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Author Topic: FLA battery new lease of life  (Read 3341 times)
Nickel2
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« on: June 19, 2019, 09:47:03 PM »

I've had my batteries for nearly a year now (2S2P 24V 400Ah) As they are old second-hand starter batteries I try to keep DOD low, ie 10-15%. Today something has changed, and at the end of the evening's use the battery has stayed at a constant 25.2 volts. Previously at this time of night after a full day's solar, ending on float it would have dropped to 25.0 V on load.
Today, I am about to go to bed, and the battery is still sitting at 25.2 V.
Do batteries have a change of heart, or has there been an internal event that I don't know about?
Hopefully this is not a last gasp before demise.
I am still learning batteries, this is new to me.
What am I doing right?
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1.140kW mono south-facing at 49*
EpEver 4210A at 24v
24V 400 Ah battery. (4x200Ah FLA)
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
oliver90owner
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« Reply #1 on: June 19, 2019, 11:00:19 PM »

What are you using to measure?  If a DVM, the battery (in the DVM) may need changing.
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Nickel2
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« Reply #2 on: June 20, 2019, 08:45:58 AM »

I'm using the GUI on my PC, that comes with the Epever MPPT, plus the GUI for the Epever inverter on the workshop machine. I did think it strange, so I replaced the batts in my DVM (Fluke 75), no difference.
It seems that the voltage does not drop off so sharply after dark, but stays above 25.0 until the morning. The inverter takes 460mA quiescent, overnight load is under 500mA.
I'm not complaining, Just slightly puzzled/curious...  Huh  most peculiar
I'm still after a Nissan leaf or Mitsubishi outlander battery. (if anyone has a spare kicking about).
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1.140kW mono south-facing at 49*
EpEver 4210A at 24v
24V 400 Ah battery. (4x200Ah FLA)
EpEver STI1000-24-230 pure sine inverter
Of course it'll work. (It hasn't caught fire yet).
nowty
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« Reply #3 on: June 20, 2019, 09:59:55 AM »

Could it simply be the days longer and the nights are shorter at this time of year ?

If you have ran it for nearly a year you may have never ran it this close to the longest day before.
« Last Edit: June 20, 2019, 10:05:57 AM by nowty » Logged

11kW+ of PV installed and 56+ MWh generated.
Lithium battery storage of 50+ kWh.
Hot water storage of 15+ kWh.
Heat storage of 15+ kWh.
6kW Ground source heatpump.
EV BMW i3 (another 30+ kWh's of storage).
260,000+ litres of water harvested from underground river.
Home grown Fruit and Veg.
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