During equalize, if my input watts go up do the amps go up as well?

[ddxv]

If I have a Classic 250 with 2400 watts coming in (at ~140v) and it is connected to a lead acid 48v battery bank of 32.7KWH.

The classic 250 is set to equalize at 64.8 volts. The Classic 250 has a maximum charging amps of 60.

If I increase the incoming watts to 3600 will this increase the amps going to the batteries during the equalization stage?


Old:
Current (Amps) = 64.8v/2400w� ≈ 37 amps

New:
Current (Amps) = 64.8v/3600w� ≈ 55.56 amps

Is this correct?

[Wizbandit]

Equalization is applied to a fully charged battery.  If adding more watts kicks up the current then the battery was not full and an EQ should not be attempted. During EQ the current should not be much more than the float current and in fact should be dropping as the EQ process progresses.

[Vic]

ddxv,

Have you tried running your proposed new configuration, using the Classic String Sizer(?):
https://midnitesolar.com/sizingTool/index.php

A good FLA battery that needs an EQ,  will need quite a lot of current, at the beginning of the EQ.  As Wizbandit mentioned,  this battery current will diminish, as the EQ progresses.

The 19 YO FLAs here,  like about 4.5 - 5% of 20-hour Capacity,  initally to reach the EQ target voltage of about 63 V (Temp Comped),   This current does taper,  but it is often,  a race,  twix finishing Absorb,  with enough time remaining to get as much as two hours at the Comped EQ voltage setting.

Just my experience with aged Surrette 4KS25s,  at 48 V.   FWIW,  Vic

[Barry Fields]

Does not 64.8v sound a bit high? 61.2v is EAST Penn recommended. Could thermal runaway explain this?

[ddxv]

Does not 64.8v sound a bit high? 61.2v is EAST Penn recommended. Could thermal runaway explain this?

You're correct, I set it a bit high a couple months ago and forgot, have just changed it back to the range from Rolls 62.4-63.6

https://rollsbattery.com/wp-content/uploads/2018/01/Rolls_Battery_Manual.pdf

I appreciate you catching that! Thanks!

[ddxv]

ddxv,

Have you tried running your proposed new configuration, using the Classic String Sizer(?):
https://midnitesolar.com/sizingTool/index.php

A good FLA battery that needs an EQ,  will need quite a lot of current, at the beginning of the EQ.  As Wizbandit mentioned,  this battery current will diminish, as the EQ progresses.

The 19 YO FLAs here,  like about 4.5 - 5% of 20-hour Capacity,  initally to reach the EQ target voltage of about 63 V (Temp Comped),   This current does taper,  but it is often,  a race,  twix finishing Absorb,  with enough time remaining to get as much as two hours at the Comped EQ voltage setting.

Just my experience with aged Surrette 4KS25s,  at 48 V.   FWIW,  Vic

RE: Stringsizer, yes I have, but at other times, looking at it I don't see anything specific about EQ or other battery charge types? Probably I should re-read the manual though.


RE: Your FLA info. Thank you, that was very informative, I think that's exactly what we were trying to figure out.

[ralph day]

Vic, how hot does your electrolyte get with 19yo units?  I couldn't eq my (since replaced 2019) 4ks units since the temp would reach and exceed 40C.  Scary. 

[Vic]

ddxv said,
 "RE: Stringsizer, yes I have, but at other times, looking at it I don't see anything specific about EQ or other battery charge types? Probably I should re-read the manual though.


RE: Your FLA info. Thank you, that was very informative, I think that's exactly what we were trying to figure out".

Hi ddxv,

While I did not specifically say it,  was really referring to the Sizing tool's judgement on the number of Cl 250s recommended, with your proposed increase in the PV array.  EQ is really just an Absorb at a higher voltage.  SO,  as long as the set EQ voltage can be reached and maintained you ARE EQing (of course).  There is no real difference in optput currrent for EQ, vs Absorb,  as long as there i s sufficiently high PV input voltage to allow the Classic to reach the EQ voltage setting (this is an initial design consideration).   But,  with 140-ish PV input voltage,  this minimumPV input voltage need not be considered.  EQing needs more input power to the CC,  as the output voltage is higher than Absorb,  and at least initially,  the battery current will be higher than the Absorb V.

There are charts of Classic output currents for each of the Classic input voltage rated models,  that show currents vs batt voltage and PV in voltage,  but `140-ish volts in is not on that chart for the 250 (probably because that  PV input V is a more in the range of expected for a Cl 200).   These charts are now found on the MN Solar site, under Classics,  in a long .pdf file.   IIRC the chart for the Cl 250, is located on Page 15.

Personally,  almost always choose to Temp Comp the EQ voltage,  but that is a preference item.

All,  IMO,   Vic

[Vic]

Vic, how hot does your electrolyte get with 19yo units?  I couldn't eq my (since replaced 2019) 4ks units since the temp would reach and exceed 40C.  Scary. 

Hi Ralph,

YES, 40 C (104-ish F. for we Yanks)  would be a bit scary.

I do not recall even seeing 30 C (84-ish F), maximum from EQing.   But the only Air Conditioning that is done here is for the Power Room,  ONLY!

During EQ,  we usually do not have enough excess PV power to reach and stay at Veq,  on Summer days,  plus the A/C,  so we let the A/C cycle,  at a bit higher temp setting.

In Summer, for EQ it can take several days to complete the EQ,  or need to Bulk charge from PV, plus genset in the early AM,  to start the EQ early enuf to have sufficient time and PV (only) power to get the EQ done in one day.

These batteries have been real troopers,  and are doing fine,  BUT,  am looking over my sholder more often,  now,   as,  any day,  now,  it is possible that battery failures could begin cropping-up. But,  there are no signs,  yet, of battery disphoria (poor-ish health).

I know that you have run Surrettes for a long time, Ralph.  IIRC,  you were running 6CS21s,  or similar.  These larger Surrettes,  in single strings,  sure do get the job done (as do the Xantrex SW+ 5548 inverter/chargers),  in my opinion.

Take care,  have FUN,  Vic

[ralph day]

You were right Vic, 6cs.  Now I've got S550's.  Lots less capacity, but I have utility power, so only "off grid" when the batteries are charged enough.  I do sometimes let things discharge to 80% or less, then charge up the next day, but not daily even in tghe summer.  HBX mode on the outback inverter/Mate3 handles things well.

[Barry Fields]

If I have a Classic 250 with 2400 watts coming in (at ~140v) and it is connected to a lead acid 48v battery bank of 32.7KWH.

The classic 250 is set to equalize at 64.8 volts. The Classic 250 has a maximum charging amps of 60.

If I increase the incoming watts to 3600 will this increase the amps going to the batteries during the equalization stage?


Old:
Current (Amps) = 64.8v/2400w� ≈ 37 amps

New:
Current (Amps) = 64.8v/3600w� ≈ 55.56 amps

Is this correct?

Original question is correct. Volts x amps = power.

In both a & b , everything the Classic can produce is going to the Batteries.