Charge controller not charging my batteries? Maybe?

[daltons_advantures]

Hey guys. I’m going to try to keep this concise.

I have a 200 amp lithium battery from renogy and the 50amp dc to dc controller with mppt. I also have a BT2 connected to the controller.

Recently my battery hasn’t been getting much charge at all, and I think the culprit is my charge controller.

According to my dc home app, my battery voltage is 13.5 and this is confirmed with a multimeter.

When I check the readout on my BT2, the charge controller thinks my battery is at 14.5 volts, so presumably it isn’t pushing any of that good San Diego sun into the system.

My alternator input is measuring 14.2 volts, and solar is 22. So I know the power is coming in. But coming out of the controller all I’m getting is 13.5.

If I change the parameters for boost charging in the BT2 module to 14.6 volts for my battery instead of 14.4 (the default) suddenly the charging rate takes off and the voltage is actually coming out of the controller.

Is this likely a faulty controller? Is there something I may be overlooking here?

The systems about 4 months old now and has been working fine up until about a month ago.

 

[mikefitz]

battery voltage is 13.5

That's fully charged.

charge controller thinks my battery is at 14.5 volts

If the battery BMS has shutdown the charge path that that's possible.

So I know the power is coming in

You would have to measure current flow, volts measurement is not enough.

Is there something I may be overlooking here?

Perhaps the battery. Unfortuantly you have a Renogy battery and a Renogy charger, the performance history for both items is not great, based on issues raised on the forum.
You had battery issues in August, it this the same Battery?
What are the cell volts Reading?

 

[daltons_advantures]

That's fully charged.

If the battery BMS has shutdown the charge path that that's possible.

You would have to measure current flow, volts measurement is not enough.

Perhaps the battery. Unfortuantly you have a Renogy battery and a Renogy charger, the performance history for both items is not great, based on issues raised on the forum.
You had battery issues in August, it this the same Battery?
What are the cell volts Reading?

That's fully charged.

If the battery BMS has shutdown the charge path that that's possible.

You would have to measure current flow, volts measurement is not enough.


Perhaps the battery. Unfortuantly you have a Renogy battery and a Renogy charger, the performance history for both items is not great, based on issues raised on the forum.
You had battery issues in August, it this the same Battery?
What are the cell volts Reading?

Thanks for the reply Mike! In hindsight, I wouldn't buy another renogy product. I thought they were solid when I was early in this process.

So my battery is reading 13.5 volts, but my app is telling me its only ~70% charged.

This is a new battery that they sent me. All the cells are reading 3.3, at least inside the dc home app.

I took some screenshots this morning for reference.

The first is with no charge coming in, just a bit of draw (it measured 13.45V with a multimeter). The second had some sun on the panels (now my battery measured 13.52V). And the third is my bluetooth device (BT2) connected to my charge controller.

 

[mikefitz]

no charge coming in, just a bit of draw (it measured 13.45V with a multimeter).

If the meter is correct then that's a high SOC, near 100%. The Renogy only showing one place of decimal volts is useless, 3.3 volts per cell does not agree with 13.45.

third is my bluetooth device (BT2

At least the volts agree with the meter, but it shows a 13 watt charge so the battery volts will be higher.

Usiing voltage to determine SOC is not easy, I would consider that if the cell volts reports 3.4 then it's fully charged. Consider the graph produced by a forum expert, ( sorry I don't have the name linked to the graph hope you dont mind me reproducing it here).
Assuming Renogy measures 3.3 volts to 3.3 +/- 0.05, the resting state of charge could be 20% to 95% SOC.