Aims 60amp Solar Charge Controller: How to Effectively 'Disable' Float?

[TedH]

I have found on my Aims Solar Charge Controller, that I can set the Float voltage to a point but not OFF. I say this because I attempted to turn Absorption and Float off according to guidance to disable for LifePO4. I have a 24v battery bank, BMS, Inverter and the Solar Charge Controller (the SCC accommodates 12/24/36/48v systems).

My question: Should I reduce Absorption and Float to MINIMUM to effectively disable those settings? There is no 'OFF' setting. I recall the minimum Voltage for 24V, is 20V.

 

[TomC4306]

The guidance you received was wrong.
I'll describe what I do.
I bulk charge at 28 volts and I absorb at 28 volts for 60 minutes this offers the cells a fixed voltage and they will take whatever current they want or need.
I float at 27 volts.
This means that the charger is offering 27 volts to the bus and if the batteries fall to that place and require a little bit more current they will take it but more importantly it allows the solar charge controller to power the loads through the inverter.

 

[TedH]

Thanks. I will apply your guidance for leveraging Bulk, Equalization and Float settings.

 

[MisterSandals]

Equalization

For LiFePO4 equalization NEEDS to be off. Some have equalization duration which can be set to 0.

 

[TedH]

For LiFePO4 equalization NEEDS to be off. Some have equalization duration which can be set to 0.

isn't Equalization = Absorption?

 

[MisterSandals]

isn't Equalization = Absorption?

No

 

[TedH]

No

Since Aims only allows Equalization to be set to a value in range 20.0 to 29.2, what would you recommend it to be set to? It cannot be turned 'OFF'.

 

[MisterSandals]

what would you recommend it to be set to? It cannot be turned 'OFF'.

Does it have an equalization duration you can set to 0 hours?

If not, my guess would be to set equalization at or below your float voltage.

 

[TomC4306]

Are you certain that's as equalization and not absorption? For the life of me I can't think of what you would want to equalize at 20 volts. Equalization is for lead acid batteries only. It applies a very high voltage to make the batteries boil. You don't want to apply that to lithium

 

[TomC4306]

What Mr sandals said

 

[TomC4306]

Set the mode to AGM just to see if it doesn't disable equalization. If it doesn't, crap charger I'd replace it

 

[TedH]

Does it have an equalization duration you can set to 0 hours?

If not, my guess would be to set equalization at or below your float voltage.

Unfortunately, the Aims SCC doesn't allow for duration value. It only allows for a numeric value of Bulk, Float and Equalization. How low can I set Equalization?

For example, if Float is set to 27.0v, can Equalization be 24.0V or should I set it at a value BELOW the point at which the Inverter will kick in and start charging (currently 23.2v)?

NOTE: I have purchased the Victron SCC and Inverters; just have not swapped them in. I wanted to get the Aims devices (SCC and Inverter) to a point where they are stand-alone reliable so that, when I sell them, I can reliably recommend settings.

 

[TomC4306]

I don't discharge below 25 volts. I think 23.2 is far too low.
But to your question, below that number so that the charger never sees the battery at that equalization setting

 

[TedH]

Set the mode to AGM just to see if it doesn't disable equalization. If it doesn't, crap charger I'd replace it

I found that the Lifepo4 setting on Aims set Bulk, Float and Equalization to 28.8 across the board.

 

[TomC4306]

There has to be some sort of algorithm to tell that charger how often to run the equalization cycle. I would go digging in the manual for more details.

 

[TomC4306]

I found that the Lifepo4 setting on Aims set Bulk, Float and Equalization to 28.8 across the board.

That float is far too high

 

[TedH]

There has to be some sort of algorithm to tell that charger how often to run the equalization cycle. I would go digging in the manual for more details.

According to the manual that came with the unit, It is a set value: every 30 days.

 

[TedH]

That float is far too high

I agree. It was causing a conflict with the Inverter with the peaks inherent with MPPT charging (in my experience with Aims Inverter and Aims SCC). That is the reason I reduced Float to a lower value. I have been toying with Float in range of 26.8 and 27.4 and had been setting Equalization to the same value. This is now about the 30th day since I started using 'Self Defined' setting and I suspect the high equalization voltage is causing issues for my Lifepo4 as the BMS is shutting off (has done this in early morning around 4-5am).

 

[mikefitz]

Having read the user instructions it's clear the designers/ instruction writers have no clue as to what is needed in a solar charger.

They refer that absorbtion is the same as equalisation and suggest that bulk, absorbtion equilization and float are all set at 28.8 volts for lithium. This is plain stupid.
There seems no method to alter absorbtion duration and no indication how the charger determine the point to enter float.
Its not clear if temperature compensation can be disabled.

I would not recomend this unit, if possible return and buy a Victron, or for economy a Epever.

If an alternative unit is not possible, set bulk, absorbtion/equilization to 28.4 volts, float to 27 volts.
Depending on battery cell balance you may need to lower the charging voltage to 28.0 or 27.6.

Why folk continue to buy rubbish products is a mystery to me. I understand the appeal of lower cost, but quality products with a proven track record and support, save customers from considerable grief, and perhaps prevent damage to expensive batteries.

Mike

 

[TedH]

Having read the user instructions it's clear the designers/ instruction writers have no clue as to what is needed in a solar charger.

They refer that absorbtion is the same as equalisation and suggest that bulk, absorbtion equilization and float are all set at 28.8 volts for lithium. This is plain stupid.
There seems no method to alter absorbtion duration and no indication how the charger determine the point to enter float.
Its not clear if temperature compensation can be disabled.

I would not recomend this unit, if possible return and buy a Victron, or for economy a Epever.

If an alternative unit is not possible set bulk, absorbtion/equilization to 28.4 volts, float to 27 volts.

Why folk continue to buy rubbish products is a mystery to me. I understand the appeal of lower cost, but quality products with a proven track record and support, save customers from considerable grief, and perhaps prevent damage to expensive batteries.

Mike

I agree the instructions and settings do not appear to support Lifepo4 even though Aims claims compatibility.

I have bought all of the new Victron components. I may proceed with the swap. At the time of Aims purchase, I was just starting and 'knew' Aims from a non-Lifep4 installation. It was bulletproof. Perhaps Aims hasn't kept up. Smart devices are the future (Victron and EPever).