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Do I need to charge the battery weekly if driving only 100 miles a week?
- Thread starter GodsPeace
- Start date
It depends on the battery you have, std lithium(2170 or 4680) or lfp batteries. LFP likes to occasionally go to 100% to rebalance cells.
Battery life is longest if on average it’s kept close 50%. So if you drive 10 miles a day then daily charging to 55% will keep the battery for many years.
The Tesla battery management system handles charging no matter how you charge.
General consensus is to be plugged in every night if you can. Your high voltage battery is happier and your lithium 15 V battery will work best.
Search the forums for all the details and stories on charging. The charging system is very forgiving and lots of owners have opinions.
Battery life is longest if on average it’s kept close 50%. So if you drive 10 miles a day then daily charging to 55% will keep the battery for many years.
The Tesla battery management system handles charging no matter how you charge.
General consensus is to be plugged in every night if you can. Your high voltage battery is happier and your lithium 15 V battery will work best.
Search the forums for all the details and stories on charging. The charging system is very forgiving and lots of owners have opinions.
Its no really a balancing thing, but its needed to make sure the BMS do not loose track of the energy in the pack. So, to keep ypou from being stranded.
This is because the voltage curve of the LFP's are so flat that the BMS have a hard time reading the SOC. A full charge set a known point to the BMS to calculate from.
What I noticed when I supercharged for the first time ever yesterday was that it calculated/calibrated for a long time. I know it slows down as you get to full charge but that last 1 mile it was like 10 minutes. It had a set limit stated of 272 miles range and was charging at 1-2 miles and hour in the end. At home it hits 273 miles(probably not actual) and completes it's charge at a consistent rate. It slows a little then hits 100% and stops right away no calculating/calibrating. I use both words because my phone said calculating at the top but the Tesla screen said calibrating at the top. I was able to stream Sling and realized I need to turn off phone bluetooth connection to get sound to work from browsing.
johnny_cakes
Member
The last percentage to 100% can take a long time. When I charged to 100% in April on a 220v charger, it took almost 1 hour to go from 99% to 100%:
A couple of weeks ago on the other hand it didn't sit at 99% for very long. Only 4 minutes to go from 99% to 100% (same 220v charger):
Tesla probably try to use terms that make sensemto people even if it actually doesnt
Make sens.
When reaching the top Voltage the charger
Can not (must not) go over the maximum allowed voltage. For Teslas lithium ion this is 4.20V/cell, for LFP I’m not 100% sure but around 3.65V or so.
It is the difference between the cell voltage and supply voltage that causes current to flow and charge the battery.
If there is no difference in voltage, there will be no current charging the battery.
When the charging voltage can not (must not) be increased the charging current will reduce as the battery voltage increase.
In the end there is very little difference in voltage and because of that, very little charging current. This is one part of the explanation.
The other part is that the cells will differ on voltage, due to slightly different capacity and sometimes slightly different SOC in the cells.
To adjust this, cell balancing is performed at high SOC to make sure all cells reach100% SOC or close to that.
The cell balancing is performed by burning off voltage from the cells with higher voltage. This takes time, as the ”burn off” function is not burning energy that fast.
So, the long time comes from charging slow in the high end plus the cell balancing.
In reality it is not ”calibrating”.
Could the duration of this "calculating" period be indicative of the degree of variations in the cells or possibly just the quantity of cells that vary? Wondering if it would be beneficial to track the time it sits charging at the top as an indication of health of the pack or just the "sway"? Meaning, does it give any insight into the charging behavior?...like if it takes a long time would it help to vary the depth of charge or charge capacity?
What's interesting is when I used the supercharger it seemed to knock 1 mile range off my max almost every time but so far several times charging at home it's still at 269 miles range. I've read we loose 5% in the first year and then stops losing much range but I wonder if the fast chargers cause more range loss than slower home chargers
Correct, whats you're point? The question is from months ago lol
Sorry you probably didn't read the 1st two comments I made in this. I didn't mean to sound irritated with your response then realized you had no idea I actually already knew to charge once a week to 100% and was just clarifying other things. Hopefully you can understand =)
I read it's good to plug it in and charge to 100% at least once a week. I was just wondering if that's a good recommendation but not necessarily proven to be beneficial. If I have 200 miles of charge still is ok to charge it when I get down to 100 miles?
Thanks Thp3. I have the LFP battery. I've read what you said to take it to 100% to rebalance. Since I'll drive so little lately probably once a week charge to 100%.
For LFP batteries, the concern is that if the battery stays in the range of ~20% to 99% for a while, where the voltage curve is close to flat, the BMS may lose the true state of charge. If the BMS thinks that the state of charge is 25% when it is really 20%, then if you do need to drive down to 1%, you may encounter a surprise 5% drop somewhere.
Charging to 100% will allow the BMS to resync its notion of state of charge to the actual state of charge.
Nosken
Active Member
If you have a garage, and a home charger, always plug it in. You could adjust your charge level to 100% weekly. You will use the same amount of energy either way, but an Earthquake happens, it would be nice to have a full charge.
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