Another End Amp Absorb problem

[SolarMusher]

Hello guys,
First post on this forum.
Could someone tell me if the End Absorb issue has been fixed, or if it will be fix only in the next firmware?
Thanks,
Erik

[Vic]

Hi Erik,

I am just a Classic user.  I've seen nothing regarding enabling the EA function.

The last FW posted on the MN site is dated 4-29-12:

http://www.midnitesolar.com/firmware.php

It is quite possible that the EA function will be included with a major FW revision ...  again,  I know nothing specific.  Would love to have that function,  too.

Vic

[SolarMusher]

Hi Vic,
Thanks for your answer.
I've seen on a post that Bob was talking to fix this problem in May.
Of course, it's not easy to manage a battery bank (830Ah @ 48VDC) with only the Absorb time and light discharge in Summer.
My BMK shows 10-15A positive every sunny day even if I set it with just 1 hour of Absorb time and steady loads (freezer and refrigerator).
Hope it's going to be fixed soon, may be Bob could tell us when he thinks that we could have this revision  .
Erik

[boB]

The EA has been fixed and will be part of the next release in hopefully, just a few days.  Less than a week I'm pretty sure.

There were a few little things that needed some attention and we were waiting for those changes to be done before releasing
the next.  We could have just released the fixed EA but  we don't like to release lots and lots of versions if we can
help it as we need to test each one pretty thoroughly first.  Bugs always seem to show themselves as the software
gets more complicated.  It just seems to turn out that way.

boB

[SolarMusher]

Hello Bob,
Happy to hear that this will be fix soon, I have two Classic 200 to install in the next weeks and it would be great to have EA and Time in order to be sure my custommers not overcharge a little every day.
I understand that you could not release a lot of version for just a few change.
Vic, did you mount your Classic with 300VDC breakers or did you keep it under 150VOC?
It's not easy here in Quebec to find 60 or 80A 300VDC panel mount breakers, don't know why at this time my supplier just want to sell 300VDC din rail breakers. Bob, is there a reason? Personnaly, I prefer to install all Classic breakers in panel mount slots and to keep din rail slots for loads, BMK, AGS.
At least, is it safe to use two 60A 150VDC (Panel mount) to make a 300VDC breaker?
Thank for your answer.
A+,
Erik

[Vic]

Hi boB,

Thanks for the info on the EA update.  Boy,  as an end-user,  I prefer to have somewhat fewer updates.   Have a Hammie Radio,  where there was an update every few days or so,  and it was almost impossible to keep up.  AND,  it kinna made the radio appear a bit "unstable".  So think that you are doing the correct thing,  not even counting the need for you folks to do all the testing on a new rev.

Erik,  you are  a true Musher -- 50 dogs in waiting.

On the Voc,  have not done any system with Voc over 140-ish V at this point,  so 150 VDC breakers have been fine.  Agree,  I prefer the Panel Mounts over the DIN Rails  for CC PVin and Batt breakers.

Here in USA,  the HomeBrewed 300 V breaker from two 150 volters,  ganged would not fly technically,  but may work well.  Bet Robin has thoughts on that.  Altho,  many AHJs miss the fine detail,  but that is a crap shoot on what one AHJ might notice.

Anyway thanks boB,  for the info on EA,  am charging the lap-top now!  Vic

[SolarMusher]

Hi Vic,
In the past we had up to 90 sled dogs around the cottage, we lived off grid far north ten hour from Montreal. It was great! We had to drill hole with chainsaw two feet width in the ice to have water in winter. I bought my first solar panel and pump at this time...
With an old Trace DR we were able to run a few appliances and tools, it was heaven...
Thanks guys
A+,
Erik

[plongson]

Erik. Vic, boB

I too get (+) positive amps on the BMK everyday. They seem "hollow" because as soon as the sun goes down, the BMK very quickly goes to 100% then slowly starts it's nightly drop. I never really understood what is going on...

So, when we get the new release with EA, is the game plan to watch the BMK hit 100% and check the SG to make sure it's up to spec. then adjust the EA to stop the absorb at that point? In theory it should work both winter and summer correct? Or is this something that need attention a couple of times a year?

BTW, I have three dog's that would piss in the house if they could when the snow fly's... Their legs are so short their junk drags and I kind'a see their point though...LOL (Two Chihuahua's and a JRT)

[boB]

Regarding Ending Amps Absorb to Float transition, just realize that the Classic does NOT know that actual current in to the battery itself as there may be other loads across the battery taking current from the Classic.

I Love the dogs !

boB

[Volvo Farmer]

I was thinking about this the other day. Seems End Amps is not a very useful measurement for anyone who is powering any sort of house with variable loads off grid. Yet it also seems that End Amps is a better way to determine the end of an Absorb cycle than voltage.

I know the list of requested improvements is never ending, but wouldn't it be a relatively simple thing to have a charge controller look at a shunt across the main bus and compare that amp reading to the charging amps to determine actual end amps into the battery?

[SolarMusher]

Hi Guys,
Totally agree with VolvoFarmer. Of course, EA is not perfect but it could help to be more accurate, it couldn't be worst than just using a fixed Absorb time (1 or 2hr) in summer.
Paul, in Summer you could try to lower your Absorb to 57.6/58.4, 1 1/2hr (check your SG) and set it to 58.8/59.2 2hr-2 1/2hr for automn/winter.
Bob and Paul, if you like dogs and need a breath of fresh air take a look at : http://www.chiensdetraineauquebec.com/commun/album/Baie_James/index.html
A+,
Erik

[vtmaps]

but wouldn't it be a relatively simple thing to have a charge controller look at a shunt across the main bus and compare that amp reading to the charging amps to determine actual end amps into the battery?

I have no idea how simple that would be.  FWIW, Outback systems can do that.  I think I read somewhere on this forum that Midnite plans to do this also.  --vtMaps

[vtmaps]

At least, is it safe to use two 60A 150VDC (Panel mount) to make a 300VDC breaker?

You mean wire them in series?  I don't think so.  They would have to trip simultaneously to be safe.  In reality, one will trip before the other and would then have to interrupt the entire 300 volts.   --vtMaps

[Vic]

Hi Erik,

Just saw this Panel Mount Breaker from MN that is available in 60 A and 80 A 300 volt sizes:
http://www.midnitesolar.com/productPhoto.php?product_ID=271&productCatName=Components - Breakers&productCat_ID=16&sortOrder=14

EDIT:  OK,  guess that I do ont know how to do a direct link to an individual item on the MN site,  so use the above link and select " Components - Breakers "  and locate this item:
MNEDC60-300, MNEDC80-300

(perhaps the link is too long ...   VB)
Retails at $40 US.

And YES,  vt,  that was the "ganged" reference in the fifth REPLY was meaning.  But,  looks like MN has done it,  and it is ETL listed.
Have fun Mushing,  Erik.     Vic

[Vic]

vf,

For my personal off-grid systems,  use EA any time I can.   And its suitability depends on the nature of the loads on the battery bank at the time where Asorb should be ending.

There are not many choices in just how to end the Asorb stage -- TIME is one,  as the VOLTAGE is fixed due the the setting in charger voltage menu ...  EA is the other,  but the CC cannot know how much current is going into the batts,  and how much is Inverter (and perhaps other) loads.

IMHO,  the most problematic loads are those that are large,  and run for a long time period.  Also,  larger battery banks are better able to deal with the effects of these loads (generally),  as a larger bank responds more slowly to the CC staying in Asorb too long,  resulting from a largish load causing the CC to believe that the BATTERY is accepting all of the current sent toward the batteries.

Intermittant largish loads,  like an A/C or heat pump cycling is usually not a problem here,  if it cycles on and off,  every few minutes.  A hair dryer could be a problem if it runs for 20 minutes,  or so.   Pumping water from a deep well into a large-ish storage tank would be a problem,  as this can easily require hours of run-time of a large pump load, quite possibly causing a CC to hang in Asorb hours too long.

vt,  I am certain that the OB CCs CANNOT measure an external Shunt (in the neg lead of the battery bank) directly.  The EA function on Net battery charge current in the OB system,  requires their Battery Monitor -- FNDC,  and the correct Mate to Monitor and End the Asorb on Net charge current.  Know that you know this,  as you were invlolved in discussions on the OB site and one other,  and you pointed out some errors in my posts -- just trying to make clear the requirement for additional hardware/FW on the OB system.

Believe that MN has made clear their plans to have a BM function in their product line in the future.

It WOULD be conceivable that a CC could have the ability to monitor an outboard shunt in the negative battery lead,  allowing the CC to EA on actual Net battery charge current.   Vic