SCC and inverter/charger charging at different voltages....any issues?

[Solarfun4jim]

In a scenario, where a SCC is set to charge at say 3.6v/cell and an inverter/charger set to charge at 3.5v/cell, would there be any issues with the different voltage settings when both charging at the same time? I'm assuming not, but always better to get confirmation.

 

[Steve_S]

Ohhh the deep rabbit hole there.
Simply put NOT a good idea.
Calibrate your gear ! Take the voltage at your battery terminals or Bus Bars if running a bus topology. No Load, fully charged & connected.
Then take the same readings on your SCC's & Inverter posts as well.
Correct for any difference up / down so when ANY device SCC/Inverter "se" the battery they see the real / actual voltage and correct so they are accurate. One can easily over run the other and potential cause overcharge conditions.

Lead Acid / AGM batteries are far more tolerant to deviations but with LFP, 0.5V can make a big difference especially if you playing with tight margins for keeping to say 90% max capacity or so.... The curve for LFP doesn't provide for much margins when getting full.

 

[burnin_daylight]

I do exactly as you describe, and have done so for years. It prioritizes solar charging over mains, as the inverter will basically stop charging when SCC is charging.

 

[Solarfun4jim]

Ohhh the deep rabbit hole there.
Simply put NOT a good idea.
Calibrate your gear ! Take the voltage at your battery terminals or Bus Bars if running a bus topology. No Load, fully charged & connected.
Then take the same readings on your SCC's & Inverter posts as well.
Correct for any difference up / down so when ANY device SCC/Inverter "se" the battery they see the real / actual voltage and correct so they are accurate. One can easily over run the other and potential cause overcharge conditions.

Lead Acid / AGM batteries are far more tolerant to deviations but with LFP, 0.5V can make a big difference especially if you playing with tight margins for keeping to say 90% max capacity or so.... The curve for LFP doesn't provide for much margins when getting full.

Just to explain Steve,
RV setting. Wishing to run the SCC at a much higher voltage(much faster moving electrons) but terminating via a dedicated BMS on hitting a lower voltage threshold. This would get the solar wattage into the batteries the quickest, but terminate before doing damage. Redundancy would be provided by a second connected BMS, whose threshold was slightly above the first BMS in case the 'solar control input' one failed(Hope this makes some sort of sense).
The inverter charger, having a stable grid 16A 240vac input, i hoped to set the charge voltage at a more reasonable & typical lifepo4 level, controlled by the charger, but protected by the 'overall BMS', in case of failure.

 

[Solarfun4jim]

I do exactly as you describe, and have done so for years. It prioritizes solar charging over mains, as the inverter will basically stop charging when SCC is charging.

Thanks for that practical experience. Not quite the outcome i was hoping for, but very useful info nonetheless.