Replacement of batteries in an existing bank is generally not recommended, however, if replacing a full string of batteries in a system is necessary you may do so as long as the existing string(s) are in good condition.  All cells should be desulfated, evenly charged and provide normal voltage readings.

When introducing batteries to an existing string you will first need to put them on a balance charge of 2.5 VPC, measuring the voltage on all units until each battery in the bank reads 2.5 VPC.  We do not recommend cycling prior to balancing the battery bank.  A balance charge will eliminate the possibility of uneven charge and ensure the bank is at the same state of charge (SOC) ready to be cycled as normal.

Modular cell replacement:

Many of our Rolls Battery Series 5000 models offer modular cell construction.  This means that each 2-volt cell is bolted together in series, rather than traditional welding, to provide the desired battery voltage.  The cells are housed in an outer container (red) and covered with a snap-on lid for protection.  The outer case provides an extra layer of protection against damage due to spills, punctures or cracks from freezing, etc.  

To replace a cell in a modular Series 5000 model, first, disconnect both terminal connections and remove the battery cover.  Most covers snap-on or may have small plastic pins along the edge which may be easily removed with a screwdriver.  You will notice a black silicone has been applied around each terminal.  This may be removed and will be replaced following the cell replacement.  A standard automotive silicone will suffice.

Note: cells are heavy and may require more than one person to safely lift from the case.

A photo is provided showing a cut-away of the modular cell construction and cell interconnections.

Each cell will be bolted together inside the outer case.  The interconnects for each terminal are keyed so they may only be attached in the correct position.  Locate the cell to be replaced and remove the bolt for both positive and negative connections.  Lift the cell out of the case and replace it with the new cell, making sure the connections are in the proper orientation.  Reinstall the connecting bolts and replace the case cover.  Last, re-apply a bead of silicone to seal around each terminal and reconnect cabling. 

Once the new cell has been installed, place the battery on a balance charge as instructed above.