I have some new batteries to replace my failed ones. They are not idea but were very cheap second hand.
They are 12 volt AGM and 100AH so I will have to have 4 parallel strings of two batteries =24volt 400AH. Not the best design but I have 20 batteries to play with.
The float voltage is 2.25-2.3vpc
Cycling 2.35
Max 2.4vpc
I'm not sure how these figures translate to the Midnite 150 settings.
There are in an offgrid system.
Can someone translate please. I guess cycling is float?
Thanks,
you may find the info here useful...http://www.cdtechno.com/pdf/ref/41_2128_0212.pdf
Hi, thanks for the link. I'll have a read. It looks quite technical.
My problem is I'm installing the replacement batteries this weekend at our remote farm and won't be back for a few weeks. I'm hoping to get the figures correct so the batteries aren't boiling away which happened to my previous batteries.
If in doubt, I'll leave them disconnected.
Thanks,
Hi asdex,
I am NO expert with AGM batteries, But, AGMs, fairly often have an Absorb voltage that is speced for batteries that will spend 99.9 or so percent of their sitting at the specified Float voltage, provided by Grid power.
For off-gridders, we Cycle our batteries daily or almost so. So, the 2.35 VPC for Cyclic use, is what one would use for off grid, or perhaps for Grid Backup power, where the batteries are cycled daily or nearly so.
Be certain that you use the BTS on half-way down the side of one battery, near the center of the pack. But with four parallel strings, there could well be some variation in battery temperatures across all of the batteries in the bank.
It IS very good news that you are not planning on running ten strings of two batteries.
Hope that you do have a Clamp DC Ammeter, as you will probably want to measure how well each string of batteries are sharing charge and discharge currents.
Make certain that you set the recommended Temperature Compensation value, in the Charge menu, and so on.
EDIT to add that 2.35 V X 12 cells = 28.2 Volts ...
Just some general comments from a non-expert. Good Luck, Vic
Thanks, that's good advice I can use. I'll take a clamp on tester with me. I can hopefully get the string resistance similar using the charge current as you suggest.
My current bank was 440 AH and running a fridge and freezer though the night took it down to around 90% (10%DOD) and it was usually back to 100% by 10am.
If I can I'll only use 3 strings.
The classic uses bulk, absorb, and float. which voltage would the cycling be? Bulk?
Thanks,
Quote from: asdex on July 11, 2016, 10:29:59 PM
... The classic uses bulk, absorb, and float. which voltage would the cycling be? Bulk?
Thanks,
Hi asdex,
That 2.35 Volts Per Cell -- 28.2 V will be the Absorb voltage. Would suggest that you use about the center of the stated Float voltage range (about 2.27 VPC) X the 12 cells as a starting point for your Classic Float voltage setting.
Does this make sense? Vic
Yes that looks good.
Absorb 28.2v
Float 27.24v
Bulk would be the initial charging rate which would be under the max of 28.8v so maybe 28.5v?
These are pretty precise voltages so I'll need to check battery voltage with a meter and adjust the controller offset.
I have done this before but didn't get consistent results. The voltage error changed at different voltage from what I remember.
Hi ascex,
Most Solar Charge Controllers, like the Classic, have NO setting for a Bulk voltage, so there is no setting for Bulk voltage.
And, YES, we have one tenth of one volt resolution in setting voltages, so, why not start with a Float voltage of about 27.2 V.
If you have a good, accurate voltmeter, then you should check the accuracy of the Classic's voltage readings, verses what you measure with your meter.
Good Luck with the new batteries. And, again, I am not an expert, especially with AGM batteries. Vic
Thanks, I'm only working from memory as I have been overseas for three months but I'm sure it sometimes says bulk on the display. I see in the manual it's also mentioned:
Bulk MPPT
This stage of the Classic means; that the Classic will be putting out as much current as it can trying to
charge the batteries to the absorb voltage set point. This is also known as constant current mode.
Battery
Voltage
12v 24v 36v 48v 60v 72v
Bulk MPPT 14.3v 28.6v 42.9v 57.2v 71.5v 85.8v
Float 13.6v 27.2v 40.8v 54.4v 68.0v 81.6v
Equalize 14.3 28.6v 42.9v 57.2v 71.5v 85.8v
To adjust these voltage set point see page 25 of this manual.
Asdex, have a read of this thread, http://kb1uas.com/mnsforum/index.php?topic=2563.15....
The thing to watch for is the sharp rise and then leveling off (maintaining) of the voltage and dropping of current which is what is supposed to happen... the sharp jump is/can be caused by the batteries internal resistance.. there are several graphs in around posts 30 and 56 or so....
hth
Thanks, will have a read tonight.
Cheers,
Quote from: asdex on July 11, 2016, 11:52:10 PM
Thanks, I'm only working from memory as I have been overseas for three months but I'm sure it sometimes says bulk on the display. I see in the manual it's also mentioned:
Bulk MPPT
This stage of the Classic means; that the Classic will be putting out as much current as it can trying to
charge the batteries to the absorb voltage set point. This is also known as constant current mode.
Battery
Voltage
12v 24v 36v 48v 60v 72v
Bulk MPPT 14.3v 28.6v 42.9v 57.2v 71.5v 85.8v
Float 13.6v 27.2v 40.8v 54.4v 68.0v 81.6v
Equalize 14.3 28.6v 42.9v 57.2v 71.5v 85.8v
To adjust these voltage set point see page 25 of this manual.
Hi asdex,
Must say that I've never seen that reference to any BulkMPPT voltage setting, and look at the Menu Map on pp 85 of the 2056 version of the Classic manual. Under "Charge" there is no place to set BulkMPPT voltage, but the customary Absorb voltage does have an entry.
Furthermore, with "BulkMPPT" , the MPPT suffix means that the Charge Controller has NOT reached a voltage setpoint (where the voltage would be maintained), additionally, there does not appear to be a way to set the Time for this Bulk voltage to be maintained, as is the case with ALL (EDIT OOOppppssss obviously (even to me, at times) that Float does not have a time parameter) other voltage regulating stages -- Absorb, and EQ. Although, it could be possible that if there WAS a Bulk voltage setting, that it could run for a fixed length of time, I guess.
IMO, you have found a slight error in the Classic Manual ... on page 32 of the 2056 manual there is the how to set the Absorb, Float, and EQ voltages, but nothing for Bulk voltage ...
FWIW, Thanks, Vic
Hi Vic, thanks for your reply. It looks like I have all the info I need then to program the charge controller. I understand what you saying regarding no settings needed for the bulk charging. I'll have a further read of the manual and make sure I have the latest one although I think my controller needs a couple of upgrades of the software.
Bye the way my water heating using waste not high is working very well. I have also used SOC to turn on aux 2 which activates a SSR to put battery power to a 24 volt element. The 40 gal tank takes about 9 hours to heat. In summer, no other water heating is needed for us.
Cheers,
Hi asdex,
Yes, you will want a Classic manual at the site. One that matches the FW version in the Classic will be a bit less confusing, probably. Documents, including Classic Manuals are on this page -- choose the CC that you have, and then, scroll to the manual that best suits your needs:
http://www.midnitesolar.com/doc_prod_list.php?menuItem=products&productCat_ID=21&productCatName=Charge Controllers - Classics
When you feel the need to Update the FW, if you have never done it before, it would be a very good idea that you have some way to access this Forum, if needed during the Update. Hope that you have the Net at your Solar powered location.
Saw your Post about WasteNot doing a great job heating water. The Classic is certainly a very flexible and capable CC.
Have fun, and good luck with the battery swap. Vic
Hi, I have my 6 Haze batteries in and going now.
One thing I'm not sure about.
The are in float but at 97% capacity.
Battery voltage is 27.6v
From the PV panels are 85.5 v and 22 watts.
there is 0.8 amps going to the batteries. This is all from the Classic screen.
I though it would be taking the batteries up to nearer 100% before it went to float.
I have the absorb voltage set at 28.2v and float at 27.2v.
I set the AH in the WBjr screen to 300AH
on Saturday the batteries had been on float for about 5 hours but were still at 98% capacity.
On Sunday morning the batteries were at 90% so I think they are not charging up enougt.
My version is 1849 and mngp is 1821. Should I update thsi?
Thanks,
Hi asdex,
Great that you have gotten some of those AGMs on-line.
As you probably know, cool battery temperature (as measured by the Battery Temp Sensor -- BTS -- that you are using, we hope), will reduce Capacity, and increase Float voltage. If your batteries are a bit cool, and you are using the BTS, this could explain both the Capacity and Vfloat.
The Remaining Capacity, is the Temperature compensated Capacity that the battery has presently, based on the Parameters that you set in the WBjr Setup.
Did you set the "WBRST" to "YES" in the Tweaks > more > more > more > more screen? This should set the SOC to 100% the moment that the Classic makes ITS transition to Float.
Also, when you mentioned that the Classic charge stage was Float, it was NOT in Float MPPT was it?
More Later, Thanks Vic
Hi Vic, thanks for your reply. Yes it was about 10 degC and I am using the battery temperature sensor.
I'll have to check the WBRST when I'm there next in a couple of weeks. I'll try and remember and I have pictures of most screens.
The Float was just float as in the picture. This picture was at 97%
I see in my pictures I have absorb time at 2 hours and efficiency at 95%
I couldn't get internet last time there but should have it sorted for next time.
Try leaving space between batts. 4 airflow. Also recommend firmware update:-)
George
OK asdex,
Hope that you can get the Internet working at your cabin.
Would strongly suggest that you have reasonably reliable internet access at the site before doing a Firmware Update on the Classic, especially if the computer you are using for the Update has not previously successfully done a previous UD. With the recent Win 10 Updater, some of this may have changed, but, still having access to this Forum may be very helpful, if the update does not go perfectly smoothly.
Have not used it, but the Local App has the ability to remember all of your customized settings in the Classic, and return them to the Classic after the required VMM (Reset Classic & Restore Factory Defaults).
Good luck, Vic
Hi, I'm able to head up to our cabin this weekend. I won't do the update at this stage though until I have the battery system working ok.
I had a reply from Haze who say to increase the absorb voltage to 29.4 to charge them faster and also to equalize them monthly.
I don't think you normally equalize AGM batteries but they said to do this as these type I have are actually designed for UPS use.
I can't complain as they were $1 each and are 3 years in to their 12 year lifespan(on paper anyway).
I'll check the other settings and do a download of the settings list as well.I have used the local app when plugged into the Classic directly but haven't got it running over Wifi yet.
Cheers,
Azdex, how far is it between the CC and the WiFi router? I think if it is close enough you might be able to connect the CC to the router and then WiFi to the computer , rather than using a bridge device ...
hth
Hi, the router is about a meter away. I can configure it as a wireless bridge too. I haven't spent alot of time on it as the app works ok when plugged in but its not as comfortable as sitting inside monitoring.
Cheers,
great, I monitor from upstairs and the bank is in the basement.... batteries in NE basement corner and WiFi in the SW corner of the attic area
Hi, the batteries are working alot better now. In the morning they are at about 91% SOC. I expected this as I have gone down 100AH in capacity. I connected my laptop and downloaded the log file as well.
I have the absorb voltage at 29.4v and float at 27.6v. They are going to 100% capacity now.
I don't think it will be a problem running to 91% as it is the middle of winter. I may replace my 12v Air-X wind generator with a 24v one which will help.
I am hoping to keep away from having four parallel strings in my battery bank.
Cheers,
Hi asdex,
Thanks for the Log File info.
Never look at this stuff, BUT, the way I read it, looks that your EQ voltage is quite high for AGM batteries ... IIRC 31.4 or 31.6 V. Do you want an EQ at this high a voltage?
At the very least, would set the EQ Time from 60 minutes, to 00 minutes.
Looks like a cool climate batteries around 6 degrees C ...
Thanks, Vic
I have mine set to Absorb voltage...
Hi, yes it is high and I didn't think you should equalise AGM batteries anyway but advice from Haze says to do this and voltage is below:
Graham
It is normally done at constant current and unlimited voltage but if you have to set a voltage limit - 15.8V
Regards
Nick
I have equalising off at the moment and will do it on manual each month as advised. The difference here is I'm using UPS batteries in a cycling situation which isn't normally done.
I have just bought an Air-X 400w wind generator and any advice with incorporating it into the system would be helpful. I can adjust the cut out on it but it's going to clash with the absorb voltage.
Diagram attached:
Cheers,
I have AGM's & they DO say to Eq them once a month , mine are CDN made units & the specs are 2.35VDC/cell eq & 2.30Vdc/cell float .AH is 1020/Cell @ 2Vdc
Massive weight
VT