Korishan
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- Jan 7, 2017
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What lithium configuration do I use for 12V, 3s or 4s?
In a perfect world, Neither
This is the major case described under Why-are-12V-24V-and-48V-widely-used-defaults where the chemistry prohibits the effective use within the 12V system:
3s lithium batteries have a range of ~9.0V when empty to 12.6V when fully charged.
4s lithium batteries have a range of ~12.0V when empty to 16.8V when fully charged.
The 12V lead-acid battery system usually ranges from ~10-11V to ~15V fully charged. In 3s, lithium is to low, you will have early cutoffs and can't use the full capacity of the battery. 4s it's to high, when fully charged you will force some devices into their over-voltage protection or simply destroy them; or you won't be able to fully charge up to ~16.8V and only go to ~15V. This means you will not be able to use the full capacity of your battery.
Lithium cells fit the 24V (7s) and 48V (14s) systems nicely, so 24V is the minimum that is recommended. If you need 12V, it is recommended to either use a DC-DC converter from 24V to 12V or use lithium iron phosphate cells (called LiFe, LiFePo or LiFePo4). They have a lower nominal voltage of 3.2V and therefore a 4s configuration will fit the 12V system. However, do not mix the two chemistries together as they have different charging curves.
In a perfect world, Neither
This is the major case described under Why-are-12V-24V-and-48V-widely-used-defaults where the chemistry prohibits the effective use within the 12V system:
3s lithium batteries have a range of ~9.0V when empty to 12.6V when fully charged.
4s lithium batteries have a range of ~12.0V when empty to 16.8V when fully charged.
The 12V lead-acid battery system usually ranges from ~10-11V to ~15V fully charged. In 3s, lithium is to low, you will have early cutoffs and can't use the full capacity of the battery. 4s it's to high, when fully charged you will force some devices into their over-voltage protection or simply destroy them; or you won't be able to fully charge up to ~16.8V and only go to ~15V. This means you will not be able to use the full capacity of your battery.
Lithium cells fit the 24V (7s) and 48V (14s) systems nicely, so 24V is the minimum that is recommended. If you need 12V, it is recommended to either use a DC-DC converter from 24V to 12V or use lithium iron phosphate cells (called LiFe, LiFePo or LiFePo4). They have a lower nominal voltage of 3.2V and therefore a 4s configuration will fit the 12V system. However, do not mix the two chemistries together as they have different charging curves.