First, one of the greatest reasons to replace SLA (sealed lead acid) with LiFePO4 batteries is that there is the huge weight difference between them. For example, a 12V 10Ah LiFePO4 battery weighs around 2.36 lbs compared to 5.5 lbs for a 12V 9Ah SLA.
Next, consider that LiFePO4 (Lithium Iron Phosphate) batteries should last up to 10 years as opposed to 3 – 5 years for SLA. They are small enough to fit in the same APCs that originally used 7Ah batteries that I was replacing every 3 – 5 years. If you know SLA batteries, you know they get damaged if they drain below 50%. It can (read will) damage the battery or possibly kill it. Since most UPS (uninterruptable Power Supply) units will allow the battery to drain below 50%, this was an issue if the power went out when I wasn’t home to shut things down properly since I run more than just computers off battery backups. On the other hand, LiFePO4 batteries can be discharged to 100% of their capacity without long-term damage, although manufacturers recommend discharging them to only 80% of their capacity (20% remaining) to extend their lifespan. So in addition to the 42% extra amp hours I get by going from 7Ah to 10Ah, I have potentially another 30% runtime due to the depth of discharge of the LiFePO4 batteries.
One thing SLA batteries may have in their favor, is how much amperage they can deliver at once (amp draw) compared to their lithium competitors. On average, an SLA battery of the same size and amp hour rating will be able to deliver more amp draw than a LiFePO4 battery. LiFePO4 batteries have a BMS (battery management system) that protects the cells, and ensures they charge and discharge correctly. In order to protect the cells, the BMS will often limit how much amperage the cells can deliver at once.
If you have a device that is using SLA batteries, it doesn’t usually make financial sense to change the battery until it needs to be changed anyway. However, if you want more runtime, or need the ability for the battery to discharge more on a regular basis, it may make sense to swap out your existing battery for LiFePO4. On the other hand, if you have to replace the battery anyway, or need a new battery for something else, it doesn’t generally make sense to stay with SLA unless you need more amperage than the LiFePO4 batteries can deliver.
— This article is a work in progress. —
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