Solar new generation solar panels

jazzeddie1234

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May 19, 2016
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I did a test with my new lithium batteries and my ecoworthy mppt controllers to see what happens. Both set to the same voltage (14.4 and 13.4) and one set slightly lower (14.3 and 13.3).

In the first case both controllers go flat out until one sees it has reached 14.4 and it drops into float - showing 0 float amps. A second later the other mppt sees 14.4 and drops into float - and shows 0 amps. Nothing happens then until the batteries drift down to 13.4 (takes ages) where the mppts start a tiny float current (way less than 1/2 amp in total)

In the second case it is all the same but one mppt drops out a lot sooner

The zero float shows the BMS is smart enough to shut off any charge when full and is not fighting the MPPT that have dropped into float. And the mppts do nothing until some load (eg lights) is switched on - then they ramp up float current to maintain 13.4 (eg if the lights need 5 amps the mppts provide 5 amps and the battery does nothing)
 

Drover

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Nov 7, 2013
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You got me going so I had a good look at a few lithiums at my favorite battery shop, Forbes Batteries in Toowoomba, goodness me my ideal set up would cost a monza for sure......... at least with my set up I just have to swap batteries and flick a switch, now wheres that grandchild I can, ooppss, cant say that now so a freindly bank manager is needed.
 
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jazzeddie1234

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May 19, 2016
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Mandurah
Another test - this time with the setec st-III on the lithiums. It ramps up to 15amps and stays there until the voltage reaches 13.7 ish. Then the current quickly drops off to less than .5 amp at 13.8 volts. So like lead acid, not a full charge but good enough for most uses and solar should top them up if required.