AIMS PICOGLF25W12V120AL Inverter Fault Shutdown, No Auto Reset…

[MadMacks]

I have an off-grid set up using a few solar panels (630 watts), a custom built LiFePO4 battery with JBD BMS, a Renogy MPPT charge controller, and a AIMS PICOGLF25W12V120AL inverter/charger. The AIMS is powering a chest freezer and a few other small A/C based items. The problem I’m trying to address is that the BMS will disconnect the battery when it hits an over voltage thresholds (like it should) or a battery full condition. When that happens it triggers a fault on the inverter, and it cuts off and starts putting out an audible alert beep. This happens, usually, around early afternoon when the battery is fully charged. If I’m around and hear the audible alert I go hit the on-off switch and things go back to normal, even if the battery is still disconnected due to the BMS protecting it. The AIMS gets enough power from the solar panels to power things just fine. And when the battery voltage drops the BMS turns the battery back on and things go back to normal.

I will probably fiddle with the settings on the Renogy MPPT controller and BMS to not quite take the battery to a high voltage cutoff level, so that might resolve the issue, but I’m wondering if there is some other way to resolve the problem differently. I’m not sure if the AIMS sees the momentary voltage change when the BMS shuts off the battery as an “error” and throws a fault, or exactly why the AIMS is shutting down (as there’s no log to show the fault condition that causes the shut down), but I really don’t want to lose a chest freezers worth of food if I’m not around to hit the on/off switch and get the AIMS running again.

Any ideas?

 

[MisterSandals]

The problem I’m trying to address is that the BMS will disconnect the battery when it hits an over voltage thresholds (like it should) or a battery full condition

It should be a very rare occurrence that your charge controller charges to the point where your BMS disconnects. The charge controller should be set to charge at safe daily voltage (in the 3.45Vpc to 3.5Vpc range). The BMS should be set to prevent cells from exceeding 3.65V or some comfort inducing amount below this.

What charge controller do you have and what are your charge parameters?

 

[MadMacks]

The solar charger is a Renogy Commander 40. I have the settings as follows…

MPPT Controller Settings

Over Voltage Disconnect: 14.5 -> 14.4 (I changed it when I was looking)
Charge Limit: 14.4 -> 14.3 (I changed it when I was looking)
Over Voltage Reconnect: 14.0
Boost Charge: 14.4 -> 14.3 (I changed it when I was looking)
Float Charge: 13.8
Boost Recovery: 13.2
BoostTime: 120m -> 90m

JBD BMS settings
Full Cell: 3400
Cell Over Voltage: 3600
Battery Over Voltage: 14.4

With the original MPPT charge limit setting at 14.4 the BMS could have cut off I guess. I don’t recall seeing that condition when I was more closely monitoring it but I made the changes listed above to see if they would help.

 

[MisterSandals]

Who recommended charging to that level?

Your battery is essentially full at 3.45Vpc which is 13.8V battery.
Charging to that level an not having one cell exceed 3.6V regularly would be an exceedingly well behave battery.

Have you checked with the app what the disconnect condition is?

 

[MisterSandals]

I recommend trying lower charge values at least to see if this solves your issue in the OP.

Charge limit and boost :13.8V
The 90min boost time should easily saturate your cells.

Float 13.4V (or just below where your battery settles on its own in an hour. This will prevent micro cycling: charge, settle, charge, settle…)

I am pretty confident this will solve your issues. You will be charging to 99.9% of capacity and not beating the crap out of them every charge cycle. Having the BMS cut out every charge cycle takes that beating to another level for your entire system.

Your BMS cell over voltage can be higher. Theoretically it can handle, conservative chargers (like me) set this lower, to around 3.63V

 

[MadMacks]

Thx. I’ll give it a try…