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I have an eco worthy 4 solar panels (2 * 12 connected in series and 2 * 24 connected in parallel). I can confirm that on a good sunny day output voltage from panels (measured on the red and black cables is about 22 to 24V) produce the output expected. On the battery side, I have 4 * 12V 30AH batteries (li Ion) connected in series(2) and then parallel to produce output 24V. Issue When I connect solar panel in series mode across the 4 batteries(I tried even just 2 of them in series) they dont seem to charge since the solar output is just less than 24V. On the other hand, if I connect the solar output in parallel on directly to one battery it charges fast (like an hour or so) to about > 13.5V. And, then it is able to handle load for a few hours. My issue I am unable to get the batteries to charge in parallel from a solar array configured to produce 24V. On the battery side, I have 4 12V 30AH batteries (li Ion) connected in series(2) and then parallel to produce output 24V.

Does anyone have any suggestions if solar panels expected to produce 24V are lesser than 24V expected(Live in a moderate weather not always bright sun)? My issue I am unable to get the batteries to charge in parallel from a solar array configured to produce 24V.

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    \$\begingroup\$ To charge 24v then you need about 28v... \$\endgroup\$ – Solar Mike May 1 at 16:35
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    \$\begingroup\$ Have you directly connected solar panel output to lithium batteries? Without a charger? Which batteries are those, LiPo, Li-ion, LiFePo? Lithium batteries need to be charged very precisely with a charger so they don't explode and start a fire. Besides a single 3.7V cell needs to be charged up to 4.2V or so to be full. \$\endgroup\$ – Justme May 1 at 17:10
  • \$\begingroup\$ @SolarMike thanks ! That was one of my doubts. That the sun generated voltage is not good enough to drive the charge for 24V batteries. Would you suggest charge each 12V battery separately? \$\endgroup\$ – Manoj Ramakrishnan May 1 at 19:47
  • \$\begingroup\$ @Justme I am talking about charging directly from solar output wires to the batteries. (since I wanted to rule out that it charges without controller) (by passing the controller) These are 12 V Li Ion batteries. \$\endgroup\$ – Manoj Ramakrishnan May 1 at 19:49
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    \$\begingroup\$ @ManojRamakrishnan You need a solar charge controller, you cannot wire the solar panel direct to the batteries. \$\endgroup\$ – Voltage Spike May 4 at 18:21

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