Battery Bank Problems

pictonrose · December 2020

I joined this group a little while ago and find it quite helpful. Recently we have been experiencing low batteries in the morning with the inverter reading 46.6vdc, that surprised us. It's been working well for the last 6 years. To note, we upgraded our solar array with more panels, now at 7kw of solar, we have 24 x 2v battery bank = 48v, xantrex inverter SW+, and 1 outback charge controller, tomorrow we r adding another one cause we have to much solar array for 1 to capture all the energy. It seems as though since we added the extra panels something hasn't been quite right. Electrician tested them and said they weren't making power, they r unhooked right now, reconnecting tomorrow as well, changing the connections to each panel. They went online in July, but it wasnt what I expected. Summer was sunny, mostly, but we seemed to need the genie sometimes, even on a sunny day. We just thought we were using too much power. Since the onset of fall, cloudy and shorter days, the inverter readings are bad, we have been running genie 2 -5 times a day, including waking up in the middle of the night to start. (Do not have autostart) I hope my batteries aren't cooked, tomorrow will be the teller. We r also adding a battery monitor, didnt know I needed that until 2 weeks ago. I also learned I have an oversized battery bank so not sure if we ever charged it fully. We normally charge it with generator until the xantrex goes into float, about 58.8vdc. Should I be letting it run longer once it goes to float? Should I have changed parameters when we added extra panels or the 5kw genie upgrade? Wish me luck for tomorrow. I hope my batteries r ok, I know they could be at there end of life.😓

mcgivor · December 2020

What batteries do you have, AGM,flooded, capacity, single 2v or monoblock? What ambient temperatures are typical and is temperature compensation used? What are the typical daily loads in kWh?

BB. · December 2020

What is the AH of the battery bank?

Bill

pictonrose · December 2020

MSE 1440 2V, 1440ah @ 8hr to 1.75V
Constant Voltage Charge 2.23-2.25V

pictonrose · December 2020

Mcgivor, no temp gauge used, installing battery monitor today. Batteries r in the house, so average living conditions. As for temp of batteries when charging, I am unsure right now. Batteries r Agm, I posted what they r under Bill's question.

pictonrose · December 2020

Mxgivor, said daily loads, unsure as well, battery monitor would five us that too

pictonrose · December 2020

Well system has been gone over, second outback installed, connections on 2nd solar array checked, making power threw outback, victron installed, says batteries 100%, down to 99%, alarm went off, set for 48.4v, when sun went down, power started dropping fast again, why is victron saying we r at 99%, still dont know why power is bleeding out so fast, system was down most of the day, no fun either

Aguarancher · December 2020

Did you ever do a initial commissioning charge on you batteries following the mfg directions? Have you ever equalized your batteries? Do you have a hydrometer and know how to use it? I assume these are flooded batteries..

Vic · December 2020

The batteries in question appear to be VRLA. And look to be targeted for Float service, not so much as Cyclic use, from a quick search (for, ' MSE 1440 2V battery '). If this is correct, six years of service is probably not too bad, IMO.

Just a drive-by Post. FWIW, Vic

Photowhit · December 2020

pictonrose said:

Should I be letting it run longer once it goes to float? Should I have changed parameters when we added extra panels or the 5kw genie upgrade? Wish me luck for tomorrow. I hope my batteries r ok, I know they could be at there end of life.😓

I'm not sure it's helpful to start another post rehashing the situation from your previous post.

https://forum.solar-electric.com/discussion/comment/413911

Did you get a chance to read the info about your batteries? They aren't made for daily cycling.

Photowhit · December 2020

pictonrose said:

Well system has been gone over, second outback installed, connections on 2nd solar array checked, making power threw outback, victron installed, says batteries 100%, down to 99%, alarm went off, set for 48.4v, when sun went down, power started dropping fast again, why is victron saying we r at 99%, still dont know why power is bleeding out so fast, system was down most of the day, no fun either

As batteries age they lose capacity.

A shunt based battery monitor, measure the flow of current (amps) into and out of the battery bank. While the Xantrex 5548 is measuring the voltage and alarming to the low voltage.

Assuming you setup the battery monitor with the original battery capacity of 1440ah, what is happening, is the battery has a much reduced capacity, perhaps as little as 1/10 the original capacity. What amounts of wattage or current (amperage) are you using after the sun goes down?

If you setup everything today, something like, fully charging the battery bank with the generator, so you could hookup the battery monitor (I think they all shunt based battery monitors require you to hook them up to a fully charged battery bank as well as entering the type and size of battery bank). Then let the solar array through the charge controllers to handle the daily loads. Then later saw the voltage drop later when the sun went down...

BB. · December 2020

Check (and log) the voltage across each cell/battery (during charging, discharging, and resting).. Ideally, the battery voltages should all be pretty closely matched... If you see one or a few batteries with much higher or much lower voltage than the rest of the batteries--You need to figure out why that is (check wiring connections, wiring crimps, look for evidence of browning/melting connections).

Or the batteries themselves could have bad cells (open or shorted cells)... Sometimes Equalize Charging can help (controlled over charging of the battey bank to 'bring' low cells back to 100% SoC)... However, sealed batteries generally do not tolerate EQ charging very well (see battery manual for details about charging).

You are in a cold climate--Cold batteries last longer than batteries operating in a hot climate--But if Vic is correct about these being float service VRLA (valve regulated lead acid) or AGM batteries--6 or 7 year life is not bad... And they may simply need to be replaced.

If you can identify "bad cell(s)" (too high of voltage when charging, too low of voltage when discharging, or low voltage when resting), you might choose to replace one or a few bad cells (can you get some "used" but good cells from your battery source?) and get the bank running again. Down the road (a few years?) you may end up having to replace the rest of the cells (just guessing).

-Bill

Photowhit · December 2020

Hi @BB.
This is from a thread about a week ago, here;
https://forum.solar-electric.com/discussion/comment/413882
They are;
C&D Technologies M.S.E.
MSE 1440 2V, 1440ah...

I tracked it down back then, they are designed for float use, Likely have very little capacity left as they are being used in daily cycling.
Perhaps C&D has some method of long Absorb voltage to recover some capacity, but basically I'd guess they are done. I think they even have a 7 year warranty...

Form the previous post since I have both in 2 windows now;

So you perhaps looked up the battery when I suggested there were differences I didn't read much when I found the 'PDF instructions for the battery bank; The title pages says;

Image: https://us.v-cdn.net/6024911/uploads/editor/xl/kxyw671jnc6j.jpg

Here's a link;

https://cdtechno.com/wp-content/uploads/2020/04/12_386_mse.pdf

I will hunt around later, they don't talk about cycles, but my guess is they will only cycle to 50% SOC a few times <200. I would NOT have recommended them for daily cycling solar electric system, it is far from their intended use.

It does appear they have a 7 year full warranty on them, so perhaps there might be some recourse. Going after your installer (in Court not with a pitchfork) might be an option as well.

Also

This might be better info, It's a manual for C&D Liberty MSE and DCS batteries. Includes the info;

"The Liberty MSE series is designed for float operation with minimal cycling. Typical applications include Telecom, Switchgear/Control and other non-UPS applications which are subjected to 20 or fewer cycles per year.

The Liberty DCS series is designed for cycling applications. Typical applications include OffGrid/Unreliable grid Telecom, Renewable energy or other stationary applications requiring a high number of cycles throughout the life of the cell."

There is info on recuperative measures by maintaining the float voltage for several hours. Perhaps it will help maintain some capacity for a while.

Image: https://us.v-cdn.net/6024911/uploads/editor/gw/59559h4muubu.jpg

Link to manual;

https://cdtechno.com/wp-content/uploads/2020/04/rs_02109_0914.pdf

Since this manual is also for DCS batteries, I was hoping it would have some cycling information, but it doesn't.
I'm use to seeing graphs of number of cycles to expected battery life.

HUP Solar does a chart of types of Flooded lead acid batteries and their expected life discharged 80% (20%SOC)
I couldn't find a chart for your MES batteries, but suspect it's much like the 'lower lead calcium plate 'marine' batteries.

Since you aren't using them to 20% SOC, they have lasted longer...

These would be great batteries for a grid tied hybrid system, where their low discharge rate and long life while only in float would make an excellent choice. They wouldn't be cycled unless the grid went down.

mike95490 · December 2020

Also, beware of AGM at end of life, they can heat up and pop the pressure relief vents, and then you are out of power.
Instead of replacing them last week while they were still working somewhat, you will rapidly reach a point where 1 or 2 of them will stop working and you have to replace tonight.

chilefrans · December 2020

I have a 48 V powers system. I hv connected (4) 12v 100AH batteries to run 48v system . (12V x 4x 100AH) x 3

The 3 sets are connected together in parallel connection to make a 48V 300AH.

I would like to add one set of (12V x 4 x 200AH) eg

(12Vx4x100AH) + ( 12Vx4x100AH) + (12Vx4x100AH) + ( 12Vx4x200AH)

is it safe to add one set of 12V x 4 x 200AH battery?

Photowhit · December 2020

chilefrans said:

I have a 48 V powers system. I hv connected (4) 12v 100AH batteries to run 48v system . (12V x 4x 100AH) x 3
The 3 sets are connected together in parallel connection to make a 48V 300AH.
I would like to add one set of (12V x 4 x 200AH) eg
(12Vx4x100AH) + ( 12Vx4x100AH) + (12Vx4x100AH) + ( 12Vx4x200AH)
is it safe to add one set of 12V x 4 x 200AH battery?

No you want the same identical batteries if in parallel.
If your batteries are very old at all, it's not a good idea to mix different age batteries.

BB. · December 2020

And worst if you mix different construction like AGM vs flooded cell or vrla, etc.

If they are safe brand and type, and different ages, they will work, but you will have batteries failing randomly over the years (older first, newer later, or even near the same time).

When you replace the back, I would suggest lager case/capacity batteries.

And do not place a bunch of 12 volt batteries in series. I try to get people to use 3 parralle strings maximum. And use (for example) 6 volt @ 200 ah batteries on series for 12 volt @ 200 ah per string.

It is fewer cells to check water and fewer strings in parallel. Plus much easier to find a bad battery using a volt meter to check the voltage of each 6 volt battery.

Bill

Battery Bank Problems

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