Still struggling with Crown Batteries

Rngr275

I had posted before about how I couldn't get my Crown batteries to full charge (Specific gravity low)  Crown recommends a bulk voltage of 58.1 and 

Start up amperage on bulk for 700AH of Battery should be 91.0 DC Amps.

 For every 100 ah of battery the DC Amps should be 12 to 15 amp.

7 X 13 dc amps= 91.0 dc amp start up.

Well this never worked and as suggested here I raised the Bulk V to ~ 59.1 and 4 hour absorb. This sort of maintained but never raised the SG to 1.275 (was sitting @~1.245-1.255).

I contacted Crown and he suggested the following 2 options (and I am using option 1)

Option1:

1. Disconnect the second battery bank for now.
2. Run on 1 battery bank.
3. This will allow you to use some amp hour capacity from the 1 battery bank.
4. You must change your DC Amp output on the charge controller to 45 amps.
5. Use mor AH’s From 1 battery bank and then you will charge the batteries harder

with more DC amp input, you should see the Spc. Gravities start to change.

1. Do this for a week and keep checking the Spc. Gravity and record it.  
2. Equalize battery bank at the end of 7 days.
3. Equalize setting: 61.92volt, 2 hours of charge.
4. If this makes the specific gravities come up then I would do the same to battery bank 2.

 Option 2:

1. Keep both battery banks together.
2. Shut Down or disconnect the charge controller and discharge the 2 battery banks

To 46.8volts.

1. Then recharge the 2 banks together. Charge at the 90.0amps input, 4 hours.
2. You may have to do the 5 or 6 times to start seeing an improvement.
3. After doing these 5 or 6 times I would equalize both banks.
4. Equalize setting: 61.92 volts 4 hours.

 In my experience Option 1 would be best to recover these faster.

Well I'm into day five and the SG is actually lower than when I started (and I've had some good days of sun and the system went into float). SG was ~1.245 and now it's ~ 1.235. I am at a loss! I've got 6.2Kw of panels and 2 Midnite Classic 200's for charge controllers. The batteries were new last summer. I thought breaking the 2 paralleled strings would help but it didn't. I had even tried turning off the panels until later in the morning so that I could get 90 amps for more of the Bulk phase instead of the amperage going up as the sun got stronger.

Never had this problem with my Trojan batteries.

Any clue as to what is happening. Stratified SG, ?, 

BTW Voltage drops pretty quick during the night with the single series string.

BB.

How much water are the batteries using?

Need to fill once a month, once every 3 months, once a week?

What is the battery bank temperature? You have a remote battery temperature sensor?

For EQ charging, once batteries are charged thru end of absorb, set/adjust EQ voltage to get around 5% rate of charge. Measure SG (temperature corrected) every hour of all cells. When all cells stop rising SG, that is the new 100% state of charge.

More that any EQ charging over 2% rate of charge can over heat batteries that are on EQ for many hours. Stop EQ if batteries reach max temperature, let cool, start EQ next day again of needed.

If water full is once a month or s bit less, normally I would guess that your absorb voltage is ok. To much water usage, reduced absorb voltage. If you rarely add water, raise voltage.

By the way, do you know the charged SG when batteries were new?

Bill "my guess" B.

Rngr275

BB. said:

How much water are the batteries using? Not very much... need to add a little every few months. There are water save caps on each cell also.

Need to fill once a month, once every 3 months, once a week? Once every couple of months need maybe 1 cup or less.

What is the battery bank temperature? You have a remote battery temperature sensor? Yes there is a remote temperature sensor. Typically the temperature is around 26 when charging (they are in my basement).

For EQ charging, once batteries are charged thru end of absorb, set/adjust EQ voltage to get around 5% rate of charge. Measure SG (temperature corrected) every hour of all cells. When all cells stop rising SG, that is the new 100% state of charge. Can I EQ even if the SG is low but has gone through Bulk/absorb/into float?

More that any EQ charging over 2% rate of charge can over heat batteries that are on EQ for many hours. Stop EQ if batteries reach max temperature, let cool, start EQ next day again of needed. Could explain this for me? 5%, 2% rate of charge based off of what?

If water full is once a month or s bit less, normally I would guess that your absorb voltage is ok. To much water usage, reduced absorb voltage. If you rarely add water, raise voltage.

By the way, do you know the charged SG when batteries were new? 1.275

Bill "my guess" B.

See above in BOLD.
Thanks BB

BB.

Using the battery 20 hour Amp*Hour capacity:

700 AH * 5% rate of charge = 35 Amps
700 AH * 2.5% rate of charge = 17.5 Amps

More or less, Lead Acid batteries are relatively efficient when charging from 10% to 80% State of Charge. During EQ charging, something like 50% of the energy goes into making H+O gases, and the 50% goes into heating the battery (as I recall).

If the batteries do not get "too hot" when absorb charging, you can probably crank up the Absorb set point a bit--Just watch that the batteries are not "boiling" (light fizzing) during through the end of charging.

Nominally, FLA battery mfg. recommend around 10-13% rate of charge for long battery life. There is nothing stopping you from doing a 5% rate of charge EQ at less than full charge (no harm)--It just takes "longer" to go from less than full charge to actual EQ charging (i.e., 90% to 100% SoC, then EQ Charging "starts" at 100%--Controlled "over charging" of your cells).

Normally EQ is done for two reasons. First is to "balance all cells to 100% full (once a month, or when cell SG varies from high to low by more than 0.030 SG units). "Full" is all cells stop rising SG units during EQ (end EQ at this time).

Also, especially for tall case batteries, the EQ gassing mixes the electrolyte (prevent stratification of dense electrolyte at bottom of cell and less dense at top). Also gassing can help shed hardened sulfate particles from plate surface (bad things to like oxygen corroding positive plate grids and such if too much EQ, as well as running batteries hot).

-Bill

Rngr275

BB. said:

Using the battery 20 hour Amp*Hour capacity:

700 AH * 5% rate of charge = 35 Amps
700 AH * 2.5% rate of charge = 17.5 Amps

More or less, Lead Acid batteries are relatively efficient when charging from 10% to 80% State of Charge. During EQ charging, something like 50% of the energy goes into making H+O gases, and the 50% goes into heating the battery (as I recall).

If the batteries do not get "too hot" when absorb charging, you can probably crank up the Absorb set point a bit--Just watch that the batteries are not "boiling" (light fizzing) during through the end of charging.

Nominally, FLA battery mfg. recommend around 10-13% rate of charge for long battery life. There is nothing stopping you from doing a 5% rate of charge EQ at less than full charge (no harm)--It just takes "longer" to go from less than full charge to actual EQ charging (i.e., 90% to 100% SoC, then EQ Charging "starts" at 100%--Controlled "over charging" of your cells).

Normally EQ is done for two reasons. First is to "balance all cells to 100% full (once a month, or when cell SG varies from high to low by more than 0.030 SG units). "Full" is all cells stop rising SG units during EQ (end EQ at this time).

Also, especially for tall case batteries, the EQ gassing mixes the electrolyte (prevent stratification of dense electrolyte at bottom of cell and less dense at top). Also gassing can help shed hardened sulfate particles from plate surface (bad things to like oxygen corroding positive plate grids and such if too much EQ, as well as running batteries hot).

-Bill

Just a couple points... at the end of the absorb the water in the batteries is giving a light fizzing (tiny little bubbles)... I expect this is normal.
Since I have split my 700Ah battery bank into 2 350AH banks a 5% charge rate would be 17.5 amps, I'm not sure how to set the amperage for EQ charging with my generator, all I have ever done is set the voltage for charging. Ideas? I have an Outback Inverter (3600W/48V) and a mate. My generator is a Kohler 12RES.

Had a full day today on the 350Ah battery bank (48V), SG sits at just over 1.240SG. That's using there 45amp and 4hour bulk/absorb.

BB.

Unless you have a small charger (limited current) or a programmable charger, the only way you can adjust the EQ current is by adjusting the voltage set point.

You are probably looking at a 2.5 to 5 % rate of charge range (aiming for 5.000% rate of charge is not possible with just voltage set point.

Using a small genset with a smaller charger will probably save fuel. Or bulk charge in the morning with genset and use solar for EQ.

Bill