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Author Topic: cant fully charge 40kwh rolls surrette series 5000 48v battery system.... ..  (Read 8138 times)
markini5
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« on: March 31, 2018, 02:04:05 PM »

Hello everyone, need some help with these batteries.     

i cant fully charge them,  my 3kw 12 panel array  isn't anywhere near enough to charge these fully

Morningstar TriStar 60a mppt charge controller.   batt temp and voltage sense are fitted and accurate.


im using rolls batt charge profile  for regular cycling/psoc  but just not enough amps  to get voltage to target voltage regulation, only on clear sunny days will this happen,  but didnt finish absorb as clouds came over and daylight was diminisihng .     absorb charge his been triggered at over 40 amps  after prelonged periods of hovering near to it... 

problem with this is as they are close to full charge they are gasing  and drinking excessive water .    everyday average voltage hovers around 58 - 61    20 - 30 amps  and on the odd clear sky  amps went to 49amps    few mins later absorb target reached. 

after 12 hours rest no loads on, voltage was 51.2v   batt temp 9 degree c
accross cells between 1,260 - 1,285  temp compensated/corrected results 


ive not got any loads on these other than  load test other day with 2000w 48v immersion heater element     2 hours under load    boiling 20 litres of water   voltage dropped to 48.4v   after 2 hours constant load.      voltage showed to be very stable  and only dropping  by 1 milivolt after approx after many minutes   

specific gravity didnt seem to have changed at all . 

electrolyte is clear  .

yesterday i changed charging profile to rolls other settings for infrequent cycling/backup power.   
these settings  are working much better,  but still below target voltage.

from what ive seen is amps need to be over 40amps 10% capacity at 20hr rating  once bulk phase is done to triger absorb and maintain these amps till they gradually fall   to a predetermined amps/time in absorb to end absorb and finish in float. .   

ive got a 3 kw array and have got space for 6 more panels  and no more....   i dont think i could use these daily  running a koi pond  and charge the batts too....   deep defict cycling  is what i fear will happen  . 

ive listed them for sale  due to growing frustration     6- 8kw is what i think these need and i cant provide more than the uk average array in my back garden .. 

i think 1/4 capacity in lithium lifepo4  is better suited to my needs.

any input would be great. 

thank you


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offthegridandy
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« Reply #1 on: March 31, 2018, 03:29:09 PM »

Hi Marki,

I think you've really answered your question your self. Your batteries need to be charged at a rate in the order of 10% of capacity, so for the initial bulk charge your going to need a charge rate in the order of 80 amps per hr based on the C5 rating. This charge rate will taper of as the batteries reach fully charged.  Even in the best of weathers a 3kw array is going to struggle to provide that.

Your MPPT charger may or may not be helping.  Depending on your set up you could consider connecting the PV direct to the battery to eliminate the power losses through the charger. This needs thinking on as you don't want to overcharge the battery if there is no load attached ever.  That said if your MPPT charger is rated at 60 Amps then you'll not get the 80 amps in any case.

I think you may need to either find an additional charging regime i.e. a generator or reduce the size of the battery.  Perhaps spilt the bank in 2 and see if you can manage to charge half of the set of cells successfully.

Cheers.

Andy
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8 KVA Lister TS2 Startamatic Genny
24 Volt 1000amp battery bank
Outback VFX3024
4.6 Kw PV array ground mounted
Outback Flexmax 80
2 X Flexmax 30 PV CC
2.5 Kw WT H Piggot design 4.5 Mtr Dia AC coupled
12 Mtr free standing Tower.
u/floor heating from oil boiler cross linked to 12 K wood stove
eabadger
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« Reply #2 on: March 31, 2018, 04:01:08 PM »

morningstar allow you to overrate the input current, i have on my 3 and get better results than without, you get an alarm saying over current or current limiting depending on software version, but with pv cheep and mppt expensive i gave it a go after talking to MS, they said no problem, so moderate days i get full charge.

steve
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1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
markini5
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« Reply #3 on: March 31, 2018, 04:08:13 PM »

Hi Andy,

Thanks for the message.

ive put post up on here before as i knew some time back i only need 10kw storage , but as i got them second hand  ive been struggling to find their true remaining capacity after 8 years of use.  

they seem in excellent condition and dont have any issue what so ever accepting charge .

im new to flooded lead acid  and these are high end worth alot and massive capacity that needs ideally expert knowledge  to keep in good health..

im not keen on by passing my controller,  and these controllers are amongst the best on the market if not the best....  

ive got limited funds  after splashing the cash on everthing so far..

i do have a second morningstar tristar 45a mppt controller  not in use    (need panels )      

i have no other means of charging..... i guess im lucky these are designed for partial state of charge or they may of been dead by now..  

id love to keep these but they take up a massive footprint  and need a huge array ..

im just beginning to understand how these work.

thanks
Mark  
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markini5
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« Reply #4 on: March 31, 2018, 04:16:28 PM »

Hi Steve,   

thanks for your input, 

ive been on morningstar string building tool ,  says i can use maximum 15 x 265w   5 strings of 3 modules     not sure if i can go over this figure.

i have got 15 panels but 1 panel glass got smashed so not put up this extra string.      i doubt 3 panels do much  extra that id notice rite now..

all panels use 6mm double insulated solar cable,   

just short on money   and havent even got an inverter yet....     


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eabadger
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« Reply #5 on: March 31, 2018, 05:44:51 PM »

look in notes bottom right of this, https://www.morningstarcorp.com/wp-content/uploads/2014/02/TSMPPTdsEng.pdf
i think calculator is just advised.
all you must not do ever is go above the maximum ever open circuit voltage of the panels, this has not protection and will fry the controller!!!
not sure what my peak array power is but i see current limiting messages most days, this week weather has been bad but we have had batteries in absorption every day, they are a 21kw lead acid at c5 rate.
we have been dumping excess to water via a ashp most days.
48v 8ka victron inverter on ebay currently.

steve

p.s see answer to Q2. https://www.morningstarcorp.com/whitepapers/morningstars-trakstar-mppt-technology-maximum-input-power/
« Last Edit: March 31, 2018, 05:49:50 PM by eabadger » Logged

1600w PV main array at 24v, excide 2v 1000a forklift cells now x 2, 320w PV secondary array at 12v. Enfield 1944 ex RAF 5.6kw diesel genset (now in pieces, big ends gone), Petter AC1 28v diesel charging set at 2.8kw.
1kw wind turbine.
26kw wood stove back boiler to underfloor heating and dhw
offthegridandy
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« Reply #6 on: March 31, 2018, 05:51:32 PM »

Sorry Mark if I have missed something so sorry if you've already said, but what do you need the set up to do for you.  You say you have no loads permanently connected.

Unlike some battery users, in winter I regularly discharge my 24 V 1000A C5 battery down below 23 Volts and recharge to 29.8V.  In summer I can have the batteries sitting at around 29V most of the day on the PV and not quite going to absorb. I've lived off batteries (off grid) for over 15 years and whilst I totally agree with looking after your batteries, they are tough beasts that take a lot of work to kill.  My first set lasted 12 years of which the last 2 were iffy.  In my learning curve I boiled em, ran them dry, ran them down below 19V accidentally and was still chuffed with their performance.  If your batteries are 8 years old they sound pretty good but me, I wouldn't get too precious.  Having the voltage around 48 V and no load shouldn't do any harm IMHO but letting them get down to say 44 or 45V and then leaving them discharged would be bad. But FLA batteries are made to be cycled so some moderate charge then discharge shouldn't kill them.  

An occasional equalise charge is a good idea I do mine a couple of times a year and with your set up I can see that being tricky on just PV.  Battery life is sometimes quoted as X nos of full charge to discharge cycles. 1600 springs to mind.

As I said before have you considered a trial to split the bank in to two and see if you can get a full charge on just 1 half? If that is sufficient for your demand then flog the other cells maybe.

Cheers.

Andy
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8 KVA Lister TS2 Startamatic Genny
24 Volt 1000amp battery bank
Outback VFX3024
4.6 Kw PV array ground mounted
Outback Flexmax 80
2 X Flexmax 30 PV CC
2.5 Kw WT H Piggot design 4.5 Mtr Dia AC coupled
12 Mtr free standing Tower.
u/floor heating from oil boiler cross linked to 12 K wood stove
markini5
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« Reply #7 on: March 31, 2018, 06:14:12 PM »

I just come a cross this steve,   i had no idea you could overload in this way..    3 panels takes me over 90v input.    4 modules according to Morningstar could go over 150v in extreme cold  .

i think my PV would be enough for your batteries,   as that is what i would prefer.

nice inverter   ideal for me but out of my price range

i want the excess power to keep my koi pond from freezing .   and maybe a diy electric central heating for my workshop/shed..

my batteries will have to run my pond pumps/uv/air ect 24/7     approx 400w an hour at 230v
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markini5
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« Reply #8 on: March 31, 2018, 06:36:24 PM »

Hi Andy,   

according to data sheet mine can do 100% discharge 1500 times  or nearly 7000 cycles 10% dod   not that i would ever do it...  max these have ever been discharged is 50%  normally 25 - 35% DOD
want to run my koi pond once its built   24/7 from these, and my workshop shed/mancave   power tools ect tv, wifi, lighting, hifi.

i have thought about splitting them and would consider this,   but had my heart set on 48vdc   and sized my wiring acordingly    less strain on batts and so forth.,.

i did think what if i split them  4 blocks in series  x 2 then parallel connect  for 24v 1640ah  20 hour rate.    but then it came to me that that may not change charging issues, unless im not correct on this..

my first batteries i used before these were 12v leoch agm  x 2 in parallel  12v 240ah      so its a drastic leap to 10k + worth of higher end batteries.     i spent 1 hour yesterday checking all cell SG and topping up where required. 

i made a osb 18mm box to keep them insulated from cold and heat   seemed to be holding a steady batt temp around 10c  compared to ambient temp in my workshop which is often 5c or lower  into minus figures few weeks back.   
box is vented  4 inch hole at bottom  4 inch hole at top  on other end of the box, thought about installing a fan for summer  keep them cooler  if possible.   

thanks
Mark
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offthegridandy
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« Reply #9 on: March 31, 2018, 08:29:05 PM »

Hi Marki,

yes you are correct if you connected the cells in 2 parallell banks you won't have changed the charging demands and if you did drop down to 24v you'd need to re calc the wiring sizes.

I have 4.5 Kw of PV in 4 arrays and in mid winter there are days when generation is less than 2 Kwhr total generation.  Our house load is about 10Kwhrs per day so we have to have a genny or wind as well.  If your demand is 400 watt hr for 24 hrs per day (around 9.5Kwhr) by my back of a fag box reconing, you'll have to have either a genny or perhaps as much as 25Kw array so provide for mid winter, depending on locale.
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8 KVA Lister TS2 Startamatic Genny
24 Volt 1000amp battery bank
Outback VFX3024
4.6 Kw PV array ground mounted
Outback Flexmax 80
2 X Flexmax 30 PV CC
2.5 Kw WT H Piggot design 4.5 Mtr Dia AC coupled
12 Mtr free standing Tower.
u/floor heating from oil boiler cross linked to 12 K wood stove
Scruff
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« Reply #10 on: April 01, 2018, 02:32:26 PM »

Hi Mark,

Simple solution. Plug this into the PV in terminals of the 45A MPPT, parallel it to the 60A TS with the same settings and same temp sensor.
You need mains on that behemoth for maintenance charging, no two ways about it.

You don't need the Eltek alarm/control unit, sell that after if it's not useful.

You'll get more power delivered with the TS MPPT than without it.

Ps. The Sunsaver MPPT rocks, I'm very impressed. Sound.  Smiley

* eltek power supply.pdf (475.28 KB - downloaded 93 times.)
« Last Edit: April 01, 2018, 02:34:51 PM by Scruff » Logged
Tinbum
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« Reply #11 on: April 01, 2018, 05:22:24 PM »


Simple solution. Plug this into the PV in terminals of the 45A MPPT, parallel it to the 60A TS with the same settings and same temp sensor.
You need mains on that behemoth for maintenance charging, no two ways about it.


I use those direct to the battery. excellent chargers. (They don't like to be switched on and off a lot though without changing the relay inside to one with different terminal material).
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85no 58mm solar thermal tubes, 28.5Kw PV, 3 x Sunny Backup 5048, 3x Sunny Island 5048, 2795 Ah (135kWh) (c20) Rolls batteries 48v, Atmos wood gasification boiler, Brosley wood burner, 2000lt buffer tank and 250lt DHW
Scruff
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« Reply #12 on: April 01, 2018, 08:06:21 PM »

Nothing I've ever met can hold a candle to MorningStar.
I've put everything I use to the hydrometer test, the best thing about hydrometers is they don't care what colour your boxes are, how expensive they were or what the sell sheet promised.


Quote from: MorningStar Corp Tech Notes
Description:

Can I use a power source other than a PV panel to charge my batteries?


We do not recommend using a DC power supply with any of our PWM controllers. While they appear to be similar to PV modules in function, DC power supplies have considerably more output capacitance. Connecting a DC power supply to our PWM controllers may cause excessive heating and premature failure. MPPT controllers can be used for this purpose without issue. In addition, AC powered battery chargers are often the best option for systems requiring AC battery charging.

Link
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markini5
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« Reply #13 on: April 01, 2018, 09:43:50 PM »

Hey Andy,   sorry for the late reply      been busy in the workshop wiring my mastervolt batman pro monitor.

25kw is far too much, most i could mount with extra mounting structures possibly 8kw
400w is a worst case, likely  will be 200 - 250w   with latest eco pumps  but cost a lot more. 
Ive had discussion with Hugh regarding VAWT,   ive done months of research into the subject and i disagree with him.  as i live in a residential area  ive been refused permission to have HAWT  even the smallest 900mm  rotor span.     vawt is where i can avoid planning permission.
hughes  argument is fairly one sided .. just because he hasnt seen one work doesnt mean that someone can research and develope new prototypes..  he is in my view has a hardened personal view to the point where you cant debate it with him..

Their are numerous examples throughout the world that do work very well..    inc hybrid types that have solar built in..

i live on top of a hill   with stronger winds and living in an end house with  6-7 metre gap between mine and our neighbours house   acts as a funnel where wind speeds are excellerated   to often extremely gusty .      ive got some idea's  and if it works... i got nothing to lose..
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Scruff
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« Reply #14 on: April 01, 2018, 10:33:20 PM »

been busy in the workshop wiring my mastervolt batman pro monitor.


Spot the difference.

vs

I agree with Hugh.
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