New configuration for 24v setup

[Vic]

Hi Simon,

What is the nature of your 24 V Fridge,  does it have a compressor?  Or, is it a Propane/AC/DC unit  ...   or   ??  If it has a compressor, it might have a considerable motor starting surge.  You may have already checked the specs on the fridge.

FWIW, Vic

[Simonbr]

Hi Simon,

What is the nature of your 24 V Fridge,  does it have a compressor?  Or, is it a Propane/AC/DC unit  ...   or   ??  If it has a compressor, it might have a considerable motor starting surge.  You may have already checked the specs on the fridge.

FWIW, Vic

Its a DC fridge that works on 12v or 24v, compressor. They also sell a power adapter thats 24v 5a but its almost $200.

https://uniqueappliances.com/product/off-grid-13-cu-ft-solar-powered-dc-refrigerator/

[ClassicCrazy]

I looked up the fridge Vic
Power Consumption: 62 W on 12V/24V - Average Run Current: 5.2A on 12V & 2.6A on 24V Fridge Temp. Range: -4 C to +10°C Freezer Temp. Range: -15°C to +6°
I don't think the surge on some of the newer DC compressors is too bad and it won't be more than the 5 amp power supply they recommend for it.
Some of the  newer DC compressors have speed control  so the surge can be controlled to minimum at startup I think.
At least the danfoss compressors I was just looking up do .
Larry

[Simonbr]

Simon,

Yes,  I have suggested changing several things. And, this approach is not Scientific.

BUT, it is generally not a good thing to allow FLA batteries to sit around in a state of under-charge. This can cause the Sulfates to harden on the plates.  This is very difficult to remove,  often, really impossible to remove, and that results in a permanent reduction in Capacity.

Yes, IIRC, you have a DC fridge, connected to the battery bank.  It is valid to be concerned with its ability of handle and operate at elevated battery voltages.  Something, with which, I have NO experience.

If your batteries are significantly under-charged,  IMO, you will not approach 1.3-ish percent of Capacity near the end of Abosrb.

Please DO take the SGs of all cells, today, around the end of Absorb, or in Float, just as a check.  AND, note diffences twix the older, and newer batts.

Thanks, Vic

Good Morning Vic,

I decided to go to camp last night at 10:30ish pm to start my generator over night to charge my batteries. Using the MyMidnite I was able to tell the batteries were low and I was worried they would die overnight. My inverter charger did the charging (Aims 24v 3k, 29.6v Boost and 13.8v float). They were getting a steady 25ish amp all night.

This morning at about 10am I went to camp (just as my generator started to run out of gas) and I checked the batteries, it seems that the inverter/charger did a not so bad job to get them back into the normal range.

I've included a photo of my battery bank and the SG, starting at the left moving towards the right, and starting from the top chamber to the bottom here are the levels. The 2 left ones are the old and two right are the new batteries.

Bat1: 1.27, 1.27, 1.27
Bat2: 1.27, 1.27, 1.265
Bat3: 1.24, 1.24, 1.25
Bat4: 1.24, 1.25, 1.25

I'm also including a screen shot of the MM2 from last night up to now.

Questions
1. My inverter charger was still showing it was doing abs charge but once I stopped the generator the CC went right into float mode instead of trying to do an abs charge. Is there a way to force the CC back into abs so it could do the final charging?

2. From the MM2 chart it looks like the charging was at 4.4a before I stopped the generator and since it was not quite complete, do you think I should lower my EA from 5.4a to something lower like 4a?

3. I have the EA on the CC set to shunt instead of the classic, is this the correct configuration I am looking for?

4. Rebulk is set to <8.0, what should this be for 24v?

[ClassicCrazy]

What charge setpoints did you have in your inverter charger ?
If you get a good sunny day after you did that generator / inverter charging then the Classic should finish it off.
Yes you have the shunt setting correct set to shunt instead of internal .
Larry

[Simonbr]

What charge setpoints did you have in your inverter charger ?
If you get a good sunny day after you did that generator / inverter charging then the Classic should finish it off.
Yes you have the shunt setting correct set to shunt instead of internal .
Larry

The setpoints are 29.6v Boost and 13.8v float (included photo), you cant change them unless you change the type of battery your using. It is rated to charge at 30a +-5% using a small trim pot. I had it tuned just bellow where the generator was working hard, as not to have it work harder burn all the gas quickly.

Right now I checked MM2 and the CC is still in float and the Wb is only seeing around 0.7a (image included). This will not complete the charge at this rate. How long does the float charge last and is there a way to force it out back into bulk/abs? Oh and the sun is out and no clouds today.

[ClassicCrazy]

On the local status app you can force it into absorb but it will probably go very quickly back to float anyway.
What you probably want to do is start an equalize cycle.  You can set that for whatever voltage you want and for as long as you want.
Like Vic mentioned - with new batteries it takes some discharge cycles to get them to full capacity . So I would just use the batteries for and let them do some cycles, keep your regular absorb settings. Keep an eye on the SG compared to the SOC . When you get it all tweaked right you will find it is pretty good indicator of the batteries charge  . You tweak it by adjusting the efficiency setting for SOC as well as figuring out the ending amps .
What you want to put on your mymidnite graph is amp hours from full - I think it has that too.
So watch the graph as it charges up and counts amps back towards zero . It should get to 0 plus some extra amps in for the efficiency - at the ending amps point and then go to float.
Nice thing about mymidnite graph is you can drag the mouse across the graph slowly in the history and watch the battery voltage, soc, whizbang amps, as it gets to either your ending amps or absorb time which ever comes first. Usually the ending amps is always going to come first. You confirm the ending amps and 100% full battery with your SG readings when you get everything tweaked .

Larry

[ClassicCrazy]

there is also some info here on ending amps
http://www.midniteftp.com/support/kb/faq.php?cid=1
Larry

[Vic]

Simon, am in the middle of things, here.

Your battery bank DOES need an EQ,  later, thanks, Vic

[Simonbr]

Simon, am in the middle of things, here.

Your battery bank DOES need an EQ,  later, thanks, Vic

Heading to camp now to do an EQ. I will use 30.5v and check the temp comped settings, does it have to be set at something specific or is it just turned on and off? I havent looked at the setting yet.

is 2 hours enough?

[ClassicCrazy]

yes temp comp for equalize is just set on or off . On MNGP you will see it on the Charge / Temp Comp settings and it will say EQ Comp'd yes or no
Larry

[Vic]

Simon,

Yes,  I have suggested changing several things. And, this approach is not Scientific.

BUT, it is generally not a good thing to allow FLA batteries to sit around in a state of under-charge. This can cause the Sulfates to harden on the plates.  This is very difficult to remove,  often, really impossible to remove, and that results in a permanent reduction in Capacity.

Yes, IIRC, you have a DC fridge, connected to the battery bank.  It is valid to be concerned with its ability of handle and operate at elevated battery voltages.  Something, with which, I have NO experience.

If your batteries are significantly under-charged,  IMO, you will not approach 1.3-ish percent of Capacity near the end of Abosrb.

Please DO take the SGs of all cells, today, around the end of Absorb, or in Float, just as a check.  AND, note diffences twix the older, and newer batts.

Thanks, Vic

Good Morning Vic,

I decided to go to camp last night at 10:30ish pm to start my generator over night to charge my batteries. Using the MyMidnite I was able to tell the batteries were low and I was worried they would die overnight. My inverter charger did the charging (Aims 24v 3k, 29.6v Boost and 13.8v float). They were getting a steady 25ish amp all night.

This morning at about 10am I went to camp (just as my generator started to run out of gas) and I checked the batteries, it seems that the inverter/charger did a not so bad job to get them back into the normal range.

I've included a photo of my battery bank and the SG, starting at the left moving towards the right, and starting from the top chamber to the bottom here are the levels. The 2 left ones are the old and two right are the new batteries.

Bat1: 1.27, 1.27, 1.27
Bat2: 1.27, 1.27, 1.265
Bat3: 1.24, 1.24, 1.25
Bat4: 1.24, 1.25, 1.25

I'm also including a screen shot of the MM2 from last night up to now.

Questions
1. My inverter charger was still showing it was doing abs charge but once I stopped the generator the CC went right into float mode instead of trying to do an abs charge. Is there a way to force the CC back into abs so it could do the final charging?

2. From the MM2 chart it looks like the charging was at 4.4a before I stopped the generator and since it was not quite complete, do you think I should lower my EA from 5.4a to something lower like 4a?

3. I have the EA on the CC set to shunt instead of the classic, is this the correct configuration I am looking for?

4. Rebulk is set to <8.0, what should this be for 24v?

Hi Simon,

Great that you ran the genset last night.  SGs looking pretty good,  but, IMO,  you should still EQ the bank.

Perhaps, the Classic woke up when the battery was being charged, and that, somehow caused it to avoid doing its own charge, dunno.

In the Tweaks>More>Force Absorb, Up arrow (IIRC), should get the Classic to start a charge cycle from Bulk.

I did not look at your MM2 screen shot,  the Wb charge current depends on the charge voltage at that time,  look at the bat volts on MM2.  Why not EQ the battery bank,  and leave EA as it is for now, anyway.  You can measure SGs during EQ, and stop it when the SGs of the lowest cells do not change, measured at about 30 minute intervals.  EQ DOES increase the battery temperature.  So, watch the bat temp (you can use the Temps menu on the MNGP. Would not let the temp go much above 35C),

ReBulk will cause a new charge cycle, when the battery V diminishes to that voltage (possibly, there might be a bit of a delay, before ReBulk starts).  Have never used it.  Folks with smallish batts, and those with spotty WX condx, etc may find it useful, but to me,  would like to get the batts charged on most days, and we have enuf capacity, that a second charge is never needed,  every charge of the batts, counts against the life-span.
There may be other obvious reasons to rebulk,  but have never needed it.

Later, thanks for the reports,  Vic

[Simonbr]

Simon,

Yes,  I have suggested changing several things. And, this approach is not Scientific.

BUT, it is generally not a good thing to allow FLA batteries to sit around in a state of under-charge. This can cause the Sulfates to harden on the plates.  This is very difficult to remove,  often, really impossible to remove, and that results in a permanent reduction in Capacity.

Yes, IIRC, you have a DC fridge, connected to the battery bank.  It is valid to be concerned with its ability of handle and operate at elevated battery voltages.  Something, with which, I have NO experience.

If your batteries are significantly under-charged,  IMO, you will not approach 1.3-ish percent of Capacity near the end of Abosrb.

Please DO take the SGs of all cells, today, around the end of Absorb, or in Float, just as a check.  AND, note diffences twix the older, and newer batts.

Thanks, Vic

Good Morning Vic,

I decided to go to camp last night at 10:30ish pm to start my generator over night to charge my batteries. Using the MyMidnite I was able to tell the batteries were low and I was worried they would die overnight. My inverter charger did the charging (Aims 24v 3k, 29.6v Boost and 13.8v float). They were getting a steady 25ish amp all night.

This morning at about 10am I went to camp (just as my generator started to run out of gas) and I checked the batteries, it seems that the inverter/charger did a not so bad job to get them back into the normal range.

I've included a photo of my battery bank and the SG, starting at the left moving towards the right, and starting from the top chamber to the bottom here are the levels. The 2 left ones are the old and two right are the new batteries.

Bat1: 1.27, 1.27, 1.27
Bat2: 1.27, 1.27, 1.265
Bat3: 1.24, 1.24, 1.25
Bat4: 1.24, 1.25, 1.25

I'm also including a screen shot of the MM2 from last night up to now.

Questions
1. My inverter charger was still showing it was doing abs charge but once I stopped the generator the CC went right into float mode instead of trying to do an abs charge. Is there a way to force the CC back into abs so it could do the final charging?

2. From the MM2 chart it looks like the charging was at 4.4a before I stopped the generator and since it was not quite complete, do you think I should lower my EA from 5.4a to something lower like 4a?

3. I have the EA on the CC set to shunt instead of the classic, is this the correct configuration I am looking for?

4. Rebulk is set to <8.0, what should this be for 24v?

Hi Simon,

Great that you ran the genset last night.  SGs looking pretty good,  but, IMO,  you should still EQ the bank.

Perhaps, the Classic woke up when the battery was being charged, and that, somehow caused it to avoid doing its own charge, dunno.

In the Tweaks>More>Force Absorb, Up arrow (IIRC), should get the Classic to start a charge cycle from Bulk.

I did not look at your MM2 screen shot,  the Wb charge current depends on the charge voltage at that time,  look at the bat volts on MM2.  Why not EQ the battery bank,  and leave EA as it is for now, anyway.  You can measure SGs during EQ, and stop it when the SGs of the lowest cells do not change, measured at about 30 minute intervals.  EQ DOES increase the battery temperature.  So, watch the bat temp (you can use the Temps menu on the MNGP. Would not let the temp go much above 35C),

ReBulk will cause a new charge cycle, when the battery V diminishes to that voltage (possibly, there might be a bit of a delay, before ReBulk starts).  Have never used it.  Folks with smallish batts, and those with spotty WX condx, etc may find it useful, but to me,  would like to get the batts charged on most days, and we have enuf capacity, that a second charge is never needed,  every charge of the batts, counts against the life-span.
There may be other obvious reasons to rebulk,  but have never needed it.

Later, thanks for the reports,  Vic

I have started the EQ for 2 hours at 30.6v and left all other options as is. I will verify the SG once its complete to see how things are going from there. Will post results later.

[Vic]

OK, Simon,  will stay tuned for your reports.    Vic

[Simonbr]

OK, Simon,  will stay tuned for your reports.    Vic

Good news and bad news!

Good news, my fridge didn't kill over on the 31.6v,
Bad news my EQ stopped at 1h 20 minutes because clouds moved in and its later in the day
Good news, just that amount of time for the EQ did rise up the levels by about 0.01 for the lower cells

So I hope to be able to do a EQ tomorrow again (maybe a full one) to bring everything back up to normal levels.