I now have my WBJR installed on my battery's main negative cable. Great product and it's doing its job well and looks to be very accurate (agrees with my other battery shunt in my inverter).
I am seeing some large discrepancies between the amps the classic is showing being sent to the battery and what the WBJR is reading it's receiving.
I understand that battery loads need to be taking into consideration when reading the WBJR AMPS. I turned off all battery loads to take that out of the equation.
It's a sunny day today and the classic was showing a steady 74A going to the battery but even with all DC loads off, the WBJR was only showing just under 55A. That's almost 20A difference. So have I just discovered a HUGE resistance in my wiring from the classic to the battery (wbjr) or is the classic showing more amps than it's really producing? I believe the WBJR is accurate as it matches what my high Quality inverters logging shunt reads.
I have the biggest cable I can fit in the classics terminals 16mm2 and it's terminated to the main knife fuse holder (about 2 feet of cable) then 95mm2 cable runs about 5 feet to the WBJR then 1 foot of 95mm2 from the wbjr to the Battery neg terminal. So I wouldn't think my wiring is undersized (though in the future my wishlist for the classic is a more substantial wire terminal block - 25mm2 minimum (10mm hole not 6mm as it is now). I know I can use a bootlace pin and step down the cable size at the end but there isn't much room in there.
I have a good quality clamp meter on order, should have it next week. To try and get to the bottom of it, I'm thinking if I clamp the output wire of the classic close to the unit I should be seeing similar amp readings to what the classic is showing. Then measure again after the fuse and keep tracing it back. 20A on a 48v system is 1000w that's a lot of resistance if it is.
Anyhow it's kind of good and bad news. Good if I can find some resistance or loss as I can fix it and gain 20A of charge that was going to waste but bad if I don't find any resistance as I'm stumped then. Having metering is great as you can get to the bottom of issues you would have been blind to without it. :)
Is anyone seeing large discrepancy between what the classic is showing in battery charge amps and what the WBJR shunt is receiving? (obviously battery loads need to be taken out of the equation)
Kurt
Kurt,
That would be impossible, the current in a single circuit will be the same at all parts of that circuit, now you may get voltage drops but the current will not vary at any place on that circuit. I would look for some other circuit where those amps are going , either that or there is a calibration error between the shunts. I have never heard of an inverter idling with that high of current so it is somewhere else
tecno
Was there any AC load (via inverter)?
There was no loads on the Battery the Inverter was completely shut down and there is no other loads on the battery. The only thing the battery was powering is the classic 150.
So it looks like the classic charge controller is saying its pumping out 74Amps when its really only pumping out 55Amps :(
I did make a post a while ago before I got the wbjr that I thought the classic was showing more amps out than was really coming out of it.
I will have the clamp meter next weekend to give me a 3rd point of reference.
Kurt
You might see maybe an amp or two of difference if the Classic wasn't quite adjusted correctly but not
as much as you are seeing. That is, unless the Classic is actually broken somehow. That's possible
but have never seen this kind of problem before.
Do you have anything other than the battery negative on the battery side of
that shunt ? Anything at all ?
I suspect something is drawing some current somewhere.
Series resistance should not make any difference if there are no other loads
or connections.
boB
What is your input voltage and output voltage ? Note the ratio of those 2 voltages and then
note the PV input current reading as well as the battery output current reading. The ratio
of input to output current should be somewhat close to the ratio of output to input voltage.
Just a possible sanity check for you to make before you get your clamp on meter.
Maybe your Classic was someone never calibrated at all ? I hope not, but that's a
possibility I suppose. If that's the case, you can adjust it. Am I having a Deja-Vu here ?
boB
Yes one or two amps wouldn't bother me at all as I didn't expect the classics internal shunt to be a 100% High resolution mesument. But when its showing 74A out at 55 or so volts x 74A Around 4000w but my battery (WBJR) is showing 55A x 55v 3000w that's a big discrepancy.
There is nothing at all on the 1 foot length of cable from the WBJR shunt to the negative terminal.
Yes we are having a Deja-Vu. As I suspected some time ago that my classic was showing more out than it really was putting out as there was a discrepancy between it and my old current shunt reader. At the time I didnt want to fiddle with the classic as I wasnt 100% possessive my shunt was accurate. But now that the WBJR is giving me the same results It just might be that my classic is out.
Another thing that got my suspicious is my system 3960w of pv often outputs 4000w for sustained periods with cloud edge effect i see 4500 -5000w (then the classic linits current) But it was my understanding I should only realistically see perhaps 3300w or so in ideal conditions?
Kurt
QuoteWhat is your input voltage and output voltage ? Note the ratio of those 2 voltages and then
note the PV input current reading as well as the battery output current reading. The ratio
of input to output current should be somewhat close to the ratio of output to input voltage.
Ok I'm not on site now but just taking a fixed referance point today 11:40AM on my mymindnite log.
11:40AM
input voltage 60.2v
input amps 64.5A
Output voltage 55.7V
output Amps 88.2A
Yikes there we go its saying its getting 3943w in and 4912W out :o 26% difference
Kurt
Quote from: offgridQLD on December 08, 2013, 04:14:16 AM
Ok Im not on site but just taking a referance point today 11:40AM on my mymindnite log.
11:40AM
input voltage 60.2v
input amps 64.5A
Output voltage 55.7V
output Amps 88.2A
Kurt
Yep. That pretty much settles it. Your Classic is current-sense challenged.
Input to output voltage is very close to each other and input to output current are far apart.
boB
Dam it I thought my PV was just doing really well :(
Hey the good news is this explains why my battery's are so inefficient because I'm not really pumping as many kwh each day into them as the classics telling me
Got to look on the possessive aspects ;D
Well next weekend I will have my clamp meter and between that and the WBJR shunt I should be able to dial it in .
Just have to dig up the instructions how to tweak the classics gain calibration pot from my previous post a while back.
Quote from: offgridQLD on December 08, 2013, 04:22:34 AM
Dam it I thought my PV was just doing really well :(
Hey the good news is this explains why my battery's are so inefficient because I'm not really pumping as many kwh each day into them as the classics telling me
Got to look on the bright sided.
Well next weekend I will have my clamp meter and between that and the WBJR shunt I should be able to dial it in .
Just have to dig up the instructions how to tweak the classics calabration from my previous post a while back.
You have to also be careful when measuring current with a clamp on meter when looking at the negative line.
That is, if the negative line is common to both battery and PV input. If they are shared, you will actually see the "difference" of input and output current on that line. Of course, clamp on probes also don't usually read the same in one direction as the opposite direction because of residual magnetization of the probe.
I would just trust the WB Jr. It's going to be more accurate than any clamp on meter as long as all of your loads and inverter are turned off. The Classic is normally very accurate too. I believe the Classic is the most accurate ammeter in any charge controller out there. (normally) Unfortunately, not in your case. But as long as a shunt hasn't fallen out or something like that, you should be able to adjust it. If not, we'll still make it right for you.
boB
No problem good points. The clamp meter is just as a quick guide. I needed one anyhow for other projects.
I just purchased A 2nd classic a few weeks back for my future upgrade so I could swap it out with the old classic and see how that one is.
Like you say I will just use the WBJR with every load on the battery shut down to calibrate.
I just took a few more sample points throughout the day and they all calculate to show a output error from the classic.
Two more sample points of In vs out from classic
9:16am ,
Input 60.5v - 21.4A =1294w in
Output 50.8v - 33.2A = 1686w out.
Roughly 30% difference.
3:04pm ,
Input 75.5v - 4.9A = 369w
Output 54.1v - 9.1A = 492w out.
Roughly 33% difference.
Kurt
Ok just to make sure the old instructions you gave me a while back are still ok
QuoteYou will need a fairly small, adjustment screwdriver.
The left side towards the front is a hole gaining access to the trimpot labelled GBATT.
(see picture)
Turn very slightly counter-clockwise (I think) and watch the current come down.
Easy now... be careful !
Make sure the offset hasn't been affected (it shouldn't) by turning mode to off
and back on again to recheck the reading. If it reads closer, great.
boB
And use the WBJR readings (with zero load on the battery) as a reference to dial it in.
Kurt
Yep. That should work pretty good I wou;d think.
If it doesn't adjust enough, then your Classic may have some other issue keeping it
from measuring correctly. There is that possibility. Won't hurt to give it a try though.
boB
Ok just to try and confirm some data today I took five reference points from the mymidnite logs and compared input and output data from the classic. I have a spread of both high and low power to try and confirm a gain issue.
6:56AM, Input 66.1v at 7.9A , Output 52.1v at 13A, 522w in VS 677w out 29% discrepancy
7:33AM, Input 65.9v at 34.2A, Output 56v at 51.8A, 2253w in VS 2900w out 28% discrepancy
8:10AM, Input 61.9v at 15.2A, Output 55.4v at 21.8A, 940w in VS 1207w out 28% discrepancy
9:06AM, Input 74v at 15.8A, Output 59.9v at 25.1A, 1169w in VS 1503w out 28% discrepancy
9:24AM, Input 73v at 13.3A, Output 60v at 21A, 970w in VS 1260w out, 29% discrepancy
So its looking very consistent even with a range of output levels, I always come up with 28-29%.
Kurt
OK, so turn up that trimpot ! Do you remember which one it is ?
Ooops ! I should say, turn it down !
boB
Yes I have your old instructions handy and will adjust the trim next Saturday 14th. I just wanted to be 110% sure it was a gain issue before fiddling with the trims.
Just hope its a nice clear day so I have a nice stable - steady PV input while I am tuning.
kurt
Ok,
I removed the front panel from my classic 150 today and tried to sort out this calibration issue. With a tiny flat head screw driver I began to Adjust the ( B gain pot) It dose absolutely nothing. I even turned it fuly left and then fully right over its full sweep (about 1/2 a turn). :-[ So somethings going on.
Next, taking note of the exact position of the( PV input gain pot) I Turned that pot ever so slightly Just to see if a got any reaction from that one. I got a immediate change/response to the input amp reading on screen. I put the input pot back to were it was. Something is wrong with this classics on the output shunt side. I think its now way beyond my tinkering ability. :o
Lucky for me I had a 2nd brand new classic 150 sitting in its box in the garage, ready for another install. So I thought why don't I just swap it out for the old one and see what it reads. After installing and powering up the new classic. It matches the WBJR shunt readings 100% spot on perfect. :)
All my current measuring devises agree with each other and the new classic. From how the new classic is performing. It looks like they do usually come well celebrated from the factory. I guess I just had some bad luck with the old one. No wonder I have been very puzzled by some of the data I have collected over the past year given it was roughly 30% out.Bummer it isn't fixable with the trim pot.
Ok, so now what do I need to do to get the old one sorted out. Do I just contact the local suppler I purchased it from ?
edit:
I have a concern regarding the new classic i swapped out for today. It might be calibrated perfectly and showing the correct output numbers (I'm happy for that) but its making some real strange and loud noises at times. It sounds like a 56k modem on steroids. Is something wrong with this one to? It's really loud and high pitched and coming form inside the classic (not the speaker). I don't remember the old one doing this. I took a little video and put it on Utube.
Link to video strange noise.http://www.youtube.com/watch?v=Ef0LdL7u11c (http://www.youtube.com/watch?v=Ef0LdL7u11c)
Kurt
Ok the noise is low max. If the PV voltage is down close to battery the inductors "Sing" this is ok unless the noise bothers you. If the noise bothers you go into tweaks and turn LMX to Off.
On the first controller email me and I will do an RMA and get it back and fixed right up for you.
ryan@midnitesolar.com
Oh that's good news then. The classic is housed in the power room outside. So only the local wild life , snakes, kangaroos that wonder by the outbuilding will get tinnitus from it ;D I just switched lowmax of via the local app and will see how it works out first light tomorrow.
Thanks for the contact details. I just sent you a email.
I just gathered up the original box and packaging from the old classic. My 6yo daughter found it while I was in the power room and thought is was a nice box to be creative with and draw all over with a marker pen. Who ever opens that one up will get a good laugh.
Kurt.
First light this morning the new classic is now totally silent :) turning off low-max last night fixed it as suggested.
Kurt.
"On the first controller email me and I will do an RMA and get it back and fixed right up for you."
Just wanted to follow up on the issue I had with my old classic 150 (output readings not correct some issue with output shunt. I was unable to rectify it personally through pot adjustments)
I sent the above classic back to DC solutions Australia with a small note explaining the issue. I received a new classic in the mail today - just over a week turn around :) The note to me with the new classic confirmed the old classic was tested and had a issue and new classic was also tested all ok and sent out.
So I just wanted to say I am very happy with how this issue has been sorted out right from the diagnosing the problem through the forum to warranty replacment through the local distributor. Couldnt have asked for more. I have always had the view that sometimes things just happen. It's not a matter of if problems happen but it all comes down to how they are handled if they do.
Kurt
Excellent news !
Wonder exactly happened with that ? It was obviously "off"
Maybe we'll see it back here and see what happened. I'll ask Mat in the back to
keep an ear out for it.
Yes it will be interesting to see what it turns out to be. It was way out 30% over in its output reading from the very beginning. It just wasn't fully investigated and confirmed until I installed the WBJR .
Speaking of the new replacement controller. It's a Jan 2014 model . I noted some nice changes for the better in this latest generation of the classic.
At the rear you can now remove the fans on a separate aluminium plate for easy service (dont remember that on my old classic or the one 2nd one i purchased last year). The 2nd improvement I notices it the main terminal block. The terminals are much larger then my 1st classic and even larger than the 2nd classic I purchased mid last year (that has slightly larger terminals). The new shape of the terminals is more square and a copper finish. Great to see the improvements .
Kurt