Hello all,
I got 6 * 320w solar with 24v deep cycle battery bank(4 of 6v US REL16 XC) and Midnite 150 classic charge controller. My question is about the Whiz Bang Jr. capacity reading. The whiz bang jr.. show the remaining battery charge is %65 while the battery voltage is 23.6v. That doesn't sound correct to me. I'm wondering if those readings are accurate or not? Please see attachment.
Thank you !
Is that Graham's Android version of the Local App? it sure looks like it.
You either have to use the MNGP or the MidNite Local App for windows to set the battery and charging parameters. Did you set those?
You can not do it with Graham's App!
Quote from: Westbranch on July 21, 2018, 04:17:05 PM
Is that Graham's Android version of the Local App? it sure looks like it.
You either have to use the MNGP or the MidNite Local App for windows to set the battery and charging parameters. Did you set those?
You can not do it with Graham's App!
Yes. Its Graham's app. I'm using this app to view the numbers. I already set things on the charge controller using the charge controller panel.
Do you have a PC so you can use the Local App, as it is much easier to review and set/reset any value
IIRC you can see all the battery factors on one 'page'...
If they are new batteries you need to cycle them a few times first to break them in to their full capacity. Vic has talked about that in other forum posts.
What do you have set for the capacity and the efficiency for the Whizbang settings on your batteries ?
When the batteries get fully charged ( to their Absorb setpoint for either Absorb time or ending amps if you have that set ) when they go to float the SOC will go to 100%/
So if you have not fully charged your batteries then the SOC will continue to go down as will the voltage too.
So the question is have your batteries received a full charge ? Also have you confirmed testing batteries electrolyte to find out if they are fully charged to 100% that specific gravity is at manufacturers point of full charge ?
The whizbang SOC is only accurate if you set it up correctly and sometimes it needs tweaking as the batteries age too. But yes it can be a very good estimate of where the batteries are at for SOC.
Larry
was that voltage reading under load or with no load? ..
Quote from: Westbranch on July 21, 2018, 09:04:50 PM
Do you have a PC so you can use the Local App, as it is much easier to review and set/reset any value
IIRC you can see all the battery factors on one 'page'...
Yes, I do have the local app. It's great ! both apps are reflecting the same numbers though. I only like the android app cause I can check on the system while am anywhere in the world.
Quote from: ClassicCrazy on July 21, 2018, 10:11:23 PM
If they are new batteries you need to cycle them a few times first to break them in to their full capacity. Vic has talked about that in other forum posts.
What do you have set for the capacity and the efficiency for the Whizbang settings on your batteries ?
When the batteries get fully charged ( to their Absorb setpoint for either Absorb time or ending amps if you have that set ) when they go to float the SOC will go to 100%/
So if you have not fully charged your batteries then the SOC will continue to go down as will the voltage too.
So the question is have your batteries received a full charge ? Also have you confirmed testing batteries electrolyte to find out if they are fully charged to 100% that specific gravity is at manufacturers point of full charge ?
The whizbang SOC is only accurate if you set it up correctly and sometimes it needs tweaking as the batteries age too. But yes it can be a very good estimate of where the batteries are at for SOC.
Larry
Hello Larry,
Thank you for your reply.
Those batteries are one year old. I haven't set the capacity and the efficiency settings (Didn't even know that I need to set it). I let Whizbang to figure it out automatically :D.
The SOC will show %100 when the batteries are fully charged, so yes, the batteries has received full charge. I've tested the batteries electrolyte (Getting about 12.75 each cell) and they are getting to manufacturers point of full charge.
So, Am I right that the %65 SOC isn't accurate since the voltage is below 24v? I saw couple charts online that shows the state of charge according to the battery voltage. Like this one:
https://modernsurvivalblog.com/wp-content/uploads/2013/06/battery-state-of-charge.jpg
Attaching the electrolyte reading at %65 SOC
You need to set the capacity in the Classic first. Efficiency too but that might be almost correct as is. Around 95% efficiency default.
The capacity might be close actually. The default I seem to remember is 400 amp-hours but you should probably check.
boB
Quote from: mohbbb1985 on July 21, 2018, 02:50:18 PM
Hello all,
I got 6 * 320w solar with 24v deep cycle battery bank(4 of 6v US REL16 XC) and Midnite 150 classic charge controller. My question is about the Whiz Bang Jr. capacity reading. The whiz bang jr.. show the remaining battery charge is %65 while the battery voltage is 23.6v. That doesn't sound correct to me. I'm wondering if those readings are accurate or not? Please see attachment.
Thank you !
If your batteries are that low it means that you either don't have enough PV to charge them every day or that you run too many loads for the battery capacity you have or you just had a series of low light days so the batteries are not charged.
I believe Vic recommends around 85% efficiency for flooded lead acid batteries. You have to figure it out by watching when the SOC says it gets to 100% and then check the SG reading to confirm that the cells are 100% . You can tweak the efficiency and capacity to get it to match the batteries performance the best .
Larry
After the batteries have been broken in and "about" at label capacity, whatever that really is, you can measure the capacity.
You have to first charge the heck out of them, let them absorb for a few hours, (watch the water level while doing this), and then run them down until the specific gravity or voltage tells you approximately what the batteries' SOC is... Note the amp-hours removed since you started the discharge... Don't discharge too hard though. Maybe at approximately the discharge rate the manufacturer specifies they are rated at.
If measuring SOC using battery voltage, make sure the load isn't very high at that time or maybe disconnect the battery for a little while and let that voltage settle.
Could also discharge to maybe 50% and then extrapolate. Or down to 75% or something other than exactly 0%. You can normally discharge down to 0% but don't want to make a habit of it.
Would love to see software that just did this automatically. Could be done if given a bit of time which we don't have at the moment unfortunately.
boB
Like many things regarding batteries, there seem to be quite a number of variables, perhaps more so, with Flooded Lead Acid (FLA) batteries.
I am no battery expert, like most of us, have dealt with FLA batteries for some years.
Most manufacturers state that for FLA (usually Lead-Antimony), the nominal Ah Charge Efficiency is about 85%. Adding insult to the injury of this relatively low number, is, that even this efficiency is on the high side.
As FLA batteries become more fully charged, the Ah charge efficiency continues to drop.
For our off grid PV charged systems, we tend to cycle batteries between about 70 or 80% SOC and full charge. This range could result in efficiencies below about 60% for common FLA batteries, with Lead Antinomy construction.
Gassing for these batteries is probably the main factor in the reduction of Ah charge efficiency at the top end of the SOC range.
In answer to the question about the correlation of measured battery voltage and SOC, as was stated above, it all depends. The chart in the Link, appears to only apply mostly, to number of Trojan batteries (with 1.277 SG at full charge), and as was noted by boB, that chart is probably only applicable to a Rested battery (no charge or discharge for many hours). So given the data that is available, it is hard to tell about the accuracy of the WbJr SOC report, verses the battery voltage (and just what the battery had experienced in charge/discharge in the previous hours.
It has been noted that, AGM batteries may well have Ah Charge Efficiencies in the range of 90%+, perhaps about 94%, but have not ever used AGMs. Believe that SGs in AGMs are set high, so there is relatively little gassing inside, at reasonable Absorb voltages and the catalyst in the caps does not need to work too hard ... just guessing.
All IMO, FWIW, Vic
I haven't seen an Amp-Hour efficiency number of 85% or lower. However, I DO know that Watt-Hour efficiencies are lower than 85%.
W-H efficiency being lower because of the energy needed to Absorb. If you don't Absorb every day, then that efficiency might be higher.
You sure you mean A-H efficiency and not W-H efficiency, Vic ? Would love to hear more.
boB
Quote from: boB on July 27, 2018, 04:13:31 PM
I haven't seen an Amp-Hour efficiency number of 85% or lower. However, I DO know that Watt-Hour efficiencies are lower than 85%.
W-H efficiency being lower because of the energy needed to Absorb. If you don't Absorb every day, then that efficiency might be higher.
You sure you mean A-H efficiency and not W-H efficiency, Vic ? Would love to hear more.
boB
Hi boB,
YES, II DID intend to state, specifically, Ah Efficiencies in the range of 85-ish percent for broken-in, but young batteries. We pay attention to Ah removed from batteries, so Ah Efficiency is what counts here. But, in re-reading my post above, only made a glancing reference to Ah Efficiency.
Again, I claim to be no expert on this. Will look for some references to Ah Efficiency statements from battery manufacturers.
More later, 73, Vic
Here is a Link to some tests done at Sandia Labs. Had read this some time ago, and probably have forgotten too many of the fine details:
https://xtronics.com/uploads/batpapsteve.pdf
More later, need to shed some loads, as it has been and continues to be hot here.
FWIW, regards, Vic
Very interesting paper! Thanks for sharing it Vic.
I was also looking and trying to find the G spot for years ;D and finally found that 88% to 90% eff. was good enough on mine with 80 to 100% SOC cycles.
A+,
Erik
Thanks for the paper link, Vic. We spent a couple of days at that lab playing with arc fault.
They do some cool stuff there.
boB
Hi Erik, boB,
I claim to know nothing about batteries, in any detail.
We are presently using 70% as the Ah Charge Efficiency value, and it appears to be too high. But, these FLAs are 13 years old ...
OK boB on spending time at the Sandia Labs with arc faults. Respect and appreciate the work that they, and the NREL do, and publish.
Best regards, Vic
That article suggests that it would be neat to have charge efficiency change with an adjustable slope above some settable SOC percentage.
Doesn't sound too difficult.
Maybe some day or in another product ?
boB