Estimating the SOC of a battery while under load

i building rc lawn mower. use wireless ps2 controller arduino steer it. in order not destroy batteries (two 12v/14ah lead acid batteries in series) discharging them much, need method estimate state of charge.  know there simple equations estimate soc when there no load on batteries, need estimate soc while batteries in use. tried google it, far fond out complex problem , there no simple way figure out soc while discharging batteries.

i guess @ least people here have faced same problem. methods have used estimate soc or protect batteries against on discharging them?

as have found out not simple task , made harder depending on type of battery 1 using. nicad , nimh batteries have 'flat' discharge curve until totaly depleted of charge. lead acid , lipo batteries have more linear discharge curve.

need accurate soc or low voltage cut-off value can used signal time power down system. think under load if battery voltage goes down 11 11.5vdc decision point cut off power. simple 2 series resistor voltage divider allow battery voltage sensed arduino analog input pin , take there software , external power down circuit or maybe buzzer signal.

lefty

Arduino Forum > Using Arduino > Motors, Mechanics, and Power (Moderator: fabioc84) > Estimating the SOC of a battery while under load

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