Back again on behalf of my little offgrid friend. Her Rolls 6v series 4000 / 530 batteries have been capacity tested by our local UK wholesalers and they are pretty much toast...!!!! We are now open to suggestions for a 24v replacement setup but I have spotted these on Fleabay (She is adamant not to go LiFePo4). If anyone reading can verify this brand It'd be very much appreciated....