Large capacity lead Acid Batteries emit Hydrogen - during Charging phase- especially during near full charge/ over charge conditions .This causes inflammable gas mixture of Hydrogen and Oxygen in the atmosphere. H2-485TX-8CH enables to gathers data from up to 8 hydrogen sensors type H2SENSE1205 and can be interfaced to a BMS on RS485 transmission bus with MODBUS protocol in RTU mode. The transmitter acts as a Slave to the BMS. H2-485TX-8CH is a high reliability product needed as safety equipment in an early warning of potential Hydrogen build up. Hydrogen thus can be kept below LEL ( Lower explosive Limit ). Typically, H2 levels of 0.5% and 1% are used to trigger ventilation and Alarm respectively, are used by the BMS. H2-485TX-8CH interfaces to a highly-selective, rugged solid state hydrogen sensors H2SENSE1205 described elsewhere.