If a picture is worth a thousand words, then this chart should be worth more. The chart below is a collection of true and correct data from many battery suppliers. This chart will help you understand the differences between battery types and their appropriate voltage range and percentage of charge / discharge.
If you are new to off-grid camping, have an off grid caravan or camper, or new to solar and solar setups – then bookmark, screenshot or print this page and chart – and place it near your battery monitoring device. You will find that this will help reinforce the connection between what you expect and what you experience.
Shown in this chart, the Depth of Discharge (DoD) is the safe level to which you can repeatedly and safely discharge the battery without significantly shortening the lifespan of the battery. For Flooded and AGM, this is 50% (50% of battery capacity); for LiFePo, this is 80% (20% of battery capacity).
Flooded Lead Acid (FLA)
Normal operating range is between 12.7V and 12.06V.
This isn’t a big range and explains why it’s so easy to over-discharge FLA batteries.
AGM (SLA)
Normal operating range is between 13.0V and 12.05.
While the range is slightly more with AGM batteries, the depth of discharge is nearly the same as Flooded Lead Acid (FLA).
The real benefit of these batteries is their affordability over the short term and their installation options.
LiFePo
Normal operating range for Lithium Iron Phosphate (LiFePo) is 14.4V to 12.9V.
Compared to both FLA and SLA batteries, the range and depth of discharge are much greater, allowing for significantly more available watt-hours per cycle.