to go from here? Lifeline recommends charging at 14.4V before temp compensation. Although, based upon the output from my unit that's what I did today, in reality, I actually spent very little time at 14.4, before compensation. I could set the dip switch to 14.6 and basically split the difference on the highest deviation between batt sense and true batt voltage.

BTW Cariboocoot, if you look at this screenshot the Target voltage dialed down from 14.22 to 14.18V as the battery temp went up a degree.

Again, thanks for all the help guys!

Cariboocoot

Re: Morningstar MPPT 60 Battery Sense

Yes, I see that.
I guess Morningstar likes to do things in reverse-fish order.

Once again, Outback is better at something.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Finally, in night mode. All readings as you think they should be. Battery sense matches battery terminal voltage and current is zero. This issue has to be current driven. A couple things to try tomorrow to see if I can get it a little closer to what it should be. Maybe, if I'm lucky, Morningstar will actually answer some of the emails I've sent to tech support since the 19th.

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I also wonder if maybe some of the updates that have come along fixed this problem. Again, would be nice to hear something from M*. I would go ahead and do the updates if I could come up with a db9 serial connector cable. Another niggle, why would you think that you can do everything to the unit through the ethernet interface I'm using right now with the MSVIEW software, except you can't do an update?? Makes no sense to me to have to go get a special cable made to do just the update, it should be able to be done through the ethernet interface as well.

Thanks again for the help.

BB.

Re: Morningstar MPPT 60 Battery Sense

Did you try measuring the remote sense voltage right at the controller's input connection (when under load) to see if the controller's Remote sense terminals are the same voltage as the battery bus? It sounds like broken wire/bad connection somewhere in the remote sense wiring.

I don't know how MorningStar does it--But the standard remote sense setup is to put a relatively high value resistor between the local output terminal and the remote sense input (maybe a few kOhms of resistance). If there is no remote sense connection, the resistors simply pass the voltage from the output terminals. If there is a remote sense cable connected--The connection to the battery (remote sense) overwhelms the ~2kOhm (or so) input resistors, and the unit "sees" the remote voltage.

-Bill

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

I measured the actual battery voltage at the two terminal screws in the controller where the battery sense wires are connected. The other end of the two wires are connected directly to the battery terminals and I verified the measurement there as well. What is so strange is when the current flow is low or zero, what you get measuring the battery sense terminal with a dvm is the same as the unit displays both on the RM2 display and in the data outputs that you see in the screenshots. When the current flow goes up the battery sense voltage displayed by the controller goes up higher than the actual voltage measured by dvm at the the battery sense terminals in the controller. In the previous posts where I talked about "actual battery voltage" that was as measured at the battery sense terminals and also at the battery terminals themselves. Those last two always agreed exactly as they should. There should be no current flow on the sense lines at all, thus no voltage drop. On this unit you get a warning from the controller if there is a break in the sense wiring. Or if you start it with the battery sense disconnected it just disappears and the unit uses the voltage off the charging line. There is, and should be a voltage drop on this line and therefore it skews everything in the charging profile by the V drop. Hence the sense line and circuitry. M* actually has a pretty good write up in the manual. I posted an excerpt back a bunch of posts now. But, it covers the problem perfectly and says that is the reason for them having the sense line. Ie, not sensing battery voltage off something affected by current flow and voltage drop. Although that is exactly what my unit is doing.

Something internal in the unit is affecting the measurement algorithm somehow, or something is actually coupling up on the sense wires that I can't see or measure just yet. Thinking about maybe trying a twisted pair or shielded line on the sense wire. Maybe some kind of a ground loop. Wish I had my scope from home here on the boat. Then again it may just be a problem in the unit?? Hope to maybe get a response to several emails I've sent to M*.

NorthGuy

Re: Morningstar MPPT 60 Battery Sense

svNorthStar wrote: »

I measured the actual battery voltage at the two terminal screws in the controller where the battery sense wires are connected. The other end of the two wires are connected directly to the battery terminals and I verified the measurement there as well. What is so strange is when the current flow is low or zero, what you get measuring the battery sense terminal with a dvm is the same as the unit displays both on the RM2 display and in the data outputs that you see in the screenshots. When the current flow goes up the battery sense voltage displayed by the controller goes up higher than the actual voltage measured by dvm at the the battery sense terminals in the controller. In the previous posts where I talked about "actual battery voltage" that was as measured at the battery sense terminals and also at the battery terminals themselves. Those last two always agreed exactly as they should. There should be no current flow on the sense lines at all, thus no voltage drop. On this unit you get a warning from the controller if there is a break in the sense wiring. Or if you start it with the battery sense disconnected it just disappears and the unit uses the voltage off the charging line. There is, and should be a voltage drop on this line and therefore it skews everything in the charging profile by the V drop. Hence the sense line and circuitry. M* actually has a pretty good write up in the manual. I posted an excerpt back a bunch of posts now. But, it covers the problem perfectly and says that is the reason for them having the sense line. Ie, not sensing battery voltage off something affected by current flow and voltage drop. Although that is exactly what my unit is doing.

I wonder what would be the measurements on controller terminals where regular current-carrying battery wires are connected?

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

The readings are reflected in the screen shot. It is labeled Battery Terminal Voltage (BTV). It seems to be pretty accurate each time I checked it against the DVM. The battery sense voltage in the controller seems to track the BTV much closer than it does the actual battery voltage. It seems to me that the whole purpose of having the battery sense, and is so stated in the manual is to get around the problem of trying regulate the current flow while reading BTM and the associated voltage drop which obviously varies with current flow. I don't know how the battery sense is coupled internally in the unit. Someone said earlier it is basically a voltage divider circuit in other units. The way the unit is working now is basically as if the battery sense were not even connected.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Going back over the data and based on BB.'s comment I got to thinking. First, a schematic would answer the question....but I digress. This thing acts like a voltage divider, similar to what BB described I think. Looking back at the data, if I take the Battery Terminal Voltage(charging lines)-Actual Battery Voltage(DVM)/2= the same difference I'm seeing in the Actual Battery Voltage(DVM) and the Battery Sense V as measured by the unit. Another way of saying this is that it is just halving the difference between Actual Battery V and Battery Terminal V.

Right now I have higher voltage drop than I should when under full charge. Can't get the wire size I need here, it's on order. So, when I change that out I should see the "error" in the Battery sense line drop in half as the voltage drop on the Battery Terminal Voltage charging lines drop in half. I still think that if what I'm saying here is true then the Battery Sense line doesn't in fact do what the manual claims, ie, give you a true reading of the battery voltage for regulation purposes. Instead it just cuts the error in half of regulating off the Battery Terminal Voltage(the charging lines)

Maybe M* will actually answer me sometime and we can find out. Does anyone know if there are schematics for the TriStar available anywhere?

Muskoka

Re: Morningstar MPPT 60 Battery Sense

Some more numbers under charge. My BV, BVS, and BSV readings all match my digital clamp meter exactly. The only reading that is consistently high is the BTV, which is always 1/2 to 1 full tenth above all the other readings. In the "help" in MSView, it is the voltage which should match the actual battery voltage the closest, but continually doesn't. This is something only Morningstar can give you / us an answer for. It has nothing to do with Temperature Compensation, the only voltage thats displayed / adjusted by compensation is the Target Voltage, all the rest very closely match my meters, as does BTV, but it's constantly high(er), but not by the .3 to .6 plus volts that temperature compensation is sometimes calling for above the Absorption set point in the winter.

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Glen

Edit: Just for your comparison, I use 1awg for my battery interconnects, and to my common busbars (16" run), which are rated at 200amp, and 4awg from my controllers to the busbars (10" run). That's why all my readings are very close, other than the BTV, which is something we need an answer from Morningstar on.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Glen,
Thanks for that. I think the Battery Volts and Battery Sense are just displaying the same thing. In real time, the second one changes the other does. The Battery Voltage(slow) is just a smoothed number, to take out any jitters in the data. Although, yesterday watching mine drop in and out of absorp every second makes me wonder why have the smoothed number since they don't appear to use it for the algorithm. If you could, when your system is charging at it's max current, could you note the Battery Terminal V and Battery Sense V and actually check that what you get with a meter on the Battery Sense terminals is what the system is displaying as Battery Sense V?

It is clear, when you watch it in real time that the battery sense displayed by the controller is not actual battery voltage. I am going into a 1200 aH battery bank and I know, and can see on my DVM and other Battery monitor that my real battery voltage isn't running up and down .2-.3V when a cloud goes overhead and then passes. Now the Battery Terminal Voltage (charging voltage) does and that makes sense as the current goes up and down. It also follows that the V drop on the same line goes up and down with the current. So if they are really just using a voltage divider, or similar, to create the battery sense V we see on the unit, then it really isn't doing what they claim it does. My situation, due to the large V drop on the charging lines right now, is magnifying the error and making it substantial enough to really affect the charging curve.

Thanks for your input.

Steve

Muskoka

Re: Morningstar MPPT 60 Battery Sense

Both controllers just went to Absorb, here's the numbers from the MPPT controller. The DVM voltage reading was 15.01v, exact same as Voltage Sense.

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Glen

NorthGuy

Re: Morningstar MPPT 60 Battery Sense

svNorthStar wrote: »

Going back over the data and based on BB.'s comment I got to thinking. First, a schematic would answer the question....but I digress. This thing acts like a voltage divider, similar to what BB described I think. Looking back at the data, if I take the Battery Terminal Voltage(charging lines)-Actual Battery Voltage(DVM)/2= the same difference I'm seeing in the Actual Battery Voltage(DVM) and the Battery Sense V as measured by the unit. Another way of saying this is that it is just halving the difference between Actual Battery V and Battery Terminal V.

Looks like it's measuring between positve sense wire and negative battery wire. Therefore it gets only half of a voltage drop (the one that occures in negative battery wire) but not the whole thing.

Negative battery wire is most likely the device ground. Negative sense wire is more negative to that (-0.4V from the viewpoint of the device). There should be something in there that would make measurement of these negative voltages possible. If it's broken, the measuring device may be unable to go below device ground and sees the negative sense wire as 0V. In this case, you would need to replace parts, or board, or unit.

Or it could be as Bill said. The negative sense wire is internally disconneced, and if there's a resistor to negative battery wire, it's peeking negative battery wire instead.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Ok, and just to verify... you measured the actual battery voltage of the bank you are charging and it was the 15.01v?

As you said before, M* is the only one who can give us an answer and for whatever reason they are silent. I've sent emails and posts through the tech support website app and they've all been ignored. In the interest of fairness, I did send them an email when I first purchased the unit and asked their opinion about series or parallel installation of the panels. They did respond the next day with an answer. Since then, 4 attempts to contact have been ignored since the 19th.

Anyway, we are having a persistent high overcast here for the last few days so I can't really get max current readings, but below this was earlier this morning and no discrepency. Of course, I'm at 5.8A current flow so very little drop between Battery Terminal Voltage(BTV) and Battery Sense (BSV) and my actual reading with the DVM matches BSV.

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This one from yesterday at was at max current for yesterday and right after it went to Absorp. Notice BTV is 14.54V and BSV is 14.22V for a V drop of .32V. The actual battery voltage that was measured on the controller terminals with DVM was 13.88V. So the "true" voltage drop would have been 14.54V-13.88V= .66V, which coincidentally is double the difference I got above. It seems to be ignoring what voltage is actually at the BSV terminals and is taking half the voltage drop between the actual battery voltage and BTV and outputting it as BSV internally. Going back and checking several shots in time this ratio appears to be consistent once enough current starts to flow.

Basically, once there is enough current flow to create a V drop of more than around 1.5-2% the BSV diverges from the true battery voltage(DVM). How this happens internally, I don't know without a schematic or someone at M* fessing up. But clearly it is not an independent V reading that ignores what's going on with the BTV as represented in the manual.

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NorthGuy

Re: Morningstar MPPT 60 Battery Sense

svNorthStar wrote: »

This one from yesterday at was at max current for yesterday and right after it went to Absorp. Notice BTV is 14.54V and BSV is 14.22V for a V drop of .32V. The actual battery voltage that was measured on the controller terminals with DVM was 13.88V. So the "true" voltage drop would have been 14.54V-13.88V= .66V, which coincidentally is double the difference I got above. It seems to be ignoring what voltage is actually at the BSV terminals and is taking half the voltage drop between the actual battery voltage and BTV and outputting it as BSV internally. Going back and checking several shots in time this ratio appears to be consistent once enough current starts to flow.

That is what you have:

Point A. Negative controller terminal where charging wire is connected: 0V
Point B. Negative battery terminal: +0.3V (added 0.3V drop in the negative wire) What I previously said was wrong!
Point C. Positive battery terminal: +14.2V (added 13.9V battery voltage)
Point D. Positive controller terminal: + 14.5V (added another 0.3V for the drop in the positive wire)
Point E. Positive sense wire directly connected to C: +14.2V
Point F. Negative sense wire directly connected to B: +0.3V

You measure between D and A, you get 14.5 - 0 = 14.5V
You measure betweeb C and B, you get 14.2 - 0.3 = 13.9V
Tou measure between E and F, you get 14.2 - 0.3 = 13.9V

Clearly, the device doesn't measure between E and F.

It measures

either between E and A 14.2 - 0 = 14.2V (most likely)
or between D and B 14.5 - 0.3 = 14.2V

As Bill said this could be simply because E is not connected internally. I would try to disconnect E completely and see if it all stays the same. If it does, the problem is with negative sense wire connection.

Muskoka

Re: Morningstar MPPT 60 Battery Sense

Yes, the dvm readings of 15.01v were taken at the actual battery, the busbars, and the terminals inside the controller (what the BTV should be showing). The BTV is supposed to read / visually represent the actual battery voltage according to MSView. From the help "Battery Terminal Voltage is voltage measured directly at the battery connection of the Tristar MPPT". Why all dvm actual voltages read 15.01v, but MSView is saying 15.16v for the terminal voltage, is beyond me. The strange thing, it's pretty constant under charge, close to a tenth, making me think it's something in the logic / programming of the Tristars. I think all the equipment is fine, physically, it's something in the programming of the Tristar. Perhaps it's time for a firmware update from Morningstar?

Glen

Edit: I should have done this earlier for comparison. I just did the same measurements on my Morningstar TS-60, and the "Battery Voltage", which is the same as the "Battery Terminal Voltage" on the MPPT controller, also shows to be 1/10 higher in voltage than all other readings. It's something they have programmed in, it has to be. The "Terminal Voltage" has nothing to do with the "Sense Voltage", nor is it temperature compensated. It's The same "higher voltage" amount on both units.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Northguy, I think you are correct. Checking for voltage drops show that the negative battery sense terminal is .3+ higher than the negative charging terminal. Yes the there is .3 V drop from the battery term to the neg charging term at around 20 amps. So the sense lines really aren't directly connected to the battery as advertised. It appears to be referencing the ground side off the neg charging term which is .3V different.

I tried removing the + sense wire. The unit still tried to use the sense voltage but was at .12V which caused the controller to come out of absorp back into mppt. Was surprised it sensed it at all and not sure about the .12v with just the - sense wire hooked up. Removed the - sense wire and the RM2 showed invalid sense and the data logged 0 V on sense. Then the controller using only the higher charging voltage dialed back into absorption mode dropped the current.

Any ideas on what I can do with this? I guess when my #4 wire gets here and the voltage drop mostly goes away then it will be a lot closer to what I want. I guess I still see this as a major design snafu, if it is actually operating as designed, in that it doesn't really use the voltage it senses on the sense lines to regulate it. It is actually using the charging line ground side as the reference point for ground on the sense side instead of just reading the sense lines.

If I haven't said it enough, I really appreciate the time you guys have put in on this.

Muskoka

Re: Morningstar MPPT 60 Battery Sense

This must be isolated to your system / controller, because I'm not seeing this at all, on either one of mine. I can measure all day long from the internal sense wire terminals, the battery terminals inside the controllers, my busbars, or the actual battery itself, the readings are always close. I can criss / cross away way I like (as per NorthGuys table above), I get the same voltage readings. The only discrepancies I have is the way the software is "reporting" the Battery Terminal Voltage.

I did the "tests" listed above and don't get anywhere close to the same results.

When I did this:

"You measure between D and A, you get 14.5 - 0 = 14.5V
You measure betweeb C and B, you get 14.2 - 0.3 = 13.9V
Tou measure between E and F, you get 14.2 - 0.3 = 13.9V"

all my voltages were the same.

"Clearly, the device doesn't measure between E and F."

Both of my controllers measure just fine between "E" and "F", I get the same voltage as all other points. I really at at a loss now to understand what your looking for. Where your getting differences in your voltage readings listed above, I don't see any measurable difference on 2 different controllers?

NorthGuy

Re: Morningstar MPPT 60 Battery Sense

svNorthStar wrote: »

Any ideas on what I can do with this? I guess when my #4 wire gets here and the voltage drop mostly goes away then it will be a lot closer to what I want. I guess I still see this as a major design snafu, if it is actually operating as designed, in that it doesn't really use the voltage it senses on the sense lines to regulate it. It is actually using the charging line ground side as the reference point for ground on the sense side instead of just reading the sense lines.

Looks like that's not something that you can easily fix. Probably somehing is not working correctly in the hardware such as some bad part or IC. It probably doesn't affect anything else.

The voltage drop that you have is certainly big, and that is bad by itself. If you're getting thicker wire and this decreases it to about 0.1V, you do not really need to use a separate sense wire.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

Muskoka...do you get anything when you measure across - batt sense and - battery charge terminal or A-F in the above description. That is where I'm getting the .3V problem I think.

NorthGuy... I am afraid you are probably correct. Hopefully, I can get someone at M* to respond. Just left something on their facebook page as well. Maybe that will prompt a response. As you say, I think if I can get the V drop down low enough, the problem mostly goes away. Although, I'd much rather it work right.

You think this might be something that could be resolved through a firmware update? Although, I just bought this unit it is HW v01.01 and SW v12 which I think is at least 3 updated ago. Guess it may have been on vendors shelf for a while??

Muskoka

Re: Morningstar MPPT 60 Battery Sense

I'm not sure what your asking me too do, check for "a proper voltage reading?" across 2 negative terminals, I'm confused...sorry.

I just tested from the (-) negative sense terminal (in the controller) to multiple (+) positive points in my system, and then the (+) positive sense terminal (in the controller) to multiple (-) negative points in my system, and I got the same voltage in all readings (+-.02-.03).

Glen

NorthGuy

Re: Morningstar MPPT 60 Battery Sense

Muskoka wrote: »

Both of my controllers measure just fine between "E" and "F", I get the same voltage as all other points. I really at at a loss now to understand what your looking for. Where your getting differences in your voltage readings listed above, I don't see any measurable difference on 2 different controllers?

Muskoka,

Because your wires are thicker, or you do not get enough current, there's nearly no voltage drop on your current-carrying wires. That's the reason you get all the same measurements.

svNorthStar has too thin wires for the current, which creates a voltage drop and therefore different measurements for different points.

svNorthStar

Re: Morningstar MPPT 60 Battery Sense

I am seeing a .3V voltage drop just measuring V across the negative charging terminal to the negative battery sense terminal. The actual reading is current dependent and higher current means higher drop. In other words my negative battery sense is a -.3V potential which is then skewing the battery sense reading the unit is working by that amount. Causing it regulate like the battery voltage is .3v higher than it really is. Undercharging....

Just put your DVM across the negative battery sense terminal and the negative charging terminal and see if there is any drop.

Muskoka

Re: Morningstar MPPT 60 Battery Sense

NorthGuy wrote: »

Muskoka,

Because your wires are thicker, or you do not get enough current, there's nearly no voltage drop on your current-carrying wires. That's the reason you get all the same measurements.

svNorthStar has too thin wires for the current, which creates a voltage drop and therefore different measurements for different points.

Yes, I totally agree. That's why I was asking what "were" looking for. I don't think there is anything inherently wrong with the Tristars (other than some "reported" voltage readings), or specifically the sense wire "system", it works just fine. He just needs some heavier cabling. I'll test and help all day long, but I don't think there's anything wrong from a controller standpoint, that's all.

Glen