I was advised to add a Battery Management System to my home inverter/battery package because my SLA 105VAbattery only lasts about 3 months due to the my battery exceeding the cycle life of the battery.   Is this true and if so where can I purchase a BMS?

Hi Martin,  First of all can you tell us a little about your system, Inverter, Load Etc....

Typically SLA Batteries should only Cycle to 50% and then the expected life cycle is between 150-450 (for Cheaper brands) and 800-1000 (for high quality true Deep Cycle) depending on the brand before you start to see some sort of degrading of capacity. In more recent Typical Load Shedding, depending on your load, this translates to 3 or more Cycles per day. So your lifecycle seems to be accurate and normal.

If the Depth of Discharge (DoD) is limited to 20% then you can see a huge improvement of lifespan. The Reality is that High Quality SLA Batteries if only used to their recommended safe DoD can last 10+ Years, But lets get real, no one buys that many batteries for their systems so they end up "overworking" the batteries and they fail faster, its a matter of chemistry and engineering and can be pretty reliably predicted.

Lithium Batteries are far more tolerant of frequent, and deeper cycles than SLA. Sure they cost more but do they really when you consider the cost of a huge bank of High Quality Lead Based Batteries.

So before spending money on a BMS system that is only going to cut off the load before the damage point of the DoD, and reduce the available time the load is supplied in order to save the battery, you may want to look at a Lithium Drop-in replacement option that has built in BMS and gives you the same or more capacity in the same footprint.