I'm planning to power some low current devices from a sealed lead acid battery that require a 12v supply. I was thinking of using an LDO linear regulator to provide the 12v. And to have some kind of voltage monitor to predict battery life.
I don't have the exact discharge curves for the one I'm using but it does seem that once the voltage drops below 12v we should stop and recharge them anyway.
Is this a reasonable assumption or should I be looking at a buck-boost dc-dc instead?
Sorry, its not a very reasonable assumption.
I've been playing with a pair of 100A 12V batteries that have been a bit neglected so I put the through several charge discharge cycles. I discharged at 20A and 5A so even my low current was high compared with yours. About half the life of the battery was below 12V. I was using 10.5V as the cutoff.
My lowest rate was 20hr and it sounds as if you are likely to be looking for much less current.
I'd need a lot more detail to make a definite suggestion for a converter/regulator but I think you'll be trading a lot of life for simplicity.
https://manualacobladaplf.z21.web.core.windows.net/lithium-battery-charging-chart.html
I'm not sure of the reliability of this graph but it looks as if you will lose about 30% of your capacity - it is much worse at higher currents.
It may not matter to you - its going to be way easier to buy a bigger battery !
MK
If you can go a bit lower you could get more life...
