Lead-acid chemistries prefer light cycling and full recharge between those cycles. Lead-acid batteries are traditional cycled to 50% depth of discharge because it offers a balance between duty life (years between failure) and bank size.¹⁾ Pulling the bank below 50% DoD in emergnecies will not automatically cause damage assuming a full charge is accomplished ASAP.

This article is about the intentional severe use of lead-acid banks by running them below the 50% mark, followed by vigorous recharging at maximal voltage.²⁾. Perhaps forgoing Float altogether. This might be desirable when:

• reducing the weight impact of lead banks
• one wants to make use of old/damaged/unsuited batteries until replacements can be sourced

For folks willing to trade battery longevity for some amount of increased capacity, common low-end targets for low voltage disconnect are:

• 60% DoD / 40% SoC, ~12.0 rested volts
• 75% DoD / 25% SoC, ~11.7 rested volts
• 80% DoD / 20% SoC, ~11.6 rested volts

• get power back into the battery ASAP after deep discharge; drive for alternator charging or run a generator to get bulk stage going. Solar alone might be sufficient but it might require meaningful overpaneling.
• fully charge lead-chemistry batteries as often as possible. This may require special measures to finishing Absorption.