Author Topic: ReBulk?? How to setup??  (Read 1594 times)

epsgunner

  • Jr. Member
  • **
  • Posts: 53
ReBulk?? How to setup??
« on: July 15, 2012, 09:57:26 PM »
What voltage should I set my Rebulk voltage for??

If my Float is set for 13.6, and my Absorb is set for 14.3.

I am guessing set it under the FLOAT setting voltage.. say 13.2?? (or less??)

I plan on running an A/C during the day and thinking about what if I'm already in FLOAT when I kick it on at say 1pm.. I'd like the option to make BULK kick back on..

Suggestions appreciated..

SolarMusher

  • Sr. Member
  • ****
  • Posts: 361
Re: ReBulk?? How to setup??
« Reply #1 on: July 16, 2012, 08:36:11 AM »
Hi,
I'm afraid that your 440AH 12V battery bank will not be large enough to supply A/C.
If you want to use A/C when in Float, you would need a strong PV array which keep your batteries in float and supply A/C load at the same time. How much PV do you have? What's your inverter?
A+,
Erik
Off Grid with 3.2kw PV
Magnum E-panel 4448- Classic 200
830Ah @ 48V Battery Bank

epsgunner

  • Jr. Member
  • **
  • Posts: 53
Re: ReBulk?? How to setup??
« Reply #2 on: July 16, 2012, 08:58:07 AM »
870 watts of PV done in 24v configuration... panels are 18VMP each.. so 3 sets of 36 VMP and 8.05 IMP.. (works to 108 volts and 24 amps going into the controller at 24v..)

Should be putting in about 50 amps/hour with MPPT.. and being in SW Texas with no trees causing shading..

Not trying to RUN them in FLOAT.. I was asking about how to set Rebulk in case I have to kick it on in FLOAT.. what voltage should I set to get it run thru another BULK cycle..

The inverter is a non-issue.. I'll be rockin a 2000 Watt Samlex SA-2000K model.. rated for 2000 cont and 4000 surge.. I've got my 3/0 wiring, switch, breakers, and fuses..

The A/C is a small 5K model.. and I've covered that on another forum to death..
« Last Edit: July 16, 2012, 09:01:01 AM by epsgunner »

Vic

  • Hero Member
  • *****
  • Posts: 713
Re: ReBulk?? How to setup??
« Reply #3 on: July 16, 2012, 02:09:49 PM »
Hi Al,

BUT,  you are not going to run all six PVs in series are you ??  Know that you could save on fuses/breakers and a Combiner that way,  but this is a high voltage for CC to deal with,  especially when using a 24 V batt bank.  The CC efficiency will be reduced and it will run hotter,  in a perhaps hot environment,  and you will harvest a bit less power.  This is not a good situation IMHO.   YES,  this would reduce wire losses/reduce the required wire size ...   but ..

How about three strings of two PV with breakers in a Combiner?

Mabe I am reading this wrong ...  or ...   Have Fun,  Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

epsgunner

  • Jr. Member
  • **
  • Posts: 53
Re: ReBulk?? How to setup??
« Reply #4 on: July 16, 2012, 04:13:20 PM »
Vic.. no not running 6 panels in series.. the above 108 was a combined total.. sorry..

It is 3 strings of 2 (12v nominal) panels each into a combiner.. each panel has a VMP of 18 and IMP of 8.05..

its going to be 36 VMP and 8.05 IMP going into the controller * 3.. so 24 amps going in.. only 36v max from the panels..
« Last Edit: July 16, 2012, 04:15:21 PM by epsgunner »

Vic

  • Hero Member
  • *****
  • Posts: 713
Re: ReBulk?? How to setup??
« Reply #5 on: July 16, 2012, 07:25:46 PM »
Hi A.

Thanks,  that was my recollection from conversations elsewhere,  just wanted to check.

Regarding Re-Bulk,  this value may need to be tweaked based on the expeience you have with the ultimate system --  A/C cycling,  etc.

Have fun with the new Classic,  which really IS the best CC in this Large CC class (IMHO).  Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

SolarMusher

  • Sr. Member
  • ****
  • Posts: 361
Re: ReBulk?? How to setup??
« Reply #6 on: July 17, 2012, 09:23:15 AM »
Hi ... and Vic
Is your A/C really drawing 5kw?
How could you run this A/C on a 2kw inverter? And on a 5.3kw capacity battery bank? 50% DOD is only +/-2.6kw.
Am I missing something?
A+,
Erik
Off Grid with 3.2kw PV
Magnum E-panel 4448- Classic 200
830Ah @ 48V Battery Bank

epsgunner

  • Jr. Member
  • **
  • Posts: 53
Re: ReBulk?? How to setup??
« Reply #7 on: July 17, 2012, 09:33:22 AM »
Erik,

5K = 5000 BTU model.. 450-550 watts when running..

Sorry I should have been more specific..

So if my FLOAT is set for 13.6, I should set my REBULK Volts to what 12.9, 13.0, ???

epsgunner

  • Jr. Member
  • **
  • Posts: 53
Re: ReBulk?? How to setup??
« Reply #8 on: August 24, 2012, 10:14:13 AM »
Erik,

5K = 5000 BTU model.. 450-550 watts when running..

Sorry I should have been more specific..

So if my FLOAT is set for 13.6, I should set my REBULK Volts to what 12.9, 13.0, ???

Anyone come up with an answer?? still wondering.. should it be set to 12.9 or 13.0 or ??

**Note I went to 1160 watts of panels..   8)

niel

  • Sr. Member
  • ****
  • Posts: 305
Re: ReBulk?? How to setup??
« Reply #9 on: August 24, 2012, 11:43:54 AM »
i agree this may need to be experimentally determined by you, but let's think about this for a moment. rebulking means to have the higher voltage be attained to start an absorb charge again. now voltages around 12.9v or 13.0v are actually above the at rest voltage point for batteries. you don't want to keep pumping the bulk and absorb stages to the batteries when they are already fully charged do you? you indicate you want to run some a/c and that is a big load. this kind of load will pull the battery voltage down even on fully charged batteries and is called the peukert effect. you have to indicate to us at what point you'd like rebulk to happen at. do you want it at 75% soc or 50% soc for example? the at rest voltage will be higher than the voltage the load drags it down to and you have some determining to do no only in what at rest voltage for a soc point you want, but also what the voltage was pulled down to by the large load to attain that at rest voltage. as such nobody here can really give you a straight up answer as to what you should put it at.

epsgunner

  • Jr. Member
  • **
  • Posts: 53
Re: ReBulk?? How to setup??
« Reply #10 on: August 24, 2012, 11:56:18 AM »
i agree this may need to be experimentally determined by you, but let's think about this for a moment. rebulking means to have the higher voltage be attained to start an absorb charge again. now voltages around 12.9v or 13.0v are actually above the at rest voltage point for batteries. you don't want to keep pumping the bulk and absorb stages to the batteries when they are already fully charged do you? you indicate you want to run some a/c and that is a big load. this kind of load will pull the battery voltage down even on fully charged batteries and is called the peukert effect. you have to indicate to us at what point you'd like rebulk to happen at. do you want it at 75% soc or 50% soc for example? the at rest voltage will be higher than the voltage the load drags it down to and you have some determining to do no only in what at rest voltage for a soc point you want, but also what the voltage was pulled down to by the large load to attain that at rest voltage. as such nobody here can really give you a straight up answer as to what you should put it at.

I got you.. what % vs. what voltage.. thank you.. makes total sense..

I'll have to wait and see how low the DROP is on start-up and figure the % after it stabilizes..

Thinking like 70% may be a good number to start with.. it will leave me some SUN to jack the battery bank back up..

Vic

  • Hero Member
  • *****
  • Posts: 713
Re: ReBulk?? How to setup??
« Reply #11 on: August 24, 2012, 02:06:20 PM »
Al,

This is an expeimental thing.  Did note your question,  previously,  but figured that you'd figure it out when your system is set up in TX.

IIRC,  set my Classic-charged system at about 49.4-ish V,  where Float is about  52.8V.  In my opinion,   you really do not want to do any additional  charge cycles on a given day if you can help it.  But,  with a smaller capacity battery bank,  ReBulk is much more important,  as you do NOT want to flatten the bank.

You have  quite a lot of PV,  which should run the A/C and other larger loads fine when in Float (I do forget your well/pump setup).  Even if you have insufficient PV power available when in Float,  ReBulk will do no good at that time.  In stormy weather,  when available PV varies a lot,  and with a smaller battery bank,  ReBulk if probably an important setting to get ironed out.

I've run my MX-60s  with ReBulk disabled for seven years now,  without any problems.  Opinions may well differ.  Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

epsgunner

  • Jr. Member
  • **
  • Posts: 53
Re: ReBulk?? How to setup??
« Reply #12 on: August 25, 2012, 12:08:51 AM »
Al,

This is an expeimental thing.  Did note your question,  previously,  but figured that you'd figure it out when your system is set up in TX.

IIRC,  set my Classic-charged system at about 49.4-ish V,  where Float is about  52.8V.  In my opinion,   you really do not want to do any additional  charge cycles on a given day if you can help it.  But,  with a smaller capacity battery bank,  ReBulk is much more important,  as you do NOT want to flatten the bank.

You have  quite a lot of PV,  which should run the A/C and other larger loads fine when in Float (I do forget your well/pump setup).  Even if you have insufficient PV power available when in Float,  ReBulk will do no good at that time.  In stormy weather,  when available PV varies a lot,  and with a smaller battery bank,  ReBulk if probably an important setting to get ironed out.

I've run my MX-60s  with ReBulk disabled for seven years now,  without any problems.  Opinions may well differ.  Vic

My water pump is a 0.9 amp AC 110-120V V model.. not really an issue I don't think.. I have a creek bed and will be doing a 4 stage Culligan system for the sinks.. and 3 stage for the shower..

I agree testing will be immediant when I hit the ground with the setup.. I agree bumping to 1160w of panels IMHo was good idea..

vtmaps

  • Sr. Member
  • ****
  • Posts: 358
  • I'd rather be floating
Re: ReBulk?? How to setup??
« Reply #13 on: August 27, 2012, 05:22:17 AM »
I must be missing something.... Why are you so concerned about rebulk? 

If you are running a 500 watt A/C with 1160 watts of panel you will not be discharging your battery.
If its late enough in the day that you do discharge your battery, there will not be enough sun to rebulk your battery anyway.

--vtMaps

Vic

  • Hero Member
  • *****
  • Posts: 713
Re: ReBulk?? How to setup??
« Reply #14 on: August 27, 2012, 02:46:13 PM »
Hi vt,

Well it is my opinion,  as had attempted to say in the prev post;

Smallish banks plus intermittant solar conditions (read Thundersrotms etc),  could make ReBulk an important item.  Also,  extraordinary loads could figure into this -- water pumping for some,  etc.

While I've set RB,  it would take days for any loads at the Classic-charged site to run the bank down to the RB setting,  so in that case RB could be disabled with identical results,   unless DefCon VII comes along.  Just my read on RB,  Results May Vary,   Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!