A novel performance additive to reduce electrolyte stratification in lead batteries: Gravity-GuardTM

Agenda for
5-9 September

Marco Robotti
Technical Manager EMEA, Hammond Group
Electrolyte stratification in lead batteries is a known cause of reduced battery life and performance. Heavy-duty cycling or low state-of-charge applications are often associated with insufficient recharge or poor acid mixing conditions resulting in electrolyte stratification.

To reduce electrolyte stratification, Hammond Group Inc. has developed a novel lead silicate performance additive, Gravity-GuardTM. As an additive to the negative, positive, or both active masses, Gravity-GuardTM creates a network of micro silica gel structures which improve the retention and distribution of H+ ions within the active material. By slowing the release of H+ ions to the bulk solution, Gravity-GuardTM minimizes acid stratification, thereby reducing lead sulphation and helping to maintain battery life and performance in applications including stationary AGM, motive power, golf car, and automotive EFB.

A L4 Taguchi DOE plan was selected to evaluate Gravity-GuardTM with particle size and loading as main variables. Testing was carried out on laboratory scale 2V cells, typically good as performance indicators, and full scale 12V batteries, at HGI’s research laboratory in collaboration with industry partners. Results showed significant positive effects in reduced acid stratification and improved battery cold-cranking and cycling performance. With flexibility in accommodating various active material chemistries for a wide range of battery market applications, Hammond’s Gravity-GuardTM offers a novel solution to a traditional problem.


Marco Robotti has a PhD in engineering and advanced technologies from the University of Barcelona. After holding a R&D Innovation Product position at Fiamm Energy Technology in Italy, he joined Hammond Expanders UK. Marco is a member of the technical team and supports customers with Hammond’s performance additives.