Evaluating your off-grid system

Discussion about OutBack Inverters in Off Grid Applications

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raysun
Forum Overlord
Posts: 10395
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Evaluating your off-grid system

Post by raysun »

This is for the forum member from Montana who is having issues with their off-grid system. The post was deleted before I could save this reply:
The usual suspect is a degraded battery. I, too, started with 200NC, and they started showing degraded performance after 4 years, so I replaced them. Eight years is a good long time for that battery design.
As the battery loses capacity, it charges quicker, but discharges quicker as well. The shortfall must be made up with another power source, and for we off-grid folks, that's usually a gas powered backup generator.
I'm assuming the battery is configured as 48V with the 12 200NC battery blocks wired in 3 banks of 4 blocks in series. Each of the battery blocks is 12V, so 4 wired in series yields a 48V battery. The 3 strings are then connected in parallel to yield 534AH (Amp Hours) of energy storage capacity. As the battery ages, the storage capacity degrades, so it's likely the battery has significantly less capacity than originally.
The physical cells within the battery blocks (there's 6 cells per block, and 12 blocks, so 96 total cells) typically degrade unevenly, with some getting to the point they won't hold much charge at all. When that happens, it drags down the entire battery's performance markedly.
Since the battery blocks are sealed, the only clue to health is measuring the voltage of each block individually. A typical multimeter with DC Voltage settings will do the job. There's no need to disconnect any wiring. Label each block with a number from 1 - 12 written on a piece of masking tape. Next, measure each blocks voltage by placing the meter +/- probes on the blocks +/- terminals. Make note of all 12 voltages. (Be careful around the battery when measuring, shorting across battery terminals can be very traumatic.) The best time to take the 12 voltage measurements is early in the morning when the battery has been discharging overnight, the generator is not running, and before solar charging starts.
Ideally, each block will measure above 12V and all 12 read about the same voltage. Post the voltage measurements, and we can suggest some next steps.
Also, it would be helpful if the details of the equipment in the system is listed in your profile. I see Mate3, that's a good start! Inverter model(s), Solar Charge Controller model(s), solar panel model(s) or total wattage, etc.
JRHill
Forum Emperor
Posts: 2590
Joined: Thu Feb 17, 2011 11:12 am
My RE system: 48v OB inverter and charge controller, hub and mate3s.
Location: PNW
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Re: Evaluating your off-grid system

Post by JRHill »

Oh, darn.

If it who I think it is I have been hard on him - but I hoped to motivate him to do some basic technical courses. He didn't have time for that if it was the same person.

What in the world is he gonna do now? I hope he finds that good woman.
raysun
Forum Overlord
Posts: 10395
Joined: Tue Jul 26, 2016 5:57 am
My RE system: Flexpower Two: (2) FXR3048A-01 - Series Stacked, (2) FM80, MATE3s, FlexNetDC
6 SimpliPhi 3.8-48 (48v @ 75AH. 450AH total)
Outback IBR3 battery enclosure
REC Alpha 440W panels - 2 arrays: each of 4 strings of 2 in series
2 Midnite Solar MNPV6 combiners w/20A DC disconnects.
Honda EU7000is gas fuel generator
Off-Grid

Re: Evaluating your off-grid system

Post by raysun »

JRHill wrote: Fri Sep 29, 2023 4:00 pm Oh, darn.

If it who I think it is I have been hard on him - but I hoped to motivate him to do some basic technical courses. He didn't have time for that if it was the same person.

What in the world is he gonna do now? I hope he finds that good woman.
Actually it was someone different.
JRHill
Forum Emperor
Posts: 2590
Joined: Thu Feb 17, 2011 11:12 am
My RE system: 48v OB inverter and charge controller, hub and mate3s.
Location: PNW
Contact:

Re: Evaluating your off-grid system

Post by JRHill »

:???: Ok. Sorry.
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