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simplesimon asked

Avoiding dead lead acid battery on smartsolar MPPT

So have been using a small phoenix inverter run off a MPPT100/20 to power a laptop. Re-charging has been done with conventional car charger as no solar panel as yet.

Normal use discharge as shown except for the dip at the end:

discharging.png


Normally the inverter or charger trips and I switch off. After a couple of hours the battery voltage is somewhere 12.3 - 12.5V so I think the State of Charge is ok before being charged again. However this time the on / off cycled like so:



battery-killer-settings.png

... and even after a full charge the battery is a 10V battery so dead.

The jumper was set on the middle pins of the controller so should operate:

Conventional algorithm:
low voltage disconnect: 11.8V
Automatic load reconnect voltage: 14.0V

However that doesn't appear to be as it's behaving as it's re-connecting at 11.9V or so.


Any ideas what has happened?

Now I will run the load as BatteryLife with the jumper removed to see if that behaves better but it's an expensive experiment if I'm doing something else wrong...

low battery warninglead-acid
discharging.png (196.9 KiB)
battery-killer-settings.png (152.2 KiB)
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4 Answers
snoobler avatar image
snoobler answered ·

If you're using the load ports on a charge controller to power an inverter, stop immediately.



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regman54 avatar image
regman54 answered ·

I agree, if you don't have solar panels you shouldn’t be using a solar charge controller to charge the batteries. Use the automotive battery charger to charge the batteries.

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simplesimon avatar image
simplesimon answered ·

Ahh, maybe I didn't explain that fully. Yes I'm using the automotive charger to charge the batteries directly. I'll try using the inverter powered directly from the battery with a remote connection from the controller.

But as the inverter is within the power rating of the controller, why shouldn't it be used from load connection?

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Justin Cook avatar image Justin Cook ♦♦ commented ·

The user manual is a good reference point for what and why this should not be done, and how to do it instead:

load-output.png

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load-output.png (58.2 KiB)
simplesimon avatar image simplesimon Justin Cook ♦♦ commented ·
Thanks, now looking for the inverting remote on-off cable as now the old Pheonix inverter is only on when the load output is off and vice versa, so would loose the battery protection without it.

I guess now the only way to monitor the load is with a BMV or similar.


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snoobler avatar image
snoobler answered ·

Most laptops are 19V input. A DC-DC converter powered by the load port would work:

Example:

https://www.amazon.com/Converter-Voltage-Regulator-Adapter-Vehicle/dp/B0B7481QCY



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