48 VDC LFP charging/float voltage...

[Mark-]

Hello,

Let's say you had a mixture of these batteries, all connected to one busbar.

Battery		Charge		Float		Max voltage/charge
RX-LFP48100		56		54.6		57.6
SG48100P		54.5		???		57.6
48V100E-2UL		56.0,56.4,56.8		54		58.4
EP48100		57		55.2-57		57.2
LFP5000		???		???		57.6
EG4®-LL-S		56.2		54		56.8
LifePower4 48V		56.2		54		58.4

What voltage would you use for charging and floating?

 

[BentleyJ]

Bulk (Constant Current) = 0.2C
Absorption (Constant Voltage) = 56V-56.8V
Float = 53.6V to 54.4V. Float is only necessary when using solar generation to power loads in order to keep the charge controller active. If the system is mostly used as back-up then no-float is recommended.

 

[Mark-]

Bulk (Constant Current) = 0.2C
Absorption (Constant Voltage) = 56V-56.8V
Float = 53.6V to 54.4V. Float is only necessary when using solar generation to power loads in order to keep the charge controller active. If the system is mostly used as back-up then no-float is recommended.

Thanks for the response.
I am a confused how to achieve limiting the current to 0.2C with multiple AOIs charging the batteries from separate PV arrays.

 

[BentleyJ]

The AOIs should have maximum charge current settings. Many have 2 settings, one for overall max and one for utility or solar.

Using your example of 7 mixed brand, 100Ah rack batteries, 0.2C is 140A. If there were 3 identical AOIs each would be limited to 45A. In a case where PV arrays connected to the AOI's were different sizes and/or facing different directions then max charge current settings would be adjusted up or down in proportion accordingly.

The sum of max current settings on the AOIs may exceed 140A in a case where the arrays were facing different directions and peak production would not occur at the same time of day. There is some engineering to be done here as well some follow up observation and adjusting as needed to dial in the settings.

 

[Mark-]

BentleyJ, thanks for your help.