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robbirobson

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Posts: 16
Reply with quote  #21 
Yes i read that 12.7 is the normal voltage when charged. However the battery keeps discharging itself. 3 batteries had about 12.8v in the evening. But the other one had 11.9v without any load connected. Ithink tjis is defective. When i disconnect this battery the voltage is higher under load.about 25v, with this particular battery connected it drops to 24.5v

stmbtwle

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Reply with quote  #22 
I think you found it.

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
Rick H Parker

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Reply with quote  #23 
But the other one had 11.9v without any load connected. I think this is defective.

100% self discharge in 5 hours is a serious defect. Normal self discharge for Lead acid is ~5% per month.

Open circuit, at rest, 11.9V is completely discharged.  State of Charge (SoC)= 0%, Depth of Discharge (DoD)= 100%

 

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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
robbirobson

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Reply with quote  #24 
I am trying to get the battery replaced today and run some tests again.The other batteries when the mppt shutsdown due to low voltage under load in the morning have 12.4v so they might be ok,  also they did not loose any charge after 2 days being disconnected they still had 12.8v. The only strange thing is what i realized they are showing me full about 26.5v and the mppt does not charge more, when there is load connected just for some few seconds it displays 50% and the mppt starts charging again.
Rick H Parker

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Reply with quote  #25 
The only strange thing is

With a defective battery in the bank, one should expect strange things.

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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
robbirobson

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Posts: 16
Reply with quote  #26 
Yes but with the 2 good batteries they also seem to not have the capacity as they should. Just now as they are charging they display 26v and almost full in the mppt and as soon as i turn something on they drop to 23 and the mppt alarm sounds.
Also i just ran a ventilator 8 hours at night, the ventilator has 20 watts. it drained the 2 good batteries and the mppt shut down. When i checked the battery this morning without load they had 12.4v but with any small load dropped to 11.5v. And yesterday in the evening they had fully charged to 12.8v.
Rick H Parker

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Reply with quote  #27 

i just recently (2 month ago installed solar power in my container).

How hot does it get in the container? You might be cooking the batteries.

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Rick H Parker
Kansas, USA
Electronics Engineering Technologist
robbirobson

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Posts: 16
Reply with quote  #28 
The container is mounted on some poles and the batteries are stored under it. There is always some fresh wind blowing so heat is not the issue. I want to buy the batteryminder charger and check the batteries with it. Because they cant be all bad. Or the problem is the mppt. Just today i had some good sun so i let the batteries charge complete. After that i turned in the fridge. As some clouds where coming and it switched to battery power the voltage just dropped to 23 volts with only 12 amps of current.
.
robbirobson

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Posts: 16
Reply with quote  #29 
It seems the mppt is draining 1 to 2 amps constantly which are not seen in the display. Its a signigicant loss after about 14 hours without sun i think i need a larger battery bank as well.
stmbtwle

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Reply with quote  #30 
That's quite a bit. Some inverters will automatically shut down if there's no load, apparently yours doesn't.

Not sure what you can do about it though. You could turn it off when not needed, but that kinda defeats the purpose if you're running a fridge.

Maybe Rick can come up with a demand activated circuit to turn it on and off.

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Solar is like the wind. It may be free, but putting it to work isn't!
Willie, Tampa Bay
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