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1
Okay good news!  So this issue with the Battery AHs reading much too low was basically what Vic had suggested, a battery temp issue.  Vic you had asked me if my sensor was adhered to the side of the battery and I said that it was stuck onto the battery* but actually it was being pinned down by one of the cables to the top of a battery. So this afternoon, when I went to actually tape it on properly I noted that the AHs were still not quite at 400. When I took hold of the sensor, just holding it in my hand for a couple of seconds caused the AH Status display to go instantly to 415 AHs!  Wow.  So I guess I must possess super powers?
Ha ha, so I taped it nice and snug with gaffers tape to the side of one of the batteries and in about 2 minutes the Status window read ~~ 400 AHs.  ~~~ ;D ;D ;D

What a surprise, operator error strikes again...   :o


*I lied!
2
B17-5 and B17-3 / Re: Inverter droop?
« Last post by boB on Today at 03:28:51 PM »
Hi Bob,

Thank you for your reply.

I will have to think about what you wrote to understand what you said. What I understand is that there are a few methods of having grid tie inverters cut back. My Magnum 4448's do some kind of frequency shift. It does not act to regulate the output of the AC coupled inverter incrementally however if I understand how it works correctly. What the Magnum seems to do is a step change to shift the frequency in order to get the AC Coupled inverter to disconnect fully, based on battery voltage. Then after the battery voltage drops it shifts the frequency back to allow the AC Coupled inverter to reconnect. On / Off control to me is far less than ideal.


You got that right !  Far from ideal !  BUT it is s quick fix for over-charging the batteries and also over-AC-voltaging connected appliances.

I can see how a DC  inverter/charger which changes the frequency in proportion to the load would work similarly to the Australian voltage system, assuming the AC coupled inverter used the frequency shift to also vary it's output incrementally as the frequency shifted. I suppose if a suitable frequency sensing device is available then once again a diversion system could be controlled using frequency.

I think I like that idea.  The GT inverters of course have that sensing.  They have to.

So the question remains but changes: Will the new Midnite inverters be capable of something like this to allow them to be used for AC coupled off grid systems that would cause the AC inverter to reduce it's output proportionately? If it is just a matter of programming then to me it would add value to this product. I appreciate that the design, fabrication and certification process has likely taken far longer than Midnite could ever have imagined. As we used to say in the pulp industry when estimating how long a project would take: Double it and add 4. Likely this would not be a good time to divert resources away from what is going on the bring the new equipment to market however maybe if the units do not have this capability now it could go on a list for later.

Thank you.
Will

Yes, of course we will make sure we design in any of these methods that make sense....  And what we have talked about there definitely make sense.

Also, you are absolutely correct about the design fabrication and especially certification takes time and money.

Certification itself for all of these new products we are working on will end up costing hundreds of thousands of dollars.

Some refer to these outfits as the mafia, LOL.

boB
3
Hi Lisa,

It is good that you are checking individual battery voltages.

With parallel strings,   things can get a bit more complex.  As an example,   if one string has a higher SOC  than the other   (which would mean that the higher SOC string would have a higher string voltage,  were it not for the other string),   so the higher SOC string begins charging the lower SOC string,  when there is no other charge source.   This will reach equilibrium over time.   A long Absorb time,   on occasion,  can help bring each string,   and each battery into closer balance.  This is what some AGM manufacturers call an EQ charge on this type of battery.


When trying to Rest a battery to determine its SOC,   a customary Rest period is about 12 hours.   And  in systems with parallel battery strings,  one would really want to separate the connection that parallels each string.  Early in this Thread,   that was where the suggestion of possibly having a battery switch that would allow separating strings,   resting one to determine its SOC,   then,  resting the other within a day or so. This would allow determining the actual SOC of each string,  and each battery in a string.   This would require data from Renogy for the battery voltage vs SOC,   and,  ideally the temperature compensation factor of this Resting voltage   ...

Your Ah Efficiency setting of 94%,   is probably a good place to start for AGM batteries,   which are considerably more efficient for charging than are Flooded batteries.

Since your system is for Grid backup,   and it appears that you are not discharging the batteries very deeply,   that you might be able to avoid recharging the batteries every day.  The Classic has the ability to Skip Days,   between full recharges.

Some backup systems with AGMs  spend almost all of their time at Float voltage.

For best results,  you would probably want to consult Renogy,   about just what they recommend for battery charging,   given the way that you are using them.

We are located in San Joaquin County,   at about 3,000 Ft,   nominal elevation.   It will get warm in the next few days,   but,  we have had a very nice Spring,   this year.

FWIW,    Enjoy the WX,    Vic
4
The "Classic" charge controller / Re: How to Monitor Classic 200SL
« Last post by justinbowser on Today at 02:27:22 PM »
I have attached this "pile-o-stuff" up to the classic and the Classic Local App does not connect, indicates 'Device not Available"  Is there something in the Classic setup I need to change?  I can ping the ESP32 and get into the configuration screen via the device IP address so I'm pretty sure the network portion is working ok.

I am talking to the ESP32 by using my cell phone as a hot-spot/router.  Would this make a difference?  Do I need to get a cheapo WIFI router to connect to this thing?
5
Thanks Vic.  What about checking the individual batteries with a multimeter?  Do you guys ever do that and can that be useful?  I do check mine all the time, although, I've read that the only proper time to do so is after the batteries have been at rest for several hours. But I don't see why checking them directly anytime you like isn't helpful...?

Oh, btw, I think I do have the latest firmware, updated 2/06/18.

Anyway, happy memorial day everyone. Hope you're all seeing incredible weather as we are in the bay area today. 

Lisa
6
Hi Lisa,  OK on the Reset that you wanted to do  …

Forget if the Renogy monitor had a BTS,   but if it did not,   then this could be the difference twix the Classic and it.

With AGMs,   (because the actual SGs cannot be directly measured),   SOC readings can be more important than for Flooded batteries.

BUT,   any SOC readings on any practical monitoring device are just approximations,   as there are SO many variables that our monitors cannot/do not take into account. The largest of which is the Peukert  effect.   This is where the amount of Remaining Ah,   and therefore SOC will vary,   based on the (current) Rate at which the battery was discharged,  on average.   There are many other factors,   SO,   IMO,   SOC readings may not be too accurate.

Have asked Renogy several additional Tech questions,   to which they have not yet responded.  One of which was for info on Resting battery voltage vs SOC,   and temperature.  This could help you better-determine the actual SOC of your batteries.

Later,   sounds like you continue to get your system dialed-in. Good work  !!
Vic
7
Hi Vic, thanks for weighing in!

Yes I do have the reference temp set at 25 deg C. Sensor is right on the battery now.  So, the charge cycle happened about an hour ago and AHs were at 385. Seems awfully low. But as with yesterday the number seems to be on it's way up. Now it's 386. Yesterday it got to 395 by the afternoon, and the battery was at 23.7 C.  (I have that temp compensation setting at 1%).

As to clearing the daily net amps, yes, I was able to do that but the problem was, I couldn't clear the negative AH and positive AH history.  Well, until just a few minutes ago! After a lot of searching I finally discovered how! 

To reset the entire cumulative amp hour history you have to go to the Logs window, press enter and when the logs window shows up press ENTER again and make sure you press it hard.  A "Clear Log: UP/DOWN chooses" selection will appear and then you  have to press the UP arrow to bring each selection out one after the other. For me the UP arrow button had to be pressed repeatedly till I got to selection 7 which read:  Clear entire NEG AMP history.  And then I pressed enter.  And that did it!!!   ;D

(Anyway, I wanted to write that out so that someone searching this topic could see it.)

So everything seems okay now except the AHs reading seems low to me. My Renogy monitor always showed the battery bank at 400 AHs when Float was reached in the morning.  So.... Not that I don't like the WBjr waaaaay better...  I definitely do, but I need to understand it.
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The "Classic" charge controller / Re: How to Monitor Classic 200SL
« Last post by justinbowser on Today at 11:42:52 AM »
Graham - or should I call you Mr. Wizard? - that worked perfectly!  I have the ESP32 flashed and configured and now just need to make the cable.  I can't thank you enough and I will update as soon as I make the cable and get attached to the classic!
9
Hi Lisa,

The Remaining Ah reading will be reduced from  100% (400 Ah),  if the battery temperature is below the Reference temperature (usually 25 degrees C).

Here is how to Reset Net Ah:

The Net Ah and SOC can be reset  Manually from the Classic MNGP front panel.   Push the left small round button on the display (IIRC,  this is the Status Button),  about four times (from the Main Status page)  --  this takes you to the WbJr Status screen.  Press the Left Soft button (square one,  upper left).  This takes you to the Net Ah screen.  Hold down the left Arrow button,  while pressing Enter.  (it may take a second or three,  but,)  This should reset the Net Ah to 0,  and the SOC to 100%.

Also,  long ago,  IIRC,  you mentioned that the Classic Battery Temp Sensor (BTS),   was suspended near a battery (or similar).   If this BTS has not been attached to a battery,   please do so now.   Normally the BTS would be stuck about midway down the side of one battery,  in the inside center of the battery bank. Having the Classic able to do its best job possible in measuring the actual battery temperature,  is important,  especially with AGM batteries (which are very sensitive to accurate charge voltages).

Later,  Vic
10
B17-5 and B17-3 / Re: Inverter droop?
« Last post by WillEert on Today at 09:22:17 AM »
Hi Bob,

Thank you for your reply.

I will have to think about what you wrote to understand what you said. What I understand is that there are a few methods of having grid tie inverters cut back. My Magnum 4448's do some kind of frequency shift. It does not act to regulate the output of the AC coupled inverter incrementally however if I understand how it works correctly. What the Magnum seems to do is a step change to shift the frequency in order to get the AC Coupled inverter to disconnect fully, based on battery voltage. Then after the battery voltage drops it shifts the frequency back to allow the AC Coupled inverter to reconnect. On / Off control to me is far less than ideal.

I can see how a DC  inverter/charger which changes the frequency in proportion to the load would work similarly to the Australian voltage system, assuming the AC coupled inverter used the frequency shift to also vary it's output incrementally as the frequency shifted. I suppose if a suitable frequency sensing device is available then once again a diversion system could be controlled using frequency.

So the question remains but changes: Will the new Midnite inverters be capable of something like this to allow them to be used for AC coupled off grid systems that would cause the AC inverter to reduce it's output proportionately? If it is just a matter of programming then to me it would add value to this product. I appreciate that the design, fabrication and certification process has likely taken far longer than Midnite could ever have imagined. As we used to say in the pulp industry when estimating how long a project would take: Double it and add 4. Likely this would not be a good time to divert resources away from what is going on the bring the new equipment to market however maybe if the units do not have this capability now it could go on a list for later.

Thank you.
Will
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