Quote:
Originally Posted by sworks
I’m looking to go EV next as I’m due to change the main car later this year and I can’t get my head round the cell balancing when charged to 100%. I work with another manufacturer and cell balancing is happening all the time whilst the battery has charge. I can’t seem to find an answer why MG’s only do it at 100%?
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MG Motors recommend balancing the battery pack around once a month in the handbook, You will get a warning message on the dash to slow charge the vehicle to balance battery pack or words to that effect, The longer you leave it the longer it will take to balance.
We don't use the car daily so the only time I fully charge to 100% is to carry out this procedure although not strictly on a monthly basis.
All the other times it's kept between 70%-80% charged. If you're plugging in every night to fully charge it for the next days usage it will do the balancing automatically,
Once the car reaches 100% the pulsating MG logo goes to fully lit to show it's balancing the pack, Depending on how out of balance it is depends on the length of time it will take, From reading other peoples comments it seems to take longer if you have been rapid charging it frequently.
Edit: Just found this which explains it better than I did.
Balance charge.
The manual also states on page 292-293 in the Maintenance section paragraph 3, that it is "recommended" "where possible" to carry out a "9-hour slow charge every month to extend the service life of the high voltage battery". This is a maintenance Balance charge which allows the Battery Management System or BMS to balance the voltages across the cells in the pack (108 cells in the ZS). In reality this can take upwards of thirty minutes (30 minutes) after Fully Charge State of Charge (100% SOC) has been reached. [There is a maximum voltage difference that can be Balance in any on session and I believe the maximum time in one session the BMS will do the Balance charge is 6 hours but
@MilesperkWh can correct me on that]. During this "Balance charging," the charge rate drops the charging rate from 7 kW to trickle of about 300 watts (as I have described in other threads) and this allows the cells with lower voltage to continue to be trickle charged to "Balance up" or "Equalise" cell voltages in the pack. There is also a degree of balancing when driving from 100% SOC down to about 97% SOC. Balancing when charging though Only happens on AC charging ie on your Type 2 Cable and NOT on CCS DC Rapid chargers. A "Granny Charger" is also an AC charger.