Lead Acid Battery Upgraded to Lithium Iron PhosphateLithium batteries have taken over as the primary battery chemistry from applications ranging from consumer electronics to electric vehicles and all kinds of other things in between. But the standard lithium ion battery has a few downsides, namely issues operating at temperature extremes. Lead acid solves some of these problems but has much lower energy density, and if you want to split the difference with your own battery youâll need to build your own lithium iron phosphate (LiFePO4) pack.[Well Done Tips] is building this specific type of battery because the lead acid battery in his electric ATV is on the decline. Heâs using cylindrical cells that resemble an 18650 battery but are much larger. Beyond the size, though, many of the design principles from building 18650 battery packs are similar, with the exception that these have screw terminals so that bus bars can be easily attached and donât require spot welding.With the pack assembled using 3D printed parts, a battery management system is installed with the balance wires cleverly routed through the prints and attached to the bus bars. The only problem [Well Done Tips] had was not realizing that LiFePO4 batteriesâ voltages settle a bit after being fully charged, which meant that he didnât properly calculate the final voltage of his pack and had to add a cell, bringing his original 15S1P battery up to 16S1P and the correct 54V at full charge.LiFePO4 has a few other upsides compared to lithium ion as well, including that it delivers almost full power until itâs at about 20% charge. Itâs not quite as energy dense but compared to the lead-acid battery he was using is a huge improvement, and is one of the reasons weâve seen them taking over various other EV conversions as well.youtube.com/embed/l-nkiqVb0J8?âŚhackaday.com/2026/01/23/lead-aâŚ