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Just want to make sure this charging configuration will work. Basically we have two solar panels and two solar charge controllers independently charging one of the two series connected batteries simultaneously. The load is a 24V electric cart. Are there any issues? Thanks!

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  • \$\begingroup\$ No, they are not equivalent and yes there will be issues. Charging at 2A is 2A +/- 5%? then imagine the top always being 1.9A and the bottom always being 2.1A --> growing imbalance until final battery inversion on the top with all the problems and risks that come with that. \$\endgroup\$
    – Asmyldof
    Apr 8, 2016 at 18:09
  • \$\begingroup\$ As almost always, it depends. Do you have an undervoltage cutout on your 24 V load? Best case you would have individual charging like you propose but an UVLO for each 12 V battery and OR the two signals together. Might be overkill for most applications. \$\endgroup\$
    – winny
    Jul 19, 2019 at 21:46

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I think the second case is fine. Each charge controller will see only its own battery, and charge it normally. A few important caveats: the two controllers, solar panels etc must be completely isolated from each other, they must receive similar amounts of sun, and they must from time to time manage to fully charge the batteries, so they get equally full.

The two are not exactly equivalent.

Your second circuit has an error - the middle wire actually carries both 2 A in for the first controller, and 2 A out for the second, so the net current on that wire is zero. But not all the time, and depending on the chargers, and so on. It had better be a thick wire, you don't want the voltage drop from one charger's current affecting the voltage reading of the other charger...

Why not just connect your two solar cells in series, and use a 24 V charge controller?

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  • \$\begingroup\$ Some people says its fine, others don't, I really don't know who to believe. It's kind of too late now because the system has been implemented for the project. To make a long story short, our original charging system used a flexible 12V solar panel and solar boost charge controller. The issue all along has been money and the desire to make a collapsible, foldable mounting structure for the panels on top of the small three wheeled cart. Charging each separately allowed us to save money on the panels/controllers because each needed to be for a 12V battery. \$\endgroup\$ Apr 8, 2016 at 21:58

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