Batteries not holding charge all of a sudden

Discussion about the OutBack Energy Cell Batteries
drjaredshelton
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My RE system: 30 280w panels, 8- 6v 430Ah.

Re: Batteries not holding charge all of a sudden

Post by drjaredshelton » Sat May 02, 2020 3:04 am

Good info. Like I said, the solar company installed all of this and obviously didn’t know what they were doing. I’ve called and called and I can not get them to return my messages. I have little idea on how to fix it, so this helps somewhat. I understand the imbalance, now what do I do to fix the issues?
30 280w panels/ 8battery bank- 6v 430Ah/ four GS8048A radian inverters/ two FM80-150VDC CC/ Mate3s
Site: Bear River Chiropractic

raysun
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My RE system: Flexpower Two: (2) FXR3048A, (2) FM80, MATE3s, FlexNetDC
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Re: Batteries not holding charge all of a sudden

Post by raysun » Sat May 02, 2020 5:54 am

There's two routes:

#1
Patch the immediate problem by replacing dead battery monoblocks, and getting the solar/battery/inverter system back up and running. This will bring the battery back on line but won't fix the underlying problem with the system design.

It looks like the CR430 is about $300 each, so $600 or so to get the system running for probably 6 months until other blocks start failing. (Service life estimate for patched battery is definitely, IMO, but others on this forum with similar problems in the past can nod in agreement or weigh in with a 2nd opinion. )

It may be better/cheaper to switch to 100% grid power, bypassing the PV/inverter system for now, and proceed to step #2 re-engineering the system properly. It needs doing sooner or later, so timing is a budget/business decision.

#2. Re-engineer the system with proper design for energy demands and self-consumption goals.

The basic steps to getting everything balanced and properly functioning is:

a) Determine peak (instantaneous) power consumption demands for the AC loads. This will be measured in kilowatts (kW.)

b) Determine average daily power consumption. This will be measured in kilowatt hours (kWH.)

c) Evaluate solar panel (PV) power generation capacity.

d) Calculate battery capacity to properly manage daily PV harvest and AC power consumption.

e) Configure inverter system to provide AC power demands in accordance with PV harvest, battery capacity and daily cycling capabilities, with any shortfall to be made up by consuming power from the grid.

As built, the system components have the potential to provide adequate power generation for a relatively decent amount of self-consumption, with grid backup to fill in the gaps. I assume this was the original design intent and this section is predicated on that.

a) and b) above can be evaluated fairly directly by switching power consumption to grid, consume grid power 100% for a period - say 1 month - and look at the bill. It will provide average daily consumption certainly as a total for the billing cycle. If you're lucky, the power company has installed smart metering that can capture peak demand which will reflect the instantaneous consumption figure needed to set peak Inverter output requirements.

If not on the bill, a manual assay of all loads in the facility can be undertaken. There are lots of worksheets and guidance on-line to step through the process. Its tedious and fraught with estimating errors however, A SWAG (simple wild-a$$ guess) and common sense may do just as well. The precision method would be to mount a meter on the AC load primary line on the facility main power panel. One that is capable of capturing consumption and peak demand will answer both questions automatically. Figure about $2,000 for purchase and installation by a licensed electrician.

c) The solar panel array, at 8.4kW nominal, is fairly decent for a modest size home/office. How much of the total daily energy demand its capable of serving depends of consumption of course, and average monthly generation, which in turn depends on solar conditions where the system is located. There are online tools that will help estimate the PV (photo-voltiactic) energy harvest potential for your locale. Also, the FM80 charge controllers capture actual harvest information on a daily basis and store it for about 120 days. The logs will be skewed, unfortunately, by the inadequate and failing battery. If the system is on OpticsRE, then the PV harvest and consumption data is there.

Let's assume using the PV array/charge controller sub-system as-is and matching the rest is the system to its capabilities. A very rough estimate, for the sake of penciling out capabilities on the back of a cocktail napkin, let's assume 4 hours of full output from the array daily. (Rounding down for generation losses and making the math easier) 8kW x 4H = 32kWH daily energy generation. That's a goodly amount and pencils out to 960kWH power generation per month.

That 960kWH is going toward battery charging. Lets assume 10% loss in the charging process so 960kWH - 96kWH ~ 865kWH battery charging potential. 865 / 30 ~ 28kWH daily charging power potential. We'll use that number later.

Conversion of DC power to AC power will have further losses. We'll calculate them momentarily.

d) Battery capacity must account for two factors: accepting full PV charging current and serving full Inverter demands.

Working from the charging current side, the maximum continuous charge current potential is 160A (2 FM80s at full output.) The battery must have sufficient capacity to handle that input current. Taking the current battery technology as the benchmark, maximum sustained charging current acceptance is 430 x 13% = 55A. Three strings of 8 monoblocks (24 total battery blocks) would handle the full 160A charging power properly.

The resulting battery would be 430AH x 3 = 1290AH capacity. Minimum charge current for proper maintenance would be 40A per string according to the manufacturer (9% of C20) of 120A - this figure would be hard to sustain on a day-to-day basis as clouds, winter solar capacity, etc., reduce PV harvest. The large battery bank, undercharged by not maintaining charging minimums, would have a shorter than desired service life.

To strike a compromise, reduce the battery size to 860AH (2 strings) and limit the PV collection to a maximum of 130A. This will potentially leave 30A of capacity "on the table" as not used, but given the array size and reality of solar harvest is a decent compromise.

Battery to be specified as:
2 parallel strings of 430AH @ 48V
16 monoblocks @ $300 ea = $4800. Additional cabling, circuit breakers, and installation ~ $1200. Total battery replacement cost $6,000.

The battery will have 48V x 860AH = 40kWH gross capacity. Daily cycling and draw of maximum 50% of capacity = 20kWH net. 10% loss in DC to AC inversion. = 18kWH. The battery will be able to deliver 18kWH daily AC power to drive loads.

The PV array has the potential of generating 28kWH of power daily, so should cover the demands and keep the battery properly charged on "typical" days. Days of less than required PV harvest will need makeup charging from the grid.

The battery would be capable of peak output of 48V x 200A = 9.6kW an amount that fits neatly into the maximum draw of a single 8kW Radian inverter.

e) Size the Inverter

The Inverter cluster is overly large for the rest of the system. Hopefully, the average power demand can be fit into a single 8kW Radian.

Two radians (one master working full time, and one slave on standby to handle peaks over 8kW for a *very* short period) should be more than enough to handle any rational power demands of a small facility.

The system can be configured to fall back to grid power should peak demand require more than instantaneous peaks greater than 16kW, but a better approach is to tailor consumption habits to match PV/Battery/Inverter capabilities.

The other two Radians are surplus. Leave them hanging on the wall, disconnected, as a monument to "live and learn" or dismantle them from the system and sell them. OB gear retains decent resale value.

You will need two skill sets to make ths upgrade:

A licensed electrician who has familiarity with wiring a solar power system. Their job will be to assure everything is wired correctly, not that the system is configured correctly.

An engineering consultant with knowledge of Outback system architecture and capability to configure the system. You may have noticed some of the most knowledgable are the group of amateur and professional engineers on this forum. I have no doubt that if your system is on OpticsRE, that the folks here could walk you through getting things set up. If you need a configuration process that can be "wet stamped" for a local power authority, and indemnified as properly commissioned, you will need to hire a professional. If you are of the realization that you will end up being your own operating engineer - these systems, even ones as bulletproof as Outback, are anything but "set and forget' - then this is the ideal time to get educated. There's a couple licenced professionals on this forum. Perhaps an offline conversation with one will get you the subject matter expert resource you need.

drjaredshelton
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Posts: 50
Joined: Mon Mar 26, 2018 9:09 am
My RE system: 30 280w panels, 8- 6v 430Ah.

Re: Batteries not holding charge all of a sudden

Post by drjaredshelton » Sat May 02, 2020 6:39 am

I am a doctor, far from an engineer for sure, lol. This is helpful though. Thank you for your time. I'm at a point of trying to figure out what to do. May be time to file a lawsuit against the solar company who installed it improperly for not knowing what they were doing. The other sad thing is that the system was passed off by the electrical inspector who should have known this was set up wrong as well. I've been looking for another installer to come and take a look at fixing it, but of course most don't want to touch something another company has done......

I don't have exact numbers, but have rough estimates. Most of the day the building is drawing between 2-14kw at any given time, with 3-4 being the average at peak times and 1-2kw when its just running lights and computers. Daily power consumption of the building is between 35-45kw most days, but I've seen as high at 75kw. I was told at the time that I would be using zero grid power most days, but that has never been the case as you can see.

I have the battery chargers turned down to 35A charging each instead of the full 80A each. I manually turned off two of the other inverters power in and out breakers since they are just sitting there doing nothing anyway. Seems these could be removed and sold for someone else to use instead of just collecting dust and doing nothing here. I'm searching for the original paperwork with the math that was used to calculate out the system as well. That may be of some more use in figuring out the solution.

I'd like to add the amount of batteries and replace the current bank, but I believe I was already taken advantage of on the first bank. I'm certain that I was told $15000 for the current bank. Of course at the time I just took their word for it and didn't look up the cost of the batteries myself.
30 280w panels/ 8battery bank- 6v 430Ah/ four GS8048A radian inverters/ two FM80-150VDC CC/ Mate3s
Site: Bear River Chiropractic

fcwlp
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My RE system: GS8048A, FM80 w/3,600 W PV Fixed, FM80 w/2,700W on Zomeworks tracker, Mate3, 24 Trojan 2V L16 1100AH @ C20, Grid-Tied with Kohler 14RESA LPG Generator and MEP-803 Diesel if needed
I also install and maintain grid-tied and off-grid systems, details will be given for these system if required
Location: 80 miles NE of Phoenix at 5500'

Re: Batteries not holding charge all of a sudden

Post by fcwlp » Sat May 02, 2020 7:12 am

drjaredshelton wrote:
Sat May 02, 2020 6:39 am
am a doctor, far from an engineer for sure, lol.
I am an engineer, not a medical doctor. :grin: But I do solar system design, procurement and help with installs. Did your previous installers, leave you a schematic of the system. If the town/county inspected it, they should have the drawings on file. Don't fault the inspector, their task is to verify electrical safety. However, most don't know what they are looking at. I have had only one competent inspector who came from our power company, but then he had been an solar system designer and installer for 15 years before working for the power company.

Is the facility in use every day?
drjaredshelton wrote:
Sat May 02, 2020 6:39 am
I'd like to add the amount of batteries and replace the current bank, but I believe I was already taken advantage of on the first bank. I'm certain that I was told $15000 for the current bank. Of course at the time I just took their word for it and didn't look up the cost of the batteries myself.
If you paid $15K for the current bank, there was a good profit margin in that for someone. For a couple of thousand more, you can get a FLA battery bank with a C20 of ~1,600AH using a single string of 2 or 4 volt batteries.

As a first pass it looks like 2 Radians at most will be adequate with a battery bank with a C20 of ~1,600AH.

JRHill
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Re: Batteries not holding charge all of a sudden

Post by JRHill » Sat May 02, 2020 11:02 am

This is really unfortunate. The design is clearly lacking but you've got top notch components, IMHO.

If you can't find a reputable company in a reasonable range to assist with the corrections and possible programming changes the next best would be for someone with the skills on this forum who is close by to step up and lend a hand. It's pretty obvious the solutions have already been suggested.

BTW, unless I missed it, is your battery bank in a place where it could be expanded? If you went with 2v batteries then its going to triple the footprint. But it would seem the best route considering the equipment into which you have already invested and would best utilize the potential. Someone may suggest adding a 2nd bank of the same batteries as a solution during the change-out. Be weary. If you were retired and solar was your hobby you would probably be happy and maintain it all. But a 2nd bank adds complexity which you probably don't need or desire. Gosh, some people do 3, 4 or more banks (Arghh).

Worst would be if you got a sour attitude and looked to get out. That would be a disappointment to all of us.

Best,
Jim

provo
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(4 strings, total 1920W)
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Re: Batteries not holding charge all of a sudden

Post by provo » Sat May 02, 2020 11:20 am

drjaredshelton wrote:
Sat May 02, 2020 6:39 am

May be time to file a lawsuit against the solar company who installed it improperly for not knowing what they were doing.
You're in Grass Valley, right? Have you talked to the people at Sierra Solar Systems? I don't believe they do installations, but if you tell them who did your install they might recommend someone else in your area to fix it....

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