EA value for Rolls 4000

[SolarMusher]

Hi,
What would be an EA value for the Rolls/Surrette serie 4000 (S-460, S-530, S-600), I know that Rolls suggests 2% EA, but what end current, have you guys seen/tested safely in real life at about 59.2/60V absorb?
Thanks,
Erik

[vtmaps]

Therewill be a difference between end amps at 59.2 volts and end amps at 60.0 volts.  End amps is also temperature dependent.  It also depends on the age and condition of the battery.

End amps is supposed to represent 100% wasted energy... the battery is fully charged and all of the power (end amps X Vabs) is dissipated as heat, corrosion, or electrolysis of water.   The higher the Vabs, (greater heat, corrosion, and electrolysis) the higher the end amps.

Another thing to consider is stratification... it is possible to asymptotically approach an 'end amps' that is not a full charge.  This occurs if the Vabs is not high enough to stir the electrolyte.

You are fortunate to have flooded batteries.  You can measure SG.  This means you can discover the the lowest Vabs with the highest end amps that works for YOUR batteries in YOUR situation.

Battery manufacturers have to give charging recommendations that will charge the vast majority of the batteries they produce... otherwise they will get too many warranty returns.  Since no two cells are the same, in order to charge ALL of their cells, they overcharge MOST of their cells. 

If you have an above average group of cells you may find that you can get their SG up to spec with lower voltages and less time.  That will be good for your battery. 

--vtMaps

[SolarMusher]

Hello Vt,
From what I saw on several Rolls battery banks, with a temp around 15°C, EA value seems to be lower than this 2% that Rolls suggested at 57.6 Vabs. On the last Rolls bank I've tuned (700Ah/48V), I've seen end current dropping easily below 12amps with a 59.2 Vabs, that is why I was wondering if thats mall 0.5/1% difference could be important at the end or in others words, are these rolls batteries really 100% charged with the settings that Rolls provides.
Erik

[vtmaps]

are these rolls batteries really 100% charged with the settings that Rolls provides.

You may get many answers to this question.  Don't believe everything you read... The only answer you can trust is your hydrometer. 

--vtMaps

[Vic]

Hi Erik,

The Surrette batteries here all seem to require almost exactly 1% of REAL 20 Hr Capacity  at about 2.42 V/cell -- 14.52 V/ 12 V.   That is,  for the S-530,  the  C is 380 Ah,  or about 3.8 A per string.  This is a temperature compensated Absorb V.  Have been using --4.5 mV/cell recently on one bank and --5 mV on another.  These currents are measured on a quality 500 A/50mV Shunt in the negative lead of the battery cable.

More later,   Vic

[SolarMusher]

Hi Vic,
Thanks for your post. Hope that you enjoy your Whizbang! I'm asking for the S-460 (700Ah/48v), but the S-530 require the same settings, this is for new rolls banks. I would like to tune this system the best I can because I know that this customer will abuse his batteries and I would like to avoid future battery problems. He called me last week because his system had shutted down when he reached LBCO. Batteries were filled up to the top (of the top  ) and PV covered by snow for more than two weeks. SG was down to 1.150, Oops! 911! I charged and EQ for 12hrs to bring it back to a steady 1.240/1.245, now I have to wait for a correct level to be sure these batteries are saved. For a few weeks, I'll keep 59.2Vabs until I reach the green zone and will lower it to 58.8Vabs/1 to 2% EA as soon as i can. For today, I have to add a remote Whizbang to this system and brush his panels.
You're very lucky not to have snow problems in California  .
Have a great Chrismas time.
Erik

[Westbranch]

Erik, do you have a baby sitting rate?  Sounds like he needs a long term sitting...

Joyeux Noël
Eric

[SolarMusher]

Haha! Salut Eric,
In fact, this was a great job I've done this summer. He also bought a 22kw Generac propane quiet source generator (liquid cooled, Mitsubishi motor), but I'm afraid he didn't understand that renewable energy means efficient loads and a little maintenance to keep this system in top shape. I've tried to explain him that he was not grid tied but I saw this morning that his Classic charged 10kw on Sunday only (3kw PV), that means he used 8/9kw in just one day! Oops!
This was a very good custommer to me so I try to apply three different rates: equalizing rate, brushing Rate and whizbang rate  .
Joyeux Noel à toi aussi, including the family!
Erik

[Westbranch]

10Kwh, ouch, what is the Ah rating for that 48v bank?

ps did you notice my new avatar?

[SolarMusher]

Yeah! Too much. I've designed this system for 5/6kwh max per day with a three days autonomy. His bank is 700Ah/48V with a 3kwh PV array on pole. I don't want to take any chance with these batteries so I've set the AGS to start the gen at 70 to 100% SOC until january  . When I came this morning, the system was drawing a steady 1.6/2 amps x24hrs for nothing (bell TV receiver and other unknown stuff). Maybe that when he'll look at his propane bill at the end of the winter he will have a better understanding on what I vainly try to explain...
How many inches did you have in Alberta, I saw that you had very low temp in the -40°C range. Oops! pretty cold for this time of the year. I could lend my plow if needed, all repaired  .
Erik

[Westbranch]

Erik, I am in S. Central BC and we had an all time record max 24 hr snowfall of 52cm about 2 weeks ago.  We only got to -30C over the weekend, so not as bad as Alberta as we usually do not get the Alberta winds from the North...