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christopher-maric asked

SmartSolar 100/50 not charging

Hi, I've got a smart solar 100/50 with a couple of panels connected to it. AGM profile selected (but also tried resetting to defaults). Have isolated any current draws from the battery. It also charges normally from 240v chargers, so don't believe there is a battery issue.

My issue is that the battery voltage isn't reading correctly. It's moving to float very quickly and putting basically nothing into the battery as a result. Checking the battery with a multimeter, battery is at 12.62v (AGM), so there's no reason for it not to accept current.

The 'battery' section of the app see's 13.8v, so it's basically moving to float straight away. Cable sizing is more than adequate, and the cable run is only 25cm.

If I turn the charge function in the app off, the battery voltage shows correctly.

If I disconnect the fuse between controller and battery while the charge function is enabled, voltage stays at 13.8v. If I repeat that test with the charge function disabled, voltage goes to 0v.

If I pull the fuse from the solar panel to the controller, pv drops to 0v as expected. Otherwise panel voltage is around 60v, also as expected.

I've replaced both of the above fuses with no change.

This system was working but suddenly had this issue. I do recall doing a firmware update not long ago as it's now on the latest firmware, so that may have something to do with it. It's as if the controller is reading the voltage it's trying to put into the battery as the battery voltage itself, so moving to float as a result. Maybe a firmware bug? Can I downgrade firmware?

Is the controller fried? It's not old and has had minimal use.

I'm trying to work out what to troubleshoot and try next.
MPPT Controllers
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klim8skeptic avatar image klim8skeptic ♦ commented ·

Post some pictures of your installation.

Post a snap of the controllers history as well showing battery voltages etc.

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wkirby answered ·

Your diagnostic steps point to the controller not being properly connected to the battery for some reason.
You have observed that the MPPT is reading its target Voltages and not the actual battery Voltage, so therefore it is not connected to the battery or there is a high resistance along the wiring between the MPPT and the battery.

You'll need to go through and verify that all your connections are sound, all fuses are good, all switches are working correctly and the wiring is not damaged.

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christopher-maric avatar image christopher-maric commented ·

The thing is - if I turn the 'charger enabled' setting to disabled, it reads the correct battery voltage.

I also just ran new pos/neg cables to the battery, no fuse as it was just temporary for testing - no change.

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wkirby avatar image wkirby ♦♦ christopher-maric commented ·

So then you have a high resistance somewhere. When the charger is disabled no significant current flows, so the Voltage difference over the circuit between the battery and MPPT is also insignificant and then the correct battery Voltage can be measured by the MPPT.
This high resistance makes it very easy for the MPPT to reach its target Voltages and so it switches to Float quickly.

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