Rolls Motive Power Bulletin

Like the majority of motive power batteries for traditionally 48 VDC lead-acid systems, Rolls Battery produces a 51.2 VDC LFP battery for golf cart applications such as the G48-105LFP A-SHORT and G48-105LFP B-LONG models. 

While an LFP battery rated at 51.2 V will typically charge at 54 to 58 VDC, a comparatively sized flooded lead-acid based battery can charge above 60 VDC. The industry has thus standardized around a 51.2 V LFP based battery bank because it is compatible with the vast majority of existing hardware.

The industry has standardized around this for a number of reasons: 

1. This enables chargers that cannot be set, but are set up only around AGM products to charge LFP batteries reasonably well. LFP batteries have a smaller voltage window in their operating range compared to lead-acid batteries.  
2. It enables a more effective packing of cells by implementing 16 prismatic cells in series as opposed to 15 in a 48 V nominal LFP pack to get better energy density in the finished battery module. (>6% more energy).

Different chargers have different philosophies, and charging batteries below their specific charge range will lead to incomplete charge cycles. Chargers may use any of the following basic algorithms to determine that a battery has "completed" charging.

• When their programmed voltage is reached
• When their programmed voltage is reached, and their current is allowed to decrease to a specific set-point
• When their programmed voltage is reached, and their current is allowed to decrease for a specific duration
• After a set amount of time (for example where time of use is important)
• Based on an advanced algorithmic estimate of capacity (much less common)

As you can see, most of these rely on the programmed voltage of the charger. If this is set incorrectly, or the voltage is too low, the battery will never reach a full state of charge because the basic chemistry requirements to store the energy cannot be met. At the same time, this can cause inaccuracies in the state of charge estimates of the battery (available when connected via the Rolls LFP Connect app or displayed on a connected SOC monitor, if available), which rely on reaching a full state of charge periodically to calibrate. For this reason, it is important to follow the charging requirements referenced in the battery operating manual, online product specifications, or at LFP Charging Guidelines.

The following is a list of suggested chargers brand make/models and battery charging profiles compatible with the following Rolls 48V LFP batteries: 

G48-105LFP A-SHORT

G48-105LFP B-LONG

R48-105EV-LFP A

R48-105EV-LFP B