Checking SOH in the winter

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tofurkeydirky

New member
Joined
Dec 8, 2020
Messages
3
While I wait for my konnwei odb2 thingy, quick question: it's winter here in Utah, will I get an accurate SOH reading with outside temps ranging from 17°F-40°F. Right now I'm at 64% and my estimated range is 32 miles it's 27°F outside.
 
Afaik, the SOH you read is determined by cell voltages measured by the EV system. If you charge the battery up (so that the cells are warm) and then take the measurement, I don't see the outside temperature exerting any influence.
 
It does. JeJuSoul had shared an internal document that detailed what a particular BMS update did - within that document was the parameters around battery calibration/SOH calibration. One those parameters was that the discharge/charge occur above 10C.

Sorry I can't link to it, my quick search suggests that they edited out the links in the post I suspect had it. Perhaps if they see this they can link to it.
 
tofurkeydirky said:
...will I get an accurate SOH reading with outside temps ranging from 17°F-40°F. Right now I'm at 64% and my estimated range is 32 miles it's 27°F outside.
Yes.
The reading for State of Health (SOH) is a calculation that comes from a stored value in the Battery Management System (BMS).
The meaning of the word 'accurate' in this case is that it is the same value that Kia will use to determine whether or nor to issue a battery replacement under warranty.

The car usually updates the SOH during a battery calibration. You have to charge the car from below 20% to 90%. Charging will warm up the battery therefore I don't think ambient temperature will be an issue. I don't live in a cold climate so I have never tested this. I don't have a battery heater so I don't know how much this warms up the battery.

A manual for updating the BMS is here - Service Action: Battery Management System (BMS) Logic Improvement (SA297)

In it we learn that battery calibration actually occurs as the battery is charged from less than 20% SOC to more than 90% SOC

Inform the customer that the BMS update will reset the adaptive learning values to default conditions. As a result, the displayed range/DTE (Distance to Empty) and charge times may be temporarily increased. It does not affect the actual range or battery charging time. These displayed values will gradually be relearned to reflect the actual battery condition with multiple drive and charge cycles performed above 50°F (10°C) from less than 20% SOC to more than 90% SOC.
 
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