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Inverter idea, but can I adjust the lowvoltage cutoff?

HR19

New Member
So I'd like to build my own inverter using LiPo batteries with a safe lowvoltage cutoff of around 2.75V/cell. I found this inverter board but it's designed for SLA's with a low voltage cutoff of 10.5. That means on a 36V system, 10s LiPo will still have around 20% (I think; estimation I guess) charge when the cutoff hits of 31.5V. Is there an easy way to modify this item to change that cutoff voltage a little? The device itself can take 24-72V so I imagine the setting switch is mostly for that cutoff voltage safety, but I'm not sure if there's more complicated electronics that would be damaged if say we ran 50V through the 24V setting.

EDIT: or even to disregard/bypass the low voltage cutoff altogether.

US $78.97 30%OFF | SUNYIMA Pure Sine Wave Inverter Board Inversor Circuit Board 24V-72V to 110V 220V 2000W-9000W Power Converter
 
Last edited:

rjenkinsgb

Well-Known Member
Most Helpful Member
It will be fine.

The cutoff voltage should never in practice be below 3V and 3.2V is "flat" level, for any LiPo cells made in the last 20 years or so.
See the solid line plot on this graph; the dotted line is for an older cell chemistry used in the 90s:


If you discharge below 3V they should be recharged soon after and not left flat for any length of time.

If lithium cells are allowed to stand either at very low voltage or held at maximum voltage, they decay far faster than if the voltage averages around mid-range. Reducing the charge "span", eg. 90% to 10% significantly increases the overall life of the cells.

See the articles below:

 

audioguru

Well-Known Member
Most Helpful Member
A more modern LiFeP04 cell is charged to 3.65V max, is nominal at 3.0V to 3.2V and has a minimum allowed voltage of 2.5V but a cutoff at 2.75V is fine.
 

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